Medicine – Scleritis

Scleritis is a painful inflammatory disorder affecting the sclera, the dense connective tissue forming the outer coat of the eye. It is clinically important because it may indicate an underlying systemic autoimmune or vasculitic disease and, in severe cases, can threaten vision.

A substantial proportion of patients have an associated systemic disorder, although scleritis can also occur without an identifiable underlying cause.

1. Clinical Presentation

The characteristic symptom of scleritis is severe, deep ocular pain.

The pain is often described as boring or aching and may radiate to the forehead, brow, temple, or jaw. It can be worse at night and may be aggravated by eye movement.

The affected eye usually develops deep redness, and patients may also experience photophobia, tearing, and reduced vision.

2. Appearance of the Eye

Scleritis causes inflammation of the deeper episcleral and scleral vessels, producing a characteristic deep red or violaceous appearance.

The deeper vessels generally do not blanch completely with topical vasoconstrictors, which can help distinguish scleritis from more superficial episcleritis.

3. Rheumatoid Arthritis

Rheumatoid arthritis (RA) is one of the classic systemic diseases associated with scleritis.

Ocular inflammation may occur in patients with longstanding or severe rheumatoid disease.

RA can also be associated with particularly destructive forms of scleral inflammation, including necrotising scleritis.

Therefore:

RA + painful red eye → consider scleritis.

4. Granulomatosis with Polyangiitis

Granulomatosis with polyangiitis (GPA), formerly called Wegener’s granulomatosis, is another particularly important association.

GPA is a systemic small- to medium-vessel vasculitis that commonly involves the respiratory tract and kidneys but may also produce significant ocular disease.

Scleritis can sometimes be an important clue to previously unrecognised systemic vasculitis.

5. Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) can be associated with scleral inflammation.

Although scleritis is less characteristic of SLE than some other ocular manifestations, a painful red eye in a patient with lupus warrants careful assessment for significant ocular inflammation.

6. Ankylosing Spondylitis

Ankylosing spondylitis and the broader group of spondyloarthritides are strongly associated with inflammatory eye disease.

However, an important distinction is that their classic ocular association is acute anterior uveitis, rather than scleritis.

Scleritis can occur in association with spondyloarthritis, but it is considerably less characteristic.

7. Inflammatory Bowel Disease

Inflammatory bowel disease, including Crohn disease and ulcerative colitis, may be associated with ocular inflammatory manifestations.

These include episcleritis and anterior uveitis, with scleritis occurring less commonly.

Nevertheless, IBD should be considered when scleritis occurs together with gastrointestinal symptoms or known inflammatory bowel disease.

8. Sarcoidosis

Sarcoidosis can involve numerous structures within the eye.

Its classic ocular manifestation is uveitis, but scleral inflammation can occasionally occur.

Therefore, sarcoidosis remains a possible systemic association of scleritis, although it is not among the most characteristic causes.

9. Infectious Scleritis

Although many cases are immune-mediated, infection must also be considered, particularly when the clinical context is atypical.

Infectious scleritis is important because treating an unrecognised infection with immunosuppression alone can worsen the disease.

10. Herpes Viruses

Both herpes simplex virus (HSV) and varicella-zoster virus (VZV) can cause infectious or infection-associated scleral inflammation.

VZV-associated disease may occur in the context of herpes zoster ophthalmicus.

Other bacterial or fungal infections may also cause infectious scleritis, particularly following ocular surgery, trauma, or other disruption of the scleral surface.

11. Types of Scleritis

Scleritis can broadly be divided into anterior and posterior disease.

Anterior scleritis is more common and can be classified into diffuse, nodular, and necrotising forms.

Necrotising disease is particularly concerning because it can cause progressive destruction and thinning of the sclera.

12. Posterior Scleritis

Posterior scleritis affects the sclera behind the equator of the globe and may therefore be less obvious on external inspection.

Patients can present with deep ocular pain, headache, reduced vision, or visual distortion.

Because the inflammation is posterior, imaging such as ocular ultrasonography may be needed to support the diagnosis.

13. Scleritis versus Episcleritis

This distinction is clinically useful.

Scleritis generally causes severe deep pain, marked tenderness and deeper violaceous redness. It has a stronger association with serious systemic autoimmune disease and may threaten vision.

Episcleritis is a more superficial inflammatory condition. It usually causes mild discomfort or irritation rather than severe pain and is generally self-limiting.

Therefore:

Very painful red eye → think scleritis rather than simple episcleritis.

14. Complications

Severe scleritis can lead to important ocular complications including scleral thinning, keratitis, uveitis, glaucoma, cataract, retinal or choroidal complications, and visual loss.

Necrotising disease carries particularly significant risk of structural ocular damage.

15. Treatment

Treatment depends on the severity and underlying cause.

Non-infectious anterior scleritis may require systemic NSAIDs, while more severe disease may require systemic corticosteroids.

Severe, recurrent, necrotising, or vasculitis-associated disease may require immunosuppressive or biologic therapy under specialist care.

If an infectious cause is identified, appropriate antimicrobial or antiviral treatment is essential rather than simply escalating immunosuppression.

16. Scleritis – Note Form

Definition: deep inflammation of the sclera.

Typical symptom: severe, deep, boring ocular pain.

Eye appearance: deep red or violaceous inflammation.

Important autoimmune association: rheumatoid arthritis.

Important vasculitic association: granulomatosis with polyangiitis (GPA; formerly Wegener’s granulomatosis).

Other autoimmune association: SLE.

Inflammatory bowel disease: associated with ocular inflammation; episcleritis and uveitis are more common, but scleritis can occur.

Ankylosing spondylitis: can be associated, although anterior uveitis is the classic ocular manifestation.

Sarcoidosis: possible association, but uveitis is more characteristic.

Infectious causes: include HSV and VZV, as well as bacterial and fungal causes in appropriate settings.

Severe form: necrotising scleritis may cause scleral destruction and is strongly associated with systemic autoimmune or vasculitic disease.

Treatment: systemic anti-inflammatory treatment or immunosuppression for non-infectious disease; targeted antimicrobial treatment when infection is responsible.

Key Clinical Pattern

Remember scleritis as:

Severe deep eye pain + deep red/violaceous eye + systemic autoimmune disease.

The two particularly important systemic associations to remember are:

Rheumatoid arthritis + GPA → scleritis.

Also remember the distinction:

Scleritis → severe pain + potentially sight-threatening.

Episcleritis → mild discomfort + usually benign.

And for examination purposes:

Ankylosing spondylitis → classically anterior uveitis.

Sarcoidosis → classically uveitis.

RA/GPA → particularly important associations with scleritis.

Medicine – Ptosis

Ptosis means drooping of the upper eyelid due to weakness or dysfunction of the structures responsible for elevating the lid, especially the levator palpebrae superioris muscle and the sympathetically supplied Müller muscle.

Ptosis may be unilateral or bilateral, congenital or acquired, and the associated neurological or ocular findings often point toward the underlying cause.

1. Unilateral Ptosis

Unilateral ptosis has a broad differential diagnosis. Important causes include congenital ptosis, third cranial nerve palsy, Horner syndrome, myasthenia gravis, eyelid masses, and idiopathic or aponeurotic causes.

2. Congenital Ptosis

Congenital ptosis is usually caused by abnormal development or dysgenesis of the levator palpebrae superioris muscle.

It is often present from birth and may affect one or both eyes, although unilateral disease is common.

If severe, the drooping eyelid can obstruct the visual axis and cause amblyopia, so children with significant ptosis require ophthalmological assessment.

3. Idiopathic or Aponeurotic Ptosis

Some patients develop ptosis without a major neurological disorder.

A common acquired mechanism is aponeurotic ptosis, in which the levator aponeurosis becomes stretched or detached, particularly with increasing age.

The eyelid crease may be elevated, and levator muscle function itself may remain relatively preserved.

4. Third Nerve Palsy

A third cranial nerve palsy can cause marked unilateral ptosis because the oculomotor nerve supplies the levator palpebrae superioris.

Associated eye movement abnormalities are usually present because the third nerve also supplies most extraocular muscles.

The classic pattern is:

Ptosis + eye positioned “down and out” + diplopia.

If parasympathetic fibres are involved, the pupil may become dilated and poorly reactive.

5. Important Third Nerve Warning Sign

A painful third nerve palsy with a dilated pupil is particularly concerning for a compressive lesion such as a posterior communicating artery aneurysm.

This requires urgent neurological assessment.

By contrast, some microvascular third nerve palsies, such as those associated with diabetes, may spare the pupil.

6. Horner Syndrome

Horner syndrome results from disruption of the sympathetic pathway supplying the eye and face.

The classic features are:

Ptosis + miosis + anhidrosis.

The ptosis is usually mild because it results from weakness of Müller muscle rather than complete levator paralysis.

The affected pupil is small because sympathetic dilator fibres are interrupted.

7. Horner Syndrome and Anisocoria

In Horner syndrome, the abnormal pupil is the smaller pupil, and the difference between the pupils is usually more obvious in the dark because the affected pupil cannot dilate normally.

This is an important distinction from third nerve palsy, in which the abnormal pupil may be dilated.

8. Myasthenia Gravis

Myasthenia gravis is an autoimmune disorder of the neuromuscular junction and is an important cause of fluctuating ptosis.

Ptosis may be unilateral or bilateral and often varies during the day.

A characteristic feature is fatigability:

Ptosis worsens with prolonged upward gaze or later in the day and improves with rest.

Diplopia may also occur because extraocular muscles are commonly involved.

9. Lid Tumour

An eyelid tumour or other mass can mechanically weigh down the upper lid and produce mechanical ptosis.

The degree of ptosis depends on the size and location of the lesion.

Examination may reveal a visible or palpable eyelid mass.

10. Bilateral Ptosis

Bilateral ptosis suggests disorders affecting the neuromuscular junction, muscles, or occasionally bilateral sympathetic pathways.

Important causes include myasthenia gravis, myotonic dystrophy, chronic progressive external ophthalmoplegia or other ocular myopathies, and rare bilateral Horner syndrome.

11. Myasthenia Gravis

Myasthenia gravis is one of the most important causes of bilateral fluctuating ptosis.

The ptosis is typically variable and fatigable and may alternate between the two eyes.

Patients may also have:

Diplopia.

Bulbar weakness.

Dysarthria or dysphagia.

Generalised limb weakness.

However, some patients have disease restricted mainly to the ocular muscles.

12. Myotonic Dystrophy

Myotonic dystrophy can cause bilateral ptosis due to progressive muscle weakness.

Other features may include:

Myotonia.

Facial weakness.

Distal muscle weakness.

Early cataracts.

Cardiac conduction abnormalities.

The overall clinical picture usually makes the diagnosis more apparent.

13. Ocular Myopathy

Primary muscle disorders can cause bilateral ptosis together with ophthalmoplegia.

An important example is chronic progressive external ophthalmoplegia, often related to mitochondrial disease.

Patients typically develop slowly progressive:

Bilateral ptosis + limitation of extraocular movements.

Unlike myasthenia gravis, the weakness is usually persistent rather than markedly fluctuating.

14. Bilateral Horner Syndrome

Bilateral Horner syndrome is rare.

It may occur in conditions affecting sympathetic pathways on both sides, including certain spinal cord lesions.

Older teaching links bilateral Horner syndrome with syringomyelia, but this is uncommon and should not be considered a typical cause of bilateral ptosis.

Syringomyelia more classically produces segmental sensory loss and can interrupt sympathetic pathways if sufficiently extensive.

15. Ptosis – Note Form

Unilateral Ptosis

Congenital ptosis: abnormal levator development, usually present from birth.

Aponeurotic/idiopathic ptosis: age-related or acquired stretching of the levator aponeurosis.

Third nerve palsy: marked ptosis with ophthalmoplegia; eye may lie “down and out.”

Third nerve pupil: may be dilated if parasympathetic fibres are involved.

Horner syndrome: mild ptosis with miosis ± anhidrosis.

Myasthenia gravis: fluctuating, fatigable ptosis that improves with rest.

Lid tumour: mechanical ptosis caused by an eyelid mass.

16. Bilateral Ptosis – Note Form

Myasthenia gravis: fluctuating and fatigable bilateral ptosis, often with diplopia.

Myotonic dystrophy: bilateral ptosis with myotonia and other muscle-system features.

Ocular myopathy: persistent bilateral ptosis with progressive ophthalmoplegia.

Bilateral Horner syndrome: rare; may occur with bilateral sympathetic pathway lesions.

17. Useful Clinical Distinctions

Third nerve palsy → ptosis + “down and out” eye ± dilated pupil.

Horner syndrome → mild ptosis + small pupil.

Myasthenia gravis → variable ptosis + fatigability + normal pupils.

Mechanical ptosis → eyelid mass or structural abnormality.

Key Clinical Pattern

When assessing ptosis, first look at the pupil and eye movements.

Ptosis + dilated pupil + ophthalmoplegia → think third nerve palsy.

Ptosis + constricted pupil → think Horner syndrome.

Fluctuating ptosis with normal pupils → think myasthenia gravis.

Bilateral slowly progressive ptosis with ophthalmoplegia → think ocular myopathy.

A particularly important emergency association is:

Painful ptosis + third nerve palsy + dilated pupil → urgently exclude a compressive intracranial aneurysm.

Medicine – Optic Neuritis

Optic neuritis is an inflammatory disorder of the optic nerve that produces acute or subacute visual impairment. It classically occurs in young adults and has an important association with multiple sclerosis (MS).

The typical presentation is unilateral visual loss developing over hours to several days, impaired colour vision, and pain that is particularly noticeable with eye movement.

1. Inflammation of the Optic Nerve

Inflammation and demyelination of the optic nerve interfere with transmission of visual signals from the retina to the brain.

The resulting visual disturbance may involve visual acuity, colour perception, contrast sensitivity, and the visual field.

2. Multiple Sclerosis

Multiple sclerosis is the classic disease associated with optic neuritis.

Optic neuritis may occur in a patient with established MS, but it can also be the first clinical manifestation of a demyelinating disorder.

For this reason, patients presenting with typical optic neuritis are assessed for evidence of demyelination elsewhere in the central nervous system.

3. Other Demyelinating Disorders

Not all demyelinating optic neuritis is caused by conventional MS.

Important modern differential diagnoses include neuromyelitis optica spectrum disorder (NMOSD), often associated with aquaporin-4 antibodies, and MOG-antibody-associated disease (MOGAD).

These disorders are important because their clinical behaviour, prognosis, and long-term treatment differ from typical MS-associated optic neuritis.

4. Infectious and Inflammatory Causes

Optic nerve inflammation can also occur in association with infections, autoimmune disease, and other inflammatory conditions.

Therefore, atypical presentations—such as bilateral severe disease, unusual age at presentation, marked optic-disc swelling, systemic symptoms, or poor recovery—should prompt investigation for alternative causes.

Clinical Features

5. Unilateral Visual Loss

Typical MS-associated optic neuritis usually causes unilateral reduction in visual acuity.

The visual loss develops relatively rapidly, generally over hours to several days, rather than occurring instantaneously.

Vision may continue to worsen for several days before stabilising and beginning to recover.

6. Reduced Colour Vision

Dyschromatopsia, or impaired colour perception, is a particularly characteristic feature.

Patients often notice that colours appear washed out or less vivid in the affected eye.

Red Desaturation

Loss of perception of red intensity is particularly useful clinically.

When comparing the two eyes, a red object may appear bright red through the unaffected eye but faded, pale, or less saturated through the affected eye.

This is known as red desaturation.

7. Pain on Eye Movement

Pain is common in typical optic neuritis and is characteristically aggravated by movement of the affected eye.

This occurs because movement of the globe can place traction on the inflamed optic nerve and surrounding tissues.

Pain may precede the visual loss or occur at approximately the same time.

8. Relative Afferent Pupillary Defect

A unilateral or asymmetrical optic neuropathy usually produces a relative afferent pupillary defect (RAPD) in the affected eye.

This can be demonstrated using the swinging flashlight test.

An RAPD is an important clinical clue that visual impairment originates from the optic nerve or severe retinal disease rather than from a simple refractive problem.

9. Central Scotoma

A central or centrocaecal scotoma is a classic visual-field abnormality in optic neuritis.

Patients may therefore have particular difficulty seeing objects directly in the centre of their visual field.

However, other patterns of visual-field loss can also occur.

10. Optic Disc Appearance

The original notes state that the optic disc is swollen, but this is not present in every patient.

In typical demyelinating optic neuritis, the optic disc often appears normal because the inflammation occurs behind the visible optic nerve head.

This is called retrobulbar neuritis.

A useful traditional description is:

“The patient sees nothing, and the doctor sees nothing.”

This refers to significant visual impairment despite a relatively normal initial fundoscopic examination.

Papillitis

In some patients, inflammation involves the visible optic nerve head and causes optic-disc swelling.

This is sometimes termed papillitis.

Therefore:

Optic neuritis → optic disc may be normal or swollen.

A normal optic disc does not exclude optic neuritis.

11. Recovery

Typical demyelinating optic neuritis generally has a good spontaneous visual prognosis.

Improvement usually begins within several weeks, and substantial recovery commonly occurs over the following weeks to months.

The older description of recovery over 2–6 weeks captures the early recovery period, although improvement may continue for considerably longer.

12. Multiple Sclerosis Risk

Optic neuritis is strongly associated with subsequent development of multiple sclerosis, but the individual risk varies considerably.

The quoted figure of 45–80% developing MS within 15 years should not be applied uniformly to every patient.

The most important predictor is the presence of demyelinating lesions on brain MRI.

A patient with multiple characteristic MRI lesions has a substantially greater future risk of MS than someone with a normal brain MRI.

Investigations

13. MRI

MRI of the brain and orbits with appropriate contrast sequences is an important investigation, particularly when assessing for demyelinating disease.

MRI may demonstrate enhancement of the affected optic nerve and can identify characteristic demyelinating lesions elsewhere in the central nervous system.

The number and distribution of brain lesions help estimate the likelihood of future or existing MS.

14. Additional Investigations

Additional testing depends on the clinical presentation.

Atypical optic neuritis may require investigation for AQP4-IgG associated NMOSD, MOG antibodies, infectious disease, systemic inflammatory disease, or other causes of optic neuropathy.

Treatment

15. Corticosteroids

High-dose corticosteroids can accelerate visual recovery in appropriate cases of acute demyelinating optic neuritis.

A traditional regimen is high-dose intravenous methylprednisolone for approximately 3 days, although modern protocols may also use appropriately dosed high-dose oral corticosteroid regimens in selected circumstances.

The exact treatment should follow specialist neurological and ophthalmological guidance.

16. Effect of Steroids on Recovery

An important distinction is that high-dose corticosteroids mainly speed the rate of visual recovery.

In typical MS-associated optic neuritis, they do not necessarily produce a major improvement in the final long-term visual acuity compared with spontaneous recovery.

Therefore, treatment decisions depend on the severity, clinical circumstances, and underlying cause.

17. Avoid Inadequate-Dose Oral Steroids Alone

Older clinical trial evidence found an increased recurrence risk with certain lower-dose oral prednisone regimens used alone.

This should not be confused with modern high-dose oral corticosteroid regimens that may achieve steroid exposure comparable to intravenous therapy.

18. Optic Neuritis – Note Form

Definition: inflammatory optic neuropathy, commonly associated with demyelination.

Classic association: multiple sclerosis.

Other important associations: NMOSD, MOG-antibody-associated disease, infections, and systemic inflammatory disorders.

Eye involvement: typical MS-associated optic neuritis is usually unilateral.

Onset: visual acuity deteriorates over hours to several days.

Pain: characteristically worse with eye movement.

Colour vision: reduced, especially red desaturation.

Visual field: central or centrocaecal scotoma is common.

Pupils: a unilateral lesion usually produces a relative afferent pupillary defect.

Optic disc: often normal in retrobulbar optic neuritis; may be swollen when the optic nerve head is involved.

Recovery: usually begins within several weeks and may continue over weeks to months.

MS risk: significant but variable; brain MRI lesions are an important predictor of future MS.

Investigation: MRI brain and orbits is particularly useful for confirming optic nerve inflammation and looking for demyelinating disease.

Treatment: high-dose corticosteroids may be used to accelerate visual recovery in appropriate cases.

Key Clinical Pattern

Remember typical optic neuritis as:

Young adult + unilateral visual loss over days + pain on eye movement + red desaturation + central scotoma + RAPD.

The optic disc may be completely normal, particularly in retrobulbar optic neuritis, so absence of disc swelling does not exclude the diagnosis.

The major association to remember is:

Optic neuritis ↔ multiple sclerosis.

MRI is especially important because demyelinating brain lesions strongly influence the patient’s future risk of MS.

Medicine – Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a group of inherited progressive retinal dystrophies in which photoreceptor cells gradually degenerate. The disease primarily affects the rods, with cone involvement occurring later in many patients.

The name is slightly misleading because RP is not primarily an inflammatory “retinitis.” It is better understood as an inherited degeneration of the retina.

1. Retinal Degeneration

In retinitis pigmentosa, there is progressive loss of photoreceptors together with characteristic pigmentary changes in the retina.

As retinal cells degenerate, pigment migrates into the retina and produces the classic bone-spicule pigmentation seen on fundoscopic examination.

Other typical retinal findings may include attenuation of retinal arterioles and a pale or waxy optic disc in more advanced disease.

2. Inheritance

Retinitis pigmentosa can follow several different inheritance patterns.

It may be:

Autosomal dominant.

Autosomal recessive.

X-linked.

There are also syndromic forms associated with systemic disease.

Because many different genes can cause RP, the age of onset, rate of progression, and severity can vary considerably between patients.

3. Rods Are Affected First

The disease predominantly affects rod photoreceptors in the early stages.

Rods are responsible mainly for vision in dim light and for much of the peripheral visual field.

This explains why the earliest symptoms are usually night blindness and progressive loss of peripheral vision.

4. Cone Involvement

As the disease progresses, cone photoreceptors may also become affected.

Cones are responsible for central visual acuity, colour vision, and vision in brighter light.

Late cone degeneration can therefore lead to loss of central vision, colour discrimination, and detailed visual acuity.

5. Night Blindness

Night blindness, or nyctalopia, is one of the earliest and most characteristic symptoms.

Patients may notice difficulty seeing in dimly lit environments, difficulty adapting when moving from bright light into darkness, or trouble navigating at night.

This occurs because rod function deteriorates before cone function.

6. Peripheral Visual-Field Loss

Loss of the peripheral visual field typically occurs before central vision is lost.

As peripheral retinal function progressively deteriorates, the visual field becomes increasingly constricted.

This eventually produces the characteristic “tunnel vision” pattern.

7. Tunnel Vision

Tunnel vision means that the patient retains a relatively narrow central area of vision while peripheral vision has been lost.

Patients may therefore have difficulty noticing objects approaching from the side, navigating unfamiliar spaces, or avoiding obstacles despite retaining relatively good central acuity early in the disease.

8. Central Vision

Central vision is often relatively preserved until later because the cones of the macula are affected after the peripheral rod system.

As cone degeneration progresses, however, central vision may decline significantly.

Complications such as cystoid macular oedema can further reduce central visual acuity.

9. Fundoscopic Findings

Classical fundoscopic features of retinitis pigmentosa include:

Bone-spicule retinal pigmentation.

Attenuated retinal vessels.

Waxy pallor of the optic disc.

These findings tend to become more obvious as the disease progresses.

10. Electroretinography

Electroretinography (ERG) can demonstrate reduced electrical responses from the retina.

Rod responses are typically reduced early, with cone responses becoming affected later.

ERG can therefore help support the diagnosis and assess the extent of generalized photoreceptor dysfunction.

11. Visual-Field Testing

Formal visual-field testing can demonstrate progressive peripheral field loss.

Ring scotomas may develop and subsequently enlarge until only a small central field remains.

This objective assessment is useful for monitoring progression and documenting functional impairment.

12. Associated Conditions

Some forms of retinitis pigmentosa occur as part of broader inherited syndromes.

An important example is Usher syndrome, in which RP is associated with sensorineural hearing loss.

Other syndromic associations can involve neurological, metabolic, renal, or skeletal abnormalities depending on the underlying genetic disorder.

13. Prognosis

Retinitis pigmentosa is usually progressive, but the rate of visual loss varies enormously between individuals and genetic subtypes.

The traditional statement that most patients are registered blind by age 40 is too absolute.

Some patients develop severe visual impairment relatively early, whereas others retain useful central vision well beyond middle age.

Therefore, prognosis should be individualised according to the specific genetic diagnosis and clinical course.

14. Treatment

There is currently no single treatment that reverses all forms of retinitis pigmentosa.

Management focuses on preserving useful vision, treating complications, providing visual rehabilitation, and identifying genetically treatable subtypes.

15. Treatment of Complications

Associated problems such as cystoid macular oedema or cataract may be treatable and can improve useful vision.

Low-vision aids, mobility training, and occupational support can also make a major difference to daily function.

16. Genetic Testing and Counselling

Because RP is genetically heterogeneous, genetic testing is increasingly important.

Identifying the causative mutation can clarify inheritance, guide family counselling, refine prognosis, and determine whether the patient may be eligible for a gene-specific therapy or clinical trial.

17. Gene Therapy

Gene therapy is available for a small subset of inherited retinal dystrophies associated with particular mutations, most notably biallelic RPE65-related retinal disease.

This does not apply to all patients with retinitis pigmentosa, but it illustrates the growing importance of precise genetic diagnosis.

18. Retinitis Pigmentosa – Note Form

Definition: inherited progressive retinal degeneration affecting photoreceptors.

Early cells affected: mainly rods.

Later cells affected: cones may become involved.

Inheritance: autosomal dominant, autosomal recessive, or X-linked.

Early symptom: night blindness.

Visual field: peripheral vision is lost first.

Typical late field defect: tunnel vision.

Fundoscopy: bone-spicule pigmentation, attenuated retinal vessels, and waxy optic-disc pallor.

Central vision: usually relatively preserved until later stages.

Investigation: visual-field testing, electroretinography, retinal imaging, and genetic testing.

Syndromic association: Usher syndrome = retinitis pigmentosa + sensorineural deafness.

Prognosis: progressive but highly variable; severe visual impairment may occur early in some patients but not universally by age 40.

Treatment: manage complications, provide low-vision support, undertake genetic counselling, and consider gene-specific therapy where applicable.

Key Clinical Pattern

Remember retinitis pigmentosa as:

Rod degeneration first → night blindness → peripheral visual-field loss → tunnel vision → later cone involvement and central visual loss.

The classic examination association is:

Night blindness + tunnel vision + bone-spicule retinal pigmentation = retinitis pigmentosa.

Medicine – Retinoblastoma

Retinoblastoma is a rare malignant tumour of the developing retina and is the most common primary intraocular malignancy of childhood. It arises from immature retinal cells following loss of normal function of the RB1 tumour-suppressor gene.

Early recognition is extremely important because retinoblastoma is potentially life-threatening, but treatment can achieve excellent survival when the disease is detected before extraocular spread.

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1. Age of Presentation

Retinoblastoma occurs almost exclusively in young children, with most cases diagnosed before the age of 5 years.

Heritable and bilateral disease tends to present particularly early, often during the first few years of life.

Therefore, the traditional association with a child younger than 3 years is a useful clinical clue, although it should not be regarded as an absolute age limit.

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2. The RB1 Tumour-Suppressor Gene

Retinoblastoma is strongly associated with abnormalities of the RB1 gene, a tumour-suppressor gene located on chromosome 13q14.

The normal RB protein helps regulate progression through the cell cycle and prevents inappropriate cellular proliferation.

When both functional copies of RB1 are lost within a retinal precursor cell, normal cell-cycle control is disrupted and a malignant tumour can develop.

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3. The Two-Hit Hypothesis

Retinoblastoma is the classic disease used to explain Knudson’s two-hit hypothesis.

Both copies of the RB1 tumour-suppressor gene must effectively be inactivated within a susceptible retinal cell for tumour formation.

However, the way these two genetic “hits” occur differs between heritable and non-heritable retinoblastoma.

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4. Heritable Retinoblastoma

In heritable retinoblastoma, the child already carries a pathogenic RB1 variant in one copy of the gene in the germline.

Therefore:

First hit → inherited or newly arising germline RB1 pathogenic variant.

A retinal cell subsequently loses or inactivates its remaining functional RB1 copy:

Second hit → somatic loss/inactivation of the remaining normal RB1 allele.

This leads to tumour formation.

Because every retinal cell already carries the first hit, several independent retinal cells may acquire a second hit.

Consequently, heritable disease is more likely to be bilateral and multifocal.

Importantly, the germline RB1 alteration may be inherited from a parent or arise de novo in the affected child, so absence of a family history does not exclude heritable disease.

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5. Non-Heritable Retinoblastoma

Not every child with retinoblastoma inherits an abnormal RB1 gene.

In non-heritable or sporadic retinoblastoma, both RB1 abnormalities generally arise somatically within the same retinal cell lineage.

Because two independent events must occur in one retinal cell, these tumours tend to occur somewhat later and are usually unilateral and unifocal.

Therefore, the original statement that all patients inherit one abnormal RB1 gene applies specifically to the heritable form, not to every retinoblastoma.

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Clinical Presentation

The classic presenting features are leukocoria, strabismus, and an abnormal or absent red reflex.

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6. White Pupil – Leukocoria

The most characteristic presentation is leukocoria, meaning a white pupillary reflex.

Instead of the normal reddish-orange reflection seen when light enters the pupil, the affected eye may show a white reflection because light is reflected from the retinal tumour.

Parents sometimes first notice leukocoria in a flash photograph, where one pupil appears white rather than showing the expected red reflex.

Leukocoria in a child requires urgent ophthalmological assessment.

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7. Squint – Strabismus

Strabismus, or squint, is another important presentation.

The affected eye may deviate because the tumour interferes with central vision, preventing normal binocular visual alignment.

A new unexplained squint in a young child therefore requires proper ocular assessment rather than being assumed to be benign.

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8. Loss of the Red Reflex

A normal eye produces a symmetrical red reflex when examined with an ophthalmoscope.

Retinoblastoma may replace this normal reflex with an abnormal, reduced, asymmetric, or white reflex.

The red-reflex examination is therefore an important part of evaluating infants and young children.

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9. Other Presentations

More advanced retinoblastoma can occasionally cause reduced vision, a red or painful eye, glaucoma, or enlargement/protrusion of the eye.

These presentations generally suggest more advanced intraocular disease and are less desirable than detecting the tumour at the leukocoria stage.

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10. Diagnosis

A child suspected of having retinoblastoma requires urgent specialist ophthalmological assessment.

Detailed examination of the retina, often under anaesthesia in young children, is central to diagnosis.

Imaging such as ocular ultrasonography and MRI can help assess the tumour and determine whether there is involvement of structures such as the optic nerve or central nervous system.

MRI is particularly useful because it avoids unnecessary ionising radiation, which is especially relevant in children with germline RB1 abnormalities.

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11. Treatment

Treatment depends on whether disease is unilateral or bilateral, the size and location of the tumour, whether vision can be preserved, and whether disease has spread beyond the eye.

Modern treatment aims first to save the child’s life, then whenever possible to preserve the eye and useful vision.

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12. Local Treatment

Small tumours may sometimes be treated with local therapies such as laser treatment or cryotherapy.

These approaches destroy tumour tissue while attempting to preserve surrounding ocular structures.

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13. Chemotherapy

Chemotherapy may be used to shrink or control retinoblastoma.

Modern specialist treatment may involve systemic chemotherapy, intra-arterial chemotherapy delivered through the ophthalmic artery, or intravitreal chemotherapy depending on the pattern and extent of disease.

These techniques have improved the ability to preserve affected eyes in selected children.

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14. Enucleation

Enucleation, or surgical removal of the affected eye, may be required for a large advanced tumour when useful vision cannot be preserved or when the tumour presents a significant risk of extraocular spread.

Although eye preservation is desirable, control of potentially fatal malignancy remains the priority.

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15. Association with Osteosarcoma

Children with heritable RB1-related retinoblastoma have an increased lifetime risk of developing second primary malignancies.

One of the classic associations is osteosarcoma.

The underlying germline RB1 abnormality predisposes cells elsewhere in the body to malignant transformation, explaining why the cancer risk extends beyond the retina.

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16. Other Second Malignancies

The increased risk is not limited to osteosarcoma.

Patients with heritable retinoblastoma may also have an increased risk of other malignancies, including soft-tissue sarcomas and melanoma, among others.

Historically, radiotherapy could further increase the risk of subsequent malignancy, particularly in genetically susceptible patients.

Long-term surveillance is therefore important.

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17. Retinoblastoma – Note Form

Definition: malignant tumour arising from the retina in young children.

⸻

Typical age: usually presents in early childhood, commonly before 5 years and often before 3 years.

⸻

Gene: associated with loss of the RB1 tumour-suppressor gene on chromosome 13q14.

⸻

Mechanism: both functional copies of RB1 must be inactivated—the classic two-hit hypothesis.

⸻

Heritable disease: one RB1 pathogenic variant is already present in the germline, followed by somatic loss of the remaining functional allele.

⸻

Pattern of heritable disease: tends to present earlier and is more likely to be bilateral and multifocal.

⸻

Sporadic/non-heritable disease: both RB1 hits usually occur somatically within retinal cells.

⸻

Pattern of sporadic disease: more commonly unilateral and unifocal.

⸻

Most characteristic presentation: leukocoria—a white pupillary reflex.

⸻

Other important presentation: strabismus (squint).

⸻

Red reflex: may be absent, asymmetric, abnormal, or replaced by a white reflex.

⸻

Treatment: specialist therapy may include local laser/cryotherapy, chemotherapy, and enucleation for selected advanced tumours.

⸻

Important association: patients with heritable RB1 disease have an increased risk of subsequent malignancies, classically osteosarcoma.

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Key Clinical Pattern

Think of retinoblastoma when a very young child develops:

White pupil (leukocoria) + abnormal/lost red reflex ± squint.

The genetics can be remembered as:

RB1 tumour suppressor → two hits required → loss of both functional copies → retinoblastoma.

Heritable disease already has the first RB1 hit in the germline, making early, bilateral, or multifocal tumours more likely and increasing the lifetime risk of other malignancies, particularly osteosarcoma.

The most important examination association is:

Child + leukocoria → retinoblastoma must be urgently excluded.

Medicine – Glaucoma

Glaucoma is a group of progressive optic neuropathies characterised by damage to the optic nerve and retinal nerve fibre layer, producing characteristic visual-field loss. Raised intraocular pressure (IOP) is the most important modifiable risk factor, but glaucoma can occur even when IOP is within the statistically normal range.

The two major forms considered here are acute angle-closure glaucoma and primary open-angle glaucoma. They differ substantially in their presentation, mechanism, urgency, and treatment.

1. Acute Angle-Closure Glaucoma

Acute angle-closure glaucoma is an ophthalmic emergency in which the drainage angle between the iris and cornea suddenly closes, causing a rapid rise in intraocular pressure.

It usually affects one eye during an acute attack, although the fellow eye is often anatomically predisposed and therefore also at future risk.

2. Normal Aqueous Humour Drainage

Aqueous humour is produced by the ciliary body in the posterior chamber.

It normally passes through the pupil into the anterior chamber and then drains mainly through the:

Trabecular meshwork → Schlemm canal → episcleral venous circulation.

A smaller proportion leaves through the uveoscleral pathway.

3. Mechanism of Acute Angle Closure

In susceptible eyes, the peripheral iris can obstruct the trabecular meshwork, preventing normal aqueous humour drainage.

Aqueous humour continues to be produced while its outflow is severely reduced.

The result is:

Blocked aqueous outflow → rapid rise in IOP → corneal oedema + iris ischaemia + optic nerve damage.

Without rapid treatment, permanent visual loss can occur.

4. Effect of Pupil Dilatation

An acute attack is particularly likely when the pupil becomes mid-dilated, because this anatomical position can increase contact between the iris and lens and promote pupillary block in susceptible eyes.

Attacks may therefore occur in dim or dark environments, where physiological pupil dilatation occurs.

Certain medications capable of causing mydriasis may also precipitate angle closure in anatomically predisposed individuals.

Clinical Features of Acute Angle-Closure Glaucoma

5. Painful Red Eye

The classic presentation is a sudden, intensely painful red eye.

The pain can be severe and may radiate around the eye or into the forehead.

6. Reduced Vision

Patients develop rapidly reduced or blurred vision.

They may describe coloured halos around lights, particularly because corneal oedema alters the passage of light through the cornea.

7. Mid-Dilated Pupil

The pupil is classically mid-dilated and poorly reactive or fixed.

Therefore, the traditional description of simply a “dilated pupil” is better remembered as:

Mid-dilated + fixed/sluggish pupil.

8. Hazy Cornea

Markedly elevated intraocular pressure causes corneal oedema, producing a characteristic cloudy or hazy appearance.

The hazy cornea contributes to the patient’s reduced vision and halos around lights.

9. Other Symptoms

The severe autonomic response to acute angle closure may cause headache, nausea, and vomiting.

This is clinically important because patients can occasionally be mistaken for having a neurological or gastrointestinal illness rather than an ophthalmic emergency.

Treatment of Acute Angle-Closure Glaucoma

The immediate objective is to rapidly reduce intraocular pressure, followed by definitive treatment to prevent recurrence.

Urgent ophthalmological assessment is required.

10. Acetazolamide

Acetazolamide is a carbonic anhydrase inhibitor that reduces aqueous humour production by the ciliary body.

It can be given systemically during an acute attack and helps rapidly lower intraocular pressure.

11. Topical β-Blockers

A topical β-blocker such as timolol can reduce aqueous humour production.

This provides an additional mechanism for lowering intraocular pressure.

Systemic absorption can occur, so β-blockers require caution in patients with conditions such as asthma, significant bradycardia, or heart block.

12. Other Pressure-Lowering Treatment

Additional topical pressure-lowering agents may be used according to the clinical situation, including α₂-adrenergic agonists.

In very severe cases, an osmotic agent may occasionally be required when the intraocular pressure remains extremely high.

13. Pilocarpine

Pilocarpine is a muscarinic agonist that causes pupillary constriction (miosis).

This can pull the peripheral iris away from the drainage angle and improve aqueous outflow once the intraocular pressure has started to fall.

A useful correction to the original wording is that pilocarpine does not literally “open the canal of Schlemm.” Its main effect is to alter iris configuration and improve access to the trabecular drainage angle.

It may initially be ineffective when the IOP is extremely high because the ischaemic iris sphincter may not respond.

14. Laser Peripheral Iridotomy

The definitive treatment for pupillary-block angle closure is usually laser peripheral iridotomy.

A small opening is created in the peripheral iris, providing an alternative pathway for aqueous humour to move from the posterior to the anterior chamber.

This equalises pressure across the iris and helps prevent recurrent pupillary block.

The fellow eye frequently receives prophylactic laser iridotomy because it may have similar anatomical risk.

15. Surgical Iridectomy

Surgical peripheral iridectomy can achieve a similar result but is now generally reserved for situations in which laser treatment cannot be performed or is unsuccessful.

Therefore, the modern term to remember first is laser peripheral iridotomy, rather than routine surgical iridectomy.

16. Primary Open-Angle Glaucoma

Primary open-angle glaucoma (POAG) is a chronic progressive optic neuropathy in which the anterior chamber angle remains anatomically open, but aqueous humour drainage through the trabecular pathway is impaired.

Unlike acute angle closure, the disease usually develops slowly and painlessly over many years.

17. Intraocular Pressure

Raised intraocular pressure is an important risk factor.

Historically, an IOP above 21 mmHg was used as an important threshold.

However, this should not be treated as the definition of glaucoma.

Some people have:

IOP >21 mmHg without optic nerve damage → ocular hypertension.

Others develop:

Glaucomatous optic nerve damage despite IOP ≤21 mmHg → normal-tension glaucoma.

Therefore, glaucoma is fundamentally an optic neuropathy, not simply an elevated pressure measurement.

18. Insidious and Asymptomatic Onset

Primary open-angle glaucoma typically develops gradually and without pain.

Central visual acuity may remain normal until relatively late, so patients can have substantial optic nerve damage before noticing symptoms.

This is why screening of at-risk individuals and routine eye examinations are important.

19. Optic Disc Cupping

Progressive loss of retinal ganglion cell axons produces characteristic cupping of the optic disc.

The cup-to-disc ratio may increase, and progressive neuroretinal rim thinning can occur.

The important relationship is:

Retinal ganglion cell loss → optic nerve damage → increased disc cupping → visual-field loss.

Visual-Field Defects

20. Arcuate Scotoma

Glaucoma produces characteristic visual-field abnormalities because damage follows the distribution of retinal nerve fibres.

An arcuate scotoma is a classic defect.

It may extend from the region of the blind spot in an arc toward the nasal visual field.

21. Other Visual-Field Changes

Early abnormalities may include paracentral defects and nasal steps.

As glaucoma progresses, arcuate defects enlarge and peripheral visual fields become increasingly restricted.

Very advanced disease may eventually produce severe tunnel vision and irreversible blindness.

Treatment of Chronic Open-Angle Glaucoma

The objective is to lower intraocular pressure sufficiently to slow or prevent further optic nerve damage.

Treatment does not usually restore optic nerve fibres that have already been lost.

22. Prostaglandin Analogues

Prostaglandin analogues, such as latanoprost, are major first-line medications for primary open-angle glaucoma.

They lower intraocular pressure primarily by increasing aqueous humour outflow, particularly through the uveoscleral pathway.

They are effective and can usually be administered once daily.

23. Topical β-Blockers

Timolol and other topical β-blockers lower IOP by reducing aqueous humour production.

They remain useful treatments but may be unsuitable for some patients because of systemic cardiovascular and respiratory effects.

24. Carbonic Anhydrase Inhibitors

Topical carbonic anhydrase inhibitors such as dorzolamide reduce aqueous humour formation.

They may be used alone or in combination with other pressure-lowering medications.

25. Other Topical Treatments

Other medications include α₂-adrenergic agonists, which can reduce aqueous production and influence aqueous outflow.

Combination preparations are frequently used when a single drug does not adequately control intraocular pressure.

26. Pilocarpine

Pilocarpine can increase conventional aqueous outflow by causing ciliary muscle contraction and altering the trabecular drainage pathway.

Although historically important, it is used much less commonly as routine long-term treatment for primary open-angle glaucoma because modern agents are generally better tolerated.

Laser and Surgical Treatment

27. Laser Trabeculoplasty

Laser trabeculoplasty, particularly selective laser trabeculoplasty (SLT), improves aqueous drainage through the trabecular meshwork.

It is now an important treatment for open-angle glaucoma and may be used as initial therapy or when medication does not provide adequate control, depending on local practice and patient factors.

28. Glaucoma Surgery

When medication and/or laser treatment fail to achieve the required pressure reduction, glaucoma surgery may be necessary.

Procedures such as trabeculectomy create an alternative pathway for aqueous drainage.

Various drainage implants and minimally invasive glaucoma procedures are also available for selected patients.

29. Iridectomy and Open-Angle Glaucoma

The original notes list iridectomy as a treatment for chronic open-angle glaucoma.

This requires correction.

Peripheral iridotomy/iridectomy is principally a treatment for angle-closure mechanisms, particularly pupillary block. It is not routine treatment for primary open-angle glaucoma, where the angle is already open.

30. Acute Angle-Closure Glaucoma – Note Form

Onset: sudden.

Eye involvement: usually unilateral during an acute attack.

Pain: severe painful red eye.

Vision: rapidly reduced or blurred; coloured halos may occur.

Cornea: cloudy or hazy because of corneal oedema.

Pupil: characteristically mid-dilated and poorly reactive.

IOP: markedly elevated.

Mechanism: peripheral iris obstructs the trabecular drainage angle.

Trigger: may occur when the pupil becomes mid-dilated, such as in dim light.

Systemic symptoms: headache, nausea, and vomiting may occur.

Initial treatment: rapid pressure reduction with agents such as systemic acetazolamide and topical pressure-lowering medication.

Pilocarpine: produces miosis and can help reopen the drainage angle after pressure begins to fall.

Definitive treatment: laser peripheral iridotomy.

Fellow eye: often requires prophylactic assessment and treatment because it may have the same anatomical predisposition.

Clinical importance: ophthalmic emergency because permanent visual loss can occur rapidly.

31. Primary Open-Angle Glaucoma – Note Form

Onset: chronic and insidious.

Pain: usually absent.

Symptoms: usually asymptomatic early.

Anterior chamber angle: remains open.

IOP: often elevated but can be within the statistically normal range.

Optic disc: progressive glaucomatous cupping.

Visual field: nasal step, paracentral defects and arcuate scotomas; advanced disease can produce severe peripheral field loss.

Latanoprost: increases aqueous outflow and is an important first-line treatment.

β-blockers: reduce aqueous humour production.

Dorzolamide: carbonic anhydrase inhibitor that reduces aqueous production.

Pilocarpine: historically used but much less common in modern routine treatment.

Laser: selective laser trabeculoplasty can improve trabecular aqueous outflow.

Surgery: trabeculectomy or other glaucoma procedures may be required when adequate pressure control cannot otherwise be achieved.

Iridectomy: not routine treatment for primary open-angle glaucoma.

Key Clinical Pattern

Remember acute angle-closure glaucoma as:

Painful + red + reduced vision + hazy cornea + mid-dilated pupil + very high IOP.

It is an ophthalmic emergency requiring immediate pressure reduction followed by definitive laser peripheral iridotomy.

Remember primary open-angle glaucoma as:

Painless + chronic + initially asymptomatic + progressive optic-disc cupping + characteristic visual-field loss.

The goal of treatment is to lower intraocular pressure and prevent further irreversible optic nerve damage, using therapies such as prostaglandin analogues, other topical pressure-lowering drugs, selective laser trabeculoplasty, and surgery when required.

Medicine – Respiratory Physiology and Pulmonary Function Tests

Pulmonary function tests (PFTs) assess how effectively the respiratory system moves air into and out of the lungs and how efficiently gas exchange occurs. Important measurements include lung volumes, lung capacities, expiratory flow, spirometry, compliance, and gas transfer.

Understanding these measurements is particularly useful for distinguishing obstructive lung disease, such as asthma and COPD, from restrictive lung disease, such as pulmonary fibrosis.

1. Pulmonary Blood Flow

Normal pulmonary blood flow is approximately 5 L/min at rest in a healthy adult.

Because the pulmonary and systemic circulations are connected in series, pulmonary blood flow is normally approximately equal to the cardiac output.

During exercise, pulmonary blood flow increases considerably as cardiac output rises.

2. Alveolar Ventilation

Alveolar ventilation refers to the volume of fresh inspired air reaching the gas-exchanging alveoli each minute.

It is different from total minute ventilation because some inspired air remains within the anatomical dead space and does not participate directly in gas exchange.

The exact normal value varies with tidal volume, respiratory rate, and dead-space volume. A resting value around 4–5 L/min is commonly expected, so the quoted value of approximately 5.25 L/min should be regarded as an approximate physiological value rather than a fixed normal.

Lung Volumes and Capacities

The amount of air within the lungs changes continuously throughout the respiratory cycle.

The major individual lung volumes are tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. Combinations of these individual volumes form capacities such as vital capacity, functional residual capacity, and total lung capacity.

3. Tidal Volume

Tidal volume (TV) is the volume of air inspired or expired during a normal quiet breath.

In a typical resting adult it is approximately 500 mL, although the actual value varies considerably with body size, metabolic demand, and activity.

During exercise, tidal volume increases to meet the body’s greater requirement for ventilation.

4. Inspiratory Reserve Volume

Inspiratory reserve volume (IRV) is the additional volume of air that can be inspired after the end of a normal tidal inspiration.

In other words, after taking a normal breath in, the additional air that can still be forcibly inhaled represents the inspiratory reserve volume.

5. Expiratory Reserve Volume

Expiratory reserve volume (ERV) is the additional volume of air that can be forcibly expired after the end of a normal tidal expiration.

It therefore represents the volume between the resting expiratory level and maximal expiration.

6. Residual Volume

Residual volume (RV) is the volume of gas remaining within the lungs following maximal forced expiration.

Even after breathing out as completely as possible, the lungs do not normally become completely empty.

Residual volume helps prevent complete alveolar collapse and allows gas exchange to continue between individual breaths.

7. Vital Capacity

Vital capacity (VC) is the maximum change in lung volume between complete inspiration and complete expiration.

It can therefore be expressed as:

VC = IRV + TV + ERV

Vital capacity does not include residual volume, because residual volume cannot voluntarily be expired.

Vital Capacity and Total Lung Capacity

The supplied notes describe vital capacity as approximately 75% of total lung capacity.

This can be a useful approximate teaching relationship, but it is not a fixed percentage in every person.

Vital capacity depends on factors such as age, sex, height, body size, respiratory muscle strength, and underlying lung disease.

Vital capacity generally decreases with increasing age as residual volume tends to increase.

8. Functional Residual Capacity

Functional residual capacity (FRC) is the volume of air remaining in the lungs at the end of a normal passive expiration.

It represents the resting equilibrium volume of the respiratory system.

FRC is calculated as:

FRC = ERV + RV

Physiological Importance of FRC

FRC provides a reservoir of gas within the lungs between breaths.

This helps prevent dramatic fluctuations in arterial oxygen and carbon dioxide concentrations during normal respiration.

Changes in lung or chest-wall mechanics can substantially alter FRC.

9. Total Lung Capacity

Total lung capacity (TLC) is the total amount of gas contained within the lungs following maximal inspiration.

It represents the maximum volume to which the lungs can be inflated.

TLC can be expressed as:

TLC = VC + RV

or equivalently:

TLC = IRV + TV + ERV + RV

Normal Total Lung Capacity

The supplied notes give approximately 6–7 L for a normal adult.

This is a reasonable approximate teaching value, but TLC varies considerably according to height, sex, age, body size, and reference population.

For clinical interpretation, measured lung volumes are therefore compared with appropriate predicted values rather than with a single universal normal volume.

10. Measuring Total Lung Capacity

TLC cannot be measured completely by ordinary spirometry because spirometry cannot directly measure residual volume.

Methods used to measure lung volumes containing RV include body plethysmography and gas-dilution techniques such as helium dilution.

Body Plethysmography

Body plethysmography measures thoracic gas volume while the patient sits inside an airtight chamber.

An important advantage is that it can detect gas trapped behind poorly communicating or closed airways.

It is therefore particularly useful when significant air trapping, such as in severe COPD, is suspected.

Helium Dilution

In helium dilution, the patient breathes from a closed system containing a known concentration of helium.

The degree to which the helium becomes diluted allows calculation of the communicating lung volume.

Because helium must communicate with the ventilated airspaces, severe air trapping can cause the technique to underestimate true lung volume.

11. Peak Expiratory Flow

Peak expiratory flow (PEF) is the maximum expiratory flow achieved during a forceful expiration beginning from full inspiration.

It provides a simple measurement of airflow through the large airways.

PEF in Asthma

PEF is particularly useful for monitoring asthma within an individual patient.

Repeated measurements can demonstrate variability in airflow obstruction and can help patients recognise deterioration.

Serial peak-flow measurements may also contribute evidence of variable airflow obstruction when investigating suspected asthma.

Therefore, the statement that PEF is simply “not effective as a diagnostic test” is too absolute. A single PEF measurement is relatively nonspecific, but serial variability can support an asthma diagnosis in the appropriate clinical setting.

12. Lung Compliance

Compliance describes the distensibility of the lungs—that is, how easily lung volume changes in response to a change in pressure.

A highly compliant lung expands relatively easily, whereas a lung with low compliance is stiff and requires greater pressure to produce the same increase in volume.

Compliance in Emphysema

Lung compliance is typically increased in emphysema.

Destruction of alveolar elastic tissue causes loss of elastic recoil, so the lungs inflate easily but have difficulty returning to their original volume during expiration.

This contributes to air trapping and hyperinflation.

Compliance in Pulmonary Fibrosis

Compliance is reduced in pulmonary fibrosis.

Fibrotic tissue makes the lungs abnormally stiff, so greater inspiratory pressure is required to expand them.

Patients therefore tend to breathe with small tidal volumes and a relatively rapid respiratory rate.

Compliance in Pulmonary Oedema

Pulmonary oedema also decreases lung compliance.

Fluid within the interstitial and alveolar compartments makes the lungs stiffer and increases the work of breathing.

Spirometry

Spirometry is one of the most important pulmonary function tests. It measures how much air a patient can forcibly expire and how rapidly that air can be expelled.

The two major measurements are FEV₁ and FVC.

13. Forced Expiratory Volume in One Second

FEV₁ is the volume of air forcibly expired during the first second of a maximal forced expiration starting from full inspiration.

FEV₁ is particularly sensitive to airflow obstruction.

When the airways are narrowed, the patient cannot expel air rapidly, so FEV₁ falls.

14. Forced Vital Capacity

Forced vital capacity (FVC) is the total volume of air that can be forcibly expired after taking a maximal inspiration.

It differs from FEV₁ because FEV₁ measures only the volume expelled during the first second, whereas FVC measures the total forced expiratory volume.

15. FEV₁/FVC Ratio

The FEV₁/FVC ratio describes the proportion of the forced vital capacity that can be expelled during the first second.

It is particularly useful for distinguishing an obstructive spirometric pattern from a possible restrictive pattern.

16. Obstructive Lung Disease

In obstructive lung disease, airflow through the airways is impaired.

Examples include asthma and COPD.

FEV₁ falls substantially because the patient cannot expel air rapidly through narrowed or collapsible airways.

FVC may be normal or reduced, but FEV₁ falls proportionately more than FVC.

The result is a reduced FEV₁/FVC ratio.

FEV₁/FVC in Obstruction

The image uses:

FEV₁/FVC <0.75 → obstructive disorder

This is useful older teaching but should not be treated as a universal modern threshold.

For COPD, a post-bronchodilator FEV₁/FVC <0.70 is commonly used, while pulmonary-function laboratories may use the lower limit of normal (LLN) based on age, sex, height, and reference equations.

The key principle remains:

Obstruction → FEV₁ falls more than FVC → FEV₁/FVC decreases.

17. Bronchodilator Reversibility

When airflow obstruction is identified, spirometry may be repeated after administering a bronchodilator.

A significant improvement in airflow after bronchodilator treatment supports the presence of variable or reversible airflow obstruction, which is particularly characteristic of asthma.

However, reversibility is not completely specific for asthma, and some patients with COPD also demonstrate bronchodilator responsiveness.

18. Restrictive Lung Disease

In a restrictive ventilatory defect, the total volume of the lungs is reduced.

Examples include interstitial pulmonary fibrosis, chest-wall restriction, and some neuromuscular disorders.

Both FEV₁ and FVC may decrease because the patient has a smaller volume of air available to expire.

However, they tend to decrease relatively proportionately.

Therefore, the FEV₁/FVC ratio remains normal or may become increased.

FEV₁/FVC in Restriction

The older notes use:

FEV₁/FVC >0.75 → restrictive disorder

The principle is correct, but a preserved or high FEV₁/FVC ratio alone does not prove restriction.

True pulmonary restriction requires demonstration of a reduced total lung capacity (TLC).

Therefore:

Low FVC + normal/high FEV₁/FVC → suspect restriction.

Reduced TLC → confirms restriction.

19. Obstructive Pattern – Note Form

Main abnormality: difficulty getting air out rapidly.

FEV₁: markedly reduced.

FVC: normal or reduced.

FEV₁/FVC: reduced.

TLC: may be normal or increased.

Residual volume: often increased when air trapping is present.

Examples: asthma and COPD.

Bronchodilator response: substantial reversibility particularly supports asthma, although reversibility can also occur in COPD.

Emphysema: compliance increased because elastic recoil is lost.

20. Restrictive Pattern – Note Form

Main abnormality: inability to fully expand the lungs or respiratory system.

FEV₁: reduced.

FVC: reduced.

FEV₁/FVC: normal or increased.

TLC: reduced and required to confirm true restriction.

Residual volume: often reduced or normal depending on the cause.

Examples: pulmonary fibrosis, severe chest-wall restriction, and neuromuscular disease.

Pulmonary fibrosis: lung compliance is reduced because the lungs become stiff.

21. Lung Volumes – Note Form

Tidal volume (TV): volume inspired or expired during an ordinary quiet breath.

Inspiratory reserve volume (IRV): additional air that can be inspired after a normal inspiration.

Expiratory reserve volume (ERV): additional air that can be expired after a normal expiration.

Residual volume (RV): air remaining after maximal expiration.

Vital capacity (VC): maximum volume that can be moved between maximal inspiration and maximal expiration.

VC = IRV + TV + ERV

Functional residual capacity (FRC): air remaining after a normal passive expiration.

FRC = ERV + RV

Total lung capacity (TLC): total volume of gas in the lungs after maximal inspiration.

TLC = VC + RV

22. Important Relationships to Remember

TLC = VC + RV

VC = IRV + TV + ERV

FRC = ERV + RV

Obstruction → FEV₁ ↓↓↓, FVC normal/↓, FEV₁/FVC ↓

Restriction → FEV₁ ↓, FVC ↓, FEV₁/FVC normal/↑, TLC ↓

Emphysema → compliance ↑

Pulmonary fibrosis → compliance ↓

Pulmonary oedema → compliance ↓

Key Clinical Pattern

For examinations, first look at the FEV₁/FVC ratio.

If the ratio is reduced, think airflow obstruction, particularly asthma or COPD.

If the ratio is normal or increased but FVC is reduced, suspect a restrictive pattern and check the TLC. A reduced TLC confirms true restriction.

Then remember the opposite effects on compliance:

Emphysema → lungs are floppy and easy to inflate → ↑ compliance + ↓ elastic recoil.

Pulmonary fibrosis → lungs are stiff and difficult to inflate → ↓ compliance.

Finally, remember that ordinary spirometry cannot directly measure RV, FRC, or TLC, because all three contain residual volume. These require additional lung-volume measurement techniques such as body plethysmography or gas dilution.

Medicine – Gas Transfer Factor

Gas transfer factor refers to the ability of gases to move from the alveoli across the alveolar–capillary membrane into the pulmonary blood. It is usually measured using carbon monoxide because carbon monoxide binds avidly to haemoglobin and its transfer can therefore be used to estimate the efficiency of pulmonary gas exchange.

The measurement is commonly called TLCO in the UK or DLCO in other settings. A reduced transfer factor may result from destruction or thickening of the alveolar–capillary membrane, loss of pulmonary capillary blood volume, reduced haemoglobin concentration, or removal of functioning lung tissue.

1. Causes of Decreased Transfer Factor

A reduced TLCO/DLCO means that carbon monoxide crosses from the alveoli into the blood less efficiently than expected.

The causes can be divided into pulmonary, cardiovascular, and haematological disorders.

Emphysema

Emphysema is a classic cause of reduced gas transfer.

Destruction of alveolar walls reduces the total surface area available for diffusion and also destroys part of the associated pulmonary capillary bed.

Therefore, even though the lungs may be hyperinflated, their effective gas-exchange surface is substantially reduced.

Interstitial Lung Disease

Interstitial lung disease, including pulmonary fibrosis, reduces gas transfer because the alveolar–capillary membrane becomes thickened and fibrotic.

Oxygen and carbon monoxide must therefore diffuse across a greater distance.

TLCO/DLCO is often one of the earliest pulmonary function abnormalities in interstitial lung disease and may fall before marked spirometric restriction develops.

Pneumonia

Pneumonia can temporarily reduce gas transfer because inflammatory exudate fills alveoli and increases the effective distance between inspired gas and pulmonary capillary blood.

The associated V/Q mismatch and alveolar inflammation further impair oxygen transfer.

Pulmonary Embolism

A pulmonary embolism can reduce TLCO/DLCO because it obstructs part of the pulmonary circulation.

Although alveoli may remain ventilated, blood flow through the corresponding pulmonary capillary bed is reduced or absent.

Therefore, there is less pulmonary capillary blood available to take up carbon monoxide.

Pneumonectomy

Following a pneumonectomy, an entire lung has been removed.

This substantially reduces the total alveolar surface area and pulmonary capillary bed available for gas exchange.

Consequently, the absolute transfer factor is reduced.

2. Cardiovascular Causes of Decreased Transfer Factor

Cardiovascular disorders can reduce gas transfer when they decrease the amount of blood reaching the pulmonary capillary circulation or interfere with the alveolar–capillary interface.

Low Cardiac Output

A low cardiac output can reduce pulmonary capillary blood volume.

With less blood flowing through the pulmonary circulation, there is less haemoglobin available to bind the carbon monoxide used during the test.

This can contribute to a reduced measured TLCO/DLCO.

Pulmonary Oedema

Pulmonary oedema can reduce gas transfer because fluid accumulates within the pulmonary interstitium and sometimes within the alveoli.

This increases the diffusion distance between alveolar gas and the pulmonary capillary blood and therefore impairs gas transfer.

The effect may vary depending on the severity and timing of the oedema.

3. Haematological Cause of Decreased Transfer Factor

Anaemia

Anaemia causes a reduced measured TLCO/DLCO because there is less haemoglobin available to bind carbon monoxide.

The lungs themselves may be structurally normal, but the test reads lower because carbon monoxide uptake depends partly on haemoglobin concentration.

For this reason, modern interpretation of TLCO/DLCO should ideally include correction for haemoglobin concentration.

4. Causes of Increased Transfer Factor

An increased TLCO/DLCO occurs when carbon monoxide uptake by the lungs is greater than expected.

This can result from increased pulmonary blood volume, increased haemoglobin concentration, or the presence of blood within the alveoli.

Pulmonary Haemorrhage

Pulmonary haemorrhage can markedly increase TLCO/DLCO.

When blood enters the alveolar spaces, haemoglobin within that blood binds the inhaled carbon monoxide directly.

This increases the measured uptake of carbon monoxide and therefore produces an artificially high transfer factor.

Anti-GBM Disease

Anti-glomerular basement membrane disease, historically called Goodpasture’s syndrome when pulmonary and renal involvement coexist, can cause diffuse alveolar haemorrhage.

The blood within the alveoli increases the apparent TLCO/DLCO because its haemoglobin absorbs carbon monoxide.

Therefore, an unexpectedly high transfer factor in a patient with haemoptysis, anaemia, and bilateral pulmonary infiltrates may support the possibility of alveolar haemorrhage.

5. Cardiovascular Cause of Increased Transfer Factor

Left-to-Right Shunt

A left-to-right cardiac shunt increases pulmonary blood flow.

The increased volume of blood within the pulmonary capillary bed provides more haemoglobin for carbon monoxide uptake.

Therefore, the measured transfer factor may be increased.

Examples of left-to-right shunts include significant atrial septal defects, ventricular septal defects, and patent ductus arteriosus before pulmonary vascular disease reverses the shunt.

6. Haematological Cause of Increased Transfer Factor

Polycythaemia

Polycythaemia increases the haemoglobin concentration of the blood.

Because more haemoglobin is available to bind inhaled carbon monoxide, TLCO/DLCO may be increased.

As with anaemia, haemoglobin concentration therefore needs to be considered when interpreting gas-transfer measurements.

7. Decreased Transfer Factor – Note Form

Emphysema: destruction of alveolar walls reduces gas-exchange surface area and pulmonary capillary bed.

Interstitial lung disease: thickening and fibrosis of the alveolar–capillary membrane impair diffusion.

Pneumonia: alveolar inflammation and exudate interfere with gas transfer.

Pulmonary embolism: reduced perfusion decreases the functioning pulmonary capillary bed.

Pneumonectomy: removal of lung tissue reduces total surface area available for diffusion.

Low cardiac output: reduced pulmonary capillary blood volume decreases carbon monoxide uptake.

Pulmonary oedema: interstitial/alveolar fluid increases diffusion distance.

Anaemia: reduced haemoglobin means less carbon monoxide can be taken up by blood.

8. Increased Transfer Factor – Note Form

Pulmonary haemorrhage: intra-alveolar blood contains haemoglobin that binds carbon monoxide, increasing the measured TLCO/DLCO.

Anti-GBM disease: diffuse alveolar haemorrhage may therefore produce an abnormally high transfer factor.

Left-to-right shunt: increased pulmonary blood flow increases pulmonary capillary blood volume and carbon monoxide uptake.

Polycythaemia: increased haemoglobin concentration increases carbon monoxide uptake.

9. Useful Interpretation with KCO

TLCO/DLCO is influenced by both the efficiency of gas transfer and the available alveolar volume.

Another measurement, KCO, represents transfer factor adjusted for alveolar volume and can sometimes help explain why the TLCO is reduced.

For example, after pneumonectomy, total TLCO is reduced because there is less lung available, but gas transfer per unit of remaining lung may be relatively preserved.

In emphysema, both destruction of alveolar surface and loss of capillaries mean gas-transfer efficiency itself is impaired, so the KCO is often reduced as well.

Key Clinical Pattern

Think of low TLCO/DLCO as occurring when there is:

Less alveolar surface area → emphysema or lung resection.

A thicker diffusion barrier → interstitial lung disease or pulmonary oedema.

Less pulmonary capillary blood flow → pulmonary embolism or low cardiac output.

Less haemoglobin → anaemia.

Think of high TLCO/DLCO as occurring when there is:

More haemoglobin → polycythaemia.

More pulmonary blood flow → left-to-right shunt.

Blood actually present inside the alveoli → pulmonary haemorrhage.

A particularly useful examination association is:

Haemoptysis + pulmonary infiltrates + unexpectedly raised TLCO/DLCO → consider diffuse alveolar haemorrhage.

Medicine – Causes of Haemoptysis

Haemoptysis means coughing up blood that originates from the lower respiratory tract, usually from the bronchi or lungs. It can range from small blood-streaked sputum to life-threatening pulmonary haemorrhage.

The important clinical priorities are to determine the amount of bleeding, whether the patient is haemodynamically or respiratory compromised, and what the underlying cause is.

1. Lung Cancer

Lung cancer is an important cause of haemoptysis, particularly in older patients and those with a significant smoking history.

Bleeding may occur because a tumour erodes into bronchial mucosa or nearby blood vessels.

Associated warning features include persistent cough, unexplained weight loss, chest pain, recurrent pneumonia, hoarseness, and reduced appetite.

Even small-volume recurrent haemoptysis in a high-risk patient warrants further investigation.

2. Pneumonia

Pneumonia can cause haemoptysis because inflammation damages the airway and alveolar tissues.

The sputum may be blood-streaked or occasionally more heavily blood-stained.

Associated features commonly include fever, productive cough, pleuritic chest pain, dyspnoea, and focal chest signs.

3. Tuberculosis

Pulmonary tuberculosis is a classic cause of haemoptysis.

Bleeding can occur from inflamed or cavitating lung tissue, particularly in post-primary disease.

Typical associated symptoms include chronic cough, weight loss, fever, night sweats, fatigue, and sometimes upper-lobe cavitation on imaging.

Significant bleeding can occur if a pulmonary vessel adjacent to a cavity is eroded.

4. Pulmonary Embolism

A pulmonary embolism (PE) may cause haemoptysis, particularly when there is associated pulmonary infarction.

The amount is usually relatively small rather than massive.

Associated features may include sudden breathlessness, pleuritic chest pain, tachycardia, hypoxaemia, syncope, or signs of deep-vein thrombosis.

5. Bronchiectasis

Bronchiectasis is a common structural cause of recurrent haemoptysis.

Chronically inflamed and abnormally dilated bronchi develop enlarged and fragile bronchial arteries, which can bleed.

Patients often have chronic productive cough, large volumes of purulent sputum, recurrent chest infections, and intermittent haemoptysis.

In some patients, bronchiectasis can cause massive haemoptysis.

6. Aspergilloma

An aspergilloma is a fungal ball, usually composed of Aspergillus hyphae, that colonises a pre-existing lung cavity.

The cavity may have resulted from previous tuberculosis, sarcoidosis, or other cavitating lung disease.

Haemoptysis is a classic presentation and may range from mild to severe.

On imaging, an aspergilloma may appear as a mobile intracavitary mass surrounded by an air crescent.

7. Pulmonary Abscess

A lung abscess is a localized area of suppurative infection with destruction and cavitation of lung tissue.

Inflammation and necrosis can damage nearby blood vessels, producing haemoptysis.

Associated features may include fever, productive cough, foul-smelling sputum, weight loss, and an air-fluid level on imaging.

8. Wegener’s Granulomatosis

The older term Wegener’s granulomatosis is now called granulomatosis with polyangiitis (GPA).

GPA is a necrotising small- and medium-vessel vasculitis that commonly affects the upper respiratory tract, lungs, and kidneys.

Pulmonary involvement may produce nodules, cavitation, pulmonary capillaritis, and diffuse alveolar haemorrhage, leading to haemoptysis.

Associated features can include sinusitis, nasal crusting, otitis, haematuria, renal impairment, and systemic inflammatory symptoms.

9. Goodpasture’s Syndrome

Goodpasture’s syndrome, more precisely called anti-glomerular basement membrane disease, can cause severe pulmonary haemorrhage.

Autoantibodies attack basement membranes in the lungs and kidneys.

Patients may present with haemoptysis, breathlessness, anaemia, haematuria, and rapidly progressive glomerulonephritis.

Pulmonary bleeding may be extensive and can cause life-threatening hypoxaemia.

Causes of Haemoptysis – Note Form

Lung cancer: tumour erosion into bronchial tissue or vessels, especially important in smokers and older patients.

Pneumonia: inflammatory damage to airways and alveoli can cause blood-streaked sputum.

Tuberculosis: cavitation and tissue destruction may produce recurrent or severe haemoptysis.

Pulmonary embolism: haemoptysis may occur with pulmonary infarction, usually together with sudden dyspnoea and pleuritic pain.

Bronchiectasis: chronically inflamed dilated bronchi with fragile bronchial arteries; can cause recurrent or massive bleeding.

Aspergilloma: fungal ball within an old lung cavity; haemoptysis is a classic feature.

Pulmonary abscess: cavitating infection with necrosis and vessel damage.

Granulomatosis with polyangiitis: pulmonary vasculitis and alveolar haemorrhage can cause haemoptysis.

Anti-GBM disease: pulmonary capillary bleeding associated with rapidly progressive renal disease.

Key Clinical Pattern

A useful way to remember haemoptysis is to think in broad groups:

Malignancy → lung cancer.

Infection → pneumonia, tuberculosis, lung abscess.

Structural airway disease → bronchiectasis.

Cavitary fungal disease → aspergilloma.

Vascular/thromboembolic → pulmonary embolism.

Pulmonary–renal syndromes → granulomatosis with polyangiitis and anti-GBM disease.

Large-volume haemoptysis is a medical emergency because the immediate danger is often airway obstruction and asphyxiation, not simply blood loss.

Medicine – Causes of Pleuritic Chest Pain

Pleuritic chest pain is a sharp, stabbing chest pain that is typically worse on inspiration, coughing, sneezing, or movement. It usually occurs when the parietal pleura or another pain-sensitive thoracic structure becomes inflamed or irritated.

The most important initial task is to distinguish benign musculoskeletal causes from potentially serious conditions such as pulmonary embolism, pneumothorax, pneumonia, or pericarditis.

1. Pleurisy

Pleurisy means inflammation of the pleura.

When the inflamed pleural surfaces rub against each other during breathing, the patient develops sharp inspiratory chest pain.

A pleural friction rub may sometimes be heard on auscultation.

Pleurisy is not a single diagnosis in itself; it may occur secondary to infection, pulmonary embolism, autoimmune disease, or other pleural disorders.

2. Pneumonia

Pneumonia can cause pleuritic pain when inflammation extends from the lung parenchyma to the adjacent pleural surface.

The pain is often associated with fever, cough, sputum production, dyspnoea, and focal chest signs.

The pleuritic pain is therefore caused by accompanying pleuritis rather than by the lung tissue itself.

3. Pulmonary Embolism

Pulmonary embolism (PE) is an important and potentially life-threatening cause of pleuritic chest pain.

The pain is often sudden and results from irritation of the pleura by a peripheral pulmonary infarct or inflammatory reaction.

Associated features may include sudden breathlessness, tachycardia, haemoptysis, hypoxaemia, syncope, or signs of deep-vein thrombosis.

A normal chest examination does not exclude PE.

4. Pneumothorax

A pneumothorax occurs when air enters the pleural cavity and causes partial or complete lung collapse.

It classically produces sudden unilateral pleuritic chest pain and acute breathlessness.

Examination may show reduced chest expansion, hyperresonance, and diminished breath sounds on the affected side.

A tension pneumothorax is a medical emergency because increasing intrathoracic pressure can impair venous return and cause cardiovascular collapse.

5. Rib Fracture

A rib fracture causes localized chest-wall pain that is typically worsened by deep inspiration, coughing, or movement.

There is often a history of trauma, although fractures can also occur after severe coughing, particularly in older adults or patients with osteoporosis.

The pain is usually reproducible with direct palpation over the affected rib.

6. Costochondritis

Costochondritis is inflammation of the costochondral or costosternal junctions.

It causes localized anterior chest pain that can mimic pleuritic or cardiac pain.

A useful feature is that the pain is often reproducible by pressing over the affected costochondral junctions.

Unlike true pleural disease, there is no underlying abnormality of the lung or pleura.

7. Pleural Effusion

A pleural effusion can cause pleuritic chest pain, particularly during the early inflammatory phase when the pleural surfaces are irritated.

As the effusion enlarges and physically separates the two pleural surfaces, the pleuritic pain may actually become less prominent.

Large effusions may instead cause progressive breathlessness, reduced breath sounds, and stony dullness to percussion.

8. Pericarditis

Acute pericarditis commonly causes sharp, pleuritic-type central chest pain.

The pain is often worse on inspiration and when lying flat, and may improve when the patient sits forward.

A pericardial friction rub may be present.

Because pericarditis can resemble pleuritic pulmonary pain, associated ECG changes and the clinical context are important.

9. Muscular Chest Pain

Muscular chest-wall pain may occur after exercise, coughing, lifting, trauma, or repetitive movement.

The pain is usually worsened by movement of the chest wall and can often be reproduced by palpation or resisted muscle contraction.

This helps distinguish it from many intrathoracic causes.

Causes of Pleuritic Chest Pain – Note Form

Pleurisy: inflammation of the pleura causing sharp pain on inspiration.

Pneumonia: pleural irritation adjacent to infected lung produces pleuritic pain.

Pulmonary embolism: sudden pleuritic pain, often with breathlessness, tachycardia, or haemoptysis.

Pneumothorax: sudden unilateral pleuritic pain with acute dyspnoea.

Rib fracture: localized pain after trauma or coughing, worsened by breathing and reproducible on palpation.

Costochondritis: localized costosternal pain reproducible by pressure over the chest wall.

Pleural effusion: may cause pleuritic pain early, with breathlessness if the effusion is large.

Pericarditis: sharp pain worse on inspiration or lying flat and often relieved by sitting forward.

Muscular chest pain: movement-related and usually reproducible on examination.

Key Clinical Pattern

Think of pleuritic chest pain as:

Sharp pain + worse with inspiration or cough.

The main serious causes to exclude early are:

Pulmonary embolism, pneumothorax, pneumonia, and pericarditis.

Pain that is reproducible with palpation or movement is more suggestive of a musculoskeletal cause such as rib injury, costochondritis, or muscular strain, although this finding alone does not completely exclude more serious disease.