![]() Kembara Xtra - Medicine -Horner Syndrome The typical triad of ipsilateral miosis, eyelid ptosis, and anhidrosis of the ipsilateral face and/or neck (with iris heterochromia in children) characterizes Horner syndrome, a collection of neurological signs and symptoms. It is brought on by a breakdown in the innervation of the head, neck, and eye by the sympathetic nervous system. System(s) impacted: exocrine, nervous Alternative names for the condition include Bernard-Horner syndrome, Bernard syndrome, Horner syndrome, cervical sympathetic syndrome, oculosympathetic syndrome, oculosympathetic deficit, and oculosympathetic paresis. Epidemiology There is no dominant age. Male = female is the dominant sex. Incidence With a birth frequency of 1 in 6,250 for those with congenital onset, the estimated incidence of pediatric Horner syndrome in children under the age of 19 is 1.42 per 100,000. The prevalence among adults is unknown. Prevalence Unknown Pathophysiology and Etiology Oculosympathetic pathway anatomy: - First-order neuron: Sympathetic nerve fibers emerge from the hypothalamus, pass through the brainstem, and converge at the Budge-Waller ciliospinal center, which is positioned between the spinal cord's C8 and T2 levels. Third-order neurons ascend along the adventitia of the internal carotid artery, through the cavernous sinus in close proximity to cranial nerve (CN) VI and the trigeminal ganglion, and join the nasociliary branch of CN V1 to enter the orbit, innervating it. Second-order neurons exit the spinal column, arch over the apex of the lung and under the subclavian artery, ascending to the superior cervical ganglion Due to a lack of sympathetic input to the orbit, a lesion affecting the sympathetic chain's first, second, or third order neurons may result in Horner syndrome's signs and symptoms. - Ptosis: Sympathetic innervation to the Müller muscle in the upper eyelid and the lower eyelid retractors helps to maintain appropriate eyelid posture. The upper lid (ptosis) and lower lid (reverse ptosis) may exhibit a modest ptosis when sympathetic innervation to these regions is disrupted. This ptosis could be slight, frequently 2 mm or less. - Meiosis: In response to stimulation from the sympathetic nervous system, the radially orientated pupillary dilator muscle dilates the pupils. In low light, aniscoria will be more noticeable as a result of the affected eye's impaired ability to dilate. Normal pupil constriction in reaction to light will occur in the damaged eye, although it will do so more slowly than the unaffected pupil. - Anhidrosis: If it's present, anhidrosis can help pinpoint where a lesion is. Before the superior cervical sympathetic ganglia, sympathetic fibers that supply the lower face's sweat glands and vasodilator muscles split off and follow the external carotid artery. Anhydrosis of the upper and lower face is more likely to result from lesions that damage primary and secondary neurons. The best way to categorize the etiologies of Horner syndrome is by the sympathetic chain neuron that is affected (first, second, or third order), as well as by age (pediatric vs. adult). ● Etiologies in adults: – First-order neuron lesions located in hypothalamus/brainstem (lateral medulla)/spinal cord (cervico-thoracic) include: ○ Arnold-Chiari malformation, basal meningitis (e.g., syphilis), cerebral vascular accident: lateral medullary (Wallenberg) syndrome, cervical cord trauma, cervical spondylosis, demyelinating disease (multiple sclerosis), Intrapontine hemorrhage, neck trauma, syringomyelia/syringobulbia, tumor (basal skull, pituitary), unintended subdural placement of lumbar epidural catheter – Second-order neuron pulmonary or cervico-thoracic lesions include: ○ Aneurysm/dissection of aorta, central venous catheterization, chest tubes, 1st rib fracture, lymphadenopathy (Hodgkin, leukemia, tuberculosis, sarcoid), mandibular tooth abscess, neuroblastoma, Pancoast tumor or infection of lung apex, proximal common carotid artery dissection, thoracic outlet obstruction (cervical rib, subclavian artery aneurysm), trauma/surgical injury, tumor (thyroid, mediastinum) – Third-order neuron lesions located in superior cervical ganglion, internal carotid artery, skull base, cavernous sinus, or orbit include: ○ Carotid cavernous fistula or other pathology, carotid endarterectomy or carotid artery stenting, cluster headaches/paroxysmal hemicrania, internal carotid artery dissection, herpes zoster, lesions of the middle ear (acute otitis media), Lyme disease, tumor (nasopharyngeal, pituitary, paratrigeminal, metastasis, skull base), tonsillectomy, trauma/surgical injury, raeder paratrigeminal syndrome The most frequent etiologies in infants are birth trauma and neck trauma (brachial plexus injury). Neuroblastoma, brainstem glioma, vascular abnormalities, neck/chest surgery, and idiopathic genetics Rare autosomal dominant inheritance Risk Elements Recent head, neck, and thorax trauma (such as from car accidents) Pancoast tumor (smoking) A known aneurysm of the subclavian or carotid arteries Known cancer, mass, or tumor Previous thoracic/neck surgery Prior head, neck, and thoracic instrumentation (chest tube, central venous catheterization) Cluster head pain Introducing History When did the symptoms start? (Chronic vs. Acute) Any visible signs? (diplopia, hazy vision, field loss, temporary visual loss) Previous eye-related history? (eye surgery, injury) Are there signs that correspond to pain? (ipsilateral head/neck/face) A recent head or neck injury? Recently performed operations? Do you experience any headaches? Any further neurologic symptoms? Does the severity of ptosis change throughout the day or with weariness? Is there any unusual sweating or facial flushing on one side? Child Safety Considerations Loss of face flushing is valued more in babies and young children than anhidrosis (the harlequin sign, in which the affected side may appear pale due to denervation supersensitivity to circulating adrenaline). A child with new-onset, non-traumatic Horner syndrome has to be checked for neuroblastoma. Alert When there is discomfort, Horner syndrome justifies an urgent evaluation and referral to the emergency room. Even in the absence of evident head/neck injuries, consider carotid artery dissection when experiencing acute, ipsilateral facial or neck pain until otherwise confirmed. - Pain from dissection typically affects the orbit and temple. A patient may also develop dysgeusia and amaurosis fugax. A potential complication is stroke, which could be overlooked. A Pancoast tumor or cervical cord lesion may be the cause of axial, shoulder, scapular, arm, or hand pain. A middle cranial fossa mass or cavernous sinus lesion is suspected in Raeder paratrigeminal syndrome type I, which includes orbital discomfort, miosis, and ptosis along with ipsilateral lesions of CN III to VI. - Type II Raeder paratrigeminal syndrome: miosis, ptosis, and episodic retrobulbar or orbital discomfort without CN lesions; suspect migraine variant. clinical assessment Determine whether anisocoria is present by measuring the pupillary diameter in both bright and low conditions. Anisocoria will be more pronounced in Horner syndrome patients under low light conditions. - Measure the accommodating and light-responsiveness of the pupil. - There may be a pupillary dilation lag, and the afflicted pupil may dilate gradually 5–15 seconds after being exposed to light. Examine the top lids for ptosis (which is frequently less than 2 mm). - A "reverse ptosis" of the lower lid, manifested as a small elevation of the lower lid in relation to the unaffected eye, may also be seen. Assessing for anhidrosis may be challenging. Skin flushing on the affected side is one of the subtle indications of anhidrosis. Constriction of the nasal passages and ipsilateral conjunctival injection are possible additional acute signs of sympathetic disruption. In congenital Horner syndrome, the iris shows reduced pigmentation, blue-gray, and mottling of the affected eye (heterochromia iridis), as iris pigment formation early in life is under sympathetic control. Biomicroscopic/slit lamp examination of the eye, including iris structure and color (if available). Nystagmus, facial swelling, lymphadenopathy, or vesicular eruptions should all be kept an eye out for. a thorough examination of the cranial nerves paying close attention to extraocular motions Checking the neck with a fingertip for any lumps or signs of trauma Chest and neurological examinations for any related physical findings Multiple Diagnoses Physiologic anisocoria (20% population) - Physiologic variation may vary during the day and frequently fluctuates by less than 1mm. Neurologic conditions as opposed to disorders of the neuromuscular junction (myasthenia gravis, botulinum toxin) Third nerve paralysis Adoneurotic ptosis Prenatal ptosis Adie tonic student Sympathetic vs. parasympathetic intermittent unilateral pupillary mydriasis The iris sphincter muscle was injured. Pharmacologic causes include the unilateral use of mydriatics or miotics, acetophenazine, alseroxylon, bupivacaine, butaperazine, carphenazine, chloroprocaine, deserpidine, diacetylmorphine, ethopropazine, etidocaine, guanethidine, influenza vaccine, levodopa, lidocaine, mepivac Laboratory Results Initial examinations (lab, imaging) Lab tests to rule out neuroblastoma in pediatric patients include CBC, FTA-ABS, VDRL, pure protein derivative, vanillylmandelic acid (VMA), and homovanillic acid I (HVA). The sympathetic nervous system's extensive route makes imaging considerations special. Horner syndrome may start at any point along this circuit, which runs from the hypothalamus all the way down to T2. In the evaluation of a patient with Horner syndrome, doctors should try to follow three steps: - A clinical diagnosis of Horner syndrome; - Pharmacological confirmation of Horner syndrome; - In the chronic setting, a single neuroimaging study of the oculosympathetic pathway extending from the hypothalamus down to T2 with a contrast-enhanced MRI, with or without MRA of the head and neck; - In the acute setting (or for patients unable With this initial CT/CTA, Horner syndrome life-threatening causes, such as carotid artery dissection, can be checked out to prevent therapeutic delays (1)[B]. Pediatric Considerations Brain, neck, and chest MRIs as described above are suitable in children of any age who don't have any contributing medical history. If the clinical suspicion of neuroblastoma is high, clinicians may also consider an MRI of the abdomen. The safety of MRI for the fetus in the population of pregnant women has not yet been demonstrated. The majority of authors agree that pregnant patients can have an MRI without any risks, but it should be emphasized that contrast agents like gadolinium fall within FDA category C (1)[B]. Other/Diagnostic Procedures A confirmation test is necessary to determine the presence of Horner syndrome. While the third test (hydroxyamphetamine) aims to identify the lesion, the first two tests—apraclonidine and cocaine—help to confirm the presence of Horner syndrome. In most cases, testing with both apraclonidine and cocaine is not essential, and most people opt for apraclonidine because getting cocaine drops is difficult. Topical apraclonidine drops, 0.5% Apraclonidine has little to no effect on the normal pupil and is a potent alpha-2 agonist and modest alpha-1 agonist. testing the dilator muscle of the pupil for denervation supersensitivity. After a break in sympathetic input, this develops. The supersensitive Horner pupil can be dilated by very minimal alpha-1 agonist action. One drop of apraclonidine is injected into each eye to check for Horner syndrome, and the patient is then reevaluated 60 minutes later. A positive test result happens when the affected pupil grows to be the larger one or when both pupils are the same size. It should be noted that the apraclonidine test might not be positive in cases of recent trauma because denervation hypersensitivity hasn't yet developed (2–5 days). Use with caution in infants under six months old since alpha-2 activity can lead to respiratory depression. Cocaine testing may be considered in this age range - 4-10% topical cocaine drops: Cocaine prevents norepinephrine from being reabsorbed from the synaptic cleft. Two drops of 4% or 10% cocaine are injected into each eye five minutes apart to test for Horner syndrome, and the pupils are then reassessed 40 to 60 minutes later. Drops of cocaine will cause the normal pupil to enlarge. Due to the lack of norepinephrine at the third-order neuron's nerve ends, the miotic pupil in Horner syndrome (independent of the location of the lesion) will not dilate or dilate inadequately after 45 minutes (2)[A]. Topical 1% hydroxyamphetamine drops (2)[A] Used to distinguish between preganglionic (first and second order neurons) and postganglionic (third order neuron) Horner syndrome. Positive test is anisocoria of less than 1 mm. The release of endogenous norepinephrine from the postganglionic neuron by hydroxyamphetamine results in dilated pupils. The pupils should be assessed an hour after the 1% hydroxyamphetamine drops are administered. Both pupils dilating suggests a first- or second-order neuronal injury. Poor or absent pupil dilation is a sign of a third-order neuron injury; the test is considered positive when anisocoria rises by at least one millimeter. There is no pharmacologic test that can tell a first-order neuron injury from a second-order neuron lesion. There must be a 24- to 72-hour gap between the cocaine and hydroxyamphetamine tests because cocaine can impair hydroxyamphetamine uptake and affect the test's accuracy. Pediatric Considerations The hydroxyamphetamine test is not accurate in minors due to transsynaptic degeneration. Management The focus of treatment is typically on any underlying causes. If symptoms have persisted for 12 months and life-threatening causes have been ruled out, cosmesis or functional visual impairment brought on by ptosis may be addressed. Medication Thrombolysis, antithrombotic therapy along with anticoagulation, and antiplatelet therapy are pharmacologic alternatives for treating carotid artery dissection. These therapeutic alternatives have not been compared in any randomized control studies. Referral Referrals to neurosurgery, oncology, interventional radiology, pulmonology, neurology/neuro-ophthalmology, and oculoplastic surgery may be made depending on the cause of Horner syndrome. Surgical Techniques Surgical treatment based on the underlying cause If symptoms have continued for 12 months or if functional visual impairment as a result of ptosis has occurred, consider ptosis repair (oculoplastics). Prognosis Postganglionic: often harmless Preganglionic and central lesions have a worse prognosis Complications Chronic constriction of the pupils The Cosmesis
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