Pathology - Intracerebral Haemorrhage (ICH)

Pathology - Intracerebral Haemorrhage (ICH)
I. Definition:

Spontaneous (non-traumatic) bleeding into the brain tissue. Crucially, this differentiates it from other types of strokes.

II. Epidemiology:

Accounts for approximately 20% of all strokes.
Predominantly affects individuals in late middle age. Note the age range for highest risk.

III. Aetiology (Causes):

Hypertension (High Blood Pressure): This is the most frequent cause. Understand the strong link between uncontrolled hypertension and ICH.
Less Common Causes: These are important to remember for differential diagnosis:
- Cerebral amyloid angiopathy (CAA)
- Ruptured arteriovenous malformation (AVM)
- Coagulation disorders (problems with blood clotting)

IV. Pathogenesis (Mechanism):

Hypertension-related ICH: Mostly caused by the rupture of Charcot-Bouchard microaneurysms (small, weakened areas in blood vessels). Focus on understanding this key mechanism.
Haematoma Formation: The resulting blood clot (hematoma) destroys brain tissue and rapidly increases intracranial pressure (ICP). This pressure increase is the primary cause of morbidity and mortality.

V. Clinical Presentation:

Sudden Onset: The symptoms appear abruptly.
Focal Neurological Deficits: Symptoms depend on the location of the bleed. Remember that the location dictates the specific neurological symptoms.
Raised Intracranial Pressure (ICP) Symptoms: These are common and can include headache, vomiting, altered consciousness.
Mortality Risk:
- Large hemorrhages can cause death rapidly due to high ICP and herniation (brain tissue displacement).
- Even small hemorrhages in vital brainstem areas (controlling breathing and heart rate) can be fatal.

VI. Macroscopic Findings (Gross Examination):

Haematoma: Visible blood clot replacing brain tissue.
Mass Effect: The hematoma pushes on surrounding brain structures, causing midline shift and potentially herniation.
Location:
- Hypertensive bleeds: Usually in basal ganglia, internal capsule, pons, or cerebellum.
- Other cause bleeds: More likely to be in the lobes (lobar). This helps in differential diagnosis.

VII. Histopathological Findings (Microscopic Examination):

Early Stages: Blood clot surrounded by brain tissue with hypoxia (lack of oxygen) and edema (swelling).
Later Stages: Reactive astrocytes (glial cells) proliferate, and the damaged area organizes similarly to an infarct (area of dead tissue from lack of blood supply).

VIII. Prognosis:

High Mortality Rate: >40% mortality due to the devastating effects of raised intracranial pressure. This highlights the seriousness of ICH.

Key Concepts to Master:

Relationship between hypertension and ICH: This is the cornerstone of understanding this condition.
Pathophysiology of haematoma formation and its consequences: Understand the chain of events leading to increased ICP and potential death.
Clinical presentation variations based on location: Different areas of the brain will cause different symptoms.
Differential diagnosis based on location and etiology: Knowing the likely cause based on the location of the hemorrhage.

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