Intracranial hemorrhages

1. Overview

Intracranial hemorrhage is bleeding within the skull; each location has characteristic causes. All are a hemorrhagia per rhexim type — bleeding from a ruptured vessel, due to altered wall pressure or trauma. The four major sites are epidural, subdural, subarachnoid, and intraparenchymal.

Type	Vessel	Trigger	CT shape / clue
Epidural	Middle meningeal artery	Temporal bone fracture	Lens (biconvex); lucid interval
Subdural	Bridging veins	Trauma; brain atrophy	Crescent (concave); slow onset
Subarachnoid	Berry aneurysm / AVM	Spontaneous rupture	“Worst headache of life”
Intraparenchymal	Charcot–Bouchard microaneurysm	Chronic hypertension	Basal ganglia / thalamus / pons

2. Apoplexia (intraparenchymal hemorrhage)

• Bleeding into brain parenchyma, related to hypertension (BP >200 mmHg is a rupture risk).
• Rupture of intraparenchymal vessels in the basal ganglia, thalamus, pons.
• Hypertension produces Charcot–Bouchard microaneurysms in small vessels; hyaline arteriolosclerosis makes the wall fragile.
• Bleeding → ↑ ICP → compression of cardiorespiratory centers → tonsillar herniation through the foramen magnum → cardiorespiratory failure → death.

3. Subarachnoid hemorrhage

• Bleeding into the subarachnoid space.
• Non-traumatic rupture of a saccular (berry) aneurysm of cerebral arteries; branching points of the circle of Willis are most aneurysmal.
• Arterial “jet-stream” bleeding → acute ↑ ICP → sudden, excruciating headache.
• A “ticking time bomb” — unpredictable timing; typically presents at 40–50 years as hypertension rises.

4. Subdural hematoma

• Bleeding into the subdural space from torn bridging veins of the dural sinuses.
• Brain atrophy in the elderly stretches these veins, increasing rupture risk (also infants — shaken-baby).
• Two forms:
  • Acute — car accidents, sudden trauma.
  • Chronic — long-term repeated trauma (boxing) → repeated bleeding → fibrosis around the meninges → neurological symptoms.

5. Epidural hematoma

• Associated with skull fracture. The dura is normally fused tightly to the inner skull (periosteum).
• The middle meningeal artery runs between dura and skull; a temporal bone fracture can rupture it → blood separates dura from periosteum → hematoma compresses the brain.
• Lucid interval — the classic clinical course: unconscious (impact) → conscious recovery → bleeding raises ICP → unconscious again. Alcoholics are more susceptible due to impaired protective reflexes.

💡 High-yield: Epidural = arterial (middle meningeal a.), biconvex/lens shape, lucid interval. Subdural = venous (bridging veins), crescent shape, elderly/atrophy. Subarachnoid = berry aneurysm, thunderclap headache. Intraparenchymal/apoplexia = hypertension + Charcot–Bouchard aneurysms, basal ganglia.