STEPTRACKERNERVOUS SYSTEM | PATHOLOGY + ANATOMY | HIGH-YIELD REVIEW

Intracranial Hemorrhage & Head Trauma

Bleeding above the dura, below it, in the subarachnoid space or into the brain itself — each with its own vessel, shape and story.

FOCUS ON

Epidural: middle meningeal artery, temporal fracture, lucid interval, biconvex, doesn't cross sutures. Subdural: bridging veins, elderly/alcoholics/shaken infants, crescent, crosses sutures. Subarachnoid: berry aneurysm, "worst headache," xanthochromia, vasospasm (nimodipine). Hypertensive bleeds: Charcot-Bouchard aneurysms in the basal ganglia. Amyloid angiopathy: lobar bleeds in the elderly.

PICTURE

LESION

VESSEL · MECHANISM

FEATURES

CLUE

How to read: axial slice of the head, front at the top. Thick outer ring = skull; gray = lateral ventricles; thin line = falx. Red = blood.

Epidural hematoma

Middle meningeal artery (from maxillary) torn by a pterion (temporal bone) fracture

Brief LOC → lucid interval → rapid decline; biconvex lens-shaped; doesn't cross sutures

Transtentorial herniation, CN III palsy · emergency evacuation

Subdural hematoma

Torn bridging veins (cortex → dural sinus) with acceleration–deceleration

Crescent-shaped; crosses sutures, not the falx; acute (hyperdense) or chronic (weeks, hypodense, slow confusion)

Elderly (atrophy), alcoholics, anticoagulants, shaken baby

Subarachnoid hemorrhage

Ruptured saccular (berry) aneurysm (ACom most common) or AVM; trauma

Sudden "worst headache of my life," neck stiffness, LOC; noncontrast CT → LP if negative: xanthochromia

Nimodipine prevents vasospasm

SAH — complications

Blood irritates vessels and blocks CSF absorption

Vasospasm (days 3–10) → delayed ischemia; rebleeding; communicating hydrocephalus; hyponatremia (SIADH, salt wasting)

Secure the aneurysm (coil or clip)

Berry aneurysm risk

Congenital weakness of the media at circle of Willis branch points

ADPKD, Ehlers-Danlos, Marfan, coarctation, smoking, hypertension

PCom aneurysm → CN III palsy with dilated pupil

Hypertensive intraparenchymal hemorrhage

Chronic HTN → Charcot-Bouchard microaneurysms of lenticulostriate and other small penetrating vessels

Putamen/basal ganglia (most), thalamus, pons (coma, pinpoint pupils), cerebellum (ataxia, vomiting)

Same vessels as lacunes

Cerebral amyloid angiopathy

β-amyloid deposits in cortical/leptomeningeal vessel walls → fragile

Recurrent lobar hemorrhages in the elderly; microbleeds

Associated with Alzheimer disease

Other causes of brain hemorrhage

Abnormal vessels, coagulopathy, drugs, tumors

AVM (young), anticoagulants, cocaine/amphetamines, hemorrhagic metastases (melanoma, RCC, choriocarcinoma, thyroid), GBM, hemorrhagic transformation

Young normotensive bleed → AVM or drugs

Germinal matrix hemorrhage

Fragile vessels of the germinal matrix in premature infants

< 32 weeks, < 1500 g; intraventricular bleeding in the first 72 h

Hydrocephalus, cerebral palsy

Diffuse axonal injury

Rotational acceleration–deceleration shears axons

Coma after trauma with a near-normal CT; MRI: punctate bleeds at gray–white junction, corpus callosum, brainstem

Axonal swellings (retraction balls)

Cerebral contusion

Brain strikes the skull: coup (impact site) and contrecoup (opposite side)

Frontal and temporal poles

Hemosiderin-stained old scars

Mechanism — why the shapes differ

Arterial bloodBetween skull and dura

→

Dura stuck at sutures

→

Biconvex, fastEpidural

Venous bloodBetween dura and arachnoid

→

Spreads along the convexity

→

Crescent, slowerSubdural

Subarachnoid blood fills sulci and cisterns; intraparenchymal blood forms a round hematoma with surrounding edema.

Epidural vs subdural

FEATURE

EPIDURAL

SUBDURAL

Vessel

Middle meningeal artery

Bridging veins

Injury

Temporal bone fracture

Shearing; minor trauma in elderly

Shape

Biconvex (lentiform)

Crescent

Sutures

Doesn't cross

Crosses

Falx / tentorium

Can cross

Doesn't cross

Course

Lucid interval → rapid decline

Gradual (chronic) or acute

How it's tested

COMMON CONFUSIONA CN III palsy from aneurysm compression dilates the pupil (parasympathetic fibers sit on the outside); a diabetic CN III palsy spares the pupil.

THE TRAPA normal CT doesn't end the SAH workup if the headache began more than 6 hours ago — do an LP and look for xanthochromia.

YOUR APPROACHTrauma or spontaneous → age and BP → imaging shape and location → vessel → complication (herniation, vasospasm, hydrocephalus) → treatment.

If you see… think…

Hit by a baseball, brief LOC, talks normally, then collapses → epidural hematoma

Older alcoholic, weeks of confusion after a fall, crescent on CT → chronic subdural

Infant with retinal hemorrhages and subdural bleeding → abusive head trauma

Thunderclap headache with neck stiffness → subarachnoid hemorrhage

New neuro deficit a week after SAH → vasospasm — nimodipine

ADPKD patient with sudden severe headache → ruptured berry aneurysm

Ptosis, eye down and out, dilated pupil, headache → PCom aneurysm

Hypertensive with sudden hemiparesis and putaminal bleed → Charcot-Bouchard rupture

85-year-old with repeated lobar hemorrhages → cerebral amyloid angiopathy

Comatose after a car crash, CT nearly normal → diffuse axonal injury