Acute subdural hematoma
Acute subdural hematoma is venous bleeding between the dura and arachnoid membrane from ruptured bridging veins, producing a crescent-shaped collection that crosses suture lines on CT. Older adults and patients with alcohol use disorder or on anticoagulation are most susceptible; a hematoma over 10 mm, a GCS under 9, or pupillary asymmetry mandate immediate surgical evacuation.
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What this article covers
- Overview
Definition: an acute subdural hematoma is a collection of venous blood between the dura mater and the arachnoid membrane, typically from rupture of the bridging veins that cross this space…
- Epidemiology
Age distribution: acute subdural hematoma occurs across all ages after significant trauma but disproportionately affects older adults, in whom cerebral atrophy increases venous vulnerability even to relatively minor trauma.
- Risk factors
Cerebral atrophy: from aging or chronic alcohol use, stretches bridging veins across an enlarged subdural space, making them more prone to shearing injury even with minor trauma.
- Pathophysiology
Bridging vein rupture: shear forces from acceleration-deceleration injury tear the veins that cross the subdural space to drain the cerebral cortex into the dural venous sinuses, releasing blood…
- Clinical features
Rapid neurologic compromise: acute subdural hematoma typically presents with coma or significant neurologic decline within hours of the inciting trauma, in contrast to the delayed presentation of chronic subdural hematoma.
- Differential diagnosis
Epidural hematoma: a lucid interval after trauma followed by rapid decline, with a biconvex, lens-shaped collection limited by suture lines on CT (rather than the crescent shape that crosses…
- Diagnosis
Acute subdural hematoma is diagnosed by noncontrast head CT showing a crescent-shaped, hyperdense extra-axial collection along the cerebral convexity that crosses suture lines, obtained emergently in…
- Management
First, secure the airway and treat hypotension and hypoxia, since normalizing oxygenation (arterial PO2 above 60 mm Hg) and blood pressure (systolic above 90 mm Hg) improves outcomes in significant traumatic brain injury.
- Complications
Transtentorial (uncal) herniation: the most feared acute complication, presenting with a dilated ipsilateral pupil and contralateral hemiparesis, requiring emergent surgical decompression.
- Prognosis
Outcome depends heavily on presenting GCS and pupillary findings: a lower GCS score and pupillary asymmetry or fixation at presentation predict substantially worse functional outcomes and higher mortality.
- Prevention
Fall-risk screening in adults 65 and older: annual gait, balance, and home-hazard assessment addresses the leading mechanism of subdural hematoma in this population, since a ground-level fall in an…
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Related articles
- Epidural hematoma
Epidural hematoma is an arterial bleed, classically from the middle meningeal artery after a temporal bone fracture, that collects between the skull and dura in a biconvex shape that does not cross suture lines; a lucid interval followed by rapid decline is classic, and a GCS below 9, anisocoria, or hematoma over 30 mL requires urgent surgical evacuation.
- Chronic subdural hematoma
A collection of liquefied blood between the dura and arachnoid that develops over weeks after often-trivial or forgotten trauma, typically in elderly or anticoagulated patients with cerebral atrophy; CT confirms the diagnosis, and burr-hole drainage is the treatment for a symptomatic hematoma with significant thickness or midline shift.
- Traumatic brain injury
Traumatic brain injury is structural or functional brain damage from biomechanical force, graded moderate (Glasgow Coma Scale 9-12) or severe (Glasgow Coma Scale 3-8) when imaging shows contusion, edema, or hemorrhage; management centers on preventing hypotension and hypoxia, controlling intracranial pressure with hyperosmolar therapy and, when refractory, decompressive craniectomy.
- Increased intracranial pressure
Sustained intracranial pressure above 20-22 mmHg from mass effect, edema, hydrocephalus, or venous outflow obstruction, diagnosed by clinical signs plus invasive monitoring and treated stepwise with head elevation, hyperosmolar therapy (mannitol or hypertonic saline), CSF diversion, and decompressive surgery when refractory.
- Intracerebral hemorrhage
Spontaneous bleeding into brain parenchyma, most often from chronic hypertension affecting deep penetrating vessels or from cerebral amyloid angiopathy in lobar locations, diagnosed by noncontrast CT and managed with acute blood pressure lowering, reversal of anticoagulation, and surgical evacuation for select cerebellar or deteriorating hemorrhages.