Neurology · PANCE / PANRE

Subdural Hematoma (SDH)

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

Bleeding between dura and arachnoid from torn bridging veins; crescent-shaped on CT.

Also known as: SDH, subdural hemorrhage, chronic subdural

Overview

Collection of blood in the potential space between the dura mater and the arachnoid mater, typically from rupture of bridging cortical veins as they cross to the dural sinuses. Classified as acute (<3 days), subacute (3 days-3 weeks), or chronic (>3 weeks) by appearance and timing.

Epidemiology

Most common in the elderly and chronic alcohol users due to cerebral atrophy stretching bridging veins. Also common in infants (suspect non-accidental trauma if no clear mechanism). Bilateral in ~15% of chronic cases.

Try two board-style Subdural Hematoma questions

Real questions from the FirstPassPA bank, with the full explanation. Pick an answer — no signup, no email.

Question 1NeurologyMedium
A 62-year-old man with a history of atrial fibrillation on warfarin (International normalized ratio (INR) 1.8) presents with progressive right-sided headache, confusion, and left arm weakness over 3 weeks. CT head shows a hypodense, crescent-shaped lesion over the right hemisphere with midline shift. Which of the following is the most likely diagnosis?
  • AIschemic stroke
  • BEpidural hematoma
  • CChronic subdural hematoma
  • DHypertensive intracerebral hemorrhage
Reveal answer & full explanation
Correct answer: C — Chronic subdural hematoma
  • AIschemic stroke
  • BEpidural hematoma
  • CChronic subdural hematoma✓
  • DHypertensive intracerebral hemorrhage

Why Chronic subdural hematoma is correct

  • Chronic subdural hematoma (SDH) presents with gradual onset symptoms over weeks, a crescent-shaped hypodense or mixed-density collection following the brain contour, and midline shift
  • It is associated with anticoagulation (even subtherapeutic INR), elderly patients, and often minor or no remembered trauma

Why the others are wrong

  • Epidural hematoma — lens-shaped (biconvex), arterial origin, and presents acutely — not chronically over weeks
  • Ischemic stroke — causes focal deficits without mass effect on CT in the acute setting
  • Hypertensive intracerebral hemorrhage (ICH) — occurs within brain parenchyma (basal ganglia, thalamus), not as an extra-axial crescent-shaped collection

Additional high-yield points

  • Treatment includes reversing anticoagulation and surgical evacuation for symptomatic SDH
Question 2NeurologyEasy
A 70-year-old male with falls develops progressive headache and confusion over 2 weeks. He is on warfarin for atrial fibrillation. CT head shows a crescent-shaped hyperdensity along the right cerebral convexity crossing suture lines. Which of the following is the most likely type of hemorrhage?
  • ASubdural hematoma
  • BIntracerebral hemorrhage
  • CEpidural hematoma
  • DSubarachnoid hemorrhage
Reveal answer & full explanation
Correct answer: A — Subdural hematoma
  • ASubdural hematoma✓
  • BIntracerebral hemorrhage
  • CEpidural hematoma
  • DSubarachnoid hemorrhage

Why Subdural hematoma is correct

  • Subdural hematoma (SDH) results from rupture of bridging veins between the cortex and dural sinuses
  • CT appearance: crescent-shaped collection that CROSSES suture lines (not bound by sutures)
  • Risk factors: elderly patients (brain atrophy stretches bridging veins), anticoagulants, alcoholism, falls
  • Acute SDH is hyperdense on CT; chronic SDH (>2 weeks) is hypodense

Why the others are wrong

  • Epidural hematoma — lens-shaped (biconvex), DOES NOT cross suture lines; caused by middle meningeal artery injury from temporal bone fracture; classic lucid interval
  • Subarachnoid hemorrhage (SAH) — presents as "worst headache of life," star-shaped blood at the base of the brain, typically from a ruptured aneurysm
  • Intracerebral hemorrhage (ICH) — parenchymal bleeding, often in the basal ganglia from chronic hypertension (HTN)
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Risk factors

  • Advanced age (cerebral atrophy)
  • Chronic alcohol use (atrophy + coagulopathy)
  • Anticoagulant or antiplatelet therapy
  • Coagulopathy, thrombocytopenia
  • Falls in elderly (often unwitnessed and minor)
  • Cerebrospinal fluid hypotension (post-LP, post-shunt, spontaneous intracranial hypotension)
  • Recent head trauma (any severity)
  • Infant with suspected abusive head trauma (shaken baby — bilateral SDH + retinal hemorrhages)

Pathophysiology

Acceleration-deceleration forces tear bridging veins crossing the subdural space, allowing low-pressure venous blood to accumulate. In the elderly with atrophy, bridging veins are stretched and tear with minor trauma. Hematoma may stabilize (chronic SDH) or expand by repeated small bleeds from neomembranes — leading to delayed presentation weeks after the inciting injury.

Clinical presentation

Symptoms

  • Acute SDH: history of significant trauma, immediate decreased consciousness, headache, vomiting
  • Chronic SDH: insidious onset over weeks-months of headache, cognitive decline, mild hemiparesis, gait disturbance — often mistaken for dementia or stroke
  • Subacute SDH: intermediate course (days to weeks)
  • Elderly may have NO recalled trauma

Signs / physical exam

  • Variable depending on size and chronicity
  • Focal deficits: contralateral hemiparesis, aphasia, gaze deviation
  • Pupillary abnormalities (uncal herniation in large acute SDH)
  • In chronic SDH: subtle confusion, gait apraxia, mild hemiparesis
  • Signs of elevated ICP if large

Classic findings

Crescentic (concave/'moon-shaped') extra-axial collection on CT that crosses suture lines. Acute = hyperdense (white), subacute = isodense (may be subtle), chronic = hypodense (dark).

Differential diagnosis

  • Epidural hematoma — Lens-shaped (biconvex), respects suture lines, arterial source (middle meningeal artery), classic lucid interval, rapid deterioration
  • Intraparenchymal hemorrhage — Within brain substance, hypertensive deep bleeds or lobar amyloid bleeds
  • Cerebral atrophy with subdural hygroma — CSF density, no blood; common in elderly
  • Dementia / delirium — Mimics chronic SDH in elderly with cognitive decline; CT excludes
  • Stroke — Acute focal deficit; CT differentiates ischemic from hemorrhagic
  • Meningioma — Slow-growing, may cause similar cognitive/focal symptoms; contrast enhancement

Diagnostic workup

Labs

  • CBC, platelets, PT/INR, PTT — anticoagulation common in this population
  • BMP, LFTs
  • Type and screen if surgical intervention likely

Imaging

  • Non-contrast head CT — first-line, identifies acute SDH easily
  • Subacute (isodense) SDH may be missed on CT; contrast or MRI helpful
  • MRI — most sensitive for small or chronic SDH and dating the bleed
  • Repeat CT in 6-24 h if patient deteriorates or has progressive symptoms

Diagnostic algorithm

FeatureSubdural HematomaEpidural Hematoma
SourceBridging veins (low pressure)Middle meningeal artery (high pressure)
Shape on CTCrescent (concave)Lens / biconvex
Crosses suture linesYesNo
Crosses midline (dural reflections)NoYes
Onset / courseVariable — acute, subacute, or chronicRapid; classic lucid interval
PopulationElderly, alcoholics, anticoagulatedYoung, after temporal blow
Subdural vs. epidural hematoma comparison.

Treatment

First-line

  • ABCs; intubate if GCS ≤8
  • Reverse anticoagulation: warfarin → 4-factor PCC + vitamin K 10 mg IV; DOACs → idarucizumab (dabigatran) or andexanet alfa / 4-factor PCC (factor Xa inhibitors); aspirin/clopidogrel — platelet transfusion controversial
  • BP control (avoid hypotension; target SBP <160 in acute SDH)
  • Manage ICP: head of bed 30°, normocapnia, hypertonic saline or mannitol if herniation signs
  • Seizure prophylaxis (short-course levetiracetam) commonly used in acute SDH

Acute SDH — Surgical

  • Craniotomy with hematoma evacuation if: thickness >10 mm, midline shift >5 mm, GCS deterioration, or pupil asymmetry
  • Best outcomes with surgery within 4 hours of deterioration

Acute SDH — Conservative

  • Small, thin, asymptomatic SDH: serial neuro exams, repeat CT, close monitoring in ICU

Chronic SDH

  • Burr hole drainage with subdural drain (preferred, lower morbidity than craniotomy)
  • Twist-drill craniostomy is an alternative
  • Middle meningeal artery embolization — emerging adjunct or alternative (EMBOLISE trial 2024)
  • Conservative management if asymptomatic and small

Second-line / adjunct

  • Discontinue antiplatelet/anticoagulant therapy and reassess risk-benefit
  • Address underlying coagulopathy and cause (fall prevention, alcohol cessation)
  • Avoid restarting anticoagulation prematurely after SDH (typical delay 4-8 weeks, individualized)

Complications

  • Cerebral edema and herniation
  • Recurrence (especially chronic SDH, ~10-20% after burr hole drainage)
  • Seizures (early or late)
  • Persistent cognitive deficits, dementia
  • Subdural empyema if infected
  • Surgical complications: bleeding, infection, tension pneumocephalus

PANCE pearls

  • Crescent shape and crossing of suture lines differentiates SDH from epidural hematoma on CT.
  • In elderly patient with insidious cognitive decline or new gait disorder — get a CT to rule out chronic SDH ('great masquerader of dementia').
  • Bilateral SDH may not produce midline shift but can still cause significant pressure — measure thickness, not just shift.
  • Subacute SDH (1-3 weeks) is isodense to brain on CT — easily missed; use MRI or contrast CT.
  • Infant SDH + retinal hemorrhages + no trauma history → suspect abusive head trauma.

References

  • Brain Trauma Foundation 2017 — Guidelines for the Management of Severe Traumatic Brain Injury (Carney et al., Neurosurgery 2017, 4th edition)
  • EMBOLISE Trial — Middle Meningeal Artery Embolization for Chronic Subdural Hematoma (Liu et al., NEJM 2024)
  • Surgical Guidelines — Surgical Management of Acute Subdural Hematomas (Bullock et al., Neurosurgery 2006)

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Commonly confused with

vs Epidural Hematoma

Related Neurology diagnoses

Ischemic StrokeHemorrhagic (Intracerebral) StrokeTransient Ischemic Attack (TIA)Subarachnoid Hemorrhage (SAH)Epidural Hematoma (EDH)Concussion / Mild Traumatic Brain InjuryMigraineTension-Type HeadacheCluster HeadacheSeizures and EpilepsyStatus EpilepticusMultiple SclerosisGuillain-Barré SyndromeMyasthenia Gravis

Differentials & related conditions

Brain Tumors (Primary and Metastatic)

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