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?
AChronic subdural hematoma
BHigh-grade glioma
CHypertensive intracerebral hemorrhage
DEpidural hematoma
EIschemic stroke
Reveal answer & full explanation
Correct answer: A — Chronic subdural hematoma
AChronic subdural hematoma✓
BHigh-grade glioma
CHypertensive intracerebral hemorrhage
DEpidural hematoma
EIschemic stroke
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
High-grade glioma — the weeks-long progression of headache, confusion, and arm weakness with midline shift fits an enlarging tumor, but a high-grade glioma is an intra-axial parenchymal mass, often irregularly enhancing with surrounding vasogenic edema, not an extra-axial crescent-shaped collection that follows the hemispheric contour
Additional high-yield points
Treatment includes reversing anticoagulation and surgical evacuation for symptomatic SDH
Question 2NeurologyMedium
A 79-year-old man is brought in by his daughter for 2 weeks of worsening confusion, unsteady gait, and mild headache. He takes warfarin for atrial fibrillation and has fallen twice at home in the past month. Vitals are normal and he is afebrile. On exam he is drowsy with mild left-sided weakness; there is no neck stiffness. A noncontrast head CT shows a crescent-shaped hyperdensity overlying the right cerebral convexity that crosses suture lines. Which of the following is the most likely diagnosis?
AIntracerebral bleed
BIschemic infarct
CSubarachnoid bleed
DSubdural hematoma
EEpidural hematoma
Reveal answer & full explanation
Correct answer: D — Subdural hematoma
AIntracerebral bleed
BIschemic infarct
CSubarachnoid bleed
DSubdural hematoma✓
EEpidural hematoma
Why Subdural hematoma is correct
This patient has a subdural hematoma.
The core concept is that a crescent-shaped (concave) collection crossing suture lines represents blood between the dura and arachnoid from torn bridging veins.
Age-related cerebral atrophy stretches and tethers these veins so that minor trauma tears them, and warfarin impairs hemostasis once they bleed; recurrent falls provide the repeated mechanical trigger.
The subacute time course (fluctuating confusion and gait decline over 2 weeks) is classic.
Why the others are wrong
Epidural hematoma — arterial bleeding (usually middle meningeal artery) that appears as a biconvex/lens-shaped collection that does NOT cross suture lines, typically after a temporal skull fracture with a lucid interval, not the crescentic pattern here.
Subarachnoid bleed — presents with a thunderclap headache and blood in the basal cisterns/sulci, not a convexity crescent, and usually from aneurysm rupture.
Ischemic infarct — would show hypodensity in a vascular territory rather than a hyperdense extra-axial crescent, and does not explain a crescentic hyperdensity crossing sutures.
Intracerebral bleed — anticoagulation does raise the risk of intracerebral hemorrhage and fresh blood is hyperdense on noncontrast CT, but an intracerebral bleed is an intra-axial collection within the brain tissue itself, not an extra-axial crescent hugging the convexity and crossing suture lines.
On anticoagulation with atrophy and falls, subdural hematoma is the expected complication.
That's 2. Get 7,700+ more.
Unlock the full FirstPassPA bank: 7,700+ board-style questions, flashcards, and an AI tutor that explains every answer. Your 7-day free trial includes everything, and there's no credit card required.
You've read your 2 free diagnosis previews. Create your free account to unlock the full Subdural Hematoma (SDH) outline — plus all 514 diagnoses, 7,700+ board-style questions, flashcards, and an AI tutor. Your 7-day free trial includes everything, and there's no credit card required.
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
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
Feature
Subdural Hematoma
Epidural Hematoma
Source
Bridging veins (low pressure)
Middle meningeal artery (high pressure)
Shape on CT
Crescent (concave)
Lens / biconvex
Crosses suture lines
Yes
No
Crosses midline (dural reflections)
No
Yes
Onset / course
Variable — acute, subacute, or chronic
Rapid; classic lucid interval
Population
Elderly, alcoholics, anticoagulated
Young, 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 4-factor PCC (factor Xa inhibitors; andexanet alfa was withdrawn from the US market in 2025); 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
Evacuate as soon as possible once indicated (classic data: lower mortality when evacuated within 4 hours of injury)
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 — adjunct to drainage or observation that lowers recurrence/progression (EMBOLISE and STEM trials)
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)
Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.