Side-by-side
| Subdural hematoma | Epidural hematoma | |
|---|---|---|
| Location | Beneath the dura | Between skull and dura |
| Classic vessel | Bridging veins | Middle meningeal artery (often) |
| CT shape | Crescent | Lens / biconvex |
| Sutures | Can cross suture lines | Typically limited by sutures |
| Dural folds | Stopped by falx and tentorium | Can cross the midline more readily |
| Typical setting | Any age; chronic form common in older adults | Often younger patients with skull fracture |
These are teaching patterns. Mixed or atypical collections occur. The images plus the exam decide care.
Why the shapes differ
Subdural blood can spread freely under the dura, so it layers in a crescent. Epidural blood is trapped between skull and a dura that is tightly adherent at the sutures, so it tends to balloon into a lens. That geometry is why a radiology report may mention “crescentic extra-axial collection” or “lentiform hematoma.”
Typical course
Epidural hematoma is classically an acute arterial emergency after skull fracture, sometimes with a lucid interval. Acute subdural hematoma is also an emergency when it expands. Chronic subdural hematoma is a different biology—weeks of membrane formation and possible recurrence—and is the setting for MMA embolization.
Confusingly, the middle meningeal artery is involved in both stories: it is the classic source of epidural bleeding when torn after fracture, and it is the artery whose branches are embolized to treat chronic subdural membranes. Same vessel, different diseases, different procedures.
Why symptoms still overlap
Headache, confusion, weakness, and declining alertness are not unique to either bleed. Call 911 for emergency symptoms. Do not try to distinguish subdural from epidural at home.
Sources & further reading
Educational content from Neurovascular Centers. Individual treatment decisions require a clinical examination and review of your imaging.