Fact-sheet: Subdural hematoma of brain
Updated on 04/09/2026 at 12:26 PM
View all RADEOS cases associated with this fact-sheet
Definition
Hematic collection located between the inner table of the dura mater and the arachnoid.
Its origin is venous (bridging veins) and results from either a direct impact or an acceleration/deceleration mechanism.
Risk factors: severe dehydration in infants, chronic alcoholism, intracranial hypotension.
Associated lesions such as subarachnoid hemorrhage, diffuse axonal injury, and intraparenchymal contusions determine the prognosis.
Clinical features
Sometimes subtle or nonspecific clinical presentation.
Headache, deficit, confusion, seizure...
Better tolerance in elderly patients with cerebral atrophy compared to younger patients.
CT
Reading window W150 HU, L70 HU
- Pericerebral or interhemispheric collection, spontaneously hyperdense, classically concave medially, very extensive and crossing suture lines, but not venous sinuses.
- Later, it becomes hypodense and may calcify peripherally.
- Possible subacute hematoma or two-stage bleeding resulting in a fluid-fluid level.
- May be bilateral
Look for signs of herniation and mass effect on the midline, and on coronal reconstructions, hyperdensities of the falx or tentorium.
MRI
Hematoma dating
- Acute (D0-D3) = isointense on T1, hypointense on T2
- Early subacute (before D7) = peripheral hyperintensity on T1 and hypointense on T2
- Late subacute (D7-D30) = hyperintense on T1 and T2 with a peripheral hypointense rim
- Chronic: hypointense on T1 and T2.
Oncologic context: look for an enhancing dural metastasis after gadolinium injection
Management
Neurosurgical emergency (evacuation via burr hole and external drainage) if:
- Thickness > 5 mm and in case of herniation with midline shift > 5 mm.
- Cerebral herniation regardless of hematoma thickness
Differential diagnosis
- Epidural hematoma: classically a biconvex hyperdense lens-shaped collection not crossing suture lines
- Widening of the subarachnoid spaces.