Subacute or chronic subdural hematoma is predominantly a disease of the elderly. It usually follows a minor trauma. A history of direct trauma to the head is absent in up to half the cases. The common manifestations are altered mental state and focal neurological deficit. Neurological state at the time of diagnosis is the most important prognostic factor. Morbidity and mortality is higher in the elderly but outcome is good in patients who undergo neurosurgical intervention.

Large SDH may appear lentiform or biconvex like EDH on coronal plane.