The condition has a high death rate, even with prompt treatment because of uncontrollable rapid increase in intracranial pressure. Subacute subdural hematoma may result in death or in permanent brain damage if untreated or, in some cases, even if treated. Symptoms such as seizures may persist for several months after treatment. Seizures may begin as late as 2 years after the injury. In adults, most recovery occurs in the first 6 months, with some improvement over approximately 2 years.
Children usually recover more quickly and completely than adults.
Incomplete recovery is the result of permanent brain damage.