RESUMEN
OBJECTIVE: The purpose of this investigation was to study the epidemiology of chronic and subacute subdural hematoma in an adult population and associated factors such as treatment, recurrence, seizures, complications, and outcome. METHODS: We retrospectively reviewed 267 consecutive cases operated for a suspected diagnosis of chronic or subacute subdural hematoma during a six-year period. RESULTS: An incorrect diagnosis was done in 12 of the cases (4.5 per cent) giving a total of 255 cases of chronic or subacute subdural hematoma. The mean age of the patients was 68-year old. Two-thirds of the cases were chronic and one-third were subacute. A history of head trauma was identified in 79 per cent of the patients occurring more frequently in the subacute group. The hematoma was bilateral in 16 per cent of the patients. Recurrence occurred in 7.8 per cent of the cases, but there was no significant difference between chronic and subacute cases nor the type of operation done. Postoperative seizures occurred in 6.2 per cent of the cases. Preoperative seizures are not associated to the development of postoperative seizures. A postoperative intracerebral hematoma occurred in 2.7 per cent of the patients and was associated in most of the cases with a poor outcome. The morbidity rate was 9 per cent and the mortality rate was 0.9 per cent. Outcome is good in 95 per cent of the patients. CONCLUSIONS: Chronic subdural hematoma occurs more frequently than subacute subdural hematoma. Surgical treatment modality and the use of a drain do not change the recurrence rate. Preoperative seizures are not associated to the development of postoperative seizures. The use of postoperative prophylactic antiepileptic drugs does not decrease the postoperative seizure rate even in the alcoholic patient, therefore, their prophylactic use is not indicated.