Subdural fluid collection following craniotomy.

The occurrence of subdural fluid collection following craniotomy for intracranial aneurysms was studied with regard to the patient's age, preoperative grade, external decompression, incidence of the craniotomy, external drainage, and ventriculoperitoneal shunt. The following results and conclusions were obtained: Enlargement of the subdural space was observed in 76 of 147 patients (51.7%). The patient's age was the most likely causative factor in producing the lesion. Six patients required surgical management for the collection: three were for subdural hygroma and three were for chronic subdural hematoma. It is estimated that two factors, multiple craniotomy and younger age, accelerated the formation of symptomatic subdural hygromas. When the patient complains of headache or motor weakness 1 or 2 months after undergoing a craniotomy, one should suspect chronic subdural hematoma, especially in an elderly patient with ruptured aneurysm.