Abstracts

RATIONALE: Subdural hematoma is an infrequent but recognized complication of invasive electrode monitoring for epilepsy surgery. CT scan has been the standard imaging study to diagnose subdural hematoma. We report two cases where patients deteriorated during intracranial EEG monitoring and were found to have subdural hematoma at operation not identified on CT scan preoperatively or following retrospective review. METHODS: Two out of 61 patients undergoing intracranial monitoring with subdural grid and strip electrodes complained of severe headaches, one of which was associated with decreased level of consciousness. Patients underwent CT scanning to evaluate for these complaints. RESULTS: Review of the CT scans by a neuroradiologist did not show visible evidence of subdural hematoma in either patient but possible subarachnoid in one after retrospecitve review. MRI did confirm the presence of subdural hematoma in one of these patients. Subdural grid recording during this period revealed reduce voltage of EEG activity. Both patients had craniotomy reopened and subdural hematoma was found underlying the grid with one clot noted to be 6 by 3 by 2 cm in size, and both clots accounted for patients' clinical deterioration. Subdural hematoma was evacuated and grid was removed. No other complications were noted. CONCLUSIONS: CT scan was not a good method to diagnose subdural hematoma in these two patients. In the presence of clinical signs and/or EEG changes that may suggest the presence of subdural hematoma, MRI may be a better choice than CT to confirm the presence of this pathology in patients with intracranial electrode monitoring.