Abstracts

Rationale: Status epilepticus (SE) is not an infrequent occurrence in hospitalized patients, especially those that are critically ill. Non-convulsive status epilepticus occurs commonly in association with many neurosurgical conditions such as subarachnoid hemorrhage, traumatic brain injury, and hypertensive intracerebral hemorrhage to name a few. While seizures have been reported in association with posterior fossa lesions, the rate of occurrence of status epilepticus in hospitalized patients with posterior fossa lesions is not known. Therefore we undertook this investigation to determine the prevalence and causes of status epilepticus in patients with posterior fossa lesions. Methods: Retrospective review of an inpatient database was conducted to identify patients with posterior fossa lesions that were admitted to St Joseph’s Hospital and Medical Center between April, 2007 and May, 2008. Of these, patients who had status epilepticus were determined by cross referencing with the EEG database. Review of the imaging and electrophysiological data was then conducted. Etiology of the posterior fossa lesions in those with and without SE was determined. Results: Retrospective database review yielded a total of 501 patients who were admitted to the hospital with subtentorial posterior fossa lesions during the study period. They included 76 patients with posterior fossa tumors, 105 with vascular malformations of the posterior fossa, 216 patients with cerebellar infarct or non-traumatic cerebellar hemorrhage, 42 patients with traumatic cerebellar hemorrhage and rest with miscellaneous etiologies such as demyelinating lesions etc. Of these, a total of 13 patients had non-convulsive status epilepticus identified on either a stat EEG or on continuous EEG monitoring. Of the 13, 3 patients had posterior fossa cavernous malformation, 3 had cerebellar hemorrhage, 1 had cerebellar infarct, 2 had cerebello pontine angle tumor, 2 had aneurysms of the posterior circulation and 2 had cerebellar infarcts. The prevalence rate of non-convulsive status epilepticus with subtentorial posterior fossa lesions in this population was about 2.6% per year. Non-convulsive status epilepticus occurred following surgery of the posterior fossa in 9 of the 13 patients. All 13 patients presented with acute mental status changes while 3 were witnessed to have clinical seizures prior to the onset of acute mental status changes. Of the patients who were identified to have non-convulsive status epilepticus, 7 had either generalized periodic epileptiform discharges (GPEDS), 4 had bilateral independent periodic epileptiform discharges (BiPEDS) and 2 had focal periodic discharges. Conclusions: Non-convulsive status epilepticus can be seen in about 2.6% of patients with subtentorial posterior fossa lesions. Further research is required into the potential causes of this complication