Abstracts

RATIONALE: Most epilepsy centers use ictal EEG recordings to localize the epileptogenic zone as an essential part of the presurgical evaluation. Monitoring in an inpatient unit is standard practice but is expensive and often inconvenient, and spontaneous seizure frequency may decrease upon hospitalization. We attempted to determine whether outpatient long-term monitoring (LTM) can be a safe and effective alternative as the sole method of recording epileptic seizures in the presurgical evaluation of patients with refractory temporal lobe epilepsy. METHODS: We reviewed clinical and EEG data on seven patients who underwent temporal lobectomy whose presurgical LTM was performed entirely outside the hospital with 24-channel ambulatory EEG employing surface and sphenoidal leads. We compared their epilepsy history, social circumstances, presurgical evaluation, and postoperative outcome to those of 14 patients who underwent temporal lobectomy after inpatient LTM. Patients with known lesions or other surgical sites were excluded. RESULTS: Patients with outpatient LTM had baseline seizure frequencies of 2 to 42 a week (mean 15). None lived alone, and none had any significant antiepileptic drug (AED) taper during LTM. Between 2 and 13 seizures were captured (mean 8) in monitoring of 5 to 21 days (mean 9.4). One patient had generalized tonic-clonic (GTC) seizures during LTM. Postoperative follow-up was 2.5 to 10 years (mean 5.5). At most recent follow-up, 6 of 7 patients (86%) were seizure-free, excluding auras; the other had a >90% reduction in seizure frequency. Patients with inpatient LTM were similar demographically and in baseline seizure frequency, LTM duration, number of seizures captured, and postoperative outcome. Eleven had at least one AED tapered completely. Four had GTC seizures during LTM, including one requiring acute intervention. CONCLUSIONS: There is a subset of patients for whom ambulatory, outpatient LTM can be used safely and effectively as the sole method of capturing ictal EEG recordings to aid in the planning of temporal lobectomy. Some clinical features help in the selection of outpatient monitoring candidates.