Abstracts

Ictal SPECT (single photon emission computed tomography) is a valuable diagnostic tool for localization of seizures in a presurgical evaluation of refractory epilepsy patients. At our institution, trained neurophysiology technicians are placed directly at the patient[apos]s bedside to monitor for seizure onset in order to obtain optimal ictal SPECT injection times. This creates additional demands on the institution for personnel and for financial resources. We proposed to analyze patients admitted for ictal SPECT to assess: 1)the success rate of obtaining an ictal SPECT study, 2)average time to record seizure that was injected for SPECT, 3)and average time of actual injection measure from seizure onset. A retrospective analysis was performed on all patients admitted for ictal SPECT scan between 2002-2004 utilizing inpatient charts, VEEG monitoring data, and monitoring reports generated by physicians. Patients are designated prior to admission to obtain an ictal SPECT. All patients have one seizure recorded prior to obtaining an ictal SPECT to characterize seizures. Day 1 was started as the time of admission until 11:59PM on that day. Patient admissions were analyzed to: 1)quantify the total number of successful ictal SPECT obtained, 2)duration to record the first seizure, 3)time between first and second seizure, 4)time to capture seizure for injection for ictal SPECT, and 5)time to actual injection of tracer from onset of seizure. A total of 93 patients were admitted over 118 admissions to obtain ictal SPECT. Out of 118 admissions, only 23(19%) were unsuccessful at obtaining an ictal SPECT scan. The most common reason was failure to capture seizure during specific hours when SPECT can be performed. The average time to capture the first seizure was on day 2.1. The average time to capture seizure for injection was on day 4.5. Time to actual injection of tracer was calculated from the onset of clinical or EEG changes, whichever occurred first. Data was available in 80/97 successful injections, and the average injection time was 13 seconds. A total of 90% of injections occurred within 30 seconds of seizure onset. Early ictal SPECT injections minimize the problem of seizure propagation and of non-localization due to an early switch from ictal hyperperfusion to postictal hypoperfusion. At our institution, 81% of admissions for ictal SPECT were successfully performed, and 90% of these patients were injected with tracer within 30 seconds of seizure onset. We feel that this data justifies the utilization of trained neurophysiology personnel to monitor patients for seizure onset at the bedside when admitted for ictal SPECT scans.