Abstracts

Rationale: Laser interstitial thermal therapy (LITT) is a new minimally invasive alternative to open temporal lobectomy. One previous large series reported on seven patients treated with LITT. One patient had an acute post-operative seizure (APOS) at home a few days after the procedure (Epilepsy Behav 2015;51:152-57). The specifics of that seizure were not described. Immediate post-LITT EEGs have not been reported. Historically it has seemed that, following other types of epilepsy surgeries, APOS matching the semiology of pre-operative seizures were a poor prognostic indicator for future seizure freedom, while aura, focal motor and generalized seizures did not hold the same significance (Epilepsia 2003;44:831-35; Seizure 2015;24:59-92; J Neurosurg 1998;89:177-82). Methods: We performed immediate post-operative video EEG (vEEG) for 24 hours on three consecutive patients treated with LITT. These vEEGs were compared to pre-operative vEEG concerning seizure, interictal epileptiform, and background activity. Neurological outcome also was examined. Results: All three patients had right mesial temporal sclerosis and had LITT for medically-refractory seizures. On pre-operative vEEG, patient 1 had right anterior temporal-onset seizures, and frequent right and occasional left frontotemporal interictal sharp waves. Post-operative vEEG revealed similar inter-ictal discharges, two partial seizures of similar electrographic onset and clinical semiology to his pre-operative seizures, and subtle loss of right temporal fast frequencies. He reported one further seizure 6 months later after an anti-epileptic medication dose reduction, but has otherwise been seizure free for 1 year. Patient 2 had pre-operative vEEG showing frequent spikes and intermittent focal theta and delta slowing right temporally, with no changes post-operatively. She has since been seizure free for 1 year. On pre-operative vEEG, patient 3 had frequent right frontotemporal epileptiform discharges occasionally in runs at 3 to 4 Hz lasting up to 10 seconds, and intermittent right temporal theta and delta slowing. Post-operative vEEG showed the same focal slowing, but the runs of epileptiform activity generally lasted only 3-4 seconds. She had no clinical seizures in 7 months since surgery. No serious adverse events occurred. Conclusions: Immediate post-operative vEEG following LITT may be helpful in characterizing both ictal and interictal discharges to monitor patient safety, and to compare to pre-operative studies. In our limited series, small post-operative changes in interictal EEG patterns, and APOS, did not seem to carry poor prognosis. This warrants further study within LITT patients. Funding: No funding was received in support of this abstract.