Abstracts

Rationale: New surgical treatments for patients with drug resistant epilepsy has recently included new surgical techniques and forms of neuromodulation. Stereotactic laser ablation (SLA) is an emerging minimally invasive procedure directed at patients with drug resistant focal seizures. We report the results of SLA at a single epilepsy center and the impact on epilepsy surgery over the last 2 years.Methods: We retrospectively reviewed the records of all case of epilepsy who underwent neurosurgery at Mayo Clinic in Florida between 2013 and 2015. Twenty-five patients underwent SLA by a single surgeon for drug-resistant localization-related epilepsy. Demographics included age, age at onset, gender, number of past AEDs, neuroimaging, PET, interictal and ictal EEG and neuropsychological/Wada testing. Post-operative data included hospital length of stay, outcome at last visit and perioperative complications. The trends in epilepsy surgery technique was evaluated over the last 2 years.Results: A total of 77 surgeries were performed in 25 patients (14 M) including 26 SLA and 29 patients undergoing surgical resection (primarily selective anteromesial temporal lobectomy) via craniotomy. The remainder were composed of neuromodulation (RNS and VNS) and intracranial EEG electrode placement. Patients had a mean age at onset of 21 years (range 0-52 years) and had taken 5.0 antiepileptic drugs prior to the mean age at operation of 45 years (range 17-67 years). MRI demonstrated a lesion in 22/25 (88%) of patients treated with SLA. Mesial temporal sclerosis (MTS) was present in 15/25 (60%) patients (9= L; 5= R; 1= B/L), 2 were normal, 2 neuronal migrational disorders, 1 atrophy and 1 post lobectomy. PET brain scans were more variable in localizaton. Temporal hypometabolism was seen in 18 (12= L; 6= R (1 also with cingulate hypometabolism), 3 did not have a PET scan, 2 were normal, and 1 had right parietal and anothr bifrontal hypometabolism. Ictal EEG was lateralized in each case to the side of surgery. The lesion on MRI predicted the ultimate side of surgery. iEEG localization was required in 2 patients who became seizure free (normal MRI). 77% of patients underwent laser ablation on one temporal lobe (L=17; 2 re-operation; R= 8) and 2 patients had frontal lobe SLA. 52% of the subjects were seizure free after surgery with a mean followup of 8.54 months. 80% of patients were discharged the day following surgery and another 12% at 48 hours. One patient experienced a visual field deficit and 3 patients had a memory deficit (2 with normal MRI and left termporal SLA). Three patients had immediate peri-operative seizures but then remained seizure free.Conclusions: Stereotactic laser ablation led to an increase in epilepsy surgery at our center despite the slightly lower seizure free outcome. Temporal lobe epilepsy was the most common SLA performed. Seizure freedom was seen in over 50% of patients with 80% discharged on the day following surgery without complications. The ease of use and lower resource utilization makes SLA an attractive procedure for epilepsy surgery centers.