Abstracts

Rationale: Magnetic resonance image-guided laser interstitial thermal therapy (LITT) is a minimally invasive alternative to surgical resection for the treatment of drug-resistant epilepsy. Seizures arising outside the temporal lobe can be difficult to treat due to the heterogeneity of anatomical locations and underlying pathology. The effectiveness of LITT ablations for extratemporal epilepsy is not well established. Here we report on the safety and outcomes of LITT for extratemporal epilepsy at Stanford Health Care Adult Hospital and Stanford Children’s Hospital.

Methods: Retrospective chart review of patients receiving LITT ablation outside of the mesial temporal lobe from 2015-2020 at a single institution was completed. Primary outcome was Engel surgical classification and reduction in seizure frequency at last follow up. Secondary outcome was post-operative complications.

Results: A total of 10 patients (4 female, 6 male; average age 27.1±7.2) underwent LITT ablation for extratemporal epilepsy. Indications for surgery included: focal cortical dysplasia (4), completions of previous anterior corpus callosotomies (3), tuberous sclerosis (1), Rasmussen syndrome (1), and Lennox-Gastaut syndrome (1). Ablated targets included deep mesial frontal (4), splenium of the corpus callosum (3), posterior cingulum (1), anterior insula (1), and occipital lobe remnant of prior hemispherectomy (1). Ablation target was determined by stereoelectroencephalography localization of epileptic foci in 6 patients; the remaining 4 were completions of prior surgeries. Six patients had prior surgeries; 3 had prior trials of neuromodulation devices (2 vagal nerve stimulation, 1 responsive neurostimulation).

Subjects had an average of 39.2±29 months of follow-up. Eight (80%) patients had an Engel Class 1 outcome, with 4 experiencing complete seizure freedom (Class 1A) and 4 experiencing only non-disabling focal aware seizures (Class 1B) at last follow-up. The two remaining patients had an Engel Class III outcome – however, notably, these patients received corpus callosotomies for the goal of treatment of frequent and injurious atonic seizures, which completely resolved by last follow-up. Nine patients had greater than 50% reduction in seizure frequency, with seven experiencing greater than 90% seizure reduction. Half of patients were able to decrease either the dosages or number of anti-seizure drugs. Peri-operative seizures were observed in 2 patients. Non-seizure complications were reported in 2 additional patients and included upper extremity apraxia and functional movement disorder. No subjects suffered permanent neurological deficits.

Conclusions: LITT ablation is a safe and effective method for the treatment of refractory extratemporal epilepsy. LITT may be a consideration in refractory extratemporal epilepsy from heterogeneous etiologies or in patients with prior surgeries.

Funding: Please list any funding that was received in support of this abstract.: No funding.