Abstracts

Rationale: Mesial temporal lobe epilepsy (MTLE) is one of the most prevalent causes of medically intractable epilepsy to date. These patients typically have focal epilepsy localized to the amygdala, hippocampus and adjacent structures. The most common pathological finding in these patients is mesial temporal lobe sclerosis (MTS). Traditionally, these patients would have effective control after surgical intervention with anterior temporal lobectomy (ATL). Minimally invasive procedures such as MR guided laser interstitial thermal therapy (LiTT) are gaining traction as an effective way to mitigate and control intractable epilepsy originating from the temporal lobe. Currently, it is thought that laser ablation has fewer long-term cognitive deficits, hospital stay/cost and adverse effects when compared to ATL. Our specific aims are to determine the number, the frequency and severity of cognitive deficits and visual field deficits after laser ablation. Also, to determine the number of patients who go on to require temporal lobectomy due to inadequate seizure control after laser ablation and determine the number of patients who acquire seizure freedom from laser ablation at long-term follow up. Methods: A retrospective chart review per inclusion and exclusion criteria was performed for patients with MTLE who underwent laser ablation at Mayo Clinic Arizona from 2013-2018. Pre-surgical, peri-surgical and postsurgical data was compiled to determine long-term outcomes. Results: A total of 25 patients were identified with an average follow-up of 1.5 years. Overall, 8 patients (33%) achieved freedom from disabling seizures (Engel class I). Twelve patients had imaging findings compatible with MTS. Among those 12 patients, 8 (67%) showed freedom from disabling seizures. This was statistically significant compared to 13 patients with either normal MRIs or other lesions, none of whom were seizure free at last follow-up (p-value 0.00054). The average hospital stay was 2.16 days with the most common side-effect being headaches. Ten patients had postoperative neuropsychometric testing and a decline was seen in 8 of those patients compared to preoperative testing. Of the 11 patients who had formal visual field testing, 5 (45%) had post-operative visual field deficits. Due to ongoing seizures, 1 patient returned for further anterior temporal ablation, 2 patients have since returned for ATL, and 1 additional patient is currently scheduled for ATL. Conclusions: Although LiTT is a less invasive option for patients with MTLE, we have found that patients still exhibit long-term neurocognitive deficits and visual field loss. This is also found in ATL and further studies will need to be done to compare the incidence and nature of these deficits with both procedures. Additionally, our data shows that seizure freedom remains difficult to obtain in patients without MTS. Our results are consistent with the previously published data showing that rates of seizure freedom with LiTT are lower compared to ATL and multiple patients require further surgery to help achieve better seizure control. We conclude that more long-term studies need to be performed to help determine which patient population would best benefit from LiTT compared to standard ATL. Funding: None