To determine the number and severity of cognitive/visual field deficits, number of patients who go on to require temporal lobectomy and those who acquire seizure freedom from laser ablation at long-term follow up.

Mesial temporal lobe epilepsy (MTLE) is a highly prevalent cause of medically intractable epilepsy. The most common pathological finding is mesial temporal lobe sclerosis (MTS). Traditionally, these patients have effective control after anterior temporal lobectomy (ATL). MR guided laser interstitial thermal therapy (LiTT) is gaining traction as an effective way to mitigate/control intractable MTLE. Currently, it is thought that LiTT has fewer long-term cognitive deficits and adverse effects when compared to ATL.

A retrospective chart review was performed for patients with MTLE who underwent LiTT at Mayo Clinic Arizona from 2013-2018 to determine long term outcomes.

Twenty-five patients were identified with an average follow-up of 1.5 years. Eight patients (33%) achieved freedom from disabling seizures (Engel class I). Eight of 12 (67%) patients with MTS showed freedom from disabling seizures. This was statistically significant compared to 13 patients without MTS, none of whom were seizure free at last follow-up (p-value 0.0013). Ten patients had postoperative neuropsychometric testing with a decline seen in 8. Five of 11 patients (45%) had post-operative visual field deficits. Four patients required further LiTT or ATL due to inadequate seizure control.

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. Our data shows that seizure freedom remains difficult to obtain in patients without MTS. These results add to the previously published data showing that rates of seizure freedom with LiTT are lower compared to ATL. We conclude that more long-term studies need to be performed to determine which patient population would best benefit from LiTT or ATL.