Laser thermal ablation for mesiotemporal epilepsy: Analysis of ablation volumes and trajectories.

OBJECTIVE: To identify features of ablations and trajectories that correlate with optimal seizure control and minimize the risk of neurocognitive deficits in patients undergoing laser interstitial thermal therapy (LiTT) for mesiotemporal epilepsy (mTLE). METHODS: Clinical and radiographic data were reviewed from a prospectively maintained database of all patients undergoing LiTT for the treatment of mTLE at the University of Miami Hospital. Standard preoperative and postoperative evaluations, including contrast-enhanced magnetic resonance imaging (MRI) and neuropsychological testing, were performed in all patients. Laser trajectory and ablation volumes were computed both by manual tracing of mesiotemporal structures and by nonrigid registration of ablation cavities to a common reference system based on 7T MRI data. RESULTS: Among 23 patients with at least 1-year follow-up, 15 (65%) were free of disabling seizures since the time of their surgery. Sparing of the mesial hippocampal head was significantly correlated with persistent disabling seizures (p = 0.01). A lateral trajectory through the hippocampus showed a trend for poor seizure outcome (p = 0.08). A comparison of baseline and postoperative neurocognitive testing revealed areas of both improvement and worsening, which were not associated with ablation volume or trajectory. SIGNIFICANCE: At 1-year follow-up, LiTT appears to be a safe and effective tool for the treatment of mTLE, although a longer follow-up period is necessary to confirm these observations. Better understanding of the impact of ablation volume and location could potentially fine-tune this technique to improve seizure-freedom rates and associated neurologic and cognitive changes.

Cognitive outcomes following laser interstitial therapy for mesiotemporal epilepsies.

OBJECTIVE: To provide a review of cognitive outcomes across a full neuropsychological profile in patients who underwent laser interstitial thermal therapy (LiTT) for mesiotemporal epilepsy (mTLE). METHODS: We examined cognitive outcomes following LiTT for mTLE by reviewing a consecutive series of 26 patients who underwent dominant or nondominant hemisphere procedures. Each patient's pre- and postsurgical performance was examined for clinically significant change (>1SD improvement or decline on standardized scores), with a neuropsychologic battery that included measures of language, memory, executive functioning, and processing speed. RESULTS: Presurgical performance was largely consistent with previous research, where patients suffering from dominant hemisphere epilepsies demonstrated deficits in verbal learning and memory, whereas patients with nondominant hemisphere scored lower on visually mediated tests. Case-by-case review comparing presurgical to postsurgical scores revealed clinically significant improvement in both dominant and nondominant patients in learning and memory and other aspects of cognition such as processing speed and executive functioning. Of the few patients who did experience clinically significant decline following LiTT, a greater proportion had undergone dominant hemisphere procedures. CONCLUSIONS: Compared with the outcome literature of dominant open anterior temporal lobectomies (ATLs), where postsurgical decline has been documented in up to 40%-60% of cases, our LiTT case series exhibited a much lower incidence of postoperative language or verbal memory decline. Moreover, promising rates of postoperative improvements were also observed across multiple cognitive domains. Future studies exploring cognitive outcomes following LiTT should include comprehensive neuropsychological findings, rather than only select domains, as clinically significant change can occur in areas other than those typically associated with mesiotemporal structures.