Cognitive outcomes following laser interstitial therapy for mesiotemporal epilepsies

Abstract

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.

Figure. Clinical case-by-case analysis of neurocognitive outcomes

++ = participant with right hemisphere language dominance (WADA); -- = scores within normal limits; * = below 5th percentile at baseline; ** = below 5th percentile at follow-up; 1SD+ = improvement of at least 1 SD; 1SD− = decline of at least 1 SD; ^^ = scores improved from previously impaired to within normal limits; !! = scores declined from normal limits to impaired; CS = continued seizures; FDS = free of disabling seizures; u = repeated measure unavailable.