A single-center learning curve for stereotactic laser amygdalohippocampotomy and a surgical framework to manage failures

Objective: Stereotactic laser amygdalohippocampotomy (SLAH) is a minimally invasive procedure for mesial temporal lobe epilepsy that preserves more tissue than open procedures. As a result, although patients have better functional outcomes, more patients do not achieve seizure freedom. The rate at which this occurs is evolving with improved surgical practices. However, the risks and benefits of further surgical management for these patients remains a question with limited data to guide decision-making.

Methods: We retrospectively reviewed a continuous series (2011-2019) of SLAH operations at our institution to determine trends in surgical management, identifying cases where further surgery was performed. Pre-operative and follow-up seizure, cognitive, and functional data, and surgical complications were collated.

Results: Of 108 patients undergoing primary SLAH, 21 (19%) underwent further surgery (23 procedures). Stereo-electroencephalography (SEEG) informed seven procedures (30%). There was a trend for quicker SLAH failure in the earlier patients. Similarly, surgical chronology was associated with progression to repeat surgery (p = .007). At 1-year follow-up, 6 of 13 patients (46%) achieved seizure freedom after repeat SLAH and 5 of 8 patients (63%) achieved seizure freedom after anterior temporal lobectomy (ATL), one of whom had failed two SLAHs. Two of three patients undergoing an ablation outside the mesial temporal lobe achieved seizure freedom at 1 year. Neuropsychological sequelae were more prevalent with ATL than SLAH, including decline in visual naming (p = .01) and functional status (p = .007).

Significance: Repeat SLAH and ATL post-SLAH are both practicable and can be effective. Surgical experience, risk to cognition, and marginal benefit relative to existing improvement are principal considerations for further surgery.