(376) Significance of the electrophysiological border between hypothalamic hamartomas and the hypothalamus for the target of ablation surgery identified by intraoperative semimicrorecording
Manager National Hospital Organization Nishiniigata Chuo Hospital Niigata, Niigata, Japan
Rationale: Drug-resistant epilepsy due to hypothalamic hamartoma (HH) requires direct surgical treatment to eliminate seizures. However, several surgical approaches have failed to obtain good seizure control and have been associated with some surgical risks as well. Since stereotactic ablation surgery using radiofrequency thermocoagultion or laser interstitial thermal therapy emerged and showed excellent seizure outcomes with minimal complication profiles, a blation surgery has become the first line of treatment for HHs. Because disconnection of the HH from the hypothalamus is critical for HH treatment, optimum targeting of ablation is mandatory. The present study aimed to evaluate the correspondence between the electrophysiological features of HHs and morphological targeting by semimicrorecording during stereotactic radiofrequency thermocoagulation (SRT).
Methods: Eighty HH patients who underwent SRT were involved. Semimicrorecording was performed on the first trajectory. The distance from the center of the target at the morphological border (TMB) determined by MRI, differences in discharge patterns, and area potentials (APs) were measured. AP (millivolt-millisecond [mVms]) was calculated as the integrated value of amplitude gained with frequency during the sampled time and represented the strength of background activity.
Results: The electrophysiological border (EB) between the HH and hypothalamus was detected by semimicrorecording in 73 (91.3%), AP-increase (API) in the HH was detected in 31 (38.8%), and spike discharges (SDs) of the HH were detected in 56 patients (70.0%). Semimicrorecording showed significantly different APs among structures passing through the trajectory, except between API and SDs (median: internal capsule, 1.7; hypothalamus, 3.6; EB, 1.9; API, 2.5; SD, 2.6; AP-decline [APD], 1.2). The median distances from the center of the TMB to the EB, API, SDs, and APD were -3.50, -2.49, -1.38, and +2.00 mm, respectively.
Conclusions: The electrophysiological features of HHs were shown by semimicrorecording during SRT. The EB corresponded to the morphological border. The electrophysiologically active area of HHs was located near the border. Ablation surgery should focus on disconnection at the border between the HH and the hypothalamus to maximize its effectiveness, as well as to reduce complications.
Funding: Please list any funding that was received in support of this abstract.: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Click here to view image/table
