Toward the optimal surgical treatment of hypothalamic hamartoma

To the Editors: We read with great interest the study reported by Shirozu et al. concerning semimicrorecordings during stereotactic thermocoagulation of hypothalamic hamartoma (HH).1 The surgical treatment of HH has been the subject of many innovations in recent years, with the introduction of laser coagulation2 and endoscopic3 or stereotaxic thermocoagulation.4 Initial data suggested a lower complication rate, with equal efficacy, in multiple-radiofrequency thermocoagulations and laser coagulations, through either stereotactic or robot-guided endoscopy, compared to laser interstitial therapy (LiTT).5 However, the introduction of resting state functional magnetic resonance imaging (rsfMRI) targeting of the HH region has reduced the complications reported with LiTT.6 The study published by Shirozu et al. is the first to report microrecordings achieving targeting1 within the hamartoma on the same principle as rsfMRI. Although the rsfMRI is a noninvasive technique, its posttreatment is based on a statistical analysis and depends on many physical parameters, making its use difficult for the moment, outside of the expert team6 that developed the analysis. On the contrary, electrophysiological recordings by microelectrodes are a technique familiar to most medicosurgical teams doing deep brain stimulation and are extremely reproducible. Nevertheless, targeting before each coagulation will require multiple transparenchymal stereotaxic trajectories, thus increasing the risks of side effects. In contrast, the placement of an intraventricular endoscope with a single robot-guided path, targeting the center of the hamartoma surface, will subsequently allow multiple targetings to be performed with the stereotactic precision of the robot. A single intraventricular working channel therefore allows the placement of the microrecording electrode and then a laser fiber or thermocoagulation probe, in multiple locations, theoretically lowering the risks and allowing direct control, in real time, of the coagulations. Finally, as in temporomesial epilepsy, the efficacy of surgery in HH-related epilepsy has been proven, and its accessibility in developing countries should be taken into account. The cost of LiTT probes remains high, as multiple trajectories are often required and few centers are available for stereotactic MRI-compatible equipment. Placement of a multiple-use laser or thermocoagulation probe through an endoscope, however, is inexpensive. All of these considerations encourage gathering single techniques developed by different teams: using a single intraventricular robot-guided working channel (1), to perform multiple microrecordings to target the lesion (2), prior to performing a real-time endoscopic-monitored multiple laser (or radiofrequency) coagulation (3).