Can We Put Aside Microelectrode Recordings in Deep Brain Stimulation Surgery?

Abstract

Microelectrode recording (MER) in deep brain stimulation (DBS) surgery has long been a recognized and efficient method for defining a target. However, in recent decades, imaging techniques, including DBS surgery, have experienced significant growth. There is convincing evidence that imaging-guided surgery can be helpful for targeting anatomically well-defined nuclei (e.g., subthalamic nucleus (STN) or internal globus pallidus (GPi)), and reductions in secondary effects have also been claimed. It has even been proposed that MER is not necessary to perform DBS, identifying in this way asleep surgery and imaging-guided DBS. However, there are several reasons why this is not the case. Neurophysiological techniques can efficiently and safely help to identify neural structures even in sleeping patients (e.g., different types of evoked potentials or motor stimulation). Deep nuclei are not homogeneous structures (even STN), so it is important to identify different places inside the putative target. Evidently, this is more relevant in the case of thalamic or hypothalamic surgery. Moreover, it is important to remember that the clinical and scientific knowledge acquired during DBS surgery can be important to gain further insight into pathologies and develop more effective treatments. Finally, the cost/efficiency of medical technology should be considered.

Neurophysiological Characterization of Posteromedial Hypothalamus in Anaesthetized Patients

“…In this work, we demonstrated that the neurophysiological properties of the hypothalamus are specific, and PMH can be identified during MER by the type of cells, the presence of atypical EAP and the pattern of discharge, which are different from those noted in the above and below regions. These properties can help to improve the precision of targeting during DBS surgery [ 39 ]. In addition, we described for the first time the presence of atypical EAP that does not fit either the classical depolarization-repolarization description or the three phases observed in the thalamus [ 8 ].…”

Features of Action Potentials from Identified Thalamic Nuclei in Anesthetized Patients

“…This is an important clinical finding because it could permit the development of a way to specifically identify certain thalamic nuclei without anatomical references and does not need the conscious collaboration of the patient. Therefore, we could perform this type of surgery under general anesthesia, considering the patient’s preferences and well-being, allowing the reduction of stress and discomfort and avoiding awake surgery [ 30 , 31 ]. However, demonstration of this possibility was clearly out of the scope of this work and we merely mention this exciting option.…”

Past, Present, and Future of Deep Brain Stimulation: Hardware, Software, Imaging, Physiology and Novel Approaches

“…The benefits of MER are clear: MER can safely identify neural structures and borders, MER can help approximate the location within the target that will be most beneficial clinically, and the information gathered from MER can be helpful for understanding disease pathophysiology. MER will likely continue to be an important technique in places that do not yet have access to more advanced imaging techniques ( 39 , 40 ). Although the use of MER does extend the length of the DBS procedure ( 41 ), MER frequently provides important physiologic information that results in lead adjustments up to 20–40% of the time, which can be especially important in instances when there is significant brain shift following preoperative imaging ( 42 , 43 ).…”

“…The accuracy of these adjustments is dependent on the technique used to adjust the DBS lead ( 40 ). In addition, as imaging and atlas techniques have improved, the role of MER has been called into question ( 39 ). At least one retrospective study has demonstrated no significant differences in mood between asleep and awake DBS cases, ( 44 ) but further work with larger, prospective studies are needed to truly compare the benefits of asleep vs. awake cases.…”