Do Microelectrode Techniques Increase Accuracy or Decrease Risks in Pallidotomy and Deep Brain Stimulation?

Abstract

Several recent publications have stated that the use of microelectrode recording (MER) during pallidotomy or deep brain stimulation (DBS) contributes to decreasing risks and side effects of surgery, and that such a technique is a prerequisite for minimizing lesion size and for accurate placement of the stereotactic lesion or the DBS electrode. To evaluate the consistency of these statements, we reviewed hundreds of papers and congress reports on MER- and non-MER-guided procedures published since 1992. This review showed that MER groups published more often than non-MER groups. While side effects of surgery were not uncommon in both groups, the rate of severe complications, such as hematoma, and mortality appeared to be higher when microelectrodes were used, both in ablative surgery and in DBS procedures. Besides, the nonaccurate placement of lesions or DBS electrodes, as assessed on published MRI figures, was not uncommon in MER publications. Lesion volume was, when reported, not different in both techniques. The electrical parameters of stimulation of implanted electrodes in the thalamic ventral intermediate (Vim) nucleus for treatment of tremor were higher in MER-guided surgery. The available literature suggests that MER techniques may increase the risks of surgery without enhancing its accuracy, compared to MRI-based macrostimulation techniques. To date, there is no randomized trial by one and the same group on the use of micro- versus macroelectrodes in surgery for movement disorders. A prerequisite for such a trial in the future must imply that the investigators have an equal nonprejudiced attitude towards, and equal confidence and experience in, either technique. Since such a prerequisite does not exist so far in the functional stereotactic community, a critical and comparative study of the available literature remains the only way to evaluate the pros and cons of either technique, in terms of targeting accuracy and surgical complications.

Deep Brain Stimulation: Awake and Asleep Options

“…41,42 Furthermore, in the setting of improved perioperative imaging, there exists no evidence that MER help prevent suboptimal electrode placement. 10,[43][44][45][46] In fact, cases of mistaking the recordings of the red nucleus for STN highlight the false sense of security that MER can provide. 47 …”

The Treatment of Movement Disorders by Deep Brain Stimulation

“…7 Despite the abundant electrophysiologic data provided by MERs, practitioners at some centers debate its necessity and have chosen to rely on macrostimulation with or without local field potentials and impedence measurements via macroelectrodes for physiologic mapping. 127 Macrostimulation generally provides the final confirmation of the optimal target location. Macrostimulation is performed in the awake patient at clinically relevant stimulation parameters.…”

Factors predicting incremental administration of antihypertensive boluses during deep brain stimulator placement for Parkinson’s disease

“…Subsequently, the sedation is discontinued and the DBS is placed followed by MER. A pre-requisite for adequate MER is an awake patient with a stable blood pressure (awake phase) [3]. Upon completion of mapping, sedation and analgesia may be restarted (asleep phase).…”

“…MER has been reported as the standard procedure in many leading centers [3,4], however it could be associated with an increased risk of brain hemorrhage due to either multiple passes of the microelectrode through the brain parenchyma or secondary to acute hypertension intraoperatively [4,5].…”