Stimulus techniques and microelectrode recordings of subthalamic-nuclei neurons in Parkinson`s during functional-neurosurgery

This study discusses the various procedures and issues involved in the acquisition of microelectrode recordings (MER) signals of subthalamic nucleus stimulations with induced deep brain stimulation electrodes very rigorously. Bellicose-invasive physiological detections through the methods of sub cortical physio logical detections, electrical induced stimulations and micro electrode recordings, stereo-tactic technique, macro-stimulation, stereo-tactic functional neurosurgical technique, stimulations such as macro and micro, induced stimuli with current and microelectrode recordings, impedance information monitoring, micro injections of test substances, evoked potentials, biomarkers/local field potentials, microelectrode fabrication methods and setups, sub cortical atlas-mapping with micro recording/microelectrode recording (M.E.R.). Thus, the study is very significant to the electrophysiological neurosurgical point of view and is very useful to the field of microelectrode recording and functional neurosurgery. This study is concerned with invasive physiological detection of deep brain structures with micro- or macro-electrodes prior to surgery followed by imaging techniques and their use in cortical and subcortical detection; detection relevant to the superficial cerebral cortex regions.

Asleep Deep Brain Stimulator Placement in the Intraoperative Magnetic Resonance Imaging System Hybrid Operating Suite: 2-Dimensional Operative Video

Asleep, image-guided deep brain stimulation (DBS) placement is rapidly gaining popularity because it offers greater patient comfort and comparable accuracy with frame-based methods using microelectrode recording.1 In this video, we demonstrate our protocol to use the frameless, stereotactic ClearPoint system (MRI Interventions Inc, Irvine, California) to place DBS electrodes within an intraoperative magnetic resonance imaging hybrid operating suite (IMRIS; Deerfield Imaging Inc, Minnetonka, Minnesota).1-4 This system uses a skull-mounted aiming device coupled with sequential, intraoperative magnetic resonance imaging guidance to direct DBS lead placement to subcortical targets.2,5 Importantly, this method allows the patient to remain asleep during the operation and does not require medication holidays or additional microelectrode recording equipment. The literature indicates it has comparable accuracy1,6 and outcomes2 with the awake method. We demonstrate this technique with the case of a patient with Parkinson disease who required lead placement in the bilateral subthalamic nuclei.7-9 The patient consented to the procedure and publication. Patient positioning, draping nuances, initial indirect targeting, and final direct targeting are demonstrated. Risks of the operation include a risk of hemorrhage, hardware failure, and infection.10 DBS is currently an underutilized treatment option for patients with Parkinson disease.11 Offering the asleep option may be more tolerable for many patients who are wary of awake surgery.

The role of intraoperative microelectrode recording and stimulation in subthalamic lead placement for Parkinson’s disease

Objective Intraoperative microelectrode recording (MER) and test-stimulation are regarded as the gold standard for proper placement of subthalamic (STN) deep brain stimulation (DBS) electrodes in Parkinson’s disease (PD), requiring the patient to be awake during the procedure. In accordance with good clinical practice, most attending neurologists will request the clinically most efficacious trajectory for definite lead placement. However, the necessity of microelectrode-test-stimulation is disputed, as it may limit the access to DBS therapy, excluding those not willing or incapable of undergoing awake surgery. Methods We retrospectively analyzed the MERs and microelectrode-test-stimulation results with regard to the decision on definite lead placement and clinical outcome in a cohort of 67 PD-patients with STN-DBS. All patients received bilateral quadripolar ring electrodes. To ascertain overall procedural efficacy, we calculated the surgical index (SI) by comparing preoperative motor improvement induced by levodopa to that induced by stimulation 7 to 18 months after surgery, measured as the relative difference between ON and OFF-states on the Unified Parkinson’s Disease Rating Scale motor part (UPDRS-3). Additionally, a side-specific surgical index (SSSI) was calculated using the unilateral assessable items of the UPDRS-3. The SSSI where microelectrode-test-stimulation overruled MER were compared to those where the result of microelectrode-test-stimulation was congruent to MER results. Results A total of 134 electrodes were analyzed. For final lead placement, the central trajectory was chosen in 54% of patient hemispheres. The mean SI was 0.99 (± 0.24). SSSI averaged 1.04 (± 0.45). In 37 lead placements, microelectrode-test-stimulation overruled MER in the final trajectory selection, in 27 of these lead placements adverse effects during microelectrode-test-stimulation were decisive. Neither the number of test electrodes used nor the STN-signal length had an impact on the SSSI. The SSSI did not differ between lead placements with MER/microelectrode-test-stimulation congruency and those where the results of microelectrode-test-stimulation initiated lead placement in a trajectory with shorter STN signal. Conclusion Intraoperative testing is mandatory to ensure an optimal motor outcome of STN DBS in PD-patients when using quadripolar ring electrodes. However, we also demonstrated that neither the length of the STN-signal on MER nor the number of test electrodes influenced the motor outcome.

O-Arm Navigated Frameless and Fiducial-Less Deep Brain Stimulation

Object: Deep brain stimulation (DBS) is a very useful procedure for the treatment of idiopathic Parkinson’s disease (PD), essential tremor, and dystonia. The authors evaluated the accuracy of the new method used in their center for the placing of DBS electrodes. Electrodes are placed using the intraoperative O-arm™ (Medtronic)-controlled frameless and fiducial-less system, Nexframe™ (Medtronic). Accuracy was evaluated prospectively in eleven consecutive PD patients (22 electrodes). Methods: Eleven adult patients with PD were implanted using the Nexframe system without fiducials and with the intraoperative O-arm (Medtronic) system and StealthStation™ S8 navigation (Medtronic). The implantation of DBS leads was performed using multiple-cell microelectrode recording, and intraoperative test stimulation to determine thresholds for stimulation-induced adverse effects. The accuracy was checked in three different steps: (1) using the intraoperative O-arm image and its fusion with preoperative planning, (2) using multiple-cell microelectrode recording and counting the number of microelectrodes with the signal of the subthalamic nucleus (STN) and finally, (3) total error was calculated according to a postoperative CT control image fused to preoperative planning. Results: The total error of the procedure was 1.79 mm; the radial error and the vector error were 171 mm and 163 mm. Conclusions: Implantation of DBS electrodes using an O-arm navigated frameless and fiducial-less system is a very useful and technically feasible procedure with excellent patient toleration with experienced Nexframe users. The accuracy of the method was confirmed at all three steps, and it is comparable to other published results.