Optimal Fixation Position of Deep Brain Stimulation Electrodes for Parkinson's Disease in Humans

Summary

The fixation of deep brain stimulation microelectrodes for Parkinson’s disease requires brain surgery. This work describes a method to determine the optimal position of the stimulation electrodes during surgery, which requires a combination of techniques.

Abstract

Certain cases of Parkinson’s disease are treated with deep brain stimulation (DBS), applying electrical stimuli to the subthalamic nucleus (STN) in the brain. Stimuli are provided by inserted stimulation electrodes within the brain that supply a square voltage signal generated in a control unit (IPG) typically located in the chest. The elimination of Parkinson’s symptoms depends directly on the location of the stimulation electrodes. This work describes a method used to determine the best fixation position of the stimulation electrodes during surgery. The procedure provides guidance to the surgeon and requires the use of three techniques: 1) use of a stereotactic frame and stereotactic robot, 2) medical imaging (e.g., MRI and CT), and 3) signal analysis provided by microelectrode recording. In DBS surgery, the patient is usually awake with light sedation; however, one of the main advantages of this method is that the patient is fully sedated with anesthesia to avoid any distress or nervousness. Deciding where to perform electrode fixation is a result of combining intraoperative imaging and signal analysis to detect the the electrode position with the highest probability of blocking the PD symptoms. A software tool for signal analysis (DBScan) was developed, assisting the surgical team in determining the location for electrode fixation. In long-term postsurgical analysis, PD disorders were successfully eliminated in all operated patients.

Introduction

Parkinson’s disease (PD) is a major health problem affecting ~1–2% of people over 65 years of age worldwide¹, causing motor disorders (e.g., bradykinesia, tremor at rest, rigidity, postural instability), and non-motor disorders (e.g., sleep disorders, cognitive dysfunctions)^2,3. The deep brain stimulation (DBS) technique consists of applying electrical stimuli to the subthalamic nucleus (STN) region of the brain. This treatment has proved to be very efficient in blocking PD motor disorders in the patient⁴, allowing a better quality of life.

Protocol

This clinical procedure was approved by the Ethical Committee for Biomedical Research of La Fe Hospital with registration number 2015/0824 in May 17, 2016. All participants signed written informed consents. These investigations using human data were carried out following the rules of the Declaration of Helsinki and its updates.

1. Presurgery: Patient screening for DBS implantation

1. Detect patients with increased drug dosages required to block PD disorders.
   NOTE: The main drug.......

Discussion

The main improvements provided by this DBS surgery method are the following: full sedation of the patient, use of a stereotactic robot for electrode insertion, and use of DBScan software for high precision fixation of the stimulation electrodes. The method provides complete confidence about the fixation location, supported by the postsurgical results showing successful blocking of PD effects.

Currently, 5% of the patients required a new DBS surgery. This was due to problems during surgery not .......

Materials

Name	Company	Catalog Number	Comments
CT - Computed Tomography	Philips	Brillance Essencial	Preoperative CT
DBS lead anchoring	Medtronic	Stimloc	Fixation system for stimulation electrode leads in the skull
DBS stimulation electrodes	Medtronic	model 3389	4 contacts
DBScan software	Univ. Valencia		Developed by authors for brain signal analysis and classification
Frameless patient registration module	Renishaw	Neurolocate	Used for fiducial points
Image Fusion and trajectory planning software	Alpha Omega	Stealthstation S7 with Framelink planning	Used for target and trajectory definition
Intraoperative CT	Medtronic	O-ARM	Used for image fusion during DBS surgery
MER electrodes	Alpha-Omega	Acute Electrode	Tungsten, glass coating, 125mm shank diameter, 2mm exposed wire, 1mm male pin, 1MW
Miroelectrode and Local Field Potential Register with automatic neuro navigation	Alpha Omega	NeuroSmart	Brain signal recorder and visualizer
Motorized electrode driver	Alpha Omega	Micromotor NeuroNav Drive	Insertion and extraction of MER and stimulation electrodes
MRI – magnetic resonance	Philips	Intera 1.5 T	Preoperative MRI
S7 Cranial software	Medtronic	S7 Cranial software
StealthStation S7	Medtronic	StealthStation S7
Stereotactic frame	Elekta	Leksell	Only used for head support, no skin incisions for fiducial positioning
Stereotactic robot	Renishaw	Neuro Mate	Substitute of arc-shaped stereotactic frame. Also used for electrode driver support