Deep Brain Stimulation

Introduction

Deep brain stimulation (DBS) is a neurosurgical technique used in the treatment of movement and psychiatric disorders. A battery-operated neurostimulator sends impulses to electrodes which have been implanted in the brain, however the precise mechanism by which DBS alters brain activity remains not fully understood.

Until the development of DBS in the 1980s, neurosurgeons only had ablative techniques to treat such movement disorders, psychiatric disorders, and epilepsy. Rather than creating lesions in functional targets, such as ablation the subthalamic nucleus in the case of Parkinson’s disease, DBS achieves a similar effect via electrical stimulation, however is reversible and adjustable.

DBS is a minimally-invasive and stereotactic procedure with or without real-time image-guided navigation as an adjunct.

By Dr. Craig Hacking, A. Prof Frank Gaillard [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

Figure 1 – A sagittal radiograph of a skull with DBS probes in-situ

Indications

Deep brain stimulation can be used to treat a range of movement disorders refractory to (or complicated by) pharmacological therapy.

Conditions that have been trialled for treatment via DBS include Parkinson’s disease, dystonia, treatment-resistant depression, and obsessive-compulsive disorder (OCD).

Procedure

DBS can be performed under local or general anaesthestia. A rigid frame is used to fix the skull and a scan is obtained, and the surgical anatomical target is identified and co-ordinated.

A burr hole is created in the cranium over the frontal bone. An electrode is advanced to the target, along a trajectory guided by the frame. Leads can be placed uni- or bi-laterally.

The leads are secured to the cranium and a wire is tunnelled under the scalp and down to the pacemaker (Fig. 2). This can be secured, typically to the fascia overlying pectoralis major (similar to a cardiac pacemaker).

The neurostimulator can be switched on and off via an external device, and can be programmed to the settings which achieve optimal symptomatic control.

By Shamir R, Noecker A and McIntyre C [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

Figure 2 – The typical positioning of DBS electrodes and connection to the pacemaker

Complications

Specific complications can be divided into operation-related, hardware-related, and stimulation-related.

• Operation-related complications include peri-operative intracranial haemorrhage and electrode malposition
• Hardware-related complications include electrode migration, electrode fracture, and infection and erosion
• Stimulation-related complications include sensorimotor conditions including dyskinesia and blepharospasm, transient confusion, mood changes, or even psychiatric conditions, such as manic episodes