Deep-brain Stimulation for Primary Dystonia

Proprietary names: Access Review Therapy Controller; Activa Deep Brain Stimulation; Activa Dystonia Therapy; Activa PC; Activa RC; Itrel; MemoryMod; Kinetra; N'Vision Programmer; NEXFRAME; SoftStart; Soletra Deep Brain Neurostimulator

Generic name: brain pacemaker

Deep brain stimulation (DBS), delivered by an implanted neurostimulator device, is based on the theory that controlled electrical stimulation modifies the activity of a part of the brain thought to contribute to a specific disorder. Although clinicians primarily use DBS to treat movement disorders, the focus of this report is DBS for primary dystonia, a neurologic movement disorder characterized by involuntary muscle contractions. Patients with primary dystonia may be candidates for unilateral or bilateral DBS if medical treatments do not sufficiently manage the condition. The procedure involves stimulation of parts of the brain thought to contribute to abnormal movement (i.e., globus pallidus interna, subthalamic nucleus). To treat dystonia, bilateral DBS is more common than unilateral DBS, because most patients with dystonia have bilateral symptoms.

In the United States, Medtronic, Inc. (Minneapolis, MN) received U.S. Food and Drug Administration (FDA) marketing approval under a Humanitarian Device Exemption (HDE) for the Activa Dystonia Therapy kit to treat patients with dystonia. The kit includes the following components:

Clinicians use several associated products with Activa Dystonia Therapy kits, including the following:

Clinicians use different product configurations in Europe and off-label in the United States to treat dystonia (see Manufacturer section).

DBS surgery involves two stages: lead placement and neurostimulator implantation. Patients typically require local anesthesia for lead placement and general anesthesia for neurostimulator implantation. The first stage of DBS begins with the application of a stereotactic frame. The physician then performs a stereotactic magnetic resonance imaging (MRI) scan to identify the deep brain target, determine the coordinates for the electrode, and find a safe trajectory to the target. After the MRI, the surgeon makes a small incision to create a burr hole in the skull bone. Microelectrode recording may be used to further define the image-derived target. Microelectrode recording involves placing a small wire into the target brain tissue to determine whether the pattern of neuronal firing matches the known patterns of the targeted brain structure. The surgeon then places and affixes the leads to the burr-hole rings and inserts the burr-hole caps. Immobilization takes about 30 to 60 minutes, and imaging, microelectrode recording, and implantation take about 6 to 8 hours to perform.

During the second stage of the procedure on a different day, the surgeon implants either two single-channel neurostimulators or one or two dual-channel neurostimulator(s) in the subclavicular or upper abdominal region. Subcutaneous extension wires connect the implanted electrode leads to the neurostimulators. This procedure takes about two hours.

For unilateral DBS, the entire procedure takes between...