Question: What are the hardware components of the DBS system? Rev. 03/03
Answer: The system consists of three implantable components:
Leads: There are metal rings on a lead that transfer electricity to the tissue. The leads are thin, insulated wires with four electrodes at the distal tip that delivers electrical stimulation to the brain. Using standard clinical imaging techniques and stereotactic equipment, the electrode is positioned in the precise location in the sub-thalamic nucleus and then the lead is anchored to the skull. Permanent positioning of the electrode is determined by CAT scan to check for optimal placement.
Extension - An insulated wire that is surgically passed under the skin of the head, neck and shoulder to connect the lead to the implanted pulse generator.
Implantable pulse generator (IPG) - This device, which contains a battery and microelectronic circuitry, is surgically implanted under the skin near the collarbone one on each side for bi-lateral STN. The pulse generator is 2 1/4 in x 2 1/4in. x 3/8 in. and weighs 1.72 oz. The device generates mild electrical pulses that are delivered by the extension and lead to the targeted structures ?the subthalamic nucleus or the globus pallidus.
The stimulation system is designed to deliver high frequency electrical stimulation using a multi-electrode lead places in the Subthalamic Nucleus (STN), Ventral Intermediate Nucleus (Vim) in the thalamus, or the globus pallidus pars interna (Gpi). The implantable pulse generator (IPG) is placed subcutaneously in the pectoral area. The IPG is attached to an extension, which is tunneled and attached to the implanted lead.
External components of the therapy include a console programmer and the patient's hand-held magnet:
Console programmer - The pulses from the IPG can be non-invasively adjusted by the neurologist, from a console programmer and transmitted painlessly via radio telemetry to the implanted device. The initial parameter settings are done on the 14th day after surgery and thereafter re-calibration takes place when needed.
Magnets ? the patient is given 2 magnets to use to turn the IPG on and off. Instances when the patient wants to use the magnet are 1) to limit the number of hours the current is on, for example some patients turn the IPG off for the night, 2) others find that having both sides on increases the likelihood of suffering unwanted symptoms and therefore they chose to improve speech, for example at the detriment to balance and gate. The patient should become comfortable using the magnet by practicing turning on and off.
To safeguard against potential problems, one magnet should be kept in the home and the other one should travel with the patient. It should be kept away from credit cards, computer components.
Cheap AM Radio ? The only way to check whether your system is functioning is by placing an AM radio not tuned to a station over the extension and IPG. The radio will give a humming sound if the devices are connected. If you are concerned that your generator was accidentally turned off by external interference, the radio test is quick and will save you an emergency trip to the doctor.
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