An implantable deep brain stimulation (DBS) device is made up of three main parts: the electrode, the pulse generator and the extension. Here's what each part of the device is designed to do:
The electrode is a small tip-shaped device (imagine the plug for a pair of headphones) that is implanted deep into the region of the brain involved with the disease symptoms. The surface of the electrode has four metal pads used to transmit pulses of electricity. These pulses of electricity are small and only stimulate the brain tissue within close range of the electrode. This allows the electrical stimulation to specifically target only the brain region closest to where the electrode is implanted.
The pulse generator (also called the stimulator) is a small, box-shaped device that generates the electrical signals that are sent to the electrode. The pulse generator is usually implanted under the skin in a space near the patient's chest. It includes a battery with a lifespan that ranges anywhere from two to seven years. The electrical patterns are generated in quick on-off pulses delivered at very high frequencies -- usually over 100 times per second. Only at these high frequencies does the stimulation help reduce the unwanted symptoms.
The last component of an implanted DBS device is the extension, which is simply an insulated cable that carries the electrical signals from the pulse generator to the electrode implanted in the brain. Having any part of the DBS device go through the skin would create a risk of infection, so the surgeon typically tunnels a small path under the skin from the pulse generator to the electrode.
Patients are typically given a handheld device that uses a magnet to communicate through their skin to the pulse generator. This allows the patient to control the dosages of electrical stimulation he or she receives. A doctor sets the range of stimulation dosages within certain limits, but the patient actually does the fine-tuning of the device based on his or her own individual needs.
Now that you know what parts make up a DBS device, let's find out how it produces the desired effect.