Deep Brain Stimulation

Deep brain stimulation regulates abnormal brain signalling with electricity instead of removing anything. Four parts make up the system: electrodes on thin insulated leads placed in a precise target in the brain, extension wires running under the skin, a pulse generator — a device much like a cardiac pacemaker — implanted beneath the skin of the chest below the collarbone, and a handheld programmer used to adjust the settings and switch stimulation on and off.

Who it is for

Parkinson's disease, essential tremor, dystonia, obsessive-compulsive disorder and epilepsy. In Parkinson's specifically, the candidates are people who have had the disease for roughly four to five years or more, whose tremor or stiffness is severe, who still respond well to levodopa but now swing between working and non-working periods, and whose symptoms disable them despite the best medication regimen. They must be fit enough for surgery both physically and psychologically: severe dementia or significant psychiatric illness rules it out. The two targets used most often are the subthalamic nucleus and the globus pallidus internus.

The assessment before it

A full neurological assessment, MRI and CT imaging of the brain, and testing of motor symptoms both on and off medication — that on-off comparison is what predicts whether stimulation will help. Neuropsychological evaluation checks the cognitive and psychiatric side. Blood and urine tests screen for other problems. Where the indication is obsessive-compulsive disorder, the Yale-Brown scale is used; where it is epilepsy, EEG.

The operation

It runs in two connected parts. First the electrodes: a stereotactic frame holds the head completely still, imaging maps the target, an incision is made in the scalp and a small opening in the skull, and the leads are guided into position. Well-equipped centres verify placement with microelectrode recording — listening to the electrical signature of the tissue the electrode is passing through — and with test stimulation before the lead is fixed. The surgery can be done awake under local anaesthetic with light sedation, or asleep. Then the generator is implanted in the chest and connected to the leads. Programming begins a few days later and is not a single appointment: the settings are refined over several sessions across weeks, and finding the right balance can take months.

Recovery, the device, and what it will not do

Expect three to five days in hospital. Headache and mild discomfort are usual early on. Most people resume normal activities within two to four weeks and avoid heavy exertion — running, swimming, sport — for four to six. A rechargeable generator needs roughly one to two hours of charging a week; a non-rechargeable primary cell is the alternative, and which suits you is worth settling before surgery rather than after. The risks are real and worth reading twice: bleeding, infection, stroke and swelling from the surgery itself; and from the hardware, a lead that shifts or sits imperfectly, wires that separate from the generator, device failure, and soreness over the generator. Stimulation can also cause loss of balance, numbness and tingling, involuntary contractions, jolt-like sensations, poorer coordination and, at some settings, increased tremor — most of which are addressed by reprogramming. Deep brain stimulation does not cure Parkinson's and does not end medication; it steadies movement and usually allows lower doses. Both sources quote a percentage improvement in motor symptoms; neither attributes it, and we do not repeat it.