Deep brain stimulation, or DBS, is a surgical procedure, which involves implanting electrodes within areas of the brain and using electrical stimulation to treat several neurological conditions, mostly to do with movement, and some psychiatric conditions. Deep structures of the brain were identified in the 1950s and theories of treating neurologic disorders with chronic stimulation began to emerge in the 1960s. Eventually, by combining new technologies, deep brain stimulation was discovered in the 1990s.
How exactly does DBS work?
Well, the brain communicates using electricity; essentially it is its language. This surgery disrupts the brain from talking in an abnormal way, instead of making the brain talk in a particular way. The movement-related symptoms of disorders and other neurological conditions are caused by disorganised electrical signals in areas of the brain that control movement. DBS interrupts these irregular signals. Take a puppet. If one of its strings breaks or is not working properly, it cannot move as it would normally. This surgery would fix the string.
What does the surgery involve?
The first part of the procedure involves the implantation of the electrodes. The patient’s head is kept still, and neuroimaging is used to map their brain and to pinpoint the area where the electrodes have to be placed. Small holes are then made in the skull and a wire lead with several electrodes at the tips is implanted inside the brain. This procedure is often done whilst the patient is awake and under local anaesthesia to numb the scalp; the brain itself does not need numbing as it has no pain receptors. Crazy, right? Our brain tells us what pain we feel, yet does not feel any pain itself. By keeping the patient awake, the effects of stimulation can be tested fully. One wrong move could damage the patient’s speech, memory or sight, so it is very important to make sure this is not the case. This is sort of like trying different lengths of string for the puppet and testing out which one works.
The second stage, which can range from a few days to a few weeks later, involves implanting a battery-operated pulse generator under the skin of the chest, near the collarbone. This is done under general anaesthesia. The wires from the electrodes are placed underneath the skin and guided down to the generator. But why do we need generator? The generator is needed because the electrodes and wires don’t do anything themselves; they act as a result of the current created by the generator. The generator is like the hand that moves the puppet. The puppet cannot move by itself; it needs someone to control it.
Several weeks after the surgery, the generator is programmed and starts to send continuous impulses to the brain. The amount of stimulation differs depending on the condition and it can take up to six months to find the optimal setting. Again depending on the condition, the stimulation may be constant or not; it could be only during the day, for example. It can be controlled using a remote control given to the patient.
Are there any risks?
DBS is generally considered to be low risk, but any surgery has the risk of complications. These include bleeding in the brain, stroke, seizure and infection. There are also possible side effects after the surgery: headache, confusion and temporary pain and swelling where the electrodes were implanted. The stimulation itself (the current created by the generator and sent to the brain) can also cause some side effects, such as numbness or tingling sensations, lightheadedness, mood changes and vision changes. The brain has to get used to stronger currents running through it. This is like the hand controlling the puppet; it needs to readjust its movements to work with the new string.
What is it used for?
DBS is used to treat conditions like Parkinson’s disease and essential tremor, where shaking can be disabling and can cause struggle with performing everyday tasks, such as dressing and eating. It can also be used to treat psychiatric conditions like depression, obsessive-compulsive disorder and Tourette syndrome (tics), although more research is needed to determine if the benefits outweigh risks and side effects.
Has it been proven successful?
One case in 2004 used DBS to treat intense OCD symptoms. The patient’s symptoms were controlled, until the batteries ran out fifteen years later, causing all the compulsions to come back. This proved that DBS had been successful.
Success rates for deep brain stimulation are high and most patients experience an improvement in their quality of life. DBS has given patients suffering from several challenging neurological and psychiatric disorders a chance to regain control over their lives. While the procedure is not risk-free, the benefits outweigh the dangers for many individuals, and it can provide life-changing relief.
Sofia B, Year 12
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