Deep brain stimulation (DBS) is a surgical treatment which is used to treat some of the treatment-resistant movement and affective disorders such as chronic pain, Parkinson's disease, tremor and dystonia. DBS surgery involves the implantation of a medical device or implant that sends electrical impulses to specific parts of the brain. The medical device is called as brain pacemaker. Even though deep brain stimulation is used to treat a variety of disabling neurological disorders, it is most commonly used to treat the debilitating symptoms of Parkinson's disease (PD), such as tremor, rigidity, stiffness, slowed movement and walking problems.
Deep Brain Stimulation is used mainly for patients who are suffering from Parkinson's disease and whose symptoms cannot be adequately controlled with medications.Parkinson's disease which is caused by degeneration of brain cells that make a chemical called dopamine, is a common disorder affecting nearly three out of one hundred persons over the age of 65 years. Nowadays Parkinson's disease is becoming increasingly diagnosed in younger persons under the age of 50 years. As mentioned earlier in Parkinson's disease thebrain cells degenerate. When these brain cells degenerate the patient runs out of dopamine and develops slowing of movement, difficulty with speech, slowed and shuffling walking and tremor. In many patients Parkinson's disease goes undiagnosed since it is often very difficult to diagnose and there is also lack of awareness among people.
Before Deep Brain Stimulation Surgery
The pre-surgery evaluation for Deep Brain Stimulation starts with a physical examination of the patient by the treating doctor. After the physical examination the doctor may prescribe imaging tests in order to locate the specific region of the brain that causes tremors and symptoms of movement disorder.One way to locate the target areas is to rely only on a computed tomography (CT) or magnetic resonance imaging (MRI) scan. While some surgeons stop there, others use an electrode recording technique to map and target the specific areas that they will need to reach. The patient will typically undergo tests like blood test, electrocardiogram, chest X-ray etc. before the surgery.
How Deep Brain Stimulation surgery works?
The brain cells function by electrically encoding, processing and transmitting information. Deep brain stimulation affects the electrical functions of neurons, but the mechanism by which it alters those functions, are unknown. According to some hypothesis, the reduction of the effects of an abnormal neuronal activity occurs because of inhibition, depolarization blockade or the adjustment of neuronal activity to a constant rate.
- Inhibition: The depolarization of axons terminating in target structure by deep brain stimulation causes these terminals to discharge and release neurotransmitters. Deep Brain Stimulation may cause a flood of inhibitory neurotransmitters that effectively shuts down neurons in thetarget structures.
- Depolarization blockade: If a neuron is constantly depolarized but below the threshold need to produce an action potential, the threshold for producing an action potential increases. Consequently, neurons find it more difficult to fire because the threshold increases.
- Altering erratic neuronal activity: Deep Brain Stimulation alters the abnormal discharge activity that results from the disease. It has been suggested that irregular or chaotic firing of neurons may be more disruptive of normal function than a constant and regular pattern of activity. It is possible that Deep Brain Stimulation drives the abnormally discharging neurons into a pattern of more regular firing that is less deleterious.
Deep brain stimulation is most commonly used to treat the symptoms of these common neurological conditions:
- Parkinson’s disease Deep brain stimulation was approved by the Food and Drug Administration (FDA) to treat Parkinson’s disease in 2002 and is now a standard treatment for this condition. Over time, the symptoms associated with Parkinson’s, which include stiffness, slowness, and tremor, become resistant to the medication. The symptoms will fluctuate as the medications provide relief for only a few hours at a time. For these patients, deep brain stimulation can offer steady symptom control for 24 hours per day, to provide better quality of life.
- Essential Tremor When patients have inadequate response to medication, deep brain stimulation is an option to effectively treat essential tremor. Research shows that medications often only elicits a response in about half of patients with essential tremor. However, patients who undergo deep brain stimulation can experience approximately 80 percent improvement in hand tremor.
- Dystonia Dystonia is a condition in which patients experience involuntary muscle contractions that force parts of the body into abnormal postures. DBS has been FDA approved for this condition under what is known as the Humanitarian Device Exemption (HDE.) This means that DBS surgery can be done on those with debilitating dystonia that does not respond well to medication, and in whom dystonia is the only neurological condition.
- Obsessive Compulsive Disorder (OCD) Deep brain stimulation has been approved by the FDA under the Humanitarian Device Exemption (HDE) for the treatment of obsessive compulsive disorder (OCD.)
The device is programmable and hence the electrical stimulation is adjustable.This is a great advantage since as the patient's response to surgery changes over time, the stimulation can be adjusted without the necessity of repeat surgery. Moreover the patient can also go for future therapies like the brain cell transplantation since DBS surgery is not a destructive surgery and the stimulator could be turned off. This may be of great help to patients with Parkinson's disease.
It has to be noted that a Deep Brain Stimulation Surgery is not suitable for everyone and is not a cure for Parkinson's symptoms. A successful Deep brain stimulation surgery may help patients to manage symptoms of health conditions such as Parkinson's disease, Tremor and Dystonia and lead a better quality of life. The extent of benefits and the time duration required may vary from patient to patient. However it is seen that many patients have experienced some benefits which has helped them to lead a better quality of life. Some of such benefits are symptom relief, the need for lesser medications, fewer side effects and the patient may be able to resume normal activities.
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location of the stroke. Each area of the brain is supplied by specific
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left arm movements is blocked, that arm becomes weak or paralyzed.
The brain cells function by electrically encoding, processing and
transmitting information. Deep brain stimulation affects the electrical
functions of neurons, but the mechanism by which it alters those
functions, are unknown. According to some hypothesis, the reduction of
the effects of an abnormal neuronal activity occurs because of
inhibition, depolarization blockade or the adjustment of neuronal
activity to a constant rate.