Deep Brain Stimulation (DBS) is a modern treatment modality in which a pacemaker is inserted into the brain and is very useful in the treatment of various Neurological disorders. DBS offers a ray of hope for the improvement in the quality of life of patients suffering from Parkinson's disease, Essential tremors, Dystonia, Chronic Pain, Epilepsy and other Neurological and Psychiatric conditions where medicines are either ineffective or no other cure is available
The human brain can be thought of as a bundle of tightly packed electrical wires. DBS involves modulating the electrical activity in various areas of the brain wherein electrodes are inserted into deep locations in the brain through a drill hole and connected to a pacemaker in the chest. The doctor is thereby able to control the function of that area by an external controller for therapeutic benefit. Such procedures have been in existence in Europe since the late 1990's
DBS is useful in the following conditions
DBS was first used in patients suffering from Parkinson’s disease. There are medical treatments available for this condition which predominantly modulate a chemical in the brain called Dopamine. Dopamine is a Neurotransmitter which is depleted in a portion of the brain called Substantia Nigra. Such medicines produce side effects after a few good years.
After the initial “honeymoon period” theeir efficacy also starts decreasing. Therefore, they increasingly become “frozen” and are unable to move and their control becomes erratic. This is called “on-off” phenomenon wherein the patients are “on” one moment when the chemical is in the brain and off in a few minutes to hours when the drug level wears off.
Parkinson’s disease causes 3 main manifestations: Tremors of the arms, Rigidity or tightening of the muscles of the body and slowness of walking. It is these main symptoms of Parkinson’s disease that DBS helps to mitigate. However, DBS is not a cure for Parkinson’s disease which continues to progress. It improves the symptoms and lets the patients lead a more normal life. Therefore it improves their Quality of Life immensely.
DBS is also very useful in a condition called Essential tremor. Here, patients are affected by tremors typically affecting one or both arms which make even the most basic acts of everyday life difficult. Writing, feeding themselves, buttoning their clothes etc., become increasingly difficult. However,
This condition was called “Benign” Essential tremors earlier – but ask any one suffering from this condition and they would vouch for the fact that this is anything but benign. When an otherwise active person finds that he cannot sign the cheques or drink his tea without help from someone it makes them very disabled and dependent. The unfortunate part is that there is hardly any medical treatment available for this condition. Some report that drinking a glass of alcohol makes them “steady”. However, this can hardly be a prescription medication.
DBS offers the chance of complete resolution of their symptoms. The cessation of the tremors is instantaneous and right on the operating table! This is usually a very dramatic moment in the operation theatre.
Generalized Dystonia is a condition that affects children and young adults. It is characterized by abnormal and un-coordinated muscle contractions that make them practically wheelchair-bound. Dystonia can also affect a specific muscle group in the body causing conditions like twisted neck – “torticollis”. These conditions have no cure. It is here that DBS offers the chance of relief of symptoms, both of the twisted muscle and of the pain that comes secondarily.
Patients suffering from medically uncontrolled Epilepsy have benefitted from DBS. When one drug after the other has been tried for a patient with fits and they dont help, surgery is usually considered. When a scar in an area of the brain is found, one can consider resective surgery- ie to try and remove that area of the brain. When resection is not possible, in some circumstances elimination of that area of the brain from the rest of the nervous system is considered. This is called Disconnection.
Neuromodulatory procedures like DBS and VNS (Vagal Nerve Stimulation) are also considered in such cases. DBS of a nucleus situated in the thalamus has been effective in helping such patients
Obsessive Compulsive Disorder (OCD) and medically uncontrolled depression are 2 psychiatric condition for which DBS is increasingly being used. The typical patients are ones who have failed all the conventional medications, failed more than 10-15 sittings of therapy and are so severely affected by their condition that their everyday life is affected. There is some evidence that such patients can be helped by DBS where the OCD and Depression scales come down significantly after DBS.
The surgery is typically done with the patient awake. A box is fitted on their head under local anaesthesia. This is called a stereotactic frame. Using this box, one can precisely locate any point within the box. A head scan is done and the target area into which the electrode must be placed is calculated precisely. Local anaesthesia is given and two small drill holes are placed on top of the head. Through this slender wires are passed and the electrical activity of the deep areas of the brain is recorded. Once satisfactory recordings are obtained, the final electrode is placed into the target. Now current is passed through the electrode and voila the patient’s tremor stops immediately!
Because the patient is awake in the operating theatre, they can appreciate their improvement in the tremor immediately. Following this, the electrodes are fixed and the wounds closed. The patient is given general anaesthesia following which the electrodes are connected through wires passed under the skin to a battery placed in the chest. The patient is discharged in a few days time.
The patient needs to be under regular follow-up when the current settings can be modified to get the best benefit. DBS technology has improved greatly over the last few years wherein the battery life has become longer and newer rechargeable batteries have come in. So, one needs to remember to recharge his/her mobile phone and DBS battery without fail lest it get drained! The recharging is done using an external charger remotely. The charging frequency is about 2-3 times a week.
In conditions like Essential tremor and Parkinson’s disease the improvement can be immediate and on the operating table! While it can greatly reduce or completely abolish the tremors in patients with essential tremor, it is very useful in reducing the motor manifestations of Parkinson’s disease (tremor, rigidity and slowing of movements). In conditions like Dystonia, Chronic pain, OCD and Depression finding the correct current settings and obtaining a benefit can take up to a year’s time.
No surgery in the brain can be considered minor, but DBS involves very little general anaesthesia time and is very safe. Common risks of any surgery include bleeding and infection. Bleeding which is serious enough to cause strokes are rare. However, infections can be troublesome and may even lead to removal of the entire hardware which has been painstakingly inserted! Therefore absolutely strict precautions against infection must be taken from before the operation, till the first few months after. The unique side effects from this procedure include stimulation side effects which occur due to spill over of the current to the adjacent areas of the brain. This is typically reversible once the stimulation settings are altered. Overall, this is a safe procedure even in the most debilitated patients.