Deep brain stimulation surgery

Dr V P Singh
Deep brain stimulation (DBS) surgery (also known as ‘brain-pacemaker’ surgery) is an established therapeutic option that has stood the test of time in improving the quality of life in patients suffering from certain advanced disabling diseases when medications and other conventional treatment strategies are falling short in controlling symptoms and/or producing debilitating side-effects.
The approved indications for DBS are a spectrum of movement disorders (including Parkinson’s disease, essential tremor, and dystonia), obsessive compulsive disorder (OCD) and intractable adult epilepsy,
In deep brain stimulation, slender insulated wires (known as brain-electrodes) are placed in specific areas of the brain, depending on the disease being treated. The electrodes are placed on one or both sides of the brain through small holes made at the top of the skull. They are then connected by long extension-wires that are channelized internally down the neck to a battery-powered stimulator (neurostimulator) implanted under the skin of the chest. Similar to a heart pacemaker, a neurostimulator uses electric pulses to regulate brain activity. When turned on, the stimulator sends electrical pulses to block the faulty nerve signals responsible for causing disease-symptoms.
In follow up sessions, the doctor can program and ‘fine-tune’ the neurostimulator settings from time to time with a programming device, depending on the disease progression. These programming sessions are essential as they allow the symptoms to be kept under control for long periods of time.
A successful DBS surgery allows patients to potentially reduce their medications and improve their quality of life. A successful DBS therapy is attributable to:
* appropriate patient selection,
* appropriate selection of the specific brain area for stimulation,
* precise positioning of the electrodes during surgery, and
* experienced programming and medications management in follow-up period.
Who is a candidate?
DBS can help treat many of the symptoms caused by:
* Parkinson’s disease: characterised by resting tremors, rigidity, and slowness of movement resulting from a steady decay of dopamine-producing nerve cells responsible for relaying messages that control body movement. Advanced Parkinson’s disease patients are candidates for DBS with worsening symptoms (tremor, stiffness) and their medications having begun to lose effectiveness, troubling “off” periods when their medication wears off before the next dose can be taken, troubling “on” periods when they develop medication-induced dyskinesias (excessive wiggling of the torso, head, and/or limbs).
* Essential tremor: suffering from involuntary rhythmic tremors of the hands and arms, occurring especially during purposeful movement.
* Dystonia: characterised by involuntary movements and prolonged muscle contraction, resulting in twisting or writhing body motions, tremor, and abnormal posture. May involve the entire body, or only an isolated area.
* Epilepsy: For epilepsy patients who would benefit from DBS, the following are the selection criteria:
– Atleast 18 years of age.
– Diagnosed with epilepsy characterised by partial-onset seizures, with/without secondary generalisation.
– Refractory to anti-epileptic medications (failure of adequate seizure control despite appropriate dosage of at least three anti-epileptic medicines, in mono-or polytherapy).
– Average of over six seizures per month for last three months (with no more than 30 days in between two consecutive seizure episodes).
* Obssessive Compulsive Disorder (OCD): DBS is indicated for chronic, severe OCD patients who are resistant to medications as well as to psychological therapy and counselling.
Technological Advances in DBS:
The essence of a successful brain-pacemaker surgery is its precision and accuracy. In this regard, the inculcation of cutting-edge technological advances in the conduction of a deep brain stimulation surgery stands to logic.
‘Directional’ leads DBS, an ingenuous innovation, has emerged as a game-changer. Unlike a conventional DBS system, which only allows neuromodulation in one direction, the ‘segmented’ electrodes (leads) of a directional DBS system help in steering & ‘directing’ the brain-stimulation of the specific region-of-interest in all three dimensions, thus significantly enhancing the focus & precision of therapeutic gains as well as minimizing inadvertent side-effects.
Another promising technological aspect being explored is a real-time ‘Brain-Sensing’ biomarker-guided feedback analysis of the local field potentials by the brain-pacemaker pulse generator itself which would then automatically release a closed-loop anticipatory stimulation response, as and when needed, back to the brain so as to alleviate any unpredictable manifestation of sypmtoms as far as possible. This technology holds the promise of obviating the need of frequent physician-dependent manual brain-pacemaker programming sessions, which were hitherto mandatory following ‘conventional’ brain-pacemaker surgery.
Recently, we implanted North India’s first ‘Directional & Brain-Sensing coupled’ deep brain stimulation system in a 70 years old patient suffering from incapacitating Parkinson’s disease for about a decade and a half.
An interesting innovation now-a-days being increasingly used in clinical practice of brain-pacemaker surgery is patient-specific direct targeting of neural-circuits (comprising of white-matter pathways interspersed with grey-matter relay stations), which is an emerging approach as the next step forward. Given that the efficacy of deep brain stimulation surgery probably depends on precise and accurate targeting of these brain-circuits, better surgical planning using information obtained from advanced brain-imaging MRI technologies such as fibre-tracking methods (for example DTI: Diffusion Tensor Imaging), has shown to improve steadily surgical outcomes.
Last year, we performed India’s first successful Robotic brain-pacemaker awake-neurosugical procedure in an intractable Parkinson’s disease patient. Robotic Deep Brain Stimulation (R-DBS) surgery gives the advantage of not only reducing dependence on manual adjustments, but also enhancing overall surgical efficacy.
The application of artificial intelligemce (AI) via machine learning holds great promise in certain salient aspects of brain-pacemaker surgery such as patient selection, surgical targeting and eventual brain-pacemaker programming optimization.
Remote-controlled satellite-aided modulation of the brain-pacemaker straight from the physician’s desk, enabling the fine-tuning of the DBS device of patients sitting at far-off places in the comfort of their living rooms, without the need to travel long-distances for follow-up programming sessions, has proved to be a game-changing innovation as well, by improving overall patient-compliance to this therapy.
Eventually, a thoughtful blend of various state-of-the-art technological innovations is necessary towards accomplishing a successful Brain-Pacemaker surgery and consequently improving the quality-of-life of thousands of severely disabled patients suffering from advanced debilitating diseases such as Parkinson’s disease, essential tremor, dystonia, obsessive compulsive disorder (OCD), and intractable adult epilepsy.
(The author is Chaiman Medanta Instituite of Neurosciences, Gurugram)