Dr Paresh Doshi, Director, Neuro-Surgery, Jaslok Hospital and Research Centre elucidates on the success of deep brain stimulation (DBS) being based on how effectively you can programme the DBS systems after surgery
During the last 20 years there has been rapid development in the field of Parkinson’s disease point it all started with deep brain stimulation surgery and later on continued in the form of innovation in the technological advance is in the hardware of DBS systems. Today we have reached a point where lots of changes are occurring in the way we apply DBS to Parkinson’s disease.
A system called a closed-loop system is being developed which will work on providing a tailor-made solution for patients suffering from Parkinson’s disease undergoing DBS. The electrodes of the brain will record the signals called local field potentials from the brain and send it to the pacemaker which in turn will modulate the amount of current required at each given moment. This will help us to give better control of Parkinson’s disease to the patient, reduce battery drainage, and side effects. There have been rapid advances in obtaining biofeedback through wearable devices, like tremor recording devices on the hand, locomotive devices to assess gait and balance function etc. Once again, this would be connected to the pacemaker so that the pacemaker can fine-tune the amount of stimulation delivered to the brain.
There have also been several advances in the technology of the pacemaker, now pacemakers can stimulate 16 electrode channels in the brain, can independently provide current source to each contact (thus helping improve patient compliance and therapy), long battery life up to 25 years, capability of programming the pacemakers from remote location through the internet in video conferencing, etc.
DBS surgery is a blind process, thus the risk of and success of the surgery is heavily dependent on the user experience and expertise. Stereotactic surgeons performing this surgery have to be highly skilled, example, according to European Society of statistic and functional neurosurgery those centres performing at least 20 surgeries near and who has performed around 200 DBS surgeries in the past can only be labelled as an expert centre. However many centres cannot reach this level of expertise and hence surgeons around the world are trying to make it safe in those hands which are less exposure in training in this field. There have been advances in robotic systems that have been employed for operating these patients. New devices called frameless stereotactic system have also been developed so that the preoperative planning and trajectory determination is made beforehand, maybe in consultation with an expert, and the operating surgeon becomes a mere technician to achieve the goal.
Another area of improved knowledge and understanding has been in the field of post-DBS programming. As much as the surgery is important to post DBS patient management and programming is equally or even more important. The success of the DBS is based on how effectively you can programme the DBS systems after the surgery. There are several things that DBS cannot improve and this is important to know as wasting time in trying to do the programming to improve the symptoms would not only tire out the surgeon for the physician but also the patients who eventually will lose faith in the therapy and give up. Recently we had a patient who had severe tremors after DBS surgery which could not be controlled by various methods. We re-evaluated his position of electrodes and found out that the contact points that the other team was using were not optimal so we change the contact points and reintroduced some amount of medications to support the programming (the electrode contact points were not the best location and hence could not have been used to get the best result).
One more advancement that has made the surgery more effective has been in the form of imaging technologies. The new 3 Tesla MRI offers excellent views of the target nuclei of the brain thus helping us to target this with great accuracy. World over several centres is developing technology to imagine the target nuclei with 7T MRI which has been found to show incredible details of the target. Following the great success of imaging-guided DBS placements in awake patients, we and several other centres across the world, are now also offering DBS surgery under anaesthesia to help those patients who cannot be subjected to surgery in awake condition due to either apprehension or some other reason.