A point of view article by four Canadian and UK neurologists who are very experienced with DEEP BRAIN STIMULATION was published in a recent issue of Annals of Neurology Journal. They analyzed and reviewed results from current and long term studies of Deep Brain Stimulation in people with Parkinson’s and compared the results of Deep Brain Stimulation to standard medical treatment for Parkinson’s. Present medical treatment for Parkinson’s consists of medical, surgical and supportive treatment.
Standard medical treatment for PARKINSON’S DISEASE has evolved considerably since the introduction of L-Dopa forty years ago and then the appearance of dopamine agonists. New brain imaging techniques and greater understanding of the natural history of the disease have come a long way to help new therapies develop. Advances in surgical technique plus the hardware for Deep Brain Stimulation have also become part of standard medical management.
Medical management has been divided into three areas: Early Parkinson’s Disease, when it first affects motor function; Late stage PARKINSON’S DISEASE, where motor complications become apparent and surgical intervention. There are standards for uncomplicated versus complicated and combinations of therapies to treat the motor problems and then complications. But PARKINSON’S DISEASE also has non-motor symptoms, such as pain or depression, which these therapies are unable to satisfactorily address. Surgical intervention has generally been reserved for those people for whom medical therapies are not sufficient or whose responses have been irregular and who have dyskinesias that cannot be resolved any other way. These are often people in the later stages of PARKINSON’S DISEASE.
Deep Brain Stimulation now has a history of 12 to 14 years, since the Food and Drug Administration granted approval. There are now some people who had Deep Brain Stimulation 10 years ago and are still showing clinically confirmed benefits. Deep Brain Stimulation has both motor and non-motor benefits. Deep Brain Stimulation reduces drug induced dyskinesias by as much as 60 to 80 per cent, while decreasing the amount of medication needed. People who have had DEEP BRAIN STIMULATION demonstrate improvement on the Unified Parkinson’s Disease Rating Scale and also report improved quality of life. While there are many qualities to recommend DEEP BRAIN STIMULATION, studies have shown that there are some side effects to be considered. For instance, DEEP BRAIN STIMULATION of the subthalamic nucleus (STN) increased the long term response to L-Dopa medication, but it also worsened the short term response with the effect of mimicking early stage PARKINSON’S DISEASE. DEEP BRAIN STIMULATION of the globus pallidus internus (GPi) was not as effective on motor symptoms as STN, but verbal fluency increased. Both types of DEEP BRAIN STIMULATION report improvement in non-motor domains of pain, akathisia, cognitive function, emotion and improvement in the activities of daily living. Many of the side effects are short term and resolve without problems.
Of course, there are other side effects of DEEP BRAIN STIMULATION, adverse events are always possible. Surgery is always serious, and DEEP BRAIN STIMULATION surgery, done while the patient is awake, carries its share of potential problems. The hardware must not only be properly placed, it must be monitored and adjusted from time to time and batteries need to be replaced. The safety profile of DEEP BRAIN STIMULATION has been so good that it is now recognized as an established therapy for PARKINSON’S DISEASE. Given the improvement of both motor and non-motor symptoms, and the improved quality of life experience with the combination of surgical and medical treatment for PARKINSON’S DISEASE, the guidelines for consideration of DEEP BRAIN STIMULATION as a therapy may need reassessment. Instead of waiting until later in the course of PARKINSON’S DISEASE to recommend DEEP BRAIN STIMULATION as a “rescue”, perhaps we should consider DEEP BRAIN STIMULATION earlier in order to “preserve” function.
Guidelines for DEEP BRAIN STIMULATION have generally been that the patient be responsive to L-Dopa therapy, be cognitively unimpaired and emotionally stable to undergo the surgery. However, cognitive impairments, emotional debility and psychotic symptoms are part of PARKINSON’S DISEASE and often occur later in the disease, possibly ruling out DEEP BRAIN STIMULATION. If DEEP BRAIN STIMULATION could be done before drug induced motor symptoms become problematic, before disease progression affects cognition and emotion, the patient could benefit from improved symptoms and improved quality of life…making it easier to remain working or socially engaged for a longer period of time.
DEEP BRAIN STIMULATION is certainly not a simple consideration. There are many aspects to consider: social, familial, personal as well as medical. Serious conversations with the medical providers, neurologists and neurosurgeon need to be undertaken. Understanding the current situation and symptoms in relation to the course of the disease while weighing them against the benefits, side effects and adverse events of DEEP BRAIN STIMULATION should be considered. While DEEP BRAIN STIMULATION now has a longer history and more people have benefited from it, at what point in the course of the disease it is appropriate to be offered needs to be re-evaluated.
deSouza, R.-M., Moro, E., Lang, A. E. and Schapira, A. H. V. (2013), Timing of deep brain stimulation in Parkinson disease: A need for reappraisal?. Ann Neurol., 73: 565–575. doi: 10.1002/ana.23890