A recent study conducted by researchers at U of T and Toronto Western Hospital shows that there is some new hope for people suffering from Parkinson’s Disease. Deep brain stimulation, a new form of surgical treatment where electric wires are implanted in the brain, has several advantages over older medication-based treatments.
Parkinson’s Disease is a disorder caused by problems in the area of the brain that controls coordination. Symptoms of the disease progress from tremors, stiffness, and difficulty walking to difficulty speaking, falling, and psychiatric problems. Between 1996 and 2001, the study followed 25 patients implanted with deep brain stimulators, monitoring their motor skills prior to and after surgery, while on and off medication.
How exactly does this treatment lessen the symptoms of Parkinson’s?
“We don’t know,” says Dr. Lang. He explains that while doctors used to treat the symptoms associated with Parkinson’s Disease by burning lesions in the brain to block abnormal wave activity, deep brain simulation works by stimulating and increasing nerve activity in those areas. Exactly how this helps to decrease the symptoms is “very confusing right now.”
The study reveals that patients using the new treatment experienced a drop of nearly 50 per cent in symptoms, making it only slightly less effective than traditional treatments. And there are several advantages of deep brain stimulation as compared to medication.
Deep brain stimulators provide a steady application of treatment throughout the day, whereas the amount of medication in a patient’s body can fluctuate. Because many patients are able to diminish their medication substantially when undergoing deep brain stimulation treatment, there is a marked decrease in side effects associated with the medication. (The study found that, on average, patients reduced their dosages by 38 per cent after the first year). This means patients suffer fewer involuntary muscle movements. In addition, because stimulators can be finely tuned and adjusted to each patient’s needs, the treatment is more precise.
There are some drawbacks to the new treatment, however. Implantation of stimulators is costly, requiring a team of neurologists and surgeons to perform the surgery and to adjust the stimulators for each patient. “Brain operations are very risky. Hardware and wires can become infected, they can become damaged and need removal, and complications can arise from the stimulators. There are also psychiatric side effects,” says Dr. Lang. He cautions that deep brain stimulation cannot fully replace drug treatment, since the drugs also help adjust mood and behaviour, which the new treatment cannot do.
Deep brain stimulation improves the patient’s motor and daily living skills for an average of two years. However, because the symptoms of Parkinson’s Disease worsen and change over time, more severe symptoms appear later which cannot yet be treated.
“One of the important features we found is that not all symptoms of Parkinson’s Disease respond equally to treatment,” notes Lang. “Over time, the tremors, stiffness and, to a lesser extent, the slowness continue to respond to surgery and medication. But certain features of the illness such as speech, stability and difficulty with walking benefit less from therapy over the course of long-term follow-up. It’s a progressive disease, and some features cannot be controlled by deep brain stimulation,” says Dr. Lang.
Dr. Lang hopes treatments will improve as our knowledge of the disease increases. “The goal is to understand the progression of the disease, why it starts and how it continues.”
