BY, Robert E. Tibbs Jr., MD
Deep brain stimulation (DBS) has become a well-recognized non-pharmacologic treatment that improves motor symptoms of patients with early and advanced Parkinson’s disease. Evidence now indicates that DBS can decrease the number and severity of non motor symptoms of patients with Parkinson’s disease (PD) as well, according to a review published in the Journal of Parkinson’s Disease.
“Non motor features are common in PD patients, occur across all disease stages, and while well described, are still under-recognized when considering their huge impact on patients’ quality of life,” says Lisa Klingelhoefer, MD, a fellow at the National Parkinson Foundation International Centre of Excellence, Department of Neurology, King’s College Hospital and King’s College, London.
For example, DBS of the subthalamic nucleus (STN) is effective for alleviating sleep problems and fatigueassociated with PD, producing noticeable long-term improvements in sleep efficiency and the quality and duration of continuous sleep. DBS also decreases nighttime and early morning dystonia and improves nighttime mobility. “DBS can contribute to better sleep, less daytime somnolence, improved mobility, and less need for dopamine replacement therapy,” says Dr. Klingelhoefer.
Previous studies have shown that DBS can improve motor function in people with Parkinson’s disease. The treatment involves electrodes surgically inserted into specific areas of the brain. An impulse generator battery–similar to what is used in pacemakers–is also implanted, under the collarbone or in the abdomen. The battery creates electrical impulses that the electrodes deliver to the brain tissue.
Dr. Frances Weaver, lead author on the study, explained the benefit of DBS: “Overall, DBS surgery has been viewed quite positively by both patients and providers. There is an immediate effect on patients who have DBS on their motor function–the dyskinesia [involuntary muscle movements] is either gone or greatly reduced. The patient can move around and do things they hadn’t been able to.”
While deep brain stimulation may improve function compared with those who do not receive it, little evidence exists on whether the treatment has any benefits to life expectancy. To answer that question, the researchers looked at data for 611 Veterans with Parkinson’s disease who had a deep brain stimulation device implanted. They compared this with data on 611 Veterans with Parkinson’s but without the device. The data came from VA and Medicare administrative files from between 2007 and 2013.
The effects of DBS on some other non motor symptoms of PD are less clear cut and transient worsening of neuropsychological and psychiatric symptoms have been reported. For instance, behavioral disorders such as impulsivity (e.g. hypersexuality, pathological gambling, and excessive eating) can occur or worsen in PD patients after STN DBS. While pre-existing drug-induced psychotic symptoms like hallucinations often disappear after STN DBS, transient psychotic symptoms such as delirium may emerge in the immediate post-operative period. Similarly, conflicting reports have found that STN DBS improves, worsens, or does not change mood disorders such as depression, mania, or anxiety.
“Further work is required in order to fully understand the mechanisms and impact of DBS of the STN or other brain structures on the non motor symptoms of PD,” concludes Dr. Klingelhoefer. She suggests that in the future, non motor symptoms of PD may become an additional primary indication for DBS.
PD is the second most common neurodegenerative disorder in the United States, affecting approximately one million Americans and five million people worldwide. Its prevalence is projected to double by 2030. The most characteristic symptoms are movement-related, such as involuntary shaking and muscle stiffness. Non motor symptoms, such as worsening depression, anxiety, olfactory dysfunction, sweating, bladder and bowel dysfunction, and sleep disturbances, can appear prior to the onset of motor symptoms.