News
We are happy to share your stories with the DBS-STN community.
If you had DBS-STN surgery, or know someone who has, and would like to submit a story for inclusion on our site, please call us toll free at 1-800-579-8440 or contact us.
The Parkinson Alliance attended the 38th Neural Interfaces Conference
The 38th Neural Interfaces Conference was held at the InterContinental Hotel in Cleveland, Ohio from June 16-18, 2008.
What are neural interfaces?
In brief, neural interfaces are systems operating at the intersection of the nervous system (the system of cells, tissues, and organs that regulates the body's responses) and an internal or external man-made device. Neural interfaces include neural prosthetics, which are artificial extensions to the body that restore or supplement function of the nervous system lost during disease or injury, and implantable neural stimulators that provide therapy (e.g., deep brain stimulation for Parkinson’s Disease). Neural interfaces are used to allow disabled individuals the ability to control their own bodies and lead fuller and more productive lives.
What is the DBS Consortium?
The National Institutes of Health (NIH) Deep Brain Stimulation (DBS) Consortium is an integral part of the Neural Interfaces research community and is comprised of a core group of multidisciplinary researchers funded under a series of NIH-sponsored programs to advance technological innovation and further understand the sites and/ or mechanisms of action of Deep Brain Stimulation.
While implementing initiatives to improve technological intervention/treatment for individuals with a debilitating neurological disease, it is vital to maintain heightened awareness regarding the patient’s experience. As we endeavor to apprehend the enhancements in the tools to facilitate the DBS therapy and to stimulate technological innovation, it will be important to maintain our focus on improving the patient’s experience during pre-surgical treatment, the surgical procedure, and post surgical therapeutic intervention. This fundamental concept is where The Parkinson Alliance strongly contributes.
What was The Parkinson Alliance’s contribution at this conference?
The Parkinson Alliance was invited to facilitate a presentation/discussion about non-motor symptoms in PD, particularly as it relates to speech disturbance, sleep disturbance, and autonomic dysfunction following DBS. Dr. Wertheimer of The Parkinson Alliance research team facilitated a presentation on these topics. The following points were conveyed during his presentation:
Speech Disturbance:
Research has found that DBS has varying results on speech functions. For example, some research has found some improvement in the motor movements related to and sound of speech during stimulation (Gentil, M et al., 2001 and 2003; Klostermann, et al., 2008). In other words, DBS has helped improve speech by impacting motor functions that were making speech worse (such as tremor within muscles and structures that help facilitate speech). Other research has found limited or no benefit to voice and speech (Dromey et al., 2000; Farrell et al., 2005). And other research has found a worsening of speech intelligibility (ability to be understood) due to DBS (Beric et al., 2001; Klostermann, et al., 2008; Krack et al., 2003 Rosseaux et al., 2004).
In the context of DBS’s role in the worsening speech, which has been found to be very common in PD, research has found that the surgical procedure for DBS can be the culprit for worsening of speech. Moreover, research has found that impaired verbal expression can result directly from the surgical procedure itself, rather than post surgical stimulation or medication changes (Amick, Chou, & Gagner, 2008). Furthermore, there has been evidence to show that the side of the brain that is stimulated (e.g., left or right STN) has a differential impact on speech expression. For example, research has found that left-sided stimulation has a negative effect on prosody (e.g., intonation, rhythm, or inflection in one's voice), articulation, and intelligibility. Right-sided stimulation does not display this side-effect for most patients. Authors claim that the speech production was very susceptible to change due to the surgical procedure itself when the surgical site was in the left-hemisphere (Santens, P., et al., 2003; Brain Lang,87(2), 253-258; Wang, E., presentation at the Acoustical Society of America, 2006; Wang, et al, 2003, Clinical Linguistics & Phonetics,17(4-5), 283-289).
Some preliminary findings from the research that The Parkinson Alliance is currently conducting on speech were also discussed. Specifically, the differences in perceived speech function were assessed for PD patients with and without DBS. Suffice it to say that preliminary findings indicate that there as indeed a difference between the two groups with a higher percentage of PD patients who have undergone DBS reporting greater speech difficulties. The findings of this speech research that The Parkinson Alliance is currently conducting will be available on this website in the near future.
Sleep Disturbance:
It is well known that sleep disturbances, including insomnia, sleep apnea, restless leg syndrome, and REM Behavioral Sleep Disorder have a high prevalence rate within the PD population. Research has found though, that DBS can improve the quality of sleep (Lyons & Pahwa, 2006; Wertheimer, et al., 2006). For example, Drs. Lyons and Pahwa found that bilateral STN-DBS increased total sleep time and reduced patient-reported sleep disturbance for up to 24 months post DBS treatment. Despite significant reductions in antiparkinsonian medications, however, STN DBS did not reduce excessive daytime sleepiness.
The Parkinson Alliance’s research on sleep that was conducted in 2006 (see survey results on DBS-STN.org) revealed that the DBS group reported significantly better sleep than the non-DBS group. Moreover, as compared to the Non-DBS group, the DBS group reported the following:
- better quality of sleep
- that it was easier to fall asleep
- better able to stay asleep
- less painful muscle cramps in their arms and legs while sleeping at night.
- less frequency of waking up early in the morning due to painful posturing of arms and legs
- less frequency of tremor upon waking
Another topic related to DBS and sleep was presented. Specifically, the role of adenosine (a brain chemical most widely known as the cause of drowsiness) has been found to play an important role in DBS (Bekar, et al., 2008, Nature Medicine). Specifically, Dr. Maiken Nedergaard and colleagues, from the University of Rochester, showed that the electrical pulses that are at the heart of DBS evoke astrocytes (cells in the central nervous system) in the area immediately around the surgery to release ATP, which is then broken into adenosine. It is the extra adenosine that has been found to assist in reducing abnormal signaling among the brain’s neurons. Dr. Nedergaard speculated that it might be possible to enhance the effectiveness of deep brain stimulation by taking advantage of the role of agents that modulate the pathways initiated by adenosine. She also stated that it might be possible to develop another type of procedure, perhaps using local targeting of adenosine pathways in a way that does not involve a surgical procedure.
Autonomic Dysfunction:
The autonomic nervous system regulates unconscious body functions, including heart rate, blood pressure, temperature regulation, gastrointestinal secretion, metabolic functions, and hormonal responses. There is little research that has been conducted on autonomic dysfunction in PD as it relates to DBS. Of the research that has been proposed, improvement in autonomic function was found following DBS. For example, research has found that orthostatic hypotension (a form of low blood pressure) is found with a high prevalence in PD (Haensch, et al., 2008; Peralto, et al., 2007; Senard, et al., 1997). Research has found that DBS-STN helps to improve postural hypotension in patients with PD (Stemper at al., 2006). Another study found that dysautonomic fluctuations (such as “drenching sweats”) showed marked improvement with DBS (Witjas, et al., 2007). Furthermore, there has been some research indicating that DBS-STN can ameliorate bladder dysfunction in PD patients (Herzog, et al., 2006).
What other information was provided at this conference?
There were several presentations pertaining to DBS as a therapeutic intervention for PD. Some presentations related to the possibility that DBS is neuroprotective (protecting the brain from cell death and degeneration). David Charles, M.D. (Vanderbilt University) and Caryl Sortwell, Ph.D. (University of Cincinnati) presented strong evidence supporting the possibility of the neuroprotective outcome of DBS. Specifically, although still a controversial point, Drs. Charles and Sortwell provided a very persuasive argument regarding the evidence that DBS may be the first therapy proven to slow the progression of PD. Dr. Charles is also conducting research on patients with early stage PD who are undergoing DBS, and recruitment includes patients within the first couple of years following their diagnosis. In fact, Dr. Charles is currently leading the only clinical trial approved by the United States Food and Drug Administration to test deep brain stimulation in people with early stage Parkinson’s disease.
Jerry Vitek, M.D., Ph.D. (Cleveland Clinic and Lerner Research Institute) and Ken Follett, M.D., Ph.D. (Nebraska Medical Center) discussed their research endeavors as it related to DBS clinical trials for movement disorders. Dr. Vitek provided some preliminary results from his randomized trial of unilateral DBS in subthalamic nucleus (STN) vs. globus pallidus (Gpi) for advanced PD. There is the significant question as to which site may be more efficacious in treating PD. It is known that both clinical and biomechanical data indicate that unilateral DBS of GPi or STN results in persistent improvements in motor functioning. That being said, however, the “ideal” structure to stimulate continues to remain controversial. Preliminary data from Dr. Vitek’s study found that there was no significant difference in outcome variables as it related to DBS of the GPi or STN. Thus, his preliminary data indicated that unilateral DBS implantation of either site should be considered an option for those patients in whom bilateral procedures are contraindicated.
Dr. Follett is the principal investigator of the VA/NIH sponsored, multi-center clinical trial that is investigating the comparison of best medical-therapy (e.g., medication intervention) to deep brain stimulation and comparing DBS of the STN to the GPi. Dr. Follet’s study enrolled over 300 patients, and it is a randomized controlled trial. The study is likely to answer the multitude of questions related to the effectiveness of DBS and whether one site for DBS might be superior to the other. Dr. Follett pointed out, however, that it may not be necessary to find out which site is better from the bigger picture, but rather the goal should be to find out which site is best for a certain set of symptoms of PD. As such, one of the main goals appears to include identifying the best means of tailoring the DBS therapy to the patient. The results of his study are likely to be revealed within the next year.
Additional presentations related to DBS intervention included detailed descriptions regarding technical functioning of the stimulator and how the stimulation impacts structures in the brain, both at the neuronal level and cellular level. Specifically, researchers are learning more about the impact of different stimulation levels on deep structures and cells in the brain, which may result in finding optimal stimulation settings to improve brain function. Current research is finding that lower stimulation parameters may effect some symptoms of PD better than others, while higher stimulation parameters may have greater benefit to other symptoms. Research continues to be in its early stages, however, and we are learning about the dynamics of neural systems and how to measure, quantify, and interact with those dynamics to best help identify the ideal stimulation parameters to assist with optimizing patient benefit.
Concluding remarks:
In closing, the scientific community continues to make impressive advancements in our understanding and treatment of the brain as it relates to PD. We continue to make major strides in the “laboratory” and in the clinical arena. Technological innovation continues to assist in our apprehending knowledge about and enhancing the tools for optimal DBS therapy, and the scientists and practitioners along with the very important patient perspective continues to lead to the improvement of the patient’s experience during pre-surgical treatment, the surgical procedure, and post surgical therapeutic intervention.
We would encourage you to review the research summaries that we have provided on this website to gain a greater understanding about research that has enhanced our knowledge about DBS-STN for PD patients.