Spinal cord stimulation can effectively decrease pain, and also may help alleviate motor symptoms, in people with Parkinson’s disease (PD), regardless of whether patients have previously undergone deep brain stimulation, a small study suggests.
There currently are two widely used treatment strategies for reducing pain and lessening the tremors, slowness of movement, and other symptoms of Parkinson’s. One is to employ therapies, specifically levodopa and its derivatives, that work to increase the levels of dopamine in the brain.
The other, known as deep brain stimulation (DBS), involves surgically implanting a device in the brain that delivers electrical impulses. The overarching idea is to normalize electrical activity in the nervous system, which is disrupted in Parkinson’s.
Conceptually, spinal cord stimulation (SCS) is similar to DBS, except that where DBS involves delivering electrical impulses to the brain, SCS electrical pulses are delivered to the spinal cord. Since the spinal cord can be accessed more easily than the brain, SCS may be safer than DBS — however, whether SCS is an effective treatment for Parkinson’s is still being investigated.
In the new study, researchers based in the U.S. and Japan recruited 15 people with Parkinson’s who were experiencing ongoing symptoms, including persistent pain, even with treatment. Eight of the participants had previously been treated with DBS.
Percutaneous (through-the-skin) electrodes were implanted near the participants’ spines, and one of three patterns of electrical stimulation were administered based on patient preference: continuous stimulation, on-off bursts, or continual bursts of varying intensity. Most participants chose one of the two patterns that included bursts.
A variety of clinical tests were then conducted to assess the effects of SCS treatment on the patients’ symptoms. Of note, these tests were done when the participants’ other medications were working effectively, or during “on” periods.
Pain was measured with a visual analogue scale. Average pain scores decreased significantly for all participants following SCS, regardless of the pattern of electrical stimulation or whether the individuals had previously been treated with DBS. In all groupings, the average pain scores decreased by about 50% or more.
“SCS could be utilized even after DBS treatment in our study and led to significant pain relief in [Parkinson’s] patients,” the researchers wrote.
Motor functioning was measured with the 10-meter walk test, which clocks the time it takes a person to walk 10 meters (about 33 feet), and the timed up and go test (TUG), which assesses the time it takes a person to stand, walk a set distance, and return to the starting seat. In both tests, lower times are generally indicative of better physical function.
There were no significant differences in the average 10-meter walk test or TUG scores before and after SCS. However, the researchers noted that eight of 11 participants (73%) who had data available showed clinically significant improvements in the 10-meter walk test following SCS. Meanwhile, seven of 11 (64%) patients with data available showed clinically significant improvements in the TUG test after SCS.
“While the mean differences between pre SCS implantation and post SCS implantation groups for motor function (10 M walk, TUG) were not statistically different, most patients that were able to complete the tests showed improvement in their completion times for both tasks,” the researchers wrote.
“However,” they added, “given the study design, it is not possible to differentiate whether these motor improvements stemmed from the effects of SCS, or if the decrease in pain allowed patient to improve their motor testing results. Thus, additional studies need to be conducted to explore the efficacy of SCS … to help alleviate [Parkinson’s] motor symptoms, and to explore the causal relationships between the SCS, pain and motor improvement.”
This study’s main limitation is its small sample size; the researchers noted a need for future studies to further explore the therapeutic potential of SCS in Parkinson’s.
Collectively, according to the researchers, this study “points to the potential utility of SCS as an option to address both pain and motor symptoms in [Parkinson’s] patients who have and have not received DBS therapy.”
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