BY DAN HURLEY
VANCOUVER—Spinal cord stimulation significantly improved gait in five patients with advanced Parkinson's disease (PD), researchers reported in a poster presented here on June 5 at the International Congress of Parkinson's Disease and Movement Disorders.
The results of the small, open-label trial come on the heels of another report published four months ago that found similar benefits from spinal cord stimulation (SCS) in four patients.
In the current study, the patients' mean United Parkinson's Disease Rating Scale (UPDRS) motor score improved by 39.4 percent six months after implantation, while results on the freezing-of-gait (FOG) questionnaire improved by 26.8 percent, and the activities-specific balance confidence (ABC) score, a 16-item self report by patients, improved by 116.9 percent. Additionally, the mean number of FOG episodes dropped from 16 before surgery to zero at six months while patients were on levodopa and off-stimulation.
Mark Hallett, MD, FAAN, chief of the human motor control section of the National Institute of Neurological Disorders and Stroke, who was not involved with the study, cautioned that the results of any small, uncontrolled study of PD must be replicated in a larger, randomized trial. But, he added: "I think if it pans out, this may well be an exciting new treatment. It's only five patients in an open-label study, but the amount of improvement was substantial. Gait dysfunction is very hard to treat, and one would think it wouldn't be that placebo-responsive."
The study involved five advanced PD male patients not eligible for deep brain stimulation, at a mean age of 71 years old, with significant gait disturbances, FOG, and postural instability. They underwent mid-thoracic SCS, the settings for which were adjusted between 200 to 500 microseconds (ms) and 30 to 130 Hz in eight study visits over a six-month period.
Three patients responded best to a combination of 300 ms and 60 Hz, with timed sit-to-stand, stride velocity, and step length improving by 63.8 percent, 76.2 percent and 91.1 percent, respectively. The other two patients responded best to a combination of 130 Hz and 200 or 300 ms, with a mean improvement in timed sit-to-stand, stride velocity and step length of 58.4 percent, 36.6 percent and 56.7 percent, respectively.
"These patients had Parkinson's for 15 to 20 years," said the senior author of the abstract, Mandar S. Jog, MD, professor of neurology at the University of Western Ontario and director of the National Parkinson Foundation Centre of Excellence at London Health Sciences Centre in London, Ontario. "One of the patients was wheelchair-bound, and another was dependent on a scooter. They were getting up and walking around [after the SCS]."
A study of four patients, published in February in the journal Movement Disorders by a Brazilian team, also found significant improvements with SCS. That study used a sham control, with assessors blinded to the settings. Gait measurements improved by 50 percent to 65 percent, and UPDRS III and quality-of-life scores improved by 35 percent to 45 percent. The active setting was 300 Hz, and the sham setting was 60 Hz.
Curiously, though, 60 Hz was the same setting found to be beneficial in the poster presented here at MDS, a contradiction not easily explained.
"We tailored the programming of each patient's kinematics to achieve the best possible response," said Dr. Jog, "whereas the previously reported paper used the same settings for all patients."
Erich Talamoni Fonoff, MD, PhD, associate professor of neurosurgery at the University of São Paulo Medical School, who was the senior author on the Movement Disorders study, noted there were some differences between the studies in regard to the settings which produced the best effect. But, he emphasized, the most noteworthy fact is that both papers found the treatment to be effective.
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International Congress of Parkinson's Disease and Movement Disorders Abstract 344: Samotus O, Kumar N, Memar S, et al. Spinal cord stimulation reduces freezing of gait and improves gait in advanced Parkinson's disease.
Pinto de Souza C, Hamani C, Oliveira Souza C, et al. Spinal cord stimulation improves gait in patients with Parkinson's disease previously treated with deep brain stimulation. Mov Disord 2017; 32(2): 278-282.