A new study finds that spinal cord stimulation could represent an alternate therapy for people with Parkinson’s disease that is resistant to conventional treatments. The researchers claim that this emerging technology may help decrease pain and improve mobility.
Close to 1 million people may be living with Parkinson’s disease in the United States. This long-term degenerative disorder results from damage to nerve cells in the brain that produce dopamine.
As the symptoms of Parkinson’s develop, a person may first experience a tremor in one hand and stiffness elsewhere in the body. The four key symptoms are:
- a tremor
- stiffness or tightness in the arms, legs, or elsewhere in the body
- slowed movement and difficulty initiating and coordinating movement — possibly presenting as a loss of facial expression or a slow, stuttering walk
- difficulty with fine movements, such as doing up buttons
Ultimately, a person experiences problems maintaining balance, and some people with Parkinson’s also develop dementia. Certain people only develop motor symptoms and others have cognitive symptoms, and doctors are still unsure why this is.
Some people refer to dopamine as the “feel-good” hormone or chemical messenger. It has various roles, including in movement coordination, and it is an active player in the brain’s reward system.
Most people with Parkinson’s also develop at least one nonmotor symptom. The most common of these are sleep disturbances, a loss of smell, pain, constipation, and excessive sweating.
People may also experience anxiety and neuropsychiatric symptoms, such as depression, apathy, or psychosis.
This wide array of symptoms can affect relationships and cause people with Parkinson’s to have lower self-worth and lose their sense of identity.
While the cause of Parkinson’s remains unknown, prescription treatments for dopamine deficiency and deep brain stimulation (DBS) are the gold-standard approaches.
But dopamine treatment can cause side effects, such as dyskinesias, involuntary twisting movements of the body. These usually diminish as the drug wears off. Other adverse effects include gastrointestinal disturbances, hallucinations, anxiety, and muscle fatigue.
Meanwhile, DBS can cause brain bleeding, infection, and seizures.
Given the urgent need for treatments that alleviate Parkinson’s symptoms with minimal risks, a group of researchers has now investigated an alternate approach: spinal cord stimulation. They have published their findings in the journal Bioelectronic Medicine.
Assessing an alternate therapy
The researchers set out to determine whether spinal cord stimulation could be a singular therapy for Parkinson’s disease and a salvage therapy, in people for whom DBS is increasingly ineffective.
The study included 15 participants, with a mean age of 74 years. On average, they had received the diagnosis of Parkinson’s disease 17 years earlier.
Eight had undergone DBS previously, and the others had only received medication, including pain relievers, as Parkinson’s treatment.
All experienced chronic pain that was resistant to pain relief medication and changes in their treatment for the disease. When a particular nerve was involved, drugs called nerve blocks had been ineffective.
Once the study had begun, electrodes were surgically implanted under the participants’ skin near their spines.
The participants could choose to receive mild electric currents in three stimulation modes: continuous tonic stimulation, continuous burst stimulation, or a cycling mode with burst stimulation, which provided stimulation for 10–15 seconds at a time, separated by pauses of 15–30 seconds.
The researchers observed that the 15 patients experienced “significant improvement” after using the spinal cord stimulator device.
Based on the visual analog scale of pain intensity — the seven patients who had never received DBS experienced a 57% reduction, on average. For those who had received DBS in the past, the average reduction in pain intensity was 61%.
In addition, the researchers found that participants who opted for the cycling mode experienced, on average, a 67% reduction pain, using the same scale. By comparison, those who chose continuous burst stimulation had, on average, a 48% reduction in their pain scores.
Of the 15 patients, 11 had been able to complete a 10-meter walk before and after the study. After the stimulation, eight people (73%) in this group showed an average improvement of 12% during their 10-meter walks. The researchers used these walks to assess the participants’ mobility and gait.
They also used a “timed up-and-go” test to measure how long it takes a person to get up from a chair, walk 3 meters, turn around, walk back to the chair, and sit down. Among the 11 participants who completed this test, seven (64%) showed improvement in their completion times.
The patients who chose a continuous burst pattern had an 18% improvement in their timed up-and-go scores. However, those who chose the cycling mode had a 7% worsening in these scores.
While many of the results seem promising, it is important to note that spinal cord stimulation carries some risks and may cause complications, including bleeding at the site of insertion.
The researchers also acknowledge that their study design had a limitation: They were unable to determine whether the improvements in scores stemmed from the stimulation itself or the resulting decrease in pain, which allowed for more mobility.
The team of researchers, based in the U.S. and Japan, observe:
“Spinal cord stimulation is an emerging technology that can potentially be utilized to treat both the motor and nonmotor symptoms, such as pain, that patients with Parkinson’s disease deal with on a daily basis.”
Another limitation involved the fact that the patients did not receive the spinal cord stimulators in the exact same location, due to differences in how their pain presented. Also, not every patient was able to return and complete the mobility tests, which reduced the already small sample size.
In addition, this small study did not include a control group, so some changes in pain scores could result from a placebo effect.
This research should thus be regarded as a proof-of-concept study. Further evaluation in larger trials is needed.
Finally, some researchers involved in this study have disclosed potential conflicts of interests due to affiliations with medical device companies and pharmaceutical companies, including Medtronic, Abbott, Boston Scientific, Kyowa Kirin, Boehringer Ingelheim, AbbVie, and FP Pharmaceutical.