Gait impairment can be a significant challenge as Parkinson’s disease (PD) advances, with balance problems, frequent falls, and freezing of gait impeding quality of life. Often these challenges do not respond to increased amounts of PD medication or deep brain stimulation (DBS).

In recent years, electrical stimulation of the spinal cord has been a research focus to help people with walking difficulties in PD. In this strategy, instead of trying to correct the abnormal nerve activity in the brain where the Parkinson’s pathology is, the stimulation is trying to correct the problem in the spinal cord – lower down in the cascade of nerve activity that leads from the brain to the legs. Several cases or case series that used this therapeutic strategy have been reported over the years. Results have been very variable, likely because of the variability of the designs in the different systems used. Spinal cord stimulation has therefore not moved very far into clinical development.

Is hope on the horizon?

A recent report, however, may move the field forward. This paper presented the results of the development of a neuroprosthesis, a device created to replace a neurologic function, in this case, walking. The device is implanted next to the lower spinal cord and is designed to stimulate the lower spine in a way that reproduces the activation of the lower spine during walking.

The report describes the development of the implant in an animal model of PD before it was tried in one person who has now had the device for two years. The neuroprosthesis significantly improved the walking experienced by the study participant. Whereas previously, he had frequent falls and freezing of gait, after a few months of rehabilitation, he now walks independently.

Although these results are exciting and encouraging, there is still a long way to go. It is important to note that the results reported are for a single individual who also has deep brain stimulation (DBS) in place. Although DBS alone did not improve his walking, the maximum benefit that the individual achieved was when both the neuroprosthesis and DBS were turned on.  Even without this caveat, PD is so variable from person to person that it will be essential to try this device in many people with PD to understand who it can help and who it does not help and why. In addition, future studies will need to control for the placebo effect – in which thinking that you received the therapy improves your clinical outcome. A future clinical trial will need to compare those whose implant is activated to those whose implant is not activated, without either group knowing which they belong to. The authors report that they are committed to designing a clinical trial as the next step to bringing this technology to more people with PD. The data from these trials will be essential to prove the safety and efficacy of the device in order for it to be approved by the FDA.

As always, APDA keeps a close eye on the latest PD research, and we will bring you news as it develops.