Effects of Spinal Cord Stimulation on Gait in Patients With Parkinson´s Disease; a Randomized, Crossover, Double Blinded, Placebo-Controlled Study

Gait impairment in Parkinson´s Disease (PD) is often refractory to standard medication therapy and functional surgery options currently explored resulting in grave loss of independence and quality of life. Spinal cord stimulation (SCS) has been explored for its role in PD after enthusiastic animal studies and despite mixed initial results is currently a very promising candidate for ameliorating hard to treat gait and balance disorders.

Consensus on tonic SCS efficacy is hampered mostly due to small samples and lack of randomized controlled trials so far, and the impossibility of subject blinding due to standard stimulation settings using currents over the paresthesia inducing threshold. Some small studies already attempted subthreshold blinding and all resulted in non significant results, however with no important difference when switching to suprathreshold settings, thus raising the possibility of non responder subjects or inefficient therapy and calling for additional exploration. The investigators aim to explore the feasibility of a placebo controlled trial using subthreshold stimulation with a larger sample and produce stronger evidence on SCS efficacy for PD.

Additionally, the possibility of non responder subjects will be explored by correlating the degree of response to SCS to patient demographic characteristics including age, PD severity and cognition, gait characteristics and the degree of response to trans spinal magnetic stimulation (TSMS), a non invasive magnetic stimulation of upper thoracic spinal region, aiming to identify prognostic factors for the therapy.

Finally, functional magnetic resonance imaging and electroencephalographic mapping will be performed in order to identify biomarkers of SCS therapy.