Spinal Cord Stimulation for Gait Disorders in Parkinson's Disease

In PD, Non-Invasive Trans-Spinal Magnetic Stimulation Enhances the Effect of Transcranial Magnetic Stimulation on Axial Motor Symptoms: A Double-Blind Randomized Clinical Trial

BACKGROUND

Axial symptoms in Parkinson's disease (PD) often respond poorly to pharmacological treatment. We evaluated whether combining repetitive transcranial magnetic stimulation (rTMS) and repetitive spinal magnetic stimulation (rSMS) is more effective than rTMS alone in improving axial and other motor disabilities in PD.

METHODS

A total of 42 PD patients with axial symptoms were randomly allocated to 2 experimental intervention groups: Group I received active rTMS + active rSMS (2000 pulses; 20 Hz; 80% resting motor threshold for each motor area "M1" + 1500 pulses rSMS 10 Hz, at 50% of maximal stimulator output). Group II received active rTMS + sham rSMS with the same number of pulses. Both groups received 10 sessions (5 consecutive days/week for 2 weeks). Assessments using Freezing of Gait Questionnaire, walking speed, Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) parts II and III, and Parkinson's Disease Questionaire-39 (PDQ-39) were performed at baseline (T0), end of sessions (T1), and 1 month later (T2).

RESULTS

At T0, Group II showed higher walking speed. At T1 and T2, Group I demonstrated significantly greater improvements in MDS-UPDRS parts II, III, and sub-items of part III. Group I showed stronger improvement in TUG-T and average fast velocity immediately post-intervention, but this effect diminished after 1 month. PDQ-39 scores for leisure activity and walking problems were significantly higher in group I.

CONCLUSIONS

These findings indicate that combining rTMS and rSMS for 10 sessions is more effective than rTMS alone in managing PD's motor and axial symptoms. The effect size of the outcome is large enough to be of significance in clinical practice.

TRIAL REGISTRATION

The study was registered prospectively on 26/12/2021 at the clinicaltrial.gov website with the registration ID: NCT05271513, https://clinicaltrials.gov/study/NCT05271513.

A Pragmatic Review on Spinal Cord Stimulation Therapy for Parkinson's Disease Gait Related Disorders: Gaps and Controversies

BACKGROUND

Parkinson's Disease (PD) is a progressive neurological disorder that results in potentially debilitating mobility deficits. Recently, spinal cord stimulation (SCS) has been proposed as a novel therapy for PD gait disorders. The highest levels of evidence remain limited for SCS.

OBJECTIVES

In this systematic review and narrative synthesis, the literature was searched using combinations of key phrases indicating spinal cord stimulation and PD.

METHODS

We included pre-clinical studies and all published clinical trials, case reports, conference abstracts as well as protocols for ongoing clinical trials. Additionally, we included trials of SCS applied to atypical parkinsonism.

RESULTS

A total of 45 human studies and trials met the inclusion criteria. Based on the narrative synthesis, a number of knowledge gaps and future avenues of potential research were identified. This review demonstrated that evidence for SCS is currently not sufficient to recommend it as an evidence-based therapy for PD related gait disorders. There remain challenges and significant barriers to widespread implementation, including issues regarding patient selection, effective outcome selection, stimulation location and mode, and in programming parameter optimization. Results of early randomized controlled trials are currently pending. SCS is prone to placebo, lessebo and nocebo as well as blinding effects which may impact interpretation of outcomes, particularly when studies are underpowered.

CONCLUSION

Therapies such as SCS may build on current evidence and be shown to improve specific gait features in PD. Early negative trials should be interpreted with caution, as more evidence will be required to develop effective methodologies in order to drive clinical outcomes.

Clinical neurophysiology in the treatment of movement disorders: IFCN handbook chapter

In this review, different aspects of the use of clinical neurophysiology techniques for the treatment of movement disorders are addressed. First of all, these techniques can be used to guide neuromodulation techniques or to perform therapeutic neuromodulation as such. Neuromodulation includes invasive techniques based on the surgical implantation of electrodes and a pulse generator, such as deep brain stimulation (DBS) or spinal cord stimulation (SCS) on the one hand, and non-invasive techniques aimed at modulating or even lesioning neural structures by transcranial application. Movement disorders are one of the main areas of indication for the various neuromodulation techniques. This review focuses on the following techniques: DBS, repetitive transcranial magnetic stimulation (rTMS), low-intensity transcranial electrical stimulation, including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), and focused ultrasound (FUS), including high-intensity magnetic resonance-guided FUS (MRgFUS), and pulsed mode low-intensity transcranial FUS stimulation (TUS). The main clinical conditions in which neuromodulation has proven its efficacy are Parkinson's disease, dystonia, and essential tremor, mainly using DBS or MRgFUS. There is also some evidence for Tourette syndrome (DBS), Huntington's disease (DBS), cerebellar ataxia (tDCS), and axial signs (SCS) and depression (rTMS) in PD. The development of non-invasive transcranial neuromodulation techniques is limited by the short-term clinical impact of these techniques, especially rTMS, in the context of very chronic diseases. However, at-home use (tDCS) or current advances in the design of closed-loop stimulation (tACS) may open new perspectives for the application of these techniques in patients, favored by their easier use and lower rate of adverse effects compared to invasive or lesioning methods. Finally, this review summarizes the evidence for keeping the use of electromyography to optimize the identification of muscles to be treated with botulinum toxin injection, which is indicated and widely performed for the treatment of various movement disorders.

A spinal cord neuroprosthesis for locomotor deficits due to Parkinson's disease

People with late-stage Parkinson's disease (PD) often suffer from debilitating locomotor deficits that are resistant to currently available therapies. To alleviate these deficits, we developed a neuroprosthesis operating in closed loop that targets the dorsal root entry zones innervating lumbosacral segments to reproduce the natural spatiotemporal activation of the lumbosacral spinal cord during walking. We first developed this neuroprosthesis in a non-human primate model that replicates locomotor deficits due to PD. This neuroprosthesis not only alleviated locomotor deficits but also restored skilled walking in this model. We then implanted the neuroprosthesis in a 62-year-old male with a 30-year history of PD who presented with severe gait impairments and frequent falls that were medically refractory to currently available therapies. We found that the neuroprosthesis interacted synergistically with deep brain stimulation of the subthalamic nucleus and dopaminergic replacement therapies to alleviate asymmetry and promote longer steps, improve balance and reduce freezing of gait. This neuroprosthesis opens new perspectives to reduce the severity of locomotor deficits in people with PD.