Spinal Cord Stimulation for Gait Dysfunction in Parkinson's Disease

Parkinson's disease (PD) is the second commonest neurodegenerative disorder, affecting over 145,000 people in the UK. Initially, PD patients experience slowness of movements, limb stiffness, and tremor.

With progressive loss of neurons over time, many patients start to experience balance and walking problems, and falls, which are resistant to currently available treatments. Falls can lead to fractures and nursing home admission, and can significantly shorten patients' life expectancy.

In this pilot study, the investigators will investigate the effects of spinal cord stimulation (SCS) on gait and balance in PD. Some open-labelled studies have shown possible beneficial effects of SCS in PD, although it is uncertain which type of PD patients will benefit most and which stimulation parameters work best. The investigators will assess the effects of SCS on posture and gait using a series of clinical, laboratory, imaging, and wearable measurements.

The participants will receive a percutaneous implantation of a spinal cord stimulator to minimise the possible adverse effects related to the surgery.

The SCS will start one month after surgery. The investigators will use a double-blind cross-over design. The participants will receive three different stimulation parameters, including sham stimulation, in a randomised order. The participants and the assessors will be blinded to the stimulation parameters.

The investigators aim to recruit up to 8 people with Parkinson's with significant gait dysfunction which is resistant to medical therapy to this study. All participants will receive implantation of a spinal cord stimulator at T8-10 levels. The procedure will be done percutaneously. The spinal cord stimulation will be commenced 2-4 weeks after surgery to allow time for recovery.

Participants will receive 3 different stimulation parameters in randomised order as outlined below:

1. Burst stimulation
2. High frequency stimulation
3. Sham stimulation Each parameter will last for up to 6 weeks. Both the patients and the researchers assessing the patients will be blinded to the settings parameters. At baseline and at the end of each stimulation settings, the participants will undergo a series of assessments (see secondary outcomes). At the end of the cross-over blinded period, the participants will be unblinded and offered to continue with the parameter that offered most symptomatic relief. The participants will then continue in this setting in an open label phase for another 10 weeks before their final assessment at 7 months.

Eligibility Criteria:
Inclusion Criteria:

* Age: 45 ≤ X ≤ 85
* PD diagnosis based on UK Parkinson's disease society brain bank criteria
* Significant gait dysfunction, particularly freezing of gait, which is resistant to optimal medical therapy
* Hoen and Yahr stage: 2-4 (in ON state)
* Stable dopaminergic treatment for at least two weeks before enrolment.
* Can provide informed consent

Exclusion Criteria:

* Atypical or secondary parkinsonism e.g. vascular, drug-induced
* Major focal brain disorders (including malignancy or stroke)
* Recent (within 3 months)/current use of acetylcholinesterase inhibitors or antidopaminergic drugs
* Concomitant treatment with deep brain stimulation
* Neurological, vestibular, visual or orthopaedic diagnosis significantly interfering with gait
* Pregnant women or planning to become pregnant
* Significant chronic back pain
* Spinal anatomical abnormalities precluding SCS surgery
* Major cognitive or psychiatric illness
* Concomitant or recent (less than 4 months) enrolment in an interventional research trial.