Mechanisms of Neurodynamic Treatments

INTRODUCTION: Carpal tunnel syndrome (CTS) is a relatively common condition caused by compression of one of the main nerves at the wrist, the median nerve. Non-surgical treatments, like steroid injections and physiotherapy, are the first line of treatment for patients with carpal tunnel syndrome. The investigators have previously shown that specific physiotherapeutic exercises (neurodynamic exercises) can reduce the need for carpal tunnel surgery in some patients. Experimental studies in animal models demonstrate that these exercises have an anti-inflammatory effect and can help the nerve to regenerate. However, the exact mechanisms of action of these exercises are not well understood in patients. A better understanding of the mechanisms of action of physiotherapeutic exercises would help clinicians to better target these treatments to those patients who may benefit from them.

AIM: To investigate the mechanisms of action of 6 weeks' neurodynamic treatments on nerve function and structure as well as patient-reported outcome measures in patients with CTS compared to a positive control intervention (routine care steroid injection) and a negative control intervention (advice).

METHODS AND ANALYSIS: In this single-blind randomised mechanistic trial, patients with confirmed mild to moderate CTS (n=78) and age and gender-matched healthy controls (n=30) will be included. Patients will be randomly allocated to a 6-week neurodynamic exercise group, steroid injection, or advice group. Outcome measures will be explored at baseline (patients and controls), post-intervention (patients), and 6-month follow-up (patients). Outcomes include diffusion-weighted and anatomical MRI of the median nerve at the wrist, quantitative sensory testing, nerve conduction studies, inflammatory markers in blood and skin biopsies, and validated questionnaires for pain, function, and psychological factors. Two-way repeated measures ANCOVAs (factors time and intervention, adjusted for baseline measurements as a continuous covariate) will be performed to identify differences in MRI parameters, clinical assessment, and inflammatory markers between patients in different groups and healthy controls.

Follow-up at 6 months will only include outcome measures from questionnaires.

Details on enrollment:

Pilot testing of healthy participants who consented to our ethics but will not be included in the study was on 13-April-2023.

* First healthy participant enrolled: 17-May-2023.
* First patient participant enrolled: 1-June-2023.

Details on amendment:

* Amendment SA2_BPOR on 3/Aug/2023 to expand recruitment through registries of patients
* Amendment SA3_REC on 22/Aug/2023 to add Thames Valley Primary Care Research Partnership, musculoskeletal clinics, and media advertisement to help with recruitment of participants.

Eligibility Criteria:
Inclusion Criteria

Patients:

1. Patients who have a diagnosis of mild to moderate carpal tunnel syndrome based on a clinical assessment and confirmed with nerve conduction studies.
2. Male or Female, aged 18 years or above.
3. Patient is willing and able to give informed consent for participation in the study.

Healthy participants:

1. Male or female aged 18 years or above.
2. Participant is willing and able to give informed consent for participation in the study.
3. No history of hand or arm symptoms
4. No history of neck pain in the past 3 months
5. No systemic medical condition
6. No strong anticoagulant medication or altered coagulation (e.g., hemophilia) preventing skin biopsies
7. Severe anxiety or depression
8. Participants are required to be age- \& sex-matched to patient participants
9. No contraindications for magnetic resonance scanning at 3T
10. Sufficient command of the English language

Exclusion Criteria

Patients:

1. Patients who already had surgery for their carpal tunnel syndrome (CTS) or are planning to undergo surgery in the next 6 weeks (patients with unilateral surgery who have unoperated CTS on the other hand are eligible to participate)
2. Patients who had a steroid injection for their CTS in the 6 months prior to the study enrolment or who had already more than 1 steroid injection into the study wrist.
3. Patients who have a diagnosis of severe carpal tunnel syndrome based on a clinical assessment and confirmed with electrodiagnostic testing
4. Electrodiagnostic testing revealing abnormalities other than CTS
5. Any other upper limb or neck problem for which they have sought treatment in the past 3 months
6. History of significant trauma to the upper limb or neck
7. Diabetes
8. Hypothyroidism
9. Severe anxiety or depression
10. Patient who is pregnant, lactating, or planning pregnancy during the study.
11. Patients on strong anticoagulant medication or altered coagulation preventing skin biopsies.
12. Contraindications for magnetic resonance imaging (assessed with MRI safety screening questionnaire).
13. Contraindications for steroid injections
14. Insufficient command of the English language