Pre-operative electrical stimulation in carpal tunnel syndrome

INTERVENTION: PROSpeCT is a ‘randomised, patient‐, surgeon‐ & assessor‐blinded, placebo‐controlled clinical trial’. This study design has been chosen as it will best allow us to determine whether the treatment makes a difference to patients. The study is 'randomised' in that participants will be divided into two groups using computer software. Which group participants end up in is due to chance, or ‘random’, though groups will be balanced for disease severity. Both groups will still receive the current gold standard treatment for carpal tunnel syndrome (carpal tunnel decompression surgery), but only one will get the new electrical stimulation treatment being studied. Randomisation is ‘stratified’ to ensure equal numbers of people with different severities of carpal tunnel syndrome are placed into each group. This approach is used because different severities of carpal tunnel syndrome have different kinds of nerve damage, which could affect response to stimulation. Placebo‐controlled means that while one group will be given the new electrical stimulation treatment and an operation, the other group will be given ‘placebo’ stimulation treatment and their operation. The placebo is a treatment that looks and feels like electrical stimulation but will not affect the nerve’s healing process. Participants will not know which group they are in; hence they are blinded. The researchers measuring outcomes at follow‐up will also be blinded. At the end of the study, results will be compared from the two groups to see if the electrical stimulation produced any improvement. This design has been chosen for two reasons. First, it is important that both the participants and the researchers do not know which group they are in (i.e. that they are ‘blinded’) because that knowledge could affect the CONDITION: Carpal tunnel syndrome scheduled to undergo primary surgical decompression ; Nervous System Diseases PRIMARY OUTCOME: Cold detection threshold to a thermode (thermal probe) being placed on the skin measured using perception of ramped thermal stimuli at baseline pre‐surgery and 6 months post‐surgery INCLUSION CRITERIA: 1. Participant is willing and able to give informed consent for participation in the study. 2. Male or female, aged 18 years old and over 3. Diagnosed with carpal tunnel syndrome based on clinical examination by a hand surgeon 4. The patient has already determined they wish to proceed with carpal tunnel decompression surgery SECONDARY OUTCOME: 1. MRI parameters of median nerve at the carpal tunnel at baseline and 3 months; 2. Median nerve sensory and motor conduction studies including motor unit number estimation (assessed by M‐Scan method) and axonal excitability; 3. Boston Carpal Tunnel Syndrome questionnaire at 12 months; 4. Visual analogue rating of symptoms at 12 months; 5. iHand nerve function questionnaire at 12 months; 6. painDETECT questionnaire at 12 months; 7. Neuropathic Pain symptom Inventory at 12 months; 8. Depression Anxiety Positive Outlook Scale at 12 months; 9. Short‐form pain Anxiety Symptoms Scale at 12 months; 10. Insomnia Severity Inde Xat 12 months; 11. EQ‐5D‐5L at 12 months; 12. Global Rating of Change questionnaire at 12 months; 13. Quantitative sensory testing (German Research Network for Neuropathic Pain short form protocol) at baseline and 6 months; 14. Histological parameters of median nerve innervated skin biopsy at baseline and 6 months