Is Chronic Whiplash-associated Pain of Neurogenic Origin? A Study Protocol of a Randomized Controlled Trial Comparing Neurolysis of Peripheral Nerves With Traditional Neck-specific Exercise

People with whiplash associated disorders (WAD) grade II-III have chronic severe pain and symptoms and reduced quality of life. The origin of the symptoms is still unknown, and there are to date no available guidelines for treatment of this condition. The lack of effective treatment leads to high costs for the patients, and to society, due to considerable medical care and work loss.

After providing a written consent, the patients will be randomized to either surgical treatment with neurolysis of peripheral nerve/s in the back of the head and/or neck plus physiotherapy or to physiotherapy (care-as-usual) only. Both groups will be treated with the same traditional neck-specific exercise program for 12 months. All participants will be evaluated with patient-reported outcomes and clinical examination at baseline, and at 6, 12 and 24 months after inclusion.

The main outcome will be change in NDI from baseline to the 2-year follow-up. A preliminary sample-size calculation shows that 27 patients are needed for each treatment arm to detect a clinically important change of 10 points in NDI, with a between-group standard deviation of 13 point (statistical power of 80 % and a 5% significance level). To account for a 20% drop-out rate, 32 patients will be included per arm. Because this is the first RCT on neurolysis vs care-as-usual treatment, a second sample-size calculation including empirical data will performed by an independent statistician, without breaking the code, when 30 patients in each group have been included. Secondary outcomes include VAS (average pain including pain in the head, neck and face), symptom index, self-efficacy, HDI, WAD-DI, psychosomatic aspects, quality of life and clinical examination. Data will be performed with parametric, or non-parametric statistics, as appropriate, in IBM SPSS Statistics version 22 for Mac (IBM Corp., Armonk, NY, USA). Analysis will be performed according to both intention-to-treat and per protocol. To account for missing data, the previous group means value will be considered to remain form the last occasion and used as carry forward. For continuous data, differences in mean change (baseline vs follow-up) will be compared between groups and adjusted in relation to baseline values. For categorical data, differences in median change (baseline vs follow-up) will be compared between groups and adjusted in relation to baseline values. Effect sizes will be calculated for all measures.

This Randomized Controlled Study is approved and funded by the National Board of Health and Welfare in Sweden (project no 6168/2007).