Authors: Jane Greening, PhD MCSP

Study Design
Cross-sectional study.

Background
Whiplash following a motor vehicle accident can result in chronic neck and arm pain. Patients frequently present with cutaneous hypersensitivities and hypoesthesia but without obvious clinical sign of nerve injury. T2-weighted magnetic resonance imaging (MRI) has previously been used to identify nerve pathology.

Objectives
To determine whether there are signs of peripheral nerve pathology on MRI in patients with chronic arm and neck pain following whiplash injury.

Methods
This study used T2-weighted MRI to examine the brachial plexus and median nerve in patients and age-matched healthy control subjects. Clinical examination included tests of plexus and nerve trunk mechanical sensitivity.

Results
T2 signal was greater in the brachial plexus and median nerve at the wrist in the patient group (mean intensity ratio = 0.52 (0.13 SD) and 2.09 (0.33 SD) respectively) compared to the control group (mean intensity = 0.45 (0.07 SD) and 1.38 (0.31 SD) respectively; p<0.05). Changes in median nerve morphology were also observed, which included an enlargement (mean area = 8.05 (1.29 SD) mm2 in the patient group and 6.52 (1.08 SD) mm2 in the control group; p<0.05) and flattening at the proximal carpal row (mean aspect ratio = 2.46 (0.53 SD) in the patient group and 1.62 (0.30 SD) in the control group; p<0.05). All patients demonstrated signs of nerve trunk mechanical sensitivity. Conclusion These findings suggest that patients with chronic whiplash may have inflammatory changes and/or mild neuropathy, which may contribute to symptoms. J Orthop Sports Phys Ther, Epub 24 Apr 2018. doi:10.2519/jospt.2018.7875