Effectiveness of Intermediate Cervical Plexus Block in Whiplash-Associated Disorder: A Prospective Observational Trial in Fifty Patients

Whiplash trauma can result in a range of symptoms, including chronic neck pain, headache, facial pain, upper back pain, and tinnitus, which comprises whiplash-associated disorder (WAD). Intermediate cervical plexus block (iCPB) is a novel intervention that targets the upper cervical nerves and anecdotal reports suggest benefits in WAD. We hypothesized that the cervical plexus may have a role in the pathogenesis of WAD and blocking the cervical plexus may provide analgesia. Prospective observational trial. Tertiary pain medicine unit at a university teaching hospital. Adult patients who presented with refractory chronic neck pain following whiplash were included in a prospective observational trial. The pragmatic trial studied the effectiveness of 2 sequential cervical plexus blocks (iCPB with local anesthetic [iCPB-LA] and iCPB with steroid and LA mixture [iCPB-Steroid]) in refractory chronic neck pain following whiplash. Patients who reported < 50% relief at 12 weeks after iCPB-LA were offered iCPB-Steroid. Primary outcome was "neck pain at its worst in the last 24 hours" at 12 weeks. Secondary outcomes included change in neck disability index, employment status, and mood. After excluding cervical zygapophyseal joint dysfunction, 50 patients underwent the iCPB-LA between June 2020 and August 2022. Five patients reported > 50% relief (durable relief) at 12 weeks and 3 patients were lost to follow-up. Forty-two patients received iCPB-Steroid. iCPB-Steroid was associated with significant reduction in neck pain, neck disability, and improvement in mood at 12 weeks when compared to the block with LA. In addition, iCPB-Steroid was associated with significant reduction in neck pain and disability at 24 weeks. Due to functional improvement, 34 patients (34/50, 78%) were able to maintain employment. This is an open-label, observational, single-center study in a limited cohort under a single physician. Cervical facet joint dysfunction was ruled out clinically and radiologically. Cervical plexus may play a central role in the pathogenesis of WAD. iCPB could potentially be a treatment option in this cohort.