234 - Case Presentation for Complex Regional Pain Syndrome Related to a Bifid Median Nerve

Case Diagnosis: Complex Regional Pain Syndrome due to Bifid Median Nerve

Case Description: We present the case of a 69-year-old African American male with carpal tunnel syndrome (CTS) who experienced pain (5/10) intermittently radiating to the left elbow, trapezius, and neck after a field block for a carpal tunnel release. The patient also reported increased sensitivity, burning sensation along the median nerve, limited range of motion (10° extension, 30° flexion), increased temperature, weakness, and diffuse swelling in the left hand. The pain began during the procedure when the needle caused severe pain and shock down the arm. Symptoms improved with methylprednisone. Ultrasound revealed a bifid median nerve with recurrent median artery and a cross-sectional area of 12 mm. Treatment included pulsed radiofrequency ablation (pRFA) and hydrodissection of the left median nerve.

Discussions: Complex regional pain syndrome (CRPS) is a neuropathic condition affecting one or more extremities due to trauma or lesion. It causes inflammation, increased nerve sensitivity, and vascular dysfunction. Though its pathogenesis is unclear, inflammatory mechanisms are suspected, supported by symptom relief from methylprednisone in this case. CRPS has two types: Type I, without nerve damage, and Type 2, with evidence of nerve injury. In this case, the onset of CRPS after a field block suggests Type 2, potentially caused by direct injury to a bifid median nerve. Treatment included pulsed radiofrequency ablation (pRFA) and hydrodissection, both of which improved symptoms at a two-month follow-up.

Conclusions: We have presented a rare form of CRPS implicated to be the result of an injury to a segment of a bifid median nerve. This case demonstrates the importance of screening for bifid median nerves in patients with CTS to prevent CRPS. Additionally, optimal therapies including pRFA and hydrodissection for the treatment of Type 2 CRPS were exhibited.