554 - Intercostal Nerve Electrodiagnostics in Rib Fracture: A Case Report

Case Diagnosis: Intercostal nerve injury resulting in rectus abdominis and intercostal muscle denervation. Nerve injury was diagnosed clinically and localized with NCS/EMG and surgically treated with intercostal nerve exploration and interpositional allograft repair.

Case Description: Patient is a 63-year-old male who developed right abdominal wall eventration and dysesthesias three months following surgical plating of the right 9^th and 10^th ribs for fractures sustained coughing from COVID-19. NCS demonstrated absence of motor responses from the rectus abdominis at T9 and T10. Ultrasound-guided needle EMG demonstrated spontaneous fibrillations and positive sharp waves of the rectus abdominis and intercostal muscles at T9 and T10 distal to the rib hardware and normal needle EMG of intercostal muscles proximal to the hardware. Based on these findings, the patient underwent an exploration, neurolysis and intercostal nerve resection and repair with interpositional allograft tissue. During surgery, damage to the intercostal nerves at T9 and T10 was confirmed and size-matched allograft nerve tissue was sutured into place. At 3-month follow up, the patient had significant improvements in pain and sensation over his right abdominal wall.

Discussions: Injury to the intercostal nerves of T7-T12 can occur from rib fractures, resulting in denervation of the rectus abdominis and intercostal muscles. Loss of innervation to these abdominal muscles can cause atrophy and eventual eventration, pain, and cosmetic issues, which is an underrecognized and thus undertreated complication of rib fractures.

Conclusions: The present case describes application of the rarely utilized intercostal electrodiagnostic technique to diagnose and localize intercostal nerve damage from rib fractures. We highlight the use of musculoskeletal ultrasound to accurately and safely guide needle EMG to the intercostal and rectus abdominis muscles. We also describe the first known case of intercostal nerve grafting as a promising intervention to help improve pain and function in this patient population.