TRAUMATIC PREGANGLIONIC AVULSION OF LEFT C6, C7, AND C8 NERVE ROOTS WITH ROTATOR CUFF DENERVATION ATROPHY: AN MRI CASE REPORT

Background: Differentiating preganglionic from postganglionic brachial plexus injuries on MRI is critical for surgical planning, as preganglionic avulsions preclude direct repair and require nerve transfer.
Case Presentation: A 38-year-old male motorcyclist sustained a high-velocity accident resulting in left upper limb sensorimotor deficit distal to the deltoid. MRI at 4 months post-injury demonstrated preganglionic avulsion of the left C6, C7, and C8 roots (root absence sign), a pseudomeningocele at the left C7–C8 neural foramen, and chronic asymmetric atrophy of the left paraspinal and periscapular musculature.
Conclusion: Combined cervical and shoulder MRI provided comprehensive injury mapping. The root absence sign and pseudomeningocele were the key direct diagnostic indicators, while paraspinal muscle denervation served as an indirect sign confirming chronicity and the preganglionic level of injury.