Disclosures: Hans L. Carlson, MD: Standard Insurance: Physician Consultant

Case Description: A 26-year-old male presents with a 5-month history of right pectoral and shoulder girdle pain and weakness with onset at the end of 4 days of extensive waterskiing. His shoulder girdle symptoms initially consisted of deep aching pain with intermittent right upper extremity paresthesias. At presentation he had no further pain, full active shoulder range of motion, visible right pectoralis atrophy, and right triceps weakness. Electrodiagnostic studies revealed degeneration consistent with an injury to the posterior division of the superior trunk of the right brachial plexus. On ultrasound, the right pectoralis major showed significant atrophy compared to the left. Investigational magnetic resonance neurography of the cervical spine and brachial plexus revealed T2 hyperintensity within the distal right C7 and possibly distal right C6 nerves without enhancement. Seven months after the initial onset, triceps and pectoralis strength were nearly normal with resolution of right pectoral atrophy.

Setting: Tertiary referral center

Patient: A 26-year-old male with right sided upper extremity weakness.

Assessment/Results: This patient had a brachial plexus injury following sustained repetitive traction with correlating electrodiagnostic and imaging findings.

Discussion: This is a unique presentation of non-traumatic brachial plexus injury potentially related to repetitive loading of the arm. Slalom waterskiing creates significant loading forces on the outstretched arm during turns. The mechanism of this injury is unique as it appears to be caused by consistent repetitive traction forces over several days rather than a single inciting incident. While idiopathic brachial plexopathies must also be considered, the nature of the activity and symptom onset suggest a mechanical etiology. This case documents the utility of newer imaging modalities (musculoskeletal ultrasound and recently introduced magnetic resonance neurography sequencing) in assisting electrodiagnostic studies with diagnosis.

Conclusion: The repetitive traction forces to the upper extremity involved with slalom waterskiing may be a risk factor for brachial plexus injury.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/shoulder-girdle-weakness-in-the-setting-of-sustained-repetitive-upper-extremity-traction-forces-an-unusual-mechanism-for-brachial-plexopathy-a-case-report/