Case Diagnosis: Acute, concurrent, severe right suprascapular and axillary neuropathies
A 24-year-old right-handed man presented with acute right shoulder pain, numbness over the deltoid, and weakness with shoulder movements. Two days prior, he spent hours at work swinging a hammer overhead, a task he had never performed before. There was no history of injury, no additional symptoms on review of systems, and shoulder-MRI was unremarkable. Physical exam revealed periscapular atrophy, numbness over the lateral-upper-arm, and 0/5 strength in shoulder abduction and external rotation on the right. EMG revealed fibrillations and no motor units firing in the supraspinatus, infraspinatus, deltoid, or teres minor. The remainder of right C5-T1 muscles and cervical paraspinals were normal. The diagnosis was acute, severe right suprascapular and axillary neuropathies.
This case is a rare instance of concurrent suprascapular and axillary neuropathies, isolated to these two nerves while sparing the rest of the brachial plexus. It’s known that suprascapular neuropathy can occur from repetitive scapular protraction from tethering of the nerve between the suprascapular notch and the upper trunk, which may have been elicited by the patient's repetitive hammering. Axillary neuropathy however is typically associated with trauma. It is possible that either compression injury from surrounding osseous or muscular structures in the quadrilateral space or repeated traction during such repetitive overhead exertion may be a rare mechanism of axillary neuropathy as well.
Repeated scapular movements with overhead exertional activity may be a cause of both suprascapular and axillary neuropathy, which remarkably occurred simultaneously in this patient. Additionally, this patient's electrodiagnostic results fit perfectly with his sensory and motor exam, given each affected nerve innervates one of the two main shoulder abductors and external rotators. This emphasizes the importance of the physiatrist's anatomic knowledge and of electrodiagnostics as an extension of a thorough exam.
Steven Markos– Resident Physician, Academic Chief, JFK Johnson Reabilitation Institute
Mina Shenouda– PM&R Resident Physician PGY3, JFK-Johnson Rehabilitation Institute
David Brown– Attending Physician; Outpatient Medical Director and Director of the Electrodiagnostic Laboratory, JFK-Johnson Rehabilitation Institute