Investigating Shoulder Pain: A Case Report on Atraumatic Medial Scapular Winging Due to Hereditary Neuropathy with Liability to Pressure Palsies

Case Diagnosis: Scapular Winging Due To Hereditary Neuropathy

Case Description or Program Description: 25-year-old female presented for right shoulder weakness and pain radiating to the right trapezius and clavicle. Symptoms began one month after lifting more than usual and worsen with abduction. Upon further questioning, she recalled years of minor pressure-induced bilateral numbness and tingling in her hands and legs that self-resolved over an hour. Her father also experienced similar symptoms. Despite right-sided symptoms, physical exam elicited medial winging of the left scapula with wall push-ups, flattening thoracic kyphosis, and limited left wrist rotation.

Setting: Outpatient Sports Medicine Clinic

Assessment/Results: She was referred for a nerve conduction study and EMG, which showed mild bilateral ulnar neuropathy and chronic left long thoracic neuropathy. Physical exam at that time showed further clinical progression with bilateral scapular winging, diminished reflexes in the right biceps, brachioradialis and triceps, and diminished pinprick over right superficial peroneal and left lateral antebrachial dermatomes. Genetic testing revealed a pathogenic heterozygous PMP22 deletion associated with hereditary neuropathy with liability to pressure palsy (HNPP). She underwent physical therapy to strengthen the serratus anterior muscles and was educated to avoid prolonged pressure on peripheral nerves. Her symptoms and pain resolved.

Discussion (relevance): Medial scapular winging results from serratus anterior weakness from a long thoracic nerve injury, usually from trauma or compression. Here, we present a rare case where the underlying etiology is HNPP, a rare autosomal dominant disorder with an estimated prevalence between 0.84-16/100,000. To our knowledge in the literature, there is no other case where the primary diagnosis was HNPP after a chief complaint of shoulder pain.

Conclusions: It is important to obtain a complete exam to narrow the broad differential for shoulder pain and pursue further workup for scapular winging. Through thorough atraumatic medial scapula winging workup, this young patient with pertinent family history and pressure-induced neuropathies was diagnosed with HNPP.