Introduction HNPP is an autosomal dominant disorder with estimated prevalence between 0.84- 16/100,000, commonly presenting as mononeuropathies involving pressure-prone areas. Presentation as both a brachial plexopathy and spinal accessory neuropathy is rare, and previously unreported.

Case Report A 30-year old female with no known medical co-morbidities presented with a 3-month history of right shoulder pain and weakness, and intermittent numbness of the elbow and hand. Examina- tion showed wasting of right trapezius and spinati muscles, shoulder droop, and weakness involving the right sternocleidomastoid, shoulder, and median and ulnar-supplied hand muscles. Nerve conduction studies and electromyography revealed axonal-loss pattern neuropathy of right suprascapular and spinal accessory nerves. Focal demyelination was seen in bilateral median and ulnar nerves across the wrists and elbows. Needle EMG showed denervation changes in right infraspinatus and trapezius muscles. Sub- sequent genetic testing of patient and her mother revealed deletion of chromosome 17p11.2 including PMP22. She improved clinically following a period of intensive physiotherapy.

Conclusion HNPP typically affects pressure-prone sites such as the median, ulnar or peroneal nerves. Brachial plexopathy is uncommon, and involvement of spinal accessory nerve is very rare. Recognition of symptoms, with appropriate targeted electrodiagnostic and genetic investigations is important in achieving an accurate diagnosis and management.