[An 18-year-old man of hereditary neuropathy with liability to pressure palsies presenting with bilateral brachial plexopathy during military training].

An 18-year-old man without familial history of neuropathy developed motor and sensory disturbance of bilateral upper limbs after maintaining shoulder abduction/external rotation and elbow flection position of both upper limbs for an hour during military training. Neurological examination and electromyography studies suggested left brachial plexopathy, although a nerve conduction study (NCS) showed mild demyelination of bilateral median nerve and right ulnar nerve. Thoracic outlet syndrome (TOS) was firstly suspected because symptoms were induced by the specific position which narrows, costoclavicular and retropectoralis minor space and cause compression of the brachial plexus; however, no findings suggesting TOS were observed on computed tomography and magnetic resonance imaging. Hence, we suspected a diagnosis of hereditary neuropathy with liability to pressure palsies (HNPP) due to having episodes of bilateral acute brachial plexopathy and mild demyelination on NCS. The diagnosis of HNPP was confirmed by the deletion of the PMP22 gene deletion.