A 21-year-old soldier was admitted due to weakness after carrying a heavy military bag and marching for a long time. Neurophysiologic investigation revealed prominent involvement of right brachial plexus and upper cervical root with mild abnormalities of multiple nerves in the other extremities. Hereditary neuropathy with liability to pressure palsy was confirmed by gene test demonstrating deletion of PMP22 gene. This study presents backpack palsy can appear as a first manifestation of hereditary neuropathy with liability to pressure. The possibility of hereditary neuropathy with liability should be strongly considered in a young patient with non-symptomatic multiple neuropathy.

Background
: Backpack palsy was described in military personnel with shoulder girdle and proximal upper extremity symptoms, predominantly motor in nature related to the use of heavy backpack. Currently, backpack were used for sports, transpoting, school books and child carriers. We evaluated clinical and electrophysiological feature of backpack palsy. Methods : We included 11 patients with brachial plexopathy as a results of wearing a heavy backpack on long distance marches. All patients were done routine blood sampling, chest X-ray, C-spine X-ray and electrophysiological studies. Results : All patients were right handed person and were not as having a thoracic outlet syndrome. Sensory changes were main initial symptoms and major persistent symptoms were motor weakness. 9 patients(81.8%) were damaged the brachial plexus on non-dominant side, 1 patients was dominant and 1 patient was bilateral involvement. 10 patients(90.9%) were damaged to upper trunk of the brachial plexus by EMG findings. The prognosis was good, 10 patients(90.0%) were complete recovery during 8 weeks, 1 patient was developed reflex sympathetic dystrophy confirmed by 3-phase bone scan. Conclusions : Depression of the clavicle and costoclavicular space probably plays a certain role in pathogenic mechanism. The non-doinant side is more frequently affected, probably due to underdevelopment of the musculature in that side.