We reported on fifty clinical features of peripheral nerve palsy in the shoulder region of which causes such as injury and ganglion could not be identified. We examined fifty patients with peripheral nerve palsy due to unknown causes from 1985 to 2001. We clarified the focus that caused paralysis, on the basis of detailed clinical symptoms and electro-physiological tests, and examined the clinical courses. Forty cases had a preceded acute pain (twenty cases had an antecedent or trigger). The diseased nerves were fifteen suprascapular nerves, nine long thoracic nerves, three axillary nerves, and nineteen cases were in more than one nerve. Most cases including the operated ones showed improvement of muscle atrophy. Seven cases that showed ES at the beginning perfectly recovered. Four cases had not improved at the point of after three years and more of onset. Among fourteen cases which could be traced the process by MRI, four cases retained a high intensity of T2, even electro-physiological test showed normal findings. Eighty percent of the fifty cases were considered as neuralgic amyotrophy reported by Parsonage & Turner in 1948, given the characteristic process. The rest-20 % indicated various clinical features, which suggested more than one pathema.
