Juvenile segmental muscular atrophy.

Unilateral upper limb atrophy is a rare entity that has been described mainly in Asia. Isolated cases were reported in the Western countries but never in the Middle East. Herein, we review the literature and describe two illustrative cases which presented typically with brachial atrophy of insidious onset. No involvement of cranial nerves, pyramidal tracts or sensory system occurred over a period of several years. The clinical and EMG features were consistent with a localized anterior horn cell lesion in the cervical spinal cord. The neuroimaging studies (CT, myelography, MRI) were normal. The benign outcome of this entity underscores the importance of its recognition.