[Two cases of neuralgic amyotrophy]

Case 1: A 27-year-old man had a fever of 38 degrees C, followed by acute onset of bilateral upper arm pain. Two days later severe muscle weakness in bilateral upper arms appeared and he was admitted to our hospital. On admission, severe atrophy of the left deltoid and mild atrophy of the right deltoid were observed, with severe muscle weakness in bilateral deltoid and mild weakness in other parts of upper extremities. Tendon reflexes were decreased in the upper extremities. Sensation was intact. CSF showed mild pleocytosis. Nerve conduction velocity was normal and electromyography showed mild NMU decrease in upper extremities. Muscle biopsy of the right deltoid one month after the onset was normal. Muscle weakness began to improve 3 months after the onset, with only mild weakness at 10 months. Case 2: A 60-year-old man had acute onset of left shoulder and upper arm pain, followed by muscle atrophy and weakness of the left upper arm. He showed marked atrophy of the left deltoid, moderate atrophy of the left biceps and left scapular region, and severe muscle weakness in the left upper arm. Deep tendon reflexes were absent in the left upper extremity. Sensation was intact. Nerve conduction velocity was normal and electromyography showed marked NMU decrease in the left upper arm. Muscle biopsy of the left biceps 4 months after the onset showed grouped atrophies on HE staining, type 2 fiber atrophies on routine ATPase staining, and many targetoid atrophic fibers on NADH-TR staining. Muscle weakness began to improve slowly 6 months after the onset, but considerable weakness persisted at 10 months. Detailed muscle biopsy findings in neuralgic amyotrophy have not been documented. Muscle biopsy of Case 2 showed marked neurogenic changes compared to Case 1, which may be associated with the difference in clinical course between the two cases.