Case 9: 42 year old man with progressive enlargement of the R.arm
42 yo left handed male presented with right forearm numbness and left shoulder pain after an abdominal surgery. He later developed atrophy and weakness of left deltoid and right biceps (0/5). Sensation was decreased in the lateral aspect of the right forearm. Right biceps jerk was absent and reflexes were otherwise symmetrical. EMG/NCV showed a right musculocutaneous neuropathy and denervation in the left deltoid ( left axillary neuropathy vs. C5 radiculopathy). Blood work was unremarkable (see laboratory addendum). Differential diagnosis included mononeuropathy multiplex and focal bilateral idiopathic brachial plexopathy.
He received a course of intravenous immunoglobulin treatment (2 g/kg). The weakness in his left deltoid and right biceps improved gradually. However, about a year and a half later the patient developed hypertrophy of the right biceps (see right column) with subsequent lack of relaxation of that muscle which significantly interfered in his function.
His examination one and half year after the onset of symptoms was remarkable for muscle hypertrophy but normal strength of R.biceps with significant limitation of the right elbow extension , 4/5 weakness in the L. deltoid, and decreased sensation in a patchy distribution on the lateral aspect of the right forearm.
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