Teaching NeuroImages: median nerve MRI changes over time in neuralgic amyotrophy.

A 40-year-old woman presented with 2 weeks of left arm pain followed by hand weakness and numbness. Electrodiagnostic testing revealed an isolated median sensorimotor axonopathy localizing proximal to the pronator teres. The working diagnosis of a forme fruste of neuralgic amyotrophy was made. MRI of the left arm was performed to exclude rare structural causes of proximal median neuropathy. The median nerve showed inflammatory features with a diffusely increased signal on sequences that enhanced with gadolinium (figure, A). Two years after onset, symptoms had resolved. Repeat MRI showed resolution of the abnormal findings (figure, B).