Magnetic Resonance Neurography in a Patient with Distal Neuralgic Amyotrophy.

The pathophysiology of neuralgic amyotrophy (NA) remains to be elucidated. However, high-resolution magnetic resonance imaging and ultrasound sonography have provided new insights into the mechanism underlying the development of NA and its diagnosis. We report a case of idiopathic distal NA with hyperintensity and thickening in the inferior trunk extending to the posterior and medial fasciculus of the left brachial plexus, which was detected by magnetic resonance neurography (MRN) with diffusion-weighted whole-body imaging with background body signal suppression (DWIBS). The abnormal signal intensity diminished after the improvement of symptoms following corticosteroid treatment. MRN with DWI can help diagnose distal NA and evaluate the post-therapeutic response.