Lumbar plexus involvement with chronic inflammatory demyelinating polyneuropathy (CIDP): a variant case of the generic disorder.

We report the magnetic resonance (MR) findings in a male patient presenting with a variant chronic idiopathic demyelinating polyneuropathy (CIDP). He developed a slowly progressive weakness of the right leg associated with sensory dysfunction. Electrophysiologic studies were pathognomonic for a lower limb demyelinating polyneuropathy based on the slowed conduction velocities of the nerves. MRI showed the two major features of the disease: marked asymmetric enlargement of the lumbar plexus nerve roots and strong hypersignal of the enlarged roots on STIR images.