[Two cases with chronic inflammatory demyelinating polyneuropathy showing high signal and enlargement of the brachial plexus in short TI inversion recovery of MRI].

We reported valuable MRI findings of the brachial plexus seen in two cases with chronic inflammatory demyelinating polyneuropathy (CIDP). Case 1 was a 44-year-old man who developed slowly progressive weakness and atrophy of the extremities with no sensory disturbances. Studies of CSF showed a normal level of protein and no increase of cell counts but nerve conduction studies demonstrated a significant conduction block between the axilla and the elbow in the right ulnar nerve. Case 2 was a 34-year-old male who had been suffering from distal limb weakness and sensory disturbance. Protein content in CSF was markedly elevated without pleocytosis, and nerve conduction studies revealed a conduction block between the elbow and the wrist in the right ulnar nerve. He received corticosteroid therapy, resulting in a good recovery. Brachial plexus in both cases showed enlargement with marked high signal on short TI inversion recovery (STIR) of MRI. STIR is a fat suppressed T2 weighted image and this technique is known to be useful to identify the morphology of peripheral nerve tissues. CIDP is one form of hypertrophic neuritis and the MRI findings seen in these two cases strongly support the diagnosis of CIDP.