Sensory ataxic dominant neuropathy associated with polyarteritis nodosa.

A 68-year-old man with sensory ataxic dominant neuropathy associated with polyarteritis nodosa (PAN) had deep sensory disturbance with unsteady gait and absence of the Achilles tendon reflex. Examination revealed weight loss, elevated CRP level, negative antineutrophil cytoplasm antibodies, decreased M-wave amplitude in the peroneal motor nerve and absence of action potentials in the sural sensory nerve. Sural nerve biopsy revealed a marked loss of myelinated fibers, myelin ovoid formation and necrotizing angiitis of large epineurial arterioles. Renal biopsy revealed global and/or segmental necrotizing angiitis in glomeruli, but not in the arcuate artery. These pathological findings were distinct from those of PAN, particularly microscopic polyangiitis (MPA). Treatment with a steroid improved the deep sensory disturbance, unsteady gait, and CRP level. This case is similar to ataxic neuropathy which can arise from various disorders. This is the first report of a case of sensory ataxic dominant neuropathy associated with MPA in PAN.