Nonvasculitic, steroid-responsive mononeuritis multiplex.

We report two patients with mononeuritis multiplex, both of whom had focal inflammation of the perineurium and endoneurium on sural nerve biopsy without necrosis of blood vessel walls, histologic evidence of lymphoid malignancy, or mycobacterial infection. The predominant early sensory symptoms were asymmetric pain and paresthesias; subsequently, muscle weakness developed. Electrophysiologic studies showed an asymmetric sensorimotor axon loss radiculoneuropathy with denervation of limb and paraspinal muscles. Spinal fluid protein was elevated in one patient. There was no cause or underlying systemic disease. Marked improvement occurred with steroid therapy.