Researchers at the Royal Children’s Hospital and Melbourne University, Victoria, Australia report a 12-year-old boy with a 12-month history of progressive weakness affecting extremities and neck flexion but no facial weakness. Gowers’ sign was positive. Reflexes were diminished or absent. Sensation was normal. Nerve conduction was nomal. EMG revealed decreased recruitment and high-amplitude poyphasic motor unit potentials. Biopsy of vastus lateralis showed grouped fiber atrophy and target fiber formation. CSF showed minimally elevated protein of 0.51 g/L. MRI spine showed no enlargement of nerve roots. Repeat neurcphysiological testing 5 months later and with further progression of weakness showed an increase in peroneal distal latencies and slowing of tibial motor nerve conduction velocity. The findings were insufficient to meet criteria for chronic inflammatory demyelinating polyneuropathy (CIDP) but an acquired demyelinating polyneuropathy was suspected, and treatment with IVIg was begun. Improvement was noted within 1 week, and at 1-year follow-up, 6 months after the last infusion, he was 80% recovered. Despite absence of all typical signs of CIDP, an empiric trial of immunomodulatory therapy was both diagnostically and therapeutically valuable. 
COMMENT. A trial of IVIg may be indicated in clinically suspected CIDP cases that lack other diagnostic criteria, including NCV, EMG, CSF, MRI, and nerve biopsy.