Difficult-to-Treat Polyradiculoneuropathy

A 51-year-old healthy man sought care for a 6-month history of progressive, distal, lower extremity weakness, imbalance, and numbness in the feet. Neurologic examination showed a steppage gait, upper and lower extremity weakness, distal greater than proximal, absent tendon reflexes, and large fiber–predominant sensation loss in the feet. Nerve conduction studies showed marked temporal dispersion and slowed conductions. Cerebrospinal fluid analysis showed an increased protein concentration, 1 white blood cell/µL, and normal glucose level. Lumbar spine magnetic resonance imaging showed enlargement and enhancement of the nerve roots in the cauda equina, along with hypointensity in lumbar vertebral bodies. He underwent right sural nerve biopsy that showed an inflammatory demyelinating process. The patient was diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy and started on intravenous immunoglobulin. He was markedly worse at 12-week follow-up, with severe proximal and distal weakness and requiring the use of a walker. The diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy was revisited. Lumbar spine magnetic resonance imaging again showed enhancement of the nerve roots. Because of concern for neurolymphomatosis, a proximal fascicular nerve biopsy of the right sciatic nerve was performed. It showed the hallmark pathologic features of chronic inflammatory demyelinating polyradiculoneuropathy: endoneurial inflammation and signs of long-standing demyelination and remyelination with stacks on Schwann cell processes. The diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy was confirmed. Intravenous immunoglobulin was stopped, and the patient was started on an aggressive plasma exchange regimen. He had modest improvement. Azathioprine was also started. The patient continued to improve. He remained on this regimen for 2 years. Over the next year, the intravenous methylprednisolone dose was reduced. He was weaned off plasma exchange and intravenous methylprednisolone. At the last follow-up the disease was still in remission. Chronic inflammatory demyelinating polyradiculoneuropathy was described and named in 1975. It is a fairly symmetric peripheral neuropathy that usually presents with proximal and distal weakness, imbalance, and large fiber sensory dysfunction. Cerebrospinal fluid analysis shows albuminocytologic dissociation in 80% to 95% of those with typical chronic inflammatory demyelinating polyradiculoneuropathy.