Diagnostic criteria for demyelinating polyneuropathy associated with monoclonal gammopathy.

In order to define diagnostic criteria for the demyelinating polyneuropathy associated with monoclonal gammopathy of undetermined significance (MGUS), we compared 30 patients with idiopathic chronic inflammatory demyelinating polyneuropathy (CIDP) without a monoclonal gammopathy, with 29 patients with polyneuropathy associated with MGUS. All 59 patients fulfilled research criteria for CIDP. In the patients with MGUS, sensory symptoms and signs predominated, there was usually no cranial nerve involvement, and the neuropathy was symmetrical with a slowly progressive course. On electrophysiological examination, an abnormal median nerve sensory action potential in combination with a normal sural nerve action potential (AMNS) was not found. In idiopathic CIDP patients, a preceding infection was frequent, motor features predominated, there was often cranial nerve involvement, the neuropathy could be asymmetrical, and AMNS was frequently found. Diagnostic criteria for demyelinating polyneuropathy associated with MGUS are presented.