Long-term follow-up of patients with chronic inflammatory demyelinating polyradiculoneuropathy, without and with monoclonal gammopathy

Abstract

We previously demonstrated differences in presentation and initial clinical course between patients with idiopathic chronic inflammatory demyelinating polyradiculoneuropathy (CIDP-I) and those in whom CIDP was associated with a monoclonal gammopathy of undetermined significance (CIDP-MGUS). We now report the long-term follow-up of 69 patients with CIDP-I and 25 patients with CIDP-MGUS. (i) The clinical course was progressive in most of the CIDP-MGUS patients. CIDP-I patients were more likely to have a monophasic or relapsing course. (ii) Impairment developed more slowly in CIDP-MGUS than CIDP-I patients, with a longer time from onset of deterioration to peak impairment for each episode. (iii) Patients with CIDP-MGUS experienced less severe functional impairment and a lesser degree of measured weakness during their worst episode than did patients with CIDP-I. The primary source of functional impairment in many CIDP-MGUS patients was sensory. In contrast, the deficits in most patients with CIDP-I were primarily motor. (iv) CIDP-MGUS patients experienced a smaller degree of improvement to a poorer functional level after each episode than did patients with CIDP-I. (v) Most patients had a good outcome. However, the strength and functional scores at the time of last follow-up were significantly poorer in CIDP-MGUS than in CIDP-I patients. (vi) The disease was reclassified in seven patients; some patients with CIDP-I developed an MGUS, while some with CIDP-I or CIDP-MGUS developed multiple myeloma or a related malignant lymphoproliferative disease. These findings have implications for patient counselling and long-term prognosis, and underscore the need for long-term clinical and immunological monitoring.