A Bioelectrical Impedance Analysis for the Assessment of Muscle Atrophy in Patients with Chronic Inflammatory Demyelinating Polyneuropathy

Intern Med. 2022 Sep 28. doi: 10.2169/internalmedicine.0066-22. Online ahead of print.

Abstract

Objective Muscle atrophy is observed in a subset of patients with chronic inflammatory demyelinating polyneuropathy (CIDP). Its manifestation is associated with a poor functional prognosis and poor response to immunomodulatory therapies. We evaluated muscle atrophy in patients with CIDP using a bioelectrical impedance analysis (BIA). Methods We enrolled 12 patients with CIDP for a BIA of muscle atrophy. Of these 12 patients, 10 were diagnosed with typical CIDP, 1 with multifocal acquired demyelinating sensory and motor neuropathy, and 1 with distal acquired demyelinating symmetric neuropathy. All 12 patients underwent a series of assessments and evaluations, including a BIA and computed tomography (CT). A correlation was found between the skeletal muscle mass determined by the BIA and that found using CT of the muscles. Results The BIA provided values for each patient's skeletal muscle mass index (SMI) ranging from 4.1 to 8.1 kg/m2. Four of the patients with CIDP had SMI values below the threshold for sarcopenia. CT of the patients' muscles provided scores indicating grades of muscle atrophy in the upper and lower extremities. A comparison of the outcomes from these two measures showed a good correlation between their muscle atrophy ratings (p <0.05). Conclusions We found that a BIA and muscle CT provided muscle atrophy assessments of equivalent accuracy. Therefore, a BIA can be a simple alternative to muscle CT that is suitable for regular use in daily clinical practice as a reliable tool for assessing muscle atrophy in patients with CIDP.

Keywords: Bioelectrical impedance analysis; Chronic inflammatory demyelinating polyneuropathy; Muscle atrophy; Skeletal muscle mass.