ID 266 – Motor unit number estimation in acute inflammatory demyelinating polyneuropathy

Abstract

Objective To evaluate motor unit loss using Multiple Point Stimulation (MPS)-Motor Unit Number Estimation (MUNE) and motor unit number index (MUNIX) in patients with Acute Inflammatory Demyelinating Polyneuropathy (AIDP). Methods MPS-MUNE and MUNIX on abductor pollicis brevis (APB) were done at week-1 and week-4 of symptom onset in 10 AIDP patients (mean age: 50.10) and in 22 healthy controls (mean age: 49.82). Motor unit size was calculated as surface-Motor-Unit-Potential (sMUP) and Motor-unit-size-index (Musix). Electromyography of APB was performed in all patients. Results In AIDP patients, MPS-MUNE (week-1: 85 (18-193), week-4: 87 (18-158)) and MUNIX (week-1: 113 (23-256), week-4: 124 (26-187)) differed from control MPS-MUNE (141 (66-329) and MUNIX (203 (116-364)) (p Conclusions Decreased MPS-MUNE and MUNIX already at week-1 in AIDP patients suggest loss of functioning axons rather than motor unit loss because of lacking denervation activity and reinnervation in most patients. Key message MUNE methods may provide valuable information to understanding the disease pathophysiology and follow-up of AIDP.