Impaired conduction of Ia sensory fibers in multifocal motor neuropathy: An electrophysiological demonstration

Eglė Sukockienė; Michel R Magistris; Ruxandra Iancu Ferfoglia; Agustina M Lascano; André Truffert

doi:10.1016/j.cnp.2020.07.002

Impaired conduction of Ia sensory fibers in multifocal motor neuropathy: An electrophysiological demonstration

Clin Neurophysiol Pract. 2020 Aug 7:5:152-156. doi: 10.1016/j.cnp.2020.07.002. eCollection 2020.

Authors

Eglė Sukockienė^{1

2}, Michel R Magistris³, Ruxandra Iancu Ferfoglia¹, Agustina M Lascano¹, André Truffert¹

Affiliations

¹ Division of Neurology, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland.
² Department of Neurology, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania.
³ Faculty of Medicine, Geneva University, Geneva, Switzerland.

Abstract

Objectives: To report the clinical and electrophysiological findings in two patients with multifocal motor neuropathy (MMN) and bilateral absent patellar and Achilles tendon reflexes despite normal strength of quadriceps and calf muscles.

Methods: The medical history and clinical evaluation were completed by electrophysiological tests: sensory and motor nerve conduction studies, needle electromyography, motor-evoked potentials (MEPs) after transcranial magnetic stimulation, patellar T (tendon) responses, quadriceps and soleus H (Hoffman) reflex recordings.

Results: In the two patients, history, clinical evaluation, nerve conduction studies, favorable response to intravenous immunoglobulins, and positive anti-GM1 antibodies fulfilled the diagnosis of MMN. The lower limbs were asymptomatic, except for a unilateral weakness of foot dorsiflexion. The patellar and Achilles tendon reflexes disappeared during the course of the disease. The sensory nerve conduction studies were normal or minimally modified, M-wave and MEP/M amplitude ratio to the quadriceps were normal, patellar T (tendon) responses were virtually absent, and H-reflex to the quadriceps and soleus muscles were absent.

Conclusions: These observations, which show the interruption of the reflex afferent pathway, raise the question of Ia afferent involvement in the lower limbs of these two patients with MMN. Further investigations should determine the frequency and significance of these findings in this disorder.

Keywords: CB, conduction block; H-reflex; IV Ig, intravenous immunoglobulins; MEP, motor evoked potential; MMN, multifocal motor neuropathy; Motor evoked potentials; Neurophysiology; QCT, quadriceps combined technique; Quadriceps combined technique (QCT); T-response; Transcranial magnetic stimulation.

Publication types

Case Reports