Peripheral Neuropathy in Multiple Sclerosis: An Electrophysiologic Study in Iranian Patients

Abstract

Multiple sclerosis (MS) is the most common cause of disability after trauma in young adults in Northern Hemisphere; it imposes a major burden on the affected young people. A significant association between MS and demyelinating peripheral neuropathy which might be due to common pathogenesis for the central and peripheral nerves demyelination has been reported in several studies. We aimed to assess if there is any peripheral nervous system involvement in a sample of Iranian MS population. Extensive nerve conduction studies (NCS) were conducted in 20 MS patients according to McDonald criteria, and 20 age and gender matched healthy appearing controls. The F-wave ratio was calculated through placing the minimum amount of F-wave proximal latency after 10 stimuli and median or tibial nerves compound motor action potential (CMAP) proximal latency in the corresponding formula. Data were compared between groups. Finally, we found the significantly lower median and tibial nerves conduction velocities (NCV) in MS patients than healthy controls (P=0.008 and 0.003 respectively, Independent Samples t-test). Also, tibial NCV had a significant statistical correlation with Kurtzke’s expanded disability scale score (EDSS) as patients with higher EDSS had lower tibial NCV (Pearson's correlation coefficient, r²=0.8). No statistical relationship was found between MS subtypes and NCS parameters. Although we found some electrodiagnostic abnormalities in Iranian MS patients in comparison to the healthy participants, these differences were small and inconclusive. More extensive well-designed electrodiagnostic studies for evaluation of peripheral nervous system involvement and its probable pattern in these patients seems to be needed.