Incidence and nature of damage to the peripheral nervous system in patients with multiple sclerosis

Introduction
Multiple sclerosis was considered a disease of the central nervous system only, but more and more evidence show the involvement of the peripheral nervous system (PNS).

Aim of the research
The aim of this study was to estimate the prevalence of PNS damage in patients with multiple sclerosis (PwMS), compared to the general population, and to evaluate selected electrophysiological parameters in these patients.

Material and methods
Ninety-three individuals (38 men and 55 women) aged between 18 and 65 years diagnosed with MS according to the 2017 modified McDonald criteria were included in the study. The control group consisted of 30 subjects (12 men and 18 women), healthy volunteers or patients with other neurological diseases, without PNS damage. PNS parameters obtained by the nerve conduction study (NCS) were analysed, including latency, sensory and motor response amplitude, conduction velocities and minimal F-wave latency in the median, ulnar, peroneal and sural nerves. Based on the values obtained, the prevalence of peripheral nervous system damage in MS patients/PwMS and the nature of this damage were determined.

Results
Abnormalities in nerve conduction studies were demonstrated in 66.6% of patients in the study group compared to 43.3% of the control group (p < 0.005). The peripheral nerve damage in patients with MS/PwMS was axonal-demyelinating in nature and tended to involve proximal segments, mainly in the ulnar and peroneal nerves. The peripheral nervous system damage was statistically significantly more frequent in patients with MS/PwMS than in the control group.

Conclusions
Electrophysiological testing, in specific cases, can be useful in the algorithm of care for a patient with MS.