Peripheral nervous system involvement in systemic sclerosis: the median nerve as target structure

Area of Science:

• Neurology
• Rheumatology
• Systemic Sclerosis Research

Background:

• Systemic sclerosis (SSc) is a complex autoimmune disease affecting connective tissues.
• Peripheral nervous system (PNS) involvement in SSc is increasingly recognized but not fully characterized.
• Understanding nerve involvement patterns is crucial for SSc patient management.

Purpose of the Study:

• To determine the frequency of peripheral nerve damage in SSc patients.
• To identify the key electrophysiological features of nerve involvement in SSc.
• To investigate canalicular passage nerve involvement in SSc.

Main Methods:

• Electrophysiological assessment using nerve conduction studies (NCS) in 32 SSc patients.
• Evaluation of Compound Muscular Action Potential (CMAP) and Sensory Action Potential (sNAP) parameters.
• Analysis of Motor Nerve Conduction Velocity (MNCV), Sensory Nerve Conduction Velocity, and Terminal Latency Index (TLI).

Main Results:

• Distal neuropathy was observed in 12.5% of SSc patients, primarily affecting the median nerve.
• A significant decrease in median nerve TLI was found in 43.7% of patients.
• While nerve conduction velocities showed no statistical difference, CMAP and sNAP amplitudes/areas were reduced in SSc patients.

Conclusions:

• Distal mononeuropathy, especially of the median nerve, is a common finding in SSc.
• Nerve involvement in SSc appears topographical, linked to tissue changes and vascular tone (e.g., Raynaud's phenomenon).
• Neurophysiological alterations suggest microvascular compromise, not solely compressive mechanisms, contributing to SSc neuropathy.