Neurophysiological impairments in multiple sclerosis-Central and peripheral motor pathways

Area of Science:

• Neuroscience
• Neurology
• Clinical Electrophysiology

Background:

• Multiple sclerosis (MS) is a chronic demyelinating disease affecting the central nervous system (CNS).
• Neurophysiological assessments are crucial for understanding functional deficits in persons with MS (PwMS).
• Comparing CNS and peripheral nervous system (PNS) neurophysiology in PwMS provides insights into disease-specific impairments.

Purpose of the Study:

• To systematically review and compare neurophysiological outcomes in PwMS versus healthy controls (HC).
• To evaluate CNS function using motor evoked potentials (MEP) via transcranial magnetic stimulation (TMS).
• To assess PNS function using electroneuronography (ENG) and neuromuscular function during maximal voluntary contraction (MVC).

Main Methods:

• Systematic literature review of studies comparing PwMS and HC.
• Inclusion criteria: studies on CNS (TMS-MEP), PNS (ENG), and neuromuscular function (MVC with EMG/ITT).
• Analysis of neurophysiological parameters including conduction times, latencies, amplitudes, and muscle activation.

Main Results:

• PwMS exhibited prolonged central motor conduction times, pathway asymmetry, and latencies compared to HC.
• PNS studies revealed near-significant motor latency prolongation and reduced nerve conduction velocities in PwMS.
• Neuromuscular assessments indicated lower voluntary muscle activation and increased central fatigue in PwMS.

Conclusions:

• Consistent and substantial impairments in CNS function are evident in PwMS.
• PNS impairments are less pronounced and more inconsistent than CNS deficits.
• PwMS demonstrate observable impairments in muscle activation, highlighting broader motor system dysfunction.