The peripheral nervous system in multiple sclerosis. A review and pathogenetic hypothesis

Area of Science:

• Neurology
• Immunology
• Pathology

Background:

• Peripheral nervous system (PNS) involvement in multiple sclerosis (MS) is more frequent than autopsy findings suggest.
• Documented cases of peripheral neuropathy in MS patients indicate a potential etiological link.
• The pathogenesis of MS may involve blood-brain barrier alterations due to immunologically induced vasculopathy, possibly from viral infections.

Purpose of the Study:

• To explore the connection between multiple sclerosis and peripheral nervous system conditions.
• To elucidate the shared pathogenetic mechanisms underlying CNS and PNS lesions in MS.

Main Methods:

• Electrophysiological studies
• Teased nerve fiber analysis
• Review of documented cases of peripheral neuropathy in MS patients

Main Results:

• Sophisticated studies reveal a higher prevalence of PNS involvement in MS.
• MS plaques in the CNS and inflammatory polyneuropathy in the PNS share common pathogenic pathways.
• Onion-bulb formations in the PNS of some MS patients are analogous to CNS plaques, resulting from repeated antigenic challenges and immunological vulnerability.

Conclusions:

• Peripheral nervous system involvement is an under-recognized feature of multiple sclerosis.
• A common pathogenetic mechanism underlies both central and peripheral nervous system lesions in MS.
• Understanding these shared mechanisms may offer new insights into MS pathogenesis and treatment.