Lewis-Sumner syndrome (LSS), also known as multifocal acquired demyelinating sensory and motor neuropathy (MADSAM), is a rare neurological disorder. It's characterized by asymmetrical weakness and dysfunction primarily affecting the hands and feet. This condition is considered a variant of chronic inflammatory demyelinating polyneuropathy (CIDP).
Key Features of Lewis-Sumner Syndrome:
- Asymmetrical Weakness: The weakness disproportionately affects one side of the body more than the other. It often begins distally (in the hands and feet) and progresses proximally (towards the center of the body).
- Sensory and Motor Involvement: Both sensory (numbness, tingling) and motor (weakness) functions are affected.
- Adult Onset: The symptoms typically appear in adulthood.
- Acquired Demyelinating Polyneuropathy: The underlying cause involves damage to the myelin sheath (the protective covering of nerves), leading to impaired nerve signal transmission.
- Dysimmune Disorder: LSS is considered a dysimmune disorder, suggesting an autoimmune component where the body's immune system mistakenly attacks the peripheral nerves.
Prevalence and Inheritance:
The prevalence of LSS is estimated to be between 1 and 9 per 1,000,000 individuals. The inheritance pattern is not clearly defined, and the condition appears to be acquired rather than inherited.
Diagnostic Considerations:
Diagnosis typically involves a combination of neurological examination, electrophysiological studies (nerve conduction studies), and blood tests to rule out other conditions.
Treatment:
Treatment options often involve immune-modulating therapies like intravenous immunoglobulin (IVIg) or corticosteroids. The specific treatment plan is tailored to the individual's needs and response to therapy.
Sources: Information synthesized from multiple sources including NIH's Genetic and Rare Diseases Information Center (GARD), PubMed, and Orphanet. Specific details regarding individual studies and clinical trials are available through links to those sources provided in the original prompt.
