Electromyographic Abnormalities in Restless Legs Syndrome: The Predominant Role of Aging Beyond Iron Deficiency

Purpose: Restless Legs Syndrome (RLS) pathophysiology involves central iron deficiency and dopaminergic dysfunction, but the role of peripheral nerves and patient-specific factors like age remains unclear. This study investigated the relationships between serum ferritin, age, and peripheral electrophysiological findings in drug-naïve RLS patients. Methods: A retrospective cohort study was conducted with 95 drug-naïve RLS patients. Comprehensive analysis included serum ferritin levels, detailed nerve conduction studies, and clinical assessments. Statistical evaluations involved subgroup comparisons (based on ferritin and EMG status), correlation analyses, and binary logistic regression to identify independent predictors of abnormal electromyography (EMG). Results: The cohort had a mean age of 53.8 years, with 14.7% having low ferritin. A striking dissociation was observed: all patients (100%) with low ferritin had normal EMG, whereas 41.2% of those with normal ferritin had abnormal EMG (p=0.002). Elderly patients were significantly more likely to exhibit abnormal EMG recordings (62.7 vs. 48.9 years, P<0.001) and had longer symptom duration. Multivariate analysis confirmed advancing age as the sole independent predictor of abnormal EMG (aOR-1:14 per year, P=0.001). Conclusion: This study demonstrates a strong association between peripheral nerve abnormalities and advanced age, particularly in patients with accompanying comorbidities, in drug-naïve RLS patients, while such abnormalities were absent in younger patients with low ferritin. These findings point to potential subgroups with differing pathophysiology. Future research should incorporate advanced electrophysiological methods to better define these subgroups and their clinical relevance.