Significance of central sensitization in the disease process of restless legs syndrome

Central sensitization (CS) refers to the activation of somatosensory perception in the central nervous system. Despite numerous studies on CS in conditions like fibromyalgia and migraine, both of which frequently accompany restless legs syndrome (RLS), the specific impact of CS on RLS remains unclear.

This study recruited patients with RLS who did not have pain-related conditions: 51 untreated patients, 55 treated patients, and 92 healthy controls. All participants completed the Central Sensitization Index (CSI), while both RLS groups completed the International Restless Legs Syndrome Rating Scale (IRLS). Additionally, the Patient Health Questionnaire-9 (PHQ-9) and Pittsburgh Sleep Quality Index (PSQI) were administered only to the untreated RLS group.

The analysis of covariance, with age and sex as covariates, showed that the CSI values scores of the untreated and treated RLS groups were significantly higher comparted to healthy group. The CSI did not differ significantly either between the untreated and treated RLS groups or between painful and non-painful RLS. The IRLS scores showed a significant positive association with the CSI in the untreated RLS group, but not in the treated RLS group. Logistic regression analysis showed that only CSI score was significantly associated with the presence of depressive symptoms, while neither the IRLS nor PSQI scores showed a significant association.

CS is common in patients with RLS without comorbid pain-related conditions, and this tendency persists even after treatment. Notably, CS may play a certain role in the development of depressive symptoms in patients with RLS.