Factors related to restless leg syndrome in neuromyelitis optica spectrum disorder

Although the feeling of unrest in the legs is frequently reported as a sensory symptom by people with Neuromyelitis Optica Spectrum Disorder (NMOSD, pwNMOSD), there are limited studies to investigate the relationship between Restless Legs Syndrome (RLS) and NMOSD. The study's primary aim is to determine the frequency and severity of RLS in pwNMOSD. The other aim is to compare the sleep quality, daytime sleepiness level, quality of life, fatigue, magnetic resonance imaging results, and cognitive functions in RLS-positive and negative pwNMOSD.

The RLS diagnosis was performed with RLS-Diagnostic Index criteria. The patient-reported outcomes were RLS Severity Rating Score, The Preference-Based Multiple Sclerosis Index (PBMSI), the Modified Fatigue Impact Scale (MFIS), Pittsburgh Sleep Quality Index (PSQI), and Epworth Sleepiness Scale (ESS). Cognitive function was assessed with The Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) battery. The neurologist recorded the demographic and clinical characteristics of the participants.

The RLS was detected in 17 (21.5 %) of the 79 pwNMOSD participants. Fifty-six pwNMOSD were reached to assess cognitive functions and patient-reported outcomes. The rate of RLS was 60.71 % in this group. The PBMSI, PSQI, MFIS, and ESS scores were significantly different in RLS-positive participants than in RLS-negative (p < 0.05). Moreover, while participants' visuospatial and verbal learning was similar, the processing speed was slow in the RLS-positive group (p > 0.05).

Our preliminary results have shown that the RLS frequency is high in pwNMOSD. This study suggests a connection between the presence of RLS and worse sleep quality, fatigue level, processing speed, and quality of life in the NMOSD population. However, our results should be considered with the fact that the study has a small sample size and needs future studies to confirm our results for solid evidence.