0549 Prevalence and Impact of Muscle Cramps in Patients with Restless Legs

Abstract Introduction Recent studies have shown alterations in Vitamin D binding protein in RLS, and Vitamin D is intimately related to calcium metabolism, while hypocalcemia is a well-known trigger for muscle cramps. The presence and consequences of muscle cramps in RLS has never been systematically studied. Therefore, the aim of this study was to determine the prevalence and impact of muscle cramps in RLS patients. Methods An email was sent to 4222 active members of the RLS foundation (RLSF) with a link to survey adult RLS patients. The survey included demographic information, questions on muscle cramps (including a visual analogue scale rating intensity), the Pittsburgh Sleep Quality Index assessing sleep disturbances, the 36-Item Short Form Survey Instrument (SF-36) evaluating health status, the 13-item short-form Cambridge-Hopkins diagnostic questionnaire (CH-RLSq13) for diagnosing RLS, and the International RLS Severity Scale measuring RLS severity. Patients who answered “yes” to the question “In the last 3 months have you experienced muscle cramps (defined as involuntary painful muscle contraction occurring at rest, not associated with exercise)?” were considered to have muscle cramps. Results A total of 509 RLSF members completed the whole electronic survey, while 317 participants (Age: 68.9±10.2; 73.1% Women; 97.8% White/Caucasian; BMI: 27.4±5.8) qualified as RLS patients and were included in further analysis. The prevalence of muscle cramps in RLS patients was 60.3%. RLS patients with (versus without) muscle cramps were more overweight (p=0.0119) and had lower scores (more disability) on several SF-36 health concepts including physical functioning (p=0.0093), role limitations due to emotional problems (p=0.0429), social functioning (p=0.0017), and more pain (p=0.0387). In addition, there was a weak (Spearman coefficient ρ=0.253) but significant positive correlation (p=0.0004) between intensity of muscle cramps and severity of RLS symptoms. Conclusion Muscle cramps were present in almost two-third of RLS patients and were associated with a negative impact on health status and severity of RLS. Therefore, from a clinical practice point of view, it seems warranted to screen for muscle cramps in RLS patients. RLS and leg cramps may theoretically be related to each other through calcium metabolism and/or through inflammatory mechanisms. Support (If Any) This study was not funded.