Diagnostic Accuracy of the Suggested Immobilization Test With Exploratory Heart Rate Variability Analysis for Restless Legs Syndrome in a Thai Population

Restless legs syndrome (RLS) represents disturbing symptoms in the lower limbs that lead to the urge to move, occurring in rest periods. Movements can partially or completely relieve these abnormal feelings. In 2014, the International RLS Study Group (IRLSSG) established five mandatory criteria for the diagnosis of RLS1.

IRLSSG essential diagnostic criteria for RLS (all must be met):

• An urge to move the legs, usually but not always accompanied by, or felt to be caused by, uncomfortable and unpleasant sensations in the legs
• The urge to move the legs and any accompanying unpleasant sensations begin or worsen during periods of rest or inactivity, such as lying down or sitting
• The urge to move the legs and any accompanying unpleasant sensations are partially or totally relieved by movement, such as walking or stretching, at least as long as the activity continues
• The urge to move the legs and any accompanying unpleasant sensations during rest or inactivity only occur or are worse in the evening or night than during the day.
• The occurrence of the above features is not solely accounted for as symptoms primary to another medical or a behavioral condition (e.g., myalgia, venous stasis, leg edema, arthritis, leg cramps, positional discomfort, habitual foot tapping) In the general population, a prevalence of RLS was reported up to 10%2. The prevalence of RLS varies considerably depending on the methods of diagnosis, country, sex, age, and comorbidity burden, which impedes comparisons between studies3. Generally, the prevalence of RLS is relatively low, approximately 1% in Asian populations4-6. In contrast, the prevalence of RLS is considerably higher, ranging from 5% to 10% in Europe and North America7. A cross-sectional nationwide survey of 6,509 Korean adults aged 18-64, using criteria established by the International RLS Study Group (IRLSSG) to define RLS, found a prevalence of 0.9% (0.6% in men and 1.3% in women)5. There was only one study focusing on the prevalence of RLS in Thailand, in which the prevalence of RLS in Thai Parkinson's patients was only 1.6%8.

The nonpharmacologic treatment of RLS includes stretching, heating, or cooling the extremities (e.g., a warm bath), and avoiding alcohol and caffeine. However, the U.S. Food and Drug Administration (FDA) has not approved physical devices such as compression stockings, heating and vibrating pads, and foot pressure wraps for the treatment of RLS9.

Pharmacologic treatment: The latest clinical practice guideline (CPG) updates the 2024 American Academy of Sleep Medicine (AASM) practice parameters and offers new recommendations for treating RLS in adult patients. The primary change in these recommendations is the inclusion of alpha-2-delta ligands (gabapentin, gabapentin enacarbil, and pregabalin) in the 'strong recommendation' category, along with a transition from the use of dopamine agonists to a 'conditional recommendation' in order to mitigate side effects such as augmentation and impulse control disorders 10.