Improving RLS diagnosis and severity assessment: polysomnography, actigraphy and RLS-sleep log.

Restless legs syndrome (RLS) has proven to often have both a difficult differential diagnosis and also problems with assessing severity. These problems contribute to some of the confusion about medication effects on RLS and also to the large placebo effect seen in clinical trials. We need to find better diagnostic and evaluative methods. The following three promising methods for better diagnosis and evaluation have been somewhat overlooked. (1) The polysomnogram with a preceding suggested immobilization test offers objective measures of the motor sign of RLS, the periodic leg movements in sleep (PLMS) under standard conditions of sleep and during quiet resting, both of which provoke RLS symptoms. The diagnostic sensitivity and specificity for these measures is about the same as that for MSLT diagnosis of narcolepsy and the use of these tests deserves to be reconsidered. (2) Leg activity measures provide an attractive less costly and more accessible alternative to the polysomnogram and can be used on repeated nights, reducing measurement problems occurring because of the well-recognized variability in symptom expression across days. (3) RLS-logs provide a more concurrent assessment of RLS symptom occurrence that provide a more direct measure of severity than questionnaires completed at clinic visits. Similar logs have been found useful in evaluating other sensory disorders such as headache. These methods need to be developed and evaluated in both our research and clinical trials of RLS because they may enhance accuracy of diagnosis and reduce the placebo response to treatments.