Restless Legs Syndrome: scoring criteria for leg movements recorded during the suggested immobilization test.

Objective: To evaluate the characteristics of leg movements experienced by patients with the restless legs syndrome (RLS) during wakefulness using the suggested immobilization test (SIT).
Methods: Forty patients with primary RLS who showed an index of leg movements greater than 40 during the SIT were selected for these analyses.
Results: In general, Coleman's criteria for scoring PLMS were appropriate for scoring leg movements during the SIT. However, a substantial number of leg movements lasted between 5 and 10 s, exceeding Coleman's maximum duration criterion. The other criteria used to score PLMS (i.e. movements separated by 4-90 s and occurring in series of four consecutive movements) allowed detection of more than 90% of all leg movements recorded during the SIT. The distribution of inter-movement intervals (IMI) suggests that a great majority of leg movements recorded during the SIT are periodic, with a modal value of IMI between 11-12 s.
Conclusion: Considering that leg movements recorded during the SIT last longer than those occurring during sleep, we recommend using a duration criterion of 0.5-10 s for scoring the former. We also recommend using the same periodicity criteria for the SIT as those used for scoring PLMS.