The Contralateral Cortical Silent Period Is Not Altered In Primary Restless Legs Syndrome/Willis-Ekbom Disease

Background: Restless legs syndrome (RLS) is characterized by unpleasant sensations and an irresistible urge to move the lower limbs. A reduction in duration of the cortical silent period (CSP) induced by transcranial magnetic stimulation, believed to reflect activity of GABAB neurons, has been inconsistently reported in RLS.Objectives: 1) To compare the CSP duration, in patients with primary RLS and in healthy subjects; 2) To correlate these measures with severity of RLS symptoms.Patients and Methods: Patients were grouped according to scores in the international RLS severity scale, IRLSS: (light/moderate [IRLSS < 20] = RLSLM; severe/very severe [IRLSS ≥ 20] = RLSSVS). Resting (rMT) and active (aMT) motor thresholds as well as CSP were measured. We obtained patient and Institutional Review Board (IRB) approval. Mann-Whitney tests were used to compare results in patients and in controls, and to compare results in patients with RLSLM and RLSSVS.Results: Thirty one (25 F/6 M) patients with primary RLS and 13 healthy subjects were included. Twenty one patients had IRLSS ≥ 20 (RLSSVS) and 10, IRLSS < 20 (RLSLM). TMS results were (RLS x controls) were: rMT (69.2 ± 13.8% x 67.9 ± 13.2%; p = 0.78); aMT (54.6 ± 10.4% x 55.3 ± 12.6%; p = 0.88); CSP duration (108.7 ± 36.3 milliseconds(ms) x 106.1 ± 36.5 ms; p = 0.83). CSP duration was not significantly different between the two groups of patients with different severities of symptoms (RLSLM 112.3 ± 34.7 x RLSSVS 103.0 ± 37.9; p = 0.51).Conclusion: These results do not support the hypothesis that GABAB neurons are relevant to RLS pathogenesis. Background: Restless legs syndrome (RLS) is characterized by unpleasant sensations and an irresistible urge to move the lower limbs. A reduction in duration of the cortical silent period (CSP) induced by transcranial magnetic stimulation, believed to reflect activity of GABAB neurons, has been inconsistently reported in RLS. Objectives: 1) To compare the CSP duration, in patients with primary RLS and in healthy subjects; 2) To correlate these measures with severity of RLS symptoms. Patients and Methods: Patients were grouped according to scores in the international RLS severity scale, IRLSS: (light/moderate [IRLSS < 20] = RLSLM; severe/very severe [IRLSS ≥ 20] = RLSSVS). Resting (rMT) and active (aMT) motor thresholds as well as CSP were measured. We obtained patient and Institutional Review Board (IRB) approval. Mann-Whitney tests were used to compare results in patients and in controls, and to compare results in patients with RLSLM and RLSSVS. Results: Thirty one (25 F/6 M) patients with primary RLS and 13 healthy subjects were included. Twenty one patients had IRLSS ≥ 20 (RLSSVS) and 10, IRLSS < 20 (RLSLM). TMS results were (RLS x controls) were: rMT (69.2 ± 13.8% x 67.9 ± 13.2%; p = 0.78); aMT (54.6 ± 10.4% x 55.3 ± 12.6%; p = 0.88); CSP duration (108.7 ± 36.3 milliseconds(ms) x 106.1 ± 36.5 ms; p = 0.83). CSP duration was not significantly different between the two groups of patients with different severities of symptoms (RLSLM 112.3 ± 34.7 x RLSSVS 103.0 ± 37.9; p = 0.51). Conclusion: These results do not support the hypothesis that GABAB neurons are relevant to RLS pathogenesis.