Presynaptic inhibition in restless legs syndrome

Abstract

Introduction: Restless legs syndrome (RLS) is a condition that particularly urges at night in resting and causes the need to move the legs. Although the pathophysiology has not yet been clarified, dopamine and iron metabolism and spinal cord pathologies are blamed for causing the condition. There are few studies on spinal reflex mechanisms on RLS. In the present study, we aimed to investigate the role of presynaptic inhibition (PreI) in the spinal cord in RLS.

Methods: Fourteen patients with RLS and 14 controls with similar demographic characteristics were included in the study. Soleus muscle H-reflex (Ht) investigation was performed for subjects whose electrophysiologic investigation was normal. The Ht response was conditioned to the stimulation of the common peroneal nerve (CPN) (Hc). The test and conditioned stimulation intervals were kept between 10 ms, 20 ms, 30 ms, 40 ms, 50 ms, 75 ms, 100 ms, 150 ms and 200 ms. In each inter-stimulus interval, nonparametric repeat measurement evaluations were conducted with the percentage value of Hc/Ht. The Hc/Ht values of the study and control groups in the same intervals were compared separately.

Results: A significant decrease was detected in Hc values in the control group in the repeat measurement values at 20 ms and 100 ms inter-stimulus intervals; however, there was not decrease in any intervals in the patient’s group.

Conclusion: The absence of any decrease in Hc reflexes for 20–100 ms intervals revealed that discernible PreI was vanished in RLS patients.

Keywords:

• Restless legs syndrome
• spinal reflexes
• presynaptic inhibition

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Concept – S.A.T; NY Design – S.A.T.; Supervision – N.Y; S.Y Materials Data Collection and/or Processing – E.S.B.; S.A.T Statistics – S.A.T.; N.Y.; O.K. Literature Search – S.A.T. S.Y.; Writing – S.A.T., N.Y Critical Reviews – N.Y.

This paper was presented as a disputable poster presentation at the 43. National Physiology Congress in Pamukkale/Turkey.

Table 1. Comparison of the two groups in terms of age and sex.

Additional information

Funding

This research is supported by Abant İzzet Baysal University Scientific Research Projects (No. 2013.08.03.636) and we are very grateful.