The evaluation of soleus MEP-80 response with transcranial cortical magnetic stimulation in restless legs syndrome

Objective and Hypothesis: The purpose of this study was to investigate the soleus MEP-80 response latency after transcranial cortical magnetic stimulation (TCCMS) in patients with restless legs syndrome (RLS). With this method we aimed to figure out the etiopathogenesis and to determine an objective diagnosis tool and prognosis indicator.Patients and Methods: In this study, 44 patients with RLS and 40 controls were included who were treated in the Department of Sleep Diseases of Dokuz Eylul University or who were newly diagnosed between June 2011 and December 2011. For all patients and controls routine laboratory investigations, electroneurography (ENG) and TCCMS were performed. Three patients without manifest motor evoked potentials (MEP) and one patient with sensorimotor polyneuropathy were excluded afterwards. Finally the MEP-80 response latency of 40 RLS patients and 40 age and gender matched controls were compared. All patients were diagnosed with the 4 criteria defined by the American Sleep Academy and the severity was classified according to the international restless legs syndrome scaling group (IRLSSG) classification.Results: The soleus MEP-80 response latency in RLS patients was determined significantly longer than in controls. According to the severity of RLS, the MEP-80 latency was longer in the severe group than in mild-moderate RLS patients. Negative correlation was determined between ferritin value and disease severity but there was no relationship between ferritin and MEP-80 latency values.Conclusion: In restless legs syndrome it is known that the corticospinal tract is not directly affected but subcortical inhibition is influenced due to functional spinal neuron impairment. Additionally, as a result of this study we determined a direct functional impairment of spinal afferent and efferent long reflexes and we recognized that corticospinal late responses are affected in RLS.