Decreased olfactory bulb volume in patients with restless legs syndrome

Objective: Restless legs syndrome (RLS) is a chronic progressive movement disorder with a pathophysiology that is still not fully known. In recent years, a growing number of studies have suggested that the disease may be of a neurodegenerative nature. We aimed to measure olfactory bulb volume (OBv) in RLS using cranial magnetic resonance imaging (MRI). Methods: The study included 24 patients (11 males, 13 females) aged 18-60 years who were diagnosed with idiopathic RLS according to the criteria of the Restless Legs Syndrome Study Group (IRLSSG) 2014 and followed up by our neurology clinic, and 26 age-matched controls (12 males, 14 females). In the cranial MRI examination of both groups, the right, left and total OBv values were manually calculated in mm(3). Results: While there was no significant difference between the right and left OBv values of the patient and control groups, the total OBv value of the patient group was found to be significantly lower compared to the control group (p=0.041). There was no significant difference between disease severity and OBv values. It was seen that right, left and total OBv values decreased significantly as the duration of the disease increased (p=0.001, p<0.001, p<0.001). Conclusion: Our study showed that the olfactory system could be involved in RLS and the underlying mechanism of RLS may be related to neurodegeneration and RLS may be a disorder of central origin. However, longitudinal follow-up studies are needed to fully assess whether neurodegeneration will occur.