Evaluation of Optical Coherence Tomography Results and Cognitive Functions in Patients with Restless Legs Syndrome

Abstract

The aim of this study was to evaluate whether retinal neural network was impaired and cognitive functions were disturbed in restless legs syndrome (RLS) considering the hypothesis that there may be a dysfunction in dopaminergic pathways in RLS like in Parkinson's disease. Therefore, we evaluated retinal neural network with optical coherence tomography (OCT) and presence of cognitive impairment with Montreal Cognitive Assessment (MOCA). Methods: OCT evaluations were performed for 30 RLS patients and 30 healthy controls. Ganglion cell complex was segmented to retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) automatically by the device, and recorded. Additionally, all the patients and the controls were evaluated using MOCA. Results: No statistically significant difference was detected between RLS and controls in RNFL, GCL, IPL, and choroidal thicknesses. However, total MOCA score and all of its subscale scores were significantly lower in the RLS patients compared with the controls. No significant correlation was detected between OCT and MOCA parameters. Conclusion: No degeneration was detected in retinal neurons (RNFL, GCL, and IPL) of RLS patients. However, impairments were seen in MOCA total and subscale scores of these patients. On the other hand, no significant correlation was detected between MOCA scores and RNFL, GCL, or IPL thicknesses. These findings suggest decrease in cognitive functions of RLS patients probably due to dopaminergic dysfunction regardless of anatomical neural degeneration. Longitudinal follow-up studies are warranted to evaluate whether neuronal degeneration will develop.

Restless Legs Syndrome and the Eyes

“…Studies on primary RLS disease and ocular findings have been contradictory. While some studies found thinning on CT,19 some studies showed no difference 20. In our study, no difference was found between the primary, secondary and control groups in terms of CT.…”

“…While some studies found thinning on CT, 19 some studies showed no difference. 20 In our study, no difference was found between the primary, secondary and control groups in terms of CT. When MV and MT, which reflect the total state of the retina, were examined, we found no difference between the study and control groups.…”

“…The optic nerve consists of axons of ganglion cells, and retinal ganglion cells are the output neurons for the retina and are thus responsible for visual signaling from the eye to target areas in the brain 24. While some studies on the RNFL and GCLT in RLS patients have found thinning, some studies, such as ours, did not find a difference 16,17,20. The INL is the dopamine depot of the retina 5–7.…”

“…24 While some studies on the RNFL and GCLT in RLS patients have found thinning, some studies, such as ours, did not find a difference. 16,17,20 The INL is the dopamine depot of the retina. [5][6][7] To the best of our knowledge, the current study is the first in the literature on INLT in RLS patients, and there was no significant difference in INLT between RLS patients and the control group.…”

Optical coherence tomography findings in conversion disorder: are there any differences in the etiopathogenesis of subtypes?

“…More recently, its use was expanded to neurodegenerative diseases because the retina is an anatomical extension of the brain, and retinal changes may occur in parallel with inflammation and CNS degeneration 7,8 . OCT has shown retinal changes in neurodegenerative diseases, such as multiple sclerosis 8 , Alzheimer's disease 9 , Parkinson's disease 10 , and restless leg syndrome 11 which correlated with the severity of clinical disease. A demonstration of retinal neuronal loss using OCT provides great evidence for degeneration.…”