Oculomotor Function in Individuals With Rett Syndrome

Abstract

BACKGROUND: Individuals with Rett syndrome (RTT) are notoriously reliant on the use of eye gaze as a primary means of communication. Underlying an ability to communicate successfully via eye gaze is a complex matrix of requirements, with an intact oculomotor system being just one element. To date, the underlying neural and motor pathways associated with eye gaze are relatively under-researched in RTT. PURPOSE: This study was undertaken to plug this gap in knowledge and to further the understanding of RTT in one specific area of development and function, namely oculomotor function. MATERIAL AND METHODS: The eye movements of 18 girls and young women with RTT were assessed by electronystagmography (ENG). This tested their horizontal saccadic and smooth pursuit eye movements as well as optokinetic nystagmus and vestibulo-ocular reflex. Their results were compared with normative data collected from 16 typically developing children and teenagers. RESULTS: Overall, the individuals with RTT demonstrated a range of eye movements on a par with their typically developing peers. However, there were a number of difficulties in executing the ENG testing with the RTT cohort which made quantitative analysis tricky, such as reduced motivation and attention to test materials and low-quality electrode signals. CONCLUSIONS: This study suggests that individuals with RTT have an intact oculomotor system. However, modifications should be made to the ENG assessment procedure to combat problems in testing and add strength to the results. Further investigation into these testing difficulties is warranted in order to inform such modifications.

A case of JOAG in a patient with Rett syndrome

“…Few studies have investigated ocular findings in patients with this syndrome, and those reports which have studied eye abnormalities found that refractive errors and gaze tracking were the main areas of concern. 4 , 5 , 6 , 7 JOAG has not been studied as a finding in Rett Syndrome, nor has there been any literature describing any type of glaucoma in patients with this condition.…”

“…Townend et al also studied the oculomotor function of 18 girls with Rett syndrome, and their work suggests that this function remains intact in Rett syndrome patients. 7 …”

Loss of MeCP2 causes subtle alteration in dendritic arborization of retinal ganglion cells

“…Various defects have been observed in RTT patients and Mecp2 null mice, but so far few have been reported to have ocular defects in RTT patients (Jain et al 2010 ; Townend et al 2018 ; de Breet et al 2019 ). This study detailed MeCP2 expression in the retina and analyzed structural changes including ganglion cell morphology in the retina of Mecp2 KO.…”

Genetics behind Cerebral Disease with Ocular Comorbidity: Finding Parallels between the Brain and Eye Molecular Pathology

“…Additionally, TCF4 is highly expressed in the adult hippocampal dentate gyrus, one of the few brain regions where neural stem/progenitor cells generate new functional neurons throughout life. Scientists also assayed whether histone deacetylase (HDAC) inhibition would be sufficient to normalize the enhanced hippocampal long-term potentiation (LTP) phenotype [ 311 ]. Surprisingly, treatment with the HDAC inhibitor trichostatin resulted in significantly reduced LTP in the Tcf4 +/− mouse hippocampus.…”