Metadata language
Title:
Eye movement abnormalities in essential tremor
Author:
Subject:
saccades ; essential tremor ; oculography ; eye movement abnormalities
Abstract:
Eye movement abnormalities are common sign of many neurodegenerative disease like Parkinson`s disease (PD), spino-cerebellar ataxia (SCA) or Huntington disease (HD). Even though essential tremor (ET) is the most prevalent movement disorders, the spectrum of eye movement abnormalities for this disease has not been entirely explored yet. There are only two papers published as yet concerning eye movement abnormalities in ET which were performed on small groups of patients (17 and 12). The presence of accompanying cerebellar or parkinsonian signs in ET patients may result in in misdiagnosis ET as SCA or PD. Oculographic examination is a sensitive biomarker enable to detect subtle changes in the nervous system, so it can be helpful for differential diagnosis of diseases with similar clinical manifestation or classification of neurodegenerative diseases. Aim of the study was to evaluate eye movement abnormalities in ET patients in comparison with matched according to age and gender controls and patients with other neurodegenerative disease like PD, SCA and HD and to assess the relations between eye movement abnormalities and other signs and course of ET. 50 ET patients and matched according to age and gender 50 PD, 42 SCA, 50 HD and 42 healthy controls were includes to the study. The severity of ET signs was assessed by STSS and CRST, PD – UPDRS, H & Y and S & E, SCA –ICARS and SARA, ; HD – UHDRS and CGI. Saccades were recorded using Saccadometer Advanced of Ober Consulting, and smooth pursuit, OKN and fixation using EOG of Hortman. For each ET patient and control subject neuropsychological tests for assessment of global cognitive functioning, memory, executive function, verbal fluency and tremor assessment by the use of accelerometer connected. The study shows that eye movement abnormalities are considerably more common in ET patients than in healthy subjects and their incidence in ET is similar to the other neurodegenerative disease like PD, SCA and HD. The most typical eye movement disturbances in ET are: reflexive saccades dysmetria, smooth pursuit slowing as well as OKN slowing. In ET patient with concomitant cerebellar signs volitional saccades latency prolongation was additionally detected. The incidence of reflexive saccades dysmetria in ET increases with disease progression. Reflexive and volitional saccades latency relates to the executive dysfunction severity in ET patients.