Cognitive Functions In Essential Tremor

Background: Essential tremor (ET) is no longer considered as tremor genic mono symptomatic movement disorder but it has several non-motor manifestations including cognitive dysfunctions. Objectives: to study the cognitive abnormalities in ET patients and their relation to the tremor severity. Methods: This study was performed on 30 ET patients and 15 healthy controls subjected to history taking, neurological examinations with tremor severity assessment using The Essential Tremor Rating Assessment Scale (TETRAS). They were also submitted to the Montreal Cognitive Assessment Scale (MoCA), Stroop Color Word Test, subtest of Wechsler Adult Intelligence Scale IV (WAIS-IV), Wisconsin Card Sorting Test (WCST), brain MRI volumetry and event related potential mismatch negativity (MMN). Results: the neuropsychological tests revealed significant impairment in the global cognitive evaluation, executive functions, attention and working memory of ET patients. Brain MRI volumetry showed significant reduction in cerebellar cortical and white matter volumes, thalamic volume and total white matter volume. Patients also had either absent or diminished amplitude and delayed MMN. Conclusion: Cognitive impairment is a common underdiagnosed ET manifestation affecting patients' socio-occupational career and should be respected in the management plan.