Essential tremor: beyond the motor features.

There is a growing evidence to suggest that apart from motor features, patients with Essential Tremor (ET) may have significant non-motor features. This review critically analyzes the available evidence of the various non-motor symptoms in patients with ET. Apart from tremor, patients with ET have been reported to have: (i) cognitive abnormalities characterized by mild frontal dysfunction that may have a functional impact, (ii) an association with dementia (both prevalent and incident) among those with late onset of tremor (>65 years), (iii) a higher prevalence of anxiety and an anxious and worrisome personality type, (iv) depressive symptomatology and may even have depression as a premotor symptom, (v) poor sleep quality and (vi) subjective hearing impairment. It is controversial whether olfactory dysfunction occurs in ET and its utility as a diagnostic aid. The biological basis for each of these observations requires further clarification and some findings need confirmation in population-based studies. However the available evidence is sufficient to support the notion that ET can no longer be considered as a pure motor disorder and further studies of these non-motor aspects will go a long way in understanding and comprehensively treating ET.