Introduction

Essential tremor (ET) is the most common movement disorder in the elderly. Senile tremor, familial tremor and benign tremor are some of the other terms used to describe ET. Although ET could be a trivial disorder, in some individuals it can be disabling and progressive and could be confused with other neurodegenerative diseases. In this chapter, we will discuss the epidemiology, clinical features and therapy of ET.

Epidemiology

ET is reported from all the regions of the world, indicating a global occurrence (Hornabrook and Nagurney 1976, Haerer et al. 1982, Rautakorpi et al. 1982, Moretti et al. 1983, Aiyesiloju et al. 1984, Rajput et al. 1984, Bharucha et al. 1988, Salemi et al. 1994). Depending on the study methods, prevalence estimates vary widely. The incidence and prevalence of ET increases with advancing age. Hornabrook and Nagurney (1976) examined a region in New Guinea for characteristics and prevalence of ET. They reported no cases of ET under 30 years old, but in the 50–59 year old age group there were 17 cases per 1000, which increased to 41 cases per 1000 over the age of 60 years. Louis et al. (1995) studied a randomized sample of 2117 Medicare recipients (older than 65 years) in the Washington Heights Inwood area in Manhattan, New York. They reported a crude prevalence of 39.2 per 1000 subjects over the age of 65 years. Age is a risk factor for ET. Data from multiple studies show a dramatic increase in the prevalence of ET with aging (see Fig. 5.1).