RT Book, Section A1 Pahwa, Rajesh A1 Lyons, Kelly E. A2 Watts, Ray L. A2 Standaert, David G. A2 Obeso, Jose A. SR Print(0) ID 55798004 T1 Chapter 25. Essential Tremor T2 Movement Disorders, 3e YR 2012 FD 2012 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-161312-5 LK neurology.mhmedical.com/content.aspx?aid=55798004 RD 2024/10/04 AB Essential tremor (ET) is the most common cause of tremor and one of the most prevalent movement disorders affecting an estimated 10 million persons in the United States.1 The first descriptions of tremor date back to ancient times; however, it was not until the 1800s that ET was recognized as a distinct disorder. At that time, it was defined as a disorder that is often hereditary with persistent action tremor without other neurological signs. The term “essential tremor” was first used in the 1800s, but several other terms have been used to describe this disorder throughout the years such as senile tremor, benign tremor, familial tremor, and benign familial tremor. It was not until the later 1900s that the term “essential tremor” was consistently used in the medical literature.1 In medical terminology, the word “essential” is often used to describe a disorder in which the cause is unknown. Therefore, “essential tremor” refers to a disorder characterized primarily by tremor for which the cause is unknown.