CME Practice Parameter : Therapies for essential tremor Report of the Quality Standards Subcommittee of the American Academy of Neurology

Background: Essential tremor (ET) is one of the most common tremor disorders in adults and is characterized by kinetic and postural tremor. To develop this practice parameter, the authors reviewed available evidence regarding initiation of pharmacologic and surgical therapies, duration of their effect, their relative benefits and risks, and the strength of evidence supporting their use. Methods: A literature review using MEDLINE, EMBASE, Science Citation Index, and CINAHL was performed to identify clinical trials in patients with ET published between 1966 and August 2004. Articles were classified according to a four-tiered level of evidence scheme and recommendations were based on the level of evidence. Results and Conclusions: Propranolol and primidone reduce limb tremor (Level A). Alprazolam, atenolol, gabapentin (monotherapy), sotalol, and topiramate are probably effective in reducing limb tremor (Level B). Limited studies suggest that propranolol reduces head tremor (Level B). Clonazepam, clozapine, nadolol, and nimodipine possibly reduce limb tremor (Level C). Botulinum toxin A may reduce hand tremor but is associated with dose-dependent hand weakness (Level C). Botulinum toxin A may reduce head tremor (Level C) and voice tremor (Level C), but breathiness, hoarseness, and swallowing difficulties may occur in the treatment of voice tremor. Chronic deep brain stimulation (DBS) (Level C) and thalamotomy (Level C) are highly efficacious in reducing tremor. Each procedure carries a small risk of major complications. Some adverse events from DBS may resolve with time or with adjustment of stimulator settings. There is insufficient evidence regarding the surgical treatment of head and voice tremor and the use of gamma knife thalamotomy (Level U). Additional prospective, double-blind, placebo-controlled trials are needed to better determine the efficacy and side effects of pharmacologic and surgical treatments of ET. NEUROLOGY 2005;64:2008–2020 Background and justification. Essential tremor (ET) is a common adult tremor disorder, with prevalence estimates from population studies ranging from 0.4% to 5%. 1,2 The incidence and prevalence of ET increase with advancing age.2 ET is characterized by the presence of postural and kinetic tremor.3 In classic ET, upper limbs ( 95% of patients) and less commonly the head ( 34%), lower limbs ( 30%), voice ( 12%), tongue ( 7%), face ( 5%), and trunk ( 5%) exhibit a postural or kinetic tremor.4 ET has been referred to as a benign condition because of the perception that it does not reduce life expectancy or cause symptoms besides tremor and impaired tandem walking. However, ET may cause substantial physical and psychosocial disability,5 and it is unclear whether ET is associated with additional comorbid symptoms.6 Tremor amplitude gradually increases over time, and patients frequently experience increasing difficulty with writing, drinking, eating, dressing, speaking, and other fine motor tasks.5 ET is a clinical diagnosis. Criteria for definite and probable ET include abnormal bilateral postural or kiFrom the Department of Neurology and Parkinson’s Disease and Movement Disorders Center (Drs. Zesiewicz and Hauser, and K.L. Sullivan), University of South Florida, Tampa; Department of Neurology (Dr. Elble), Southern Illinois University School of Medicine, Springfield; GH Sergievsky Center and Department of Neurology (Dr. Louis), College of Physicians and Surgeons, Columbia University, New York, NY; University of Texas Southwestern Medical Center (Dr. Dewey), Dallas; Department of Neurology (Dr. Ondo), Baylor College of Medicine, Houston, TX; Department of Neurology (Dr. Gronseth), University of Kansas Medical Center, Kansas City; and Department of Neurology (Dr. Weiner), University of Maryland School of Medicine, Baltimore. Approved by the Quality Standards Subcommittee on July 24, 2004; by the Practice Committee on January 29, 2005; and by the AAN Board of Directors on