Zesiewicz et al second group. Modest benefit was demonstrated by clinical ratings of postural and kinetic tremor 6-weeks postinjection in both groups. Subsequent evaluations 12- and 16-weeks post-injection did not note tremor reduction compared to baseline. Hand weakness was common and occurred in 30% of patients who received 50 U of BTX and in 70% of patients that received 100 U. One additional controlled study and four uncontrolled studies also demonstrated improvement in limb tremor with BTX. Surgical treatment Surgical procedures may provide treatment of refractory ET. Thalamotomy is a stereotactic procedure that creates a lesion in the ventral intermediate nucleus (VIM) of the thalamus. Studies have typically reported an 80%–90% improvement in tremor symptoms compared to baseline.74–76 Side effects of thalamotomy include dysarthria, verbal or cognitive defi- cits, weakness, confusion, somnolence, and paralysis. These usually resolve over time, although hemiparesis and speech difficulties persisted in 16% of patients in one study.77 Due to the risk of adverse events, bilateral thalamotomies are no longer performed to treat ET. Using placement strategies similar to those used for thalamotomy, DBS uses high frequency electrical stimulation from an implanted electrode to modify activity in the target area, usually the VIM thalamus. The electrodes are connected to a pulse generator which is implanted in the chest wall. The primary advantage of DBS compared to thalamotomy is that simulation parameters such as voltage, pulse frequency, and pulse width can be adjusted to optimize tremor control in the contralateral limbs. These parameters can be adjusted for con- tinued management of tremor. Several studies have evaluated the effect of DBS on ET and have noted a mean improvement in tremor of 60%–90% on clinical ratings.78,79 Adverse events have been reported in approximately 18% of patients in various VIM DBS studies.34 These events were usually related to equipment malfunction or lead mis- placement. However, other side effects included dysarthria, imbalance, paresthesias, weakness, ischemic changes, and generalized motor seizures. One study reported a death following the procedure due to intracerebral hemorrhage.80 Surgical treatment of tremor is usually reserved for patients who are refractory to pharmacotherapy. Thalamo- tomy and DBS both suppress tremor and the choice of pro- cedure primarily depends upon the patient’s circumstances, risk of complications as well as the feasibility of ongoing programming which is required with DBS. 406 submit your manuscript | www.dovepress.com Dovepress events have been noted to occur in 14%–47% of patients, and The authors report no conflicts of interest in this work. Dovepress Conclusion Despite being one of the most prevalent movement dis- orders in adults, there are still gaps in the knowledge of pathogenesis and effective treatment of ET. Up to 50% of patients with ET are misdiagnosed and symptoms of ET can overlap with symptoms of other conditions such as PD. It is important for physicians to understand this disorder and its diagnosis. Many pharmacologic therapies have been tested for effectiveness in treating tremor, but few agents have sufficient data available for their use to be widely recom- mended and only one agent, propranolol, is indicated for the treatment of ET. Botulinum toxin and surgical interventions are indicated for tremor control but may be associated with more severe or persistent side effects than pharmacologic therapies. Future controlled studies of treatments for ET are warranted. Disclosure References 1. Physicians’ Desk Reference. 63rd ed. Montvale, NJ: Thomson PDR; 2009. 2. Benito-Leon J, Louis ED, Bermejo-Pareja F. Population-based case- control study of cognitive function in essential tremor. Neurology. 2001;66:69–74. 3. Louis ED, Benito-Leon J, Bermejo-Pareja F. Self-reported depression and anti-depressant medication use in essential tremor: cross-sectional and prospective analyses in a population-based study. Eur J Neurol. 2007;14:1138–1146. 4. Louis ED, Ottman R, Hauser WA. 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