Essential Tremor

Tremor is a common presenting concern and is associated with a wide range of potential etiologies. This article reviews the approach to the clinical evaluation of tremor, the diagnosis of essential tremor, differential diagnoses, and management options.

Although new investigational drugs are being studied, no medication besides propranolol has been approved by the US Food and Drug Administration (FDA) as a treatment for essential tremor. Thalamic deep brain stimulation (DBS) has been approved for use since 1997, and refinement of the stimulation target is currently being investigated. Focused ultrasound thalamotomy was approved by the FDA in 2016, and some devices with FDA approval can administer noninvasive transcutaneous afferent patterned stimulation of the median and radial nerves to treat essential tremor. Finally, botulinum toxin injections have shown potential effectiveness for treating head and voice tremors, and methods are currently being refined for potential application in the treatment of upper limb tremors.

Tremor is a common neurologic symptom and should be distinguished from other movement disorders that may superficially resemble tremor. In addition, essential tremor, a primary tremor disorder consisting of bilateral upper limb action tremor, is commonly misdiagnosed. A careful history and clinical examination for other neurologic findings, such as bradykinesia, dystonia, or evidence of peripheral neuropathy, can reveal potential alternative etiologies of tremor. Drug-induced tremor and metabolic disturbances should always be considered in patients with recent-onset tremor. Oral pharmacotherapies, including propranolol and primidone, are mainstays of treatment, whereas DBS and focused ultrasound thalamotomy can be offered to alleviate disabling, medication-refractory tremor. Novel oral pharmacologic agents, noninvasive stimulation for tremor, and botulinum toxin injections for hand and head tremor need further study but may serve as potential future treatment options.