No new positive recommendations emerge.

To revise and update the 2005 American Academy of Neurology practice parameters for treating essential tremor (ET), the Quality Standards Subcommittee examined the ET literature from 2004 to April 2010. A computer-based search identified 589 articles, of which 252 were scrutinized fully by two or more committee members.

The committee concluded that the following recommendations from 2005 should remain unchanged:

• Propranolol and primidone should be offered for limb tremor (Level A).
• Drugs that are probably effective and should be considered (Level B) are alprazolam, atenolol, gabapentin, sotalol, and topiramate for limb tremor and propranolol for head tremor.
• Treatments that remain categorized as possibly effective for limb tremor (Level C) are nadolol, nimodipine, clonazepam, botulinum toxin A injection, thalamic deep brain stimulation, unilateral thalamotomy, and clozapine.
• Drugs still judged possibly not effective for limb tremor are methazolamide, mirtazapine, nifedipine, and verapamil.
• Drugs that are probably not effective are acetazolamide, isoniazid, pindolol, and trazodone.

New or altered recommendations since 2005 are as follows:

• Levetiracetam and 3,4-diaminopyridine are probably not effective (Level B), based on two Class II randomized, crossover studies of levetiracetam and one Class I study of 3,4-diaminopyridine.
• Clozapine has now been transferred from possibly effective for limb tremor to unknown (Level U), as a new study showed no benefit.
• The present review adds flunarizine to the list of drugs judged possibly not effective for limb tremor, based on two negative Class III studies.
• Treatments already categorized as Level U (for which evidence is contradictory or insufficient, so recommendations cannot be made) were gamma knife thalamotomy, direct subthalamic stimulation and/or zona incerta/prelemniscal stimulation, amantadine, clonidine, glutethimide, L-tryptophan/pyridoxine, metoprolol, nicardipine, oxcarbazepine, phenobarbital, quetiapine, sodium oxybate, tiagabine, and theophylline. To this list, the present review adds pregabalin, zonisamide, clozapine, and olanzapine.

Comment: Essential tremor is the most common movement disorder, causing significant disability in the population. New therapies are needed, yet this evidence-based review of a 6-year period did not add a single new positive recommendation. The failure to find new therapies reflects serious underfunding of ET research.

Source: Journal Watch Neurology