The American Academy of Neurology is releasing an updated guideline on how to best treat essential tremor, which is the most common type of tremor disorder and is often confused with other movement disorders such as Parkinson's disease. The guideline is published in the October 19, 2011, online issue of Neurology®, the medical journal of the American Academy of Neurology.

Essential tremor affects the hands, head and voice and can be disabling for the estimated 10 million people in the United States living with the disorder. Essential tremor usually starts after age 40, although symptoms can appear at any age and may cause problems with daily activities such as eating, writing, sewing or shaving.

According to the guideline, the high blood pressure drug propranolol and the drug primidone, which is used to treat seizures, are the most effective at improving shaking in people with essential tremor. The guideline also found the seizure drugs gabapentin and topiramate, along with the high blood pressure drugs atenolol and sotalol and the anxiety drug alprazolam, can be helpful.

"More and better research is needed since not all people with essential tremor benefit from these drugs," said lead guideline author Theresa A. Zesiewicz, MD, with the University of South Florida in Tampa and a Fellow of the American Academy of Neurology. "For people who are not benefitting from these drugs, it's important they work with their neurologist to explore other types of treatments."

The guideline found two types of brain surgery, deep brain stimulation and thalamotomy, may be helpful in treating essential tremor for those patients who do not benefit from drug treatment.

In addition, there was weak evidence to show the high blood pressure drugs nadolol and nimodipine, as well as the seizure drug clonazepam and botulinum toxin A, may be helpful in treating people with essential tremor.

This updated guideline differs from the Academy's 2005 guideline in that it does not recommend using the seizure drugs levetiracetam and flunarizine or the drug 3,4-diaminopyridine (used in rare muscle diseases) to treat tremors of the arms and legs. In addition, the updated guideline found insufficient evidence to support using clozapine, a drug used to treat schizophrenia, to help people with essential tremor.

The guideline is endorsed by the International Essential Tremor Foundation.