Benign Essential Tremor (BET)

Key Glossary Terms

Neurological Voice Disorders
Voice problems caused by abnormal control, coordination, or strength of voice box muscles due to an underlying neurological disease such as: stroke, Parkinson's disease, multiple sclerosis, myasthenia gravis, or ALS

Dysarthria
Difficulty forming words – presenting with imprecise consonants and hard-to-understand speech as seen with stroke patients

Speech Disorder
Malfunction of the tongue and/or lip muscles resulting in garbled words or parts or words.

Glossary

BET is a neurologic disease that involves abnormal control of muscle contraction. The result is a "tremor" or shake of the involved muscle(s) either at rest or when the muscle(s) are in use. This often causes a periodic "shake" in the hand with and/or without use.

BET can occur in the muscles of the palate, tongue, throat, and vocal folds. The result is an inability to keep the voice steady. Thus, the sound of the voice has a periodic (regular) wobble or shake.

BET is one of the more common neurological disorders that can affect the voice. The symptoms that may be present are:

• Tremor in the hands
• Tremor involving the head
• Shaky or tremulous voice

All three symptoms may be present, or only one may dominate.

As with most neurological disorders, the cause is not fully understood. BET is more common in females and often does not present until age 40 to 50. It may be hereditary in certain instances. No other risk factors are known.

The diagnosis is most often made by careful history and physical examination by a neurologist.

• Without a laryngological examination, BET may be misdiagnosed by a neurologist if only vocal tremors are present and head and hand tremors are absent. In these cases, a fiberoptic laryngoscopy exam by a laryngologist/voice specialist may be needed to make the diagnosis.
• Other neurological disorders may have tremor as a component and be mistaken for BET, especially in the case of adductor spasmodic dysphonia with tremor. (For more information, see Spasmodic Dysphonia.)
• Other disorders such as Parkinson's disease, ALS, and cerebellar ataxia may have vocal tremor as a component of the voice disorder but are rarely mistaken for BET.

Medications such as propranolol are sometimes employed to control the tremor, however they usually only have a mild effect on the vocal tremor. Botulinum toxin injection into the vocal folds may be attempted, but success is generally lower than that achieved for spasmodic dysphonia patients (usually 50 to 75 percent).