Benign Essential Tremor (BET)
What is benign essential tremor?
Tremor from Abnormal Muscle Contraction
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.
Voice Wobble or Shake in BET
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.
What are the typical symptoms of voice dysfunction in patients with BET?
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.
What is the cause of BET?
Who is at risk?
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.
Difficulties in Diagnosis
- 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).
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