What
is essential voice tremor?
Essential tremor is a disease of involuntary movement.
It causes the affected body part – most often
the arms and hands – to shake while a person
is attempting to do something with it. This can make
it difficult to write, handle eating utensils, or perform
other necessary day-to-day activities. Essential tremor
can also involve the larynx, vocal folds and throat,
causing changes in the voice.
The
cause of essential tremor is unknown. In about half of cases,
it is inherited from a parent. Essential tremor tends to worsen
with age.
What
are the symptoms of essential voice tremor?
Essential
vocal tremor causes rhythmic changes in voice which vary in
severity. In cases of mild tremor, there might only be minor
quavering in the voice. More severe tremor can actually cause
interruptions in voice. The key feature is that the variations
in loudness (and sometimes in pitch) caused by tremor are rhythmic
and are always present, no matter what type of vocalizing is
being done. Persons with voice tremor may adopt whispering
as a standard mode of speaking, since it masks these variations.
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When
severe, essential tremor can easily be confused with spasmodic
dysphonia. In fact, this is a frequent error
in diagnosis, probably because many physicians do not realize
that essential
tremor can cause such dramatic voice changes. In spasmodic
dysphonia, however, vocal cord contractions are not usually
rhythmic, do not appear during breathing, and may not appear
during special types of voicing like singing. In addition,
spasmodic dysphonia rarely extends out of the larynx to involve
the tongue and palate. In contrast, essential voice tremor
is rhythmic and present across all voice tasks.
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What does essential voice tremor look like?
Essential tremor is a rhythmic, alternating contraction of opposing muscles.
This results in oscillatory
movement of the affected body part. When tremor affects the voice, it usually
involves not only the vocal folds,
but also the muscles of the pharynx ,
back of the tongue and palate. The vocal cords flutter open and closed during
voicing, and also sometimes during
quiet breathing. The cycle typically occurs four to twelve times per second.
This motion is synchronized with similar muscle activity in all affected areas.
There
is no specific test to diagnose essential voice tremor. Diagnosis
is based on the observation of the typical vocal cord movements
during voicing. The presence of essential tremor in the head
or the hands is suggestive as well, although it is not required
to make the diagnosis. It is not widely known, even among doctors,
that essential tremor may affect only the voice.
How
is essential voice tremor treated?
There is no generally accepted treatment for essential voice tremor. Usually,
the choice lies between medication and injections of botulinum toxin. Voice
therapy typically offers little relief, since the vocal fold motion
is involuntary.
When
it affects other parts of the body, essential tremor sometimes
responds to medication. Propranolol, which is usually used to
control blood pressure, and primidone, which is a seizure medication,
are common prescription drugs used for treatment. Neither of
these has been clearly shown to help people with essential voice
tremor in studies, but they may help in individual cases. Each
has important side effects that should be discussed with a physician
prior to use.
Botulinum
toxin is a naturally-occurring substance which weakens muscle.
In laryngology ,
it enjoys its greatest use in the treatment of spasmodic
dysphonia. It can be helpful
in severe cases of essential tremor. It is injected into the
vocal folds though the skin of the neck and helps to even out
the voice and make speaking less effortful. The effect is temporary
and injections need to be repeated every three or four months.
While its effect in essential tremor is not as dramatic and complete
as it is in spasmodic dysphonia, some people benefit a great
deal.
Individuals
with essential voice tremor are probably best advised to discuss
the treatment options with a neurologist, who will probably be
able to give them the best and latest information on available
medication, and an otolaryngologist who is able to inform them
regarding botulinum toxin injections. It is important to understand
that neither treatment cures the tremor, but simply helps with
its symptoms.
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