Parkinson's Disease
What are the typical symptoms of voice dysfunction in patients with Parkinson's disease?
Parkinson's disease patients typically have a low-volume voice with
a monotone (expressionless) quality. The speech pattern is often
produced in short bursts with inappropriate silences between words and
long pauses before initiating speech. The speech may also be slurred. A
small percentage of patients (about 15 percent) may also have a
tremulous voice.
 Key Information
As with most neurological disorders, voice and speech disturbance are
merely a small fraction of Parkinson's disease symptoms. Tremor in the
hands, slow, shuffling gait, and other movement disturbances dominate
the picture and often appear long before vocal difficulties arise.
What is the cause of voice dysfunction in Parkinson's disease? Who is at risk?
The cause of Parkinson's disease is not fully understood. Loss of
nerve cells in select areas of the brainstem occurs through an unknown
mechanism. The disease is more common in men (3:2 male-to-female
ratio), and the age of onset is usually above the age of 50. No risk
factors are known.
How is Parkinson's disease diagnosed?
A neurologist diagnoses Parkinson's disease via patient history and
physical examination. MRI and/or CAT scans are often obtained to help
rule out other conditions.
Difficulties in Diagnosis: Disorders That Can Mimic Parkinson's Disease
Exposure to certain toxic substances, such as carbon monoxide, and
side effects from certain anti-seizure medications can cause symptoms
similar to Parkinson's disease.
How is Parkinson's disease treated?
- A team approach with involvement of specialists in
neurology, speech pathology, and otolaryngology is recommended.
Rehabilitation of speech, voice, and swallowing ability is typically
handled by a speech pathologist.
- Medication (levodopa) is
commonly used for the motor manifestations of Parkinson's but may have
little effect on the voice and speech.
- The main treatment
of communication problems (slurred speech and soft, weak voice)
involves the use of a specialized voice therapy treatment method called Lee Silverman Voice Treatment (LSVT).
Prior to LSVT, speech therapy for Parkinson's disease patients had very
little success. Recent research, however, has shown significant
improvement in quality of life, speech, and vocal function following
the LSVT program. (For more information, see Voice Therapy.)
- An
otolaryngologist may be consulted to suggest surgical treatments that
can help a patient enhance voice volume. Typically, medialization
laryngoplasty or injection laryngoplasty (with fat, collagen, and a
variety of other substances) is used to "bulk" up the weakened vocal
folds. However, results of these procedures are often disappointing due
to the global nature of the voice problem.
- Deep brain
stimulation has been used to treat Parkinson's disease; unfortunately,
voice symptoms may not improve, and may actually worsen with this
treatment.
Key Information
In
the late 1990s, patients with Parkinson's disease felt some hope that
medialization laryngoplasty or injection laryngoplasty would cure their
vocal difficulties. Unfortunately, such a cure has not been found.
Injections of collagen (autologous or bovine) do result in improved
vocal fold contact, but most laryngologists believe this results in
little to no benefit in the patient's voice.
The primary
problem with Parkinson's patients' voices is due to the hypokinetic
nature of their disease (reduced effort, reduced airflow) rather than
any loss of muscular tissue in the vocal folds. This probably explains
the disappointing results with collagen injection and medialization
laryngoplasty.
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