Parkinson's Disease

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

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.

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.

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.

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.

• 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.