Information on the following diseases can be found in the Related Disorders section of this report:

• Chronic Stuttering
• Benign Essential Tremor
• Vocal Cord Polyps
• Vocal Cord Nodules
• Vocal Cord Paralysis
• Squamous Cell Carcinoma of the Larynx
• Benign Essential Blepharospasm
• Spasmodic Torticollis
• Dystonia
• .

Spasmodic dysphonia is a speech disorder caused by neurological dysfunction. The most frequent symptom of this disorder is a sudden, momentary lapse or interruption of the voice. Other common symptoms include momentary periods of uncontrolled vocal spasms, tightness in the throat, and/or recurrent hoarseness. Affected individuals must make a conscious effort to speak.

There are two types of this disorder, adductor spasmodic dysphonia and abductor spasmodic dysphonia. Adductor spasmodic dysphonia, the more common type, occurs when the vocal cords draw together, sometimes becoming locked. Abductor spasmodic dysphonia occurs when the vocal cords draw apart. In some cases, affected individuals may exhibit both types of SD. Both types cause difficulty in speaking.

Adductor spasmodic dysphonia is characterized by a tight, strained, harsh voice, while abductor spasmodic dysphonia is characterized by breathy, whispered speech, and loss of the voice for short periods of time (aphonia). In most cases, singing and laughing remain relatively unaffected. Individuals affected by the abductor type may have difficulty controlling speech after certain sounds (e.g., "P," "T," and/or "K").

In some cases of chronic spasmodic dysphonia, symptoms gradually progress for the first two years then generally stabilize. In most cases, symptoms do not progress into other forms of dystonia. The disorder usually remains chronic without marked changes over a period of years, although symptoms may worsen with stress. The number and severity of symptoms varies widely among affected individuals.
.

The exact cause of spasmodic dysphonia is not known. Some researchers believe that the condition originates in a part of the brain called the basal ganglia. Dystonia may also be caused by trauma to the head and/or exposure to certain drugs or toxins.

When people speak, nerve impulses from the brain send messages to the vocal cords and the muscles that control the voice. In individuals with spasmodic dysphonia, these messages are abnormal. This results in the inappropriate vocal cord spasms that characterize this disorder.

Spasmodic dysphonia is a subtype of a group of neurological movement disorders known as the dystonias. The dystonias include such disorders as blepharospasm, cervical dystonia (which affects the neck), and/or generalized dystonia, which affects the limbs, torso, neck, and face. (For more information on these disorders, choose "Dystonia" as your search term in the Rare Disease Database.)
.

Spasmodic dysphonia occurs more often in females than males. Onset is usually between 20 and 60 years of age.
.

Symptoms of the following disorders can be similar to those of chronic spasmodic dysphonia. Comparisons may be useful for a differential diagnosis:

Chronic Stuttering is a common speech disorder characterized by an abnormal speech pattern that is composed of repetitions, prolongations, and unusual hesitations that disrupt the rhythmic flow of speech. The disorder usually appears before age 12 and often affects more than one family member (familial).

Benign Essential Tremor is a neurological movement disorder primarily affecting a person's hands and head. However, as the disease progresses other parts of the body may become involved including the tongue and/or the vocal cords. The primary symptom of this disorder is a fine or coarse rhythmic tremor that occurs approximately four to 12 times per second; the tremor may occur on only one side of the body. When tremors affect the tongue, some affected individuals may have difficulty speaking (dysarthria). Tremors that cause the involuntary movements of the vocal cords are produced by rhythmic, alternate contractions of opposing muscles in the larynx. Benign Essential Tremor is usually inherited but may occur for no apparent reason (sporadic). (For more information, choose "Benign Essential Tremor" as your search term in the Rare Disease Database.)

Vocal cord polyps, which are smooth round swellings that form on the vocal cords, may be caused by repetitive straining of the voice, allergies affecting the larynx, or irritation of the vocal cords by industrial fumes or cigarette smoke. Vocal cord polyps typically result in hoarseness and breathiness.

Vocal cord nodules (e.g., singer's, teacher's, or screamer's nodules) are concentrations of connective tissue on the vocal cords. These small, beadlike enlargements may be caused by chronic straining of the voice, overuse, and/or abnormal lowering of the voice. This results in a hoarse, breathy voice quality. In addition, affected individuals may need to make a concentrated effort to speak and may experience reduced vocal endurance.

Vocal cord paralysis may result from lesions in several locations, namely the 10th cranial nerve (nervus vagus), laryngeal nerves, neck, and/or the upper part of the chest (thorax). Infectious diseases such as diphtheria and viral illnesses may also cause vocal cord paralysis. Vocal cord paralysis may affect speech, breathing (respiration), and/or swallowing. High-pitched, noisy respiration (stridor) is the most common symptom. Affected individuals may also experience wheezing during moderate activity.

Squamous cell carcinoma of the larynx is the most common malignant laryngeal tumor (neoplasm). The larynx is the organ that controls voice production and is commonly called the voice box. Most often, the earliest symptom of this disorder is hoarseness. (For more information on this disorder, choose "Squamous Cell Carcinoma" as your search term in the Rare Disease Database.)

The following disorders may be associated with Chronic Spasmodic Dysphonia as secondary characteristics. They are not necessary for a differential diagnosis:

Blepharospasm is a form of dystonia in which the muscles of the eyelids (orbiculares oculi) do not function properly. This disorder is characterized in the early stages by an unusually frequent or forceful blinking of the eyes as well as occasional short episodes of involuntary eye closure. Over a period of years, these episodes increase in frequency and duration. The exact cause of blepharospasm is unknown. (For more information on this disorder, choose "Benign Essential Blepharospasm" as your search term in the Rare Disease Database.)

Spasmodic Torticollis (also known as cervical dystonia) is a form of dystonia characterized by continuous or intermittent spasms of the neck muscles; these spasms result in an often painful involuntary rotation and tilting of the head. There are three different forms of the disorder: tonic, which causes sustained turning of the head to one side due to increased asymmetric muscle tone in one or more neck muscles; clonic, which causes shaking movements of the head; and mixed tonic and clonic, which involves both kinds of movements. The cause of this disorder is usually unknown. (For more information on this disorder, choose "Spasmodic Torticollis" or “Cervical Dystonia” as your search term in the Rare Disease Database.)

Generalized Dystonia is a neurological movement disorder characterized by involuntary contortions of muscles in the neck, torso and extremities although the face, eyes, and vocalchords may also be affected. Focal dystonias (such as blepharospasm and cervical dystonia) are localized to one body part. The involvement of several muscle groups may produce a sideways gait and the body may twist as if writhing or distorted. Dystonia may be inherited as a recessive, dominant or X-linked recessive trait. It may also be an acquired disorder. (For more information on this disorder, choose "Torsion Dystonia" or “Dystonia” as your search term in the Rare Disease Database.)
.

The diagnosis of spasmodic dysphonia usually includes inspection of the voice box (laryngoscopy) to rule out structural abnormalities of the vocal cords such as nodules, polyps, or tumors. The diagnosis may require speech pathology, otolaryngology, and neurology consultations. Laryngeal electromyogram (EMG) and nuclear magnetic resonance imaging (NMRI) have been used to identify any associated neurological disorders.

Botulinum toxin therapy is the standard treatment for spasmodic dysphonia. The drug is injected into the vocal cords every three or four months, to reduce vocal cord spasms. Some patients can wait longer between injections before symptoms return and more injections are needed. The degree of effectiveness of Botulinum toxin will differ in each individual case. Botulinum toxin is approved by the Food and Drug Administration (FDA) for cervical dystonia and is widely used “off label” to treat all forms of dystonia. Botulinum toxin is manufactured by Allergan Pharmaceuticals (as BOTOX©) and Elan Pharmaceuticals (as MYOBLOC).

The National Institute of Neurological Disorders and Stroke (NINDS) is sponsoring a study of air stream in voice production which is intended to better understand the abnormalities associated with spasmodic dysphonia, the sufferers of which have uncontrolled muscle spasms during speech. After videotaping, and voice-recording, patients will undergo nasolaryngoscopy, which enables investigators to film the movement of the vocal folds as well as changes in the position and movement of the vocal chords during various voicings (continuous sounds of various strengths and tones) made by patients undergoing the tests.

Official Title: Laryngeal Resistance in Abductor Spasmodic Dysphonia.

Study ID Numbers: 010169; 01-N-0169

Interested persons may obtain more information on this clinical trial by contacting:

The National Institute of Neurological Disorders and Stroke (NINDS)
9000 Rockville Pike
Bethesda, MD 20892

Patient Recruitment and Public Liaison Office
Tel: 1-800-411-1222
e-mail: prpl@mail.cc.nih.gov

McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No: 193680; Last Update: 6/7/95.

REVIEW ARTICLES
Verheyden j, Blitzer A, Brin MF. Other noncosmetic uses of BOTOX. Semin Cutan Med Surg. 2001;20:121-126.

Ramig LO, Gray S, Baker K, et al. The aging voice: a review, treatment data and familial and genetic perspectives. Folia Phoniatr Logop. 2001;53:252-65.

Blitzer A, Sulica L. Botulinum toxin: basic science and clinical uses in otolaryngology. Laryngoscope. 2001;111:218-26.

McMurray JS. Medical and surgical treatment of pediatric dysphonia. Otolaryngol Clin North Am. 2000;33:1111-26.

Casper JK, Murry T. Voice therapy methods in dysphonia. Otolaryngol Clin North Am. 2000;33:983-1002.

Rubin J, Ratcliffe P. The GP’s role in managing voice disorders. Practitioner. 1998;242:448-50, 453-54.

JOURNAL ARTICLES
Galardi G, Guerriero R, Amadio S, et al. Sporadic failure of botulinum toxin treatment in usually responsive patients with adductor spasmodic dysphonia. Neurol Sci. 2001;22:303-06.

Leonard R, Kendall K. Phonoscopy—a valuable tool for otolaryngologists and speech-language pathologists in the management of dysphonic patients. Laryngoscope. 2001;111:1760-66.

Hogikyan ND, Wodchis WP, Spak C, et al. Longitudinal effects of botulinum injections on voice-related quality of life (V-RQOL) for patients with adductory spasmodic dysphonia. J Voice. 2001;15:576-86.

Edgar JD, Sapienza CM, Bidus K, et al. Acoustic measures of symptoms in abductor spasmodic dysphonia. J Voice. 2001;15:362-72.

Benninger MS, Gardner G, Grywalski C. Outcomes of botulinum toxin treatment for patients with spasmodic dysphonia. Arch Otolaryngol Head Neck Surg. 2001;127:1083-85.

Cimino-Knight AM, Sapienza CM. Consistency of voice produces by patients with adductor spasmodic dysphonia: a preliminary investigation. J Speech Lang Hear Res. 2001;44:793-802.

Langeveld TP, van Rossum M, Houtman EH, et al. Evaluation of voice quality in adductor spasmodic dysphonia before and after botulinum toxin treatment. Ann Otol Rhinol Laryngol. 2001;110(7 Pt 1):627-34.