Spasmodic dysphonia
Encyclopedia
Spasmodic dysphonia is a voice disorder characterized by involuntary movements of one or more muscle
s of the larynx
(vocal folds or voice box) during speech.
(brain and nerves)."
SD is a neurological disorder rather than a disorder of the larynx, and as in other forms of dystonia, interventions at the end organ (i.e., larynx) have not offered a definitive cure, only symptomatic relief. The pathophysiology underlying dystonia is becoming better understood as a result of discoveries in genetically based forms of the disorder, and this approach is the most promising avenue to a long-term solution.
The National Institute of Neurological Disorders and Stroke (NINDS) and the American Academy of Neurology (AAN) classify SD as a neurological disorder. However, because the voice can sound normal or near normal at times, some practitioners believe it to be psychogenic, that is, originating in the affected person's mind rather than from a physical cause. No medical organizations or groups take this position. A comparison of SD patients compared with vocal fold paralysis (VFP) patients found that 41.7% of the SD patients met the DSM-IV criteria for psychiatric comorbidity compared with 19.5% of the VFP group. However, another study found the opposite, with SD patients having significantly less psychiatric comorbidity compared to VFP patients: "The prevalence of major psychiatric cases varied considerably among the groups, from a low of seven percent (1/14) for spasmodic dysphonia, to 29.4 percent (5/17) for functional dysphonia, to a high of 63.6 percent (7/11) for vocal cord paralysis." A review in the journal Swiss Medicine Weekly states that "Psychogenic causes, a 'psychological disequilibrium', and an increased tension of the laryngeal muscles are presumed to be one end of the spectrum of possible factors leading to the development of the disorder". Alternatively, many investigators into the condition feel that the psychiatric comorbidity associated with voice disorders is a result of the social isolation and anxiety that patients with these conditions feel as a consequence of their difficulty with speech, as opposed to the cause of their dysfluency. The opinion that SD is psychogenic is not upheld by experts in the scientific community.
Supporting evidence that SD is a neurological disorder includes:
. The otolaryngologist examines the vocal folds to look for other possible causes for the voice disorder. Fiberoptic laryngoscopy
, a method whereby a small lighted flexible tube is passed through the nose and into the throat, is a helpful tool that allows the otolaryngologist to evaluate vocal cord movement during speech. Additional diagnostic testing may include stroboscopy
, which allows the physician to view the vibrations of the vocal cords in slow motion. The speech-language pathologist evaluates the patient's voice and voice quality. The neurologist evaluates the patient for signs of other movement disorders.
The most effective treatment for reducing the symptoms of spasmodic dysphonia is injections of very small amounts of botulinum toxin
(sold commercially under the brand names Botox, Dysport, and Myobloc) directly into the affected muscles of the larynx. The toxin weakens muscles by blocking the nerve impulse to the muscle. The botulinum toxin injections generally improve the voice for a period of three to four months after which the voice symptoms gradually return. This treatment requires continual injections to maintain a good speaking voice.
SD is sometimes confused with other hyperfunctional voice disorders that may respond to voice therapy, however voice therapy is not effective in treating SD.
An operation that cuts one of the nerves of the vocal folds (the recurrent laryngeal nerve) has improved the voice of many for several months to several years but the improvement is often temporary.
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
s of the larynx
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
(vocal folds or voice box) during speech.
Types of spasmodic dysphonia
The three types of spasmodic dysphonia (SD) are adductor spasmodic dysphonia, abductor spasmodic dysphonia and mixed spasmodic dysphonia.Adductor spasmodic dysphonia
In adductor spasmodic dysphonia, sudden involuntary muscle movements or spasms cause the vocal folds (or vocal cords) to slam together and stiffen. These spasms make it difficult for the vocal folds to vibrate and produce voice. Words are often cut off or difficult to start because of the muscle spasms. Therefore, speech may be choppy and sound similar to stuttering. The voice of an individual with adductor spasmodic dysphonia is commonly described as strained or strangled and full of effort. Surprisingly, the spasms are usually absent while laughing, speaking at a high pitch, speaking while breathing and singing, but singers can experience a loss of range or the inability to produce certain notes of a scale or with projection. Stress, however, often makes the muscle spasms more severe.Abductor spasmodic dysphonia
In abductor spasmodic dysphonia, sudden involuntary muscle movements or spasms cause the vocal folds to open. The vocal folds can not vibrate when they are open. The open position of the vocal folds also allows air to escape from the lungs during speech. As a result, the voices of these individuals often sound weak, quiet and breathy or whispery. As with adductor spasmodic dysphonia, the spasms are often absent during activities such as laughing or singing but singers can experience a loss of range or the inability to produce certain notes of a scale or with projection.Mixed spasmodic dysphonia
Mixed spasmodic dysphonia involves muscles that open the vocal folds as well as muscles that close the vocal folds and therefore has features of both adductor and abductor spasmodic dysphonia.Origins
The exact cause of spasmodic dysphonia (SD) is unknown. According to the National Institute on Deafness and Other Communication Disorders "research has revealed increasing evidence that most cases of spasmodic dysphonia are in fact neurogenic or having to do with the nervous systemNervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
(brain and nerves)."
SD is a neurological disorder rather than a disorder of the larynx, and as in other forms of dystonia, interventions at the end organ (i.e., larynx) have not offered a definitive cure, only symptomatic relief. The pathophysiology underlying dystonia is becoming better understood as a result of discoveries in genetically based forms of the disorder, and this approach is the most promising avenue to a long-term solution.
The National Institute of Neurological Disorders and Stroke (NINDS) and the American Academy of Neurology (AAN) classify SD as a neurological disorder. However, because the voice can sound normal or near normal at times, some practitioners believe it to be psychogenic, that is, originating in the affected person's mind rather than from a physical cause. No medical organizations or groups take this position. A comparison of SD patients compared with vocal fold paralysis (VFP) patients found that 41.7% of the SD patients met the DSM-IV criteria for psychiatric comorbidity compared with 19.5% of the VFP group. However, another study found the opposite, with SD patients having significantly less psychiatric comorbidity compared to VFP patients: "The prevalence of major psychiatric cases varied considerably among the groups, from a low of seven percent (1/14) for spasmodic dysphonia, to 29.4 percent (5/17) for functional dysphonia, to a high of 63.6 percent (7/11) for vocal cord paralysis." A review in the journal Swiss Medicine Weekly states that "Psychogenic causes, a 'psychological disequilibrium', and an increased tension of the laryngeal muscles are presumed to be one end of the spectrum of possible factors leading to the development of the disorder". Alternatively, many investigators into the condition feel that the psychiatric comorbidity associated with voice disorders is a result of the social isolation and anxiety that patients with these conditions feel as a consequence of their difficulty with speech, as opposed to the cause of their dysfluency. The opinion that SD is psychogenic is not upheld by experts in the scientific community.
Evidence for a neurological basis
SD is formally classified as a movement disorder, one of the focal dystonias, and is also known as laryngeal dystonia.Supporting evidence that SD is a neurological disorder includes:
- SD may co-occur with other neurological movement disorders such as blepharospasm (excessive eye blinking and involuntary forced eye closure), tardive dyskinesia (involuntary and repetitious movement of muscles of the face, tongue, body, arms and legs), oromandibular dystonia (involuntary movements of the jaw muscles, lips and tongue), torticollis (involuntary movements of the neck muscles), or tremor (rhythmic, quivering muscle movements).
- Spasmodic dysphonia runs in some families and is thought to be inherited. Research has identified a possible gene on chromosome 9 that may contribute to the spasmodic dysphonia that is common to certain families.
- Histological examination of the nerve to the vocal cords in patients with SD demonstrates that the percentage of abnormally thin nerve fibers was higher than in normal controls
- Functional MRI signal is reduced in sensorimotor cortices associated with movement of the affected body part in laryngeal dystonia, supporting a dystonic basis for this voice disorder.
Diagnosis
Unfortunately, diagnosis of spasmodic dysphonia is often delayed due to lack of recognition of its symptoms by screening physicians. Most patients who are correctly diagnosed are evaluated by a team that usually includes an otolaryngologist, a speech-language pathologist and a neurologistNeurologist
A neurologist is a physician who specializes in neurology, and is trained to investigate, or diagnose and treat neurological disorders.Neurology is the medical specialty related to the human nervous system. The nervous system encompasses the brain, spinal cord, and peripheral nerves. A specialist...
. The otolaryngologist examines the vocal folds to look for other possible causes for the voice disorder. Fiberoptic laryngoscopy
Laryngoscope
Laryngoscopy is a medical procedure that is used to obtain a view of the vocal folds and the glottis. Laryngoscopy may be performed to facilitate tracheal intubation during general anesthesia or cardiopulmonary resuscitation or for procedures on the larynx or other parts of the upper...
, a method whereby a small lighted flexible tube is passed through the nose and into the throat, is a helpful tool that allows the otolaryngologist to evaluate vocal cord movement during speech. Additional diagnostic testing may include stroboscopy
Stroboscope
A stroboscope, also known as a strobe, is an instrument used to make a cyclically moving object appear to be slow-moving, or stationary. The principle is used for the study of rotating, reciprocating, oscillating or vibrating objects...
, which allows the physician to view the vibrations of the vocal cords in slow motion. The speech-language pathologist evaluates the patient's voice and voice quality. The neurologist evaluates the patient for signs of other movement disorders.
Treatment
There is no known cure for spasmodic dysphonia.The most effective treatment for reducing the symptoms of spasmodic dysphonia is injections of very small amounts of botulinum toxin
Botulinum toxin
Botulinum toxin is a protein produced by the bacterium Clostridium botulinum, and is considered the most powerful neurotoxin ever discovered. Botulinum toxin causes Botulism poisoning, a serious and life-threatening illness in humans and animals...
(sold commercially under the brand names Botox, Dysport, and Myobloc) directly into the affected muscles of the larynx. The toxin weakens muscles by blocking the nerve impulse to the muscle. The botulinum toxin injections generally improve the voice for a period of three to four months after which the voice symptoms gradually return. This treatment requires continual injections to maintain a good speaking voice.
SD is sometimes confused with other hyperfunctional voice disorders that may respond to voice therapy, however voice therapy is not effective in treating SD.
An operation that cuts one of the nerves of the vocal folds (the recurrent laryngeal nerve) has improved the voice of many for several months to several years but the improvement is often temporary.
Notable people with spasmodic dysphonia
- Scott AdamsScott AdamsScott Raymond Adams is the American creator of the Dilbert comic strip and the author of several nonfiction works of satire, commentary, business, and general speculation....
, the creator of the comic strip DilbertDilbertDilbert is an American comic strip written and drawn by Scott Adams. First published on April 16, 1989, Dilbert is known for its satirical office humor about a white-collar, micromanaged office featuring the engineer Dilbert as the title character...
. - Frank Allison, musician, leader of Frank Allison and the Odd Sox
- Johnny BushJohnny BushJohnny Bush, born February 17, 1935 as John Bush Shinn III in Houston, Texas, is a country music singer, songwriter, and drummer. Bush, nicknamed the "Country Caruso," is best-known for his distinctive voice and as the writer of "Whiskey River," a top-ten hit for himself and Willie Nelson's...
, country & western musician and songwriter - Keath FraserKeath FraserKeath Fraser is a Canadian fiction author . Keath Fraser lived in London, England from 1970 to 1973 where he studied at the University of London and he Earned his Ph.D. and taught English in Calgary, Alberta, Canada for five years as a tenured professor...
, Canadian author who has documented the challenges and treatment of his condition in the book The Voice Gallery: Travels With a Glass Throat (2002). - Sjors Fröhlich, former Dutch radio presenter, who had to give up his job as a presenter due to this disease.
- Robert F. Kennedy, Jr.Robert F. Kennedy, Jr.Robert Francis Kennedy, Jr. is an American radio host, activist, and attorney specializing in environmental law. He is the third of eleven children born to Ethel Skakel Kennedy and Robert F. Kennedy and is the nephew of John F. Kennedy and Edward M. Kennedy...
, son of United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
SenatorUnited States SenateThe United States Senate is the upper house of the bicameral legislature of the United States, and together with the United States House of Representatives comprises the United States Congress. The composition and powers of the Senate are established in Article One of the U.S. Constitution. Each...
and presidential candidateUnited States presidential election, 1968The United States presidential election of 1968 was the 46th quadrennial United States presidential election. Coming four years after Democrat Lyndon B. Johnson won in a historic landslide, it saw Johnson forced out of the race and Republican Richard Nixon elected...
Robert F. KennedyRobert F. KennedyRobert Francis "Bobby" Kennedy , also referred to by his initials RFK, was an American politician, a Democratic senator from New York, and a noted civil rights activist. An icon of modern American liberalism and member of the Kennedy family, he was a younger brother of President John F...
, political and environmental activist - Fred LaveryFred LaveryFred Lavery is a music producer, singer-songwriter, and co-owner of Lakewind Sound. He was born and raised in Cape Breton. In 1978 he released "Song For Noel". In 1981 the artist's full length album “First Impressions” was released on Glencoe Records, produced by Paul Mills and engineered by...
, a music producer, writer, musician, and recording studio co-owner from Cape Breton, Nova Scotia. Was lead singer of recording group Road and was later a solo artist, but developed the condition in the 1980s, and was forced to quit singing. Receives injections to keep voice fairly normal. - Mary Lou LordMary Lou LordMary Lou Lord is an indie folk musician, busker and recording artist.-Biography:Mary Lou Lord first gained notice playing acoustic guitar and singing in and around Boston's subway stations Lord became friends with...
- Andy MacWilliams, former radio broadcaster for the Cincinnati StingersCincinnati StingersThe Cincinnati Stingers was an ice hockey team based in Cincinnati, Ohio, that played in the World Hockey Association from 1975 to 1979. Its home arena was Riverfront Coliseum and it was the only major-league hockey team ever to play in Cincinnati.-History:The Stingers franchise was awarded in...
, Chicago BlackhawksChicago BlackhawksThe Chicago Blackhawks are a professional ice hockey team based in Chicago, Illinois. They are members of the Central Division of the Western Conference of the National Hockey League . They have won four Stanley Cup championships since their founding in 1926, most recently coming in 2009-10...
and Cincinnati CyclonesCincinnati CyclonesThe Cincinnati Cyclones are a professional hockey team based in Cincinnati, Ohio. The team is a member of the ECHL. Founded in 1990, the team first played their games in the Cincinnati Gardens and now play at U.S. Bank Arena....
. - Darryl McDanielsDarryl McDaniels-Video game appearances:*The Warriors - Scopes*Guitar Hero: Aerosmith - Himself- External links :* * * * * http://articles.latimes.com/2009/dec/12/entertainment/la-et-people-speak12-2009dec12...
of the rap group Run DMC - Diane RehmDiane RehmDiane Rehm is an American public radio talk show host. Her program, The Diane Rehm Show, is distributed nationally and internationally by National Public Radio. It is produced at WAMU, which is licensed to American University in Washington, D.C....
, host of the The Diane Rehm ShowThe Diane Rehm ShowThe Diane Rehm Show is a National Public Radio call-in show based in the United States. In October, 2007, The Diane Rehm Show was named to Audience Research Analysis’ list of the top ten most powerful national programs in public radio – the only talk show on the list...
on National Public Radio (NPR). - Mark StuartMark Stuart (musician)Mark Allen Stuart is a Christian rock musician, and is best known for being the vocalist for the now-retired Christian rock band Audio Adrenaline.-Early life:...
, American rock musician (Audio AdrenalineAudio AdrenalineAudio Adrenaline was a Christian rock band that formed in the late 1980s at Kentucky Christian University in Grayson, Kentucky. During the band's 17-year existence, they were awarded two Grammy awards, multiple Dove Awards and they released 17 number one singles. They were regular performers at the...
) - Linda ThompsonLinda Thompson (singer)Linda Thompson is a British singer. Born Linda Pettifer in Hackney, Thompson became one of the most recognised names—and voices—in the British folk rock movement of the 1970s and 1980s, in collaboration with her former husband and fellow British folk rock musician, guitarist Richard...
, British folk-rock musician.
External links
- Spasmodic Disphonia Online Community (VoiceMatters.net)
- American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS)
- American Speech-Language-Hearing Association (ASHA)
- National Spasmodic Dysphonia Association, Inc. (NSDA)
- American Academy of Neurology
- Worldwide Education and Awareness for Movement Disorders (WE MOVE)
- Spasmodic Dysphonia section of VoiceInfo.org
- Dystonia Society Network Group – for sufferers and carers to share experiences
- Society for the Management of Spasmodic Dysphonia