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Spasmodic dysphonia

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Spasmodic dysphonia (or laryngeal dystonia) is a voice disorder characterized by involuntary movements or spasms of one or more muscles of the larynx (vocal folds or voice box) during speech.[1]

Types

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,(ADSD) sudden involuntary muscle movements or spasms cause the vocal folds (or vocal cords) to slam together and stiffen.[1] 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.[2]

Abductor spasmodic dysphonia

In abductor spasmodic dysphonia, sudden involuntary muscle movements or spasms cause the vocal folds to open.[1] 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.[2]

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.[1]

Cause

The exact cause of spasmodic dysphonia (SD) is unknown.[1] 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 system (brain and nerves)."[2]

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.[3]

The National Institute of Neurological Disorders and Stroke (NINDS) and the American Academy of Neurology (AAN) classify SD as a neurological disorder.[4] 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.[5] 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."[6] 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".[7] 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.[8] The opinion that SD is psychogenic is not upheld by experts in the scientific community.[6][9]

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. [10] 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).[1]
  • 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.[1]
  • 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[11]
  • 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.[12]

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 neurologist. 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.[2]

Treatment

There are a number of potential treatments for spasmodic dysphonia including: botox, surgery and voice therapy.[13] A number of medications have also been tried including anticholinergics (such as benztropine) which have been found to be effective in 40-50% of people but associated with a number of side effects.[14]

Voice therapy

Voice therapy appears to be ineffective in cases of true spasmodic dysphonia,[15] however as it is difficult to distinguish between spasmodic dysphonia and functional dysphonias and misdiagnosis is relatively common,[16] a trial of voice therapy is often recommended before more invasive procedures are tried.[13] Some also state that it is useful in mild symptoms and as an add on to botox therapy[17] and other report success in more severe cases.[18]

Surgery

A number of operations 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 may be temporary.[2]

An operation called "selective laryngeal adductor denervation-rennervation (SLAD-R)" is effective specifically for adductor spasmodic dysphonia which has shown good outcomes in about 80% of people at 4 years.[15] Post-surgery voices can be imperfect and about 15% of people have significant difficulties.[15] If symptoms do recur this is typically in the first 12 months.[15] Another operation called "recurrent laryngeal nerve avulsion" has positive outcomes of 80% at three years.[17]

Botox

While botox is a commonly tried treatment, the evidence for its use is limited.[19] It results in periods of some improvement but in most the duration of benefit is brief and repeat injection is required.[13]

Notable cases

References

  1. ^ a b c d e f g "Definition of Spasmodic dysphonia". MedTerms medical dictionary. MedicineNet.com. Retrieved 2007-05-11.
  2. ^ a b c d e "Spasmodic Dysphonia". Publication No. 97-4214. National Institute on Deafness and Other Communication Disorders. Retrieved 2007-05-11.Includes text taken directly from the website. As a work of the National Institutes of Health, part of the United States Department of Health and Human Services, this text constitutes a work of the U.S. federal government, therefore it is in the public domain.
  3. ^ 1: Curr Opin Otolaryngol Head Neck Surg. 2004 Dec;12(6):543–8. PMID 15548915
  4. ^ Dystonias Fact Sheet: National Institute of Neurological Disorders and Stroke (NINDS)
  5. ^ Gündel H, Busch R, Ceballos-Baumann A, Seifert E (2007). [PMID 17615166 "Psychiatric comorbidity in patients with spasmodic dysphonia - a controlled study"]. J Neurol Neurosurg Psychiatry. {{cite journal}}: Check |url= value (help); Cite journal requires |journal= (help); templatestyles stripmarker in |url= at position 1 (help)CS1 maint: multiple names: authors list (link)
  6. ^ a b Newswise Medical News | Patients with Selected Voice Disorders Are Subject to Psychiatric Problems
  7. ^ Seifert, E.; Kollbrunner, J. (2005-07-09). [PMID 16220409 "Stress and distress in non-organic voice disorder"]. Swiss Med Weekly. Retrieved 2007-05-11. {{cite journal}}: Check |url= value (help); Cite journal requires |journal= (help); templatestyles stripmarker in |url= at position 1 (help)CS1 maint: multiple names: authors list (link)
  8. ^ Ann Otol Rhinol Laryngol. 2001 Oct;110(10):941–5.
  9. ^ Spasmodic Dysphonia is a Neurological Disorder Current Evidence and References, by Christy L. Ludlow, Ph.D.
  10. ^ Otolaryngol Head Neck Surg. 2005 Nov;133(5):654–65. PMID 16274788
  11. ^ Otolaryngol Head Neck Surg. 1999 Jan;120(1):129–33
  12. ^ Neurology. 2005 Nov 22;65(10):1562–9 PMID 16301482
  13. ^ a b c Ludlow, CL (2009 Jun). "Treatment for spasmodic dysphonia: limitations of current approaches". Current opinion in otolaryngology & head and neck surgery. 17 (3): 160–5. PMID 19337127. {{cite journal}}: Check date values in: |date= (help)
  14. ^ Grillone, GA (2006 Feb). "Laryngeal dystonia" (PDF). Otolaryngologic clinics of North America. 39 (1): 87–100. PMID 16469657. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  15. ^ a b c d Chhetri, DK (2006 Feb). "Treatment of adductor spasmodic dysphonia with selective laryngeal adductor denervation and reinnervation surgery" (PDF). Otolaryngologic clinics of North America. 39 (1): 101–9. PMID 16469658. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  16. ^ Bressman, edited by Thomas T. Warner, Susan B. (2007). Clinical diagnosis and management of dystonia. London: Informa Healthcare. p. 111. ISBN 9781841843179. {{cite book}}: |first= has generic name (help)CS1 maint: multiple names: authors list (link)
  17. ^ a b Wackym,, James B. Snow,... P. Ashley (2009). Ballenger's otorhinolaryngology : head and neck surgery (17th ed. ed.). Shelton, Conn.: People's Medical Pub. House/B C Decker. p. 918. ISBN 9781550093377. {{cite book}}: |edition= has extra text (help)CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link)
  18. ^ Klaben, Joseph C. Stemple, Leslie Glaze, Bernice Gerdeman (2000). Clinical voice pathology : theory and management (3. ed. ed.). San Diego, Calif.: Singular Publ. Group. p. 368. ISBN 9780769300054. {{cite book}}: |edition= has extra text (help)CS1 maint: multiple names: authors list (link)
  19. ^ Watts, C (2006 Feb). "Botulinum toxin for treating spasmodic dysphonia (laryngeal dystonia): a systematic Cochrane review". Clinical rehabilitation. 20 (2): 112–22. PMID 16541931. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  20. ^ "'Dilbert' creator recovers from rare disorder". Associated Press. 2006-10-27. Retrieved 2007-07-30.
  21. ^ Frank Allison
  22. ^ Beal Jr., Jim (1998-04-29). "Golden country Johnny Bush hasn't run dry after almost 50 years of heartaches and honky-tonks". San Antonio Express-News.
  23. ^ The Voice Gallery - Thomas Allen Publishers - Thomas Allen & Son Limited
  24. ^ Liebovich, Mark (2006-06-25). "Another Kennedy Living Dangerously". The New York Times. Retrieved 2007-07-30.
  25. ^ Sullivan, Jim (2004-02-19). "Hello, Mary Lou – Goodbye, Heartache". Boston Globe.
  26. ^ Heffernan, Virginia (2006-02-25). "After the Hit Records, A Search for His Roots". The New York Times.
  27. ^ "About Diane Rehm". WAMU 88.5 American University Radio. Retrieved 2007-07-30.
  28. ^ "Mark Stuart informs his Facebook followers that he has Spasmodic Dyphonia".
  29. ^ "Thompson's Trials: UK Folk Rock Great Makes Triumphant Return to the Stage". Tim Perlich, NOW Toronto. 2002-10-17. Retrieved 2007-08-23.
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