spasmodic dysphonia (laryngeal dystonia)

Introduction

Voice disorder caused by involuntary movements of one or more muscles of the larynx.

Classification

• adductor spasmodic dysphonia
• abductor spasmodic dysphonia
• mixed spasmodic dysphonia

Etiology

• unknown
• once thought to be psychogenic
  • psychogenic forms of spasmodic dysphonia exist
  • most cases of spasmodic dysphonia are neurogenic
• may co-occur with other movement disorders
  • blepharospasm
  • tardive dyskinesia
  • oromandibular dystonia
  • torticollis
  • tremor
• may occur following an upper respiratory tract infection, injury to the larynx, a long period of voice use, or stress

Epidemiology

• can affect anyone
• first signs most often occur 30-50 years of age
• women appear to be affected more often than men

Pathology

• adductor spasmodic dysphonia
  • spasms cause the vocal folds (or vocal cords) to slam together & stiffen
  • spasms make it difficult for the vocal folds to vibrate & produce voice
• abductor spasmodic dysphonia,
  • 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
• mixed spasmodic dysphonia
  • involves muscles that open the vocal folds as well as muscles that close the vocal folds

Genetics

• some cases may run in families
• possible gene on chromosome 9 that may contribute

Clinical manifestations

• adductor spasmodic dysphonia
  • words are often cut off or difficult to start (dysarthria)
  • speech may be choppy & sound similar to stuttering
  • commonly described as strained or strangled & full of effort
  • spasms are usually absent while whispering, laughing, singing, speaking at a high pitch or speaking while breathing in
  • stress often makes the muscle spasms more severe
• abductor spasmodic dysphonia,
  • voice often sounds weak, quiet & breathy or whispery
  • spasms are often absent when laughing or singing
• mixed spasmodic dysphonia
  • features of both adductor & abductor spasmodic dysphonia

Diagnostic procedures

• fiberoptic nasolaryngoscopy

Management

• no cure; treatment is symptomatic
• voice therapy may reduce some symptoms, especially in mild cases
• surgery: severing the recurrent laryngeal nerve may improve the voice of many for several months to several years but the improvement is often temporary
• psychological counseling
• Botox injections directly into the affected muscles of the larynx
  • generally improve the voice for a period of 3-4 months after which the voice symptoms gradually return
  • injections every 3-4 months are necessary to maintain a good speaking voice
  • may relieve the symptoms of both adductor & abductor spasmodic dysphonia

More general terms

• dysphonia
• dystonia
• vocal cord dysfunction; inducible laryngeal obstruction