What is spasmodic dysphonia?
Spasmodic (or "spastic") dysphonia (voice disturbance) is a diagnosis given to patients with specific kinds of voice interruptions. These patients may have a variety of diseases that produce the same vocal result, which is called a laryngeal dystonia (involuntary movement disorder). There are also many interruptions in vocal fluency that are incorrectly diagnosed as spasmodic dysphonia. It is important to avoid this error, because different types of dysphonia require different evaluations, treatments and carry different prognostic implications. Spasmodic dysphonia is subclassified into adductor and abductor types.
Abductor spasmodic dysphonia is similar to adductor spasmodic dysphonia except that voice is interrupted by breathy, unphonated bursts, rather than constricted and shut off. Like adductor spasmodic dysphonia, various causes may be responsible. The abductor tend to be most severe during unvoiced consonants, better during voiced consonants, and absent or least troublesome during pronunciation of vowels. Both abductor and adductor spastic dysphonia characteristically progress gradually, and both are aggravated by psychological stress.
Adductor spasmodic dysphonia is the most common and is characterized by hyperadduction of the vocal folds producing an irregularly interrupted, effortful, strained, staccato voice. It is generally considered neurologic in etiology and its severity varies substantially among patients and over time. It is considered a focal dystonia. In many cases, the voice may be normal or more normal during laughing, coughing, crying or other non-voluntary vocal activities, or during singing. Adduction may involve the true vocal folds alone, or the false vocal folds and the supraglottis may squeeze shut. Because of the possibility of serious underlying neurologic dysfunction or association with other neurologic problems as seen in Meige(s) syndrome (blepharospasm involving the eyes, mild facial spasm and spasmodic dysphonia), a complete neurological and neurolaryngological evaluation is required. Adductor spasmodic dysphonia may also be associated with spastic torticollis (wry neck), and more generalized neurologic problems such as extrapyramidal dystonia.
After comprehensive work up to rule out treatable organic causes, treatment for spasmodic dysphonia should begin with voice therapy. Adductor spastic dysphonia is much more common, and most speech therapy and surgical techniques have been directed at treatment of this form. Unfortunately, traditional voice therapy is often not successful. Speaking on inhalation has worked well in some cases. Patients who are able to sing without spasms or interruptions but are unable to speak may benefit from singing lessons. We have used singing training as a basic approach to voice control, and then bridged the singing voice into speech. In a few patients, medications such as Baclofen [Watson] or Dilantin [Parke Davis] have also been helpful, but these patients are in the minority. When all other treatment modalities fail, various invasive techniques have been used. Recurrent laryngeal nerve section produces vocal fold paralysis and improves spasmodic dysphonia initially in many patients. However, there is a high incidence of recurrence. We do not generally recommend this approach. Other surgical techniques that alter vocal fold length and modify the thyroid cartilage may also be efficacious. A new technique for sectioning the nerve branch to only one muscle also shows promise. However, the most encouraging treatment at present for patients disabled by severe spasmodic dysphonia is botulinum toxin injection. Botulinum toxin is a natural poison that causes paralysis. Injected in small, carefully controlled amounts, it has numerous medical uses.
Laryngeal injection is usually done with electromyographic guidance, and the technique produces temporary paralysis of selected muscles. This results in relief or resolution of the spasmodic dysphonia. However, the injections need to be repeated periodically in most patients.