Spasmodic Dysphonia

Adductor and Abductor Types

Spasmodic dysphonia remains a curious and unresolved voice disorder, due to its uncertain etiology and treatment potential. Spasmodic dysphonia is a descriptive term for a family of symptoms, all of which include some form of strained, strangled, and effortful voice production. The cause of this disorder has been debated for many years. Recent evidence has demonstrated strong evidence that spasmodic dysphonia has a neurologic origin and should be considered a focal dystonia specific to the larynx and similar to other dystonias such as blepharospasm and torticollis. Theories abound, but neither definitive etiology nor structural defect has been identified.

There are two principle types of spasmodic dysphonia: adductor type and abductor type. Adductor spasmodic dysphonia is the most common type, and results in a severely hyperfunctional voice, including a "strained-strangled" quality, multiple pitch or voice breaks and occasional voicing "blocks" of tension or effort that interrupt the continuity of phonation. Intermittent periods of normal voicing may occur during speech production, during both laughter and angry outbursts of speech, and while singing. Some patients are able to reduce the frequency and severity of the spasms when talking at a pitch level that is slightly higher than normal. The majority of patients with adductor spasmodic dysphonia find it difficult, if not impossible to shout. Many patients with adductor type spasmodic dysphonia complain of physical fatigue, tightness of the neck, back, and shoulder muscles and shortness of breath due to their efforts to phonate through the closed glottis. The severity of the symptoms of adductor spasmodic dysphonia varies within and among individuals. Some patients experience only a very mild interruption in normal phonation, while others may be rendered voiceless by the severity of the spasms. Abductor spasmodic dysphonia is a virtual "mirror image" of the adductor type. Instead of the vocal folds spasming closed (adductor SD), the vocal folds spasm open creating an involuntary moment of no voice, which is accompanied by a burst of air. Voice is characterized by involuntary voice breaks and intermittent aphonia, with uncontrolled prolonged bursts of breathy phonation. Voice onset may appear normal, and then loss of voice ensues with continued speaking. The vocal fold spasms appear to occur primarily during the production of unvoiced consonants (such as /p/, /f/, /s/) and can occur during all positions within words, on whole words, and on several words in succession. Often, patients report that their voices improved when they were angry, increased their intensity, or altered their pitch. Voice quality worsened when they were anxious or fatigued.

The incidence of spasmodic dysphonia is unknown, but is thought to be relatively low. The disorder is said to occur equally in men and women with the most common onset in middle age. Rarely, symptoms of spasmodic dysphonia can occur in adolescence. Some patients experience a rapid onset associated with the occurrence of a traumatic event. Others report a more gradual onset following hoarseness associated with an upper respiratory infection. Still others appear to present with an idiopathic spasmodic dysphonia. The severity of the vocal symptoms appears to peak within the first year following the onset of the disorder.

Many patients with spasmodic dysphonia have experienced long and discouraging searches for many years, first for a diagnosis of the disorder and then for a treatment to cure or reduce the symptoms. To this end patients may have seen several otolaryngologists, neurologists, psychologists, and speech pathologists. They may have received voice therapy, psychotherapy, psychological counseling, stress reduction interventions, drug therapies, EMG and thermal biofeedback, relaxation training, acupuncture, hypnosis, and faith healing. Unfortunately, none of these approaches has proved to be consistently effective in relieving the vocal symptoms. In the past two decades, a specialized form of chemodenervation has been used with good success to treat spasmodic dysphonia. Percutaneous injections of botulinum toxin (BOTOX) into the intrinsic laryngeal muscles have provided temporary reprieve from symptoms of spasmodic dysphonia.