The disorder is a result of involuntary, forceful separation of the vocal folds which interrupts the airstream. The average age of onset is 45 to 50 years. The full etiology of SD is not yet known. However, tremor and dystonia are closely related with SD which suggests SD is related to dysfunction of the extrapyramidal system, specifically dysfunction in the basal ganglia or cerebellar control circuits. There are three broad etiologic possibilities for the disorder.
Spasmodic dysphonia can be neurogenic, psychogenic, or idiopathic.
Symptoms may worsen due to factors such as anxiety, stress, depression, physical exertion, or concentrating on speech. This disorder may cause a stained-strangled, choked, effortful voice quality, often with abrupt initiation and termination of voicing, and a broken speech pattern. Abductor spasmodic dysphonia is caused by an overcontraction of the muscles that separate the vocal folds. This disorder may cause a choppy and breathy whispering voice pattern or an irregular voice tremor. The SLP may be responsible for preparing an evaluation for the ENT, and may or may not perform a videostroboscopy.