Spasmodic dysphonia is reported to be one of the
most frequently misdiagnosed conditions in Speech-Language Pathology.
Because there is no definitive test for the SD, the diagnosis rests on the
presence of characteristic clinical symptoms and signs in the absence of
other conditions that may mimic spasmodic dysphonia.
It is important that an interdisciplinary team of professionals evaluate and
provide accurate differential diagnosis. This team usually includes a
speech-language pathologist who evaluates voice production and voice
quality; a neurologist who carefully searches for other signs of dystonia or
other neurological conditions; and an otolaryngologist who examines the
vocal cords and their movements.
The otolaryngologist examines the vocal folds to look for other possible
causes for the voice disorder. Fiberoptic nasolaryngoscopy, a method whereby
a small lighted 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. The speech-language pathologist evaluates the
person's voice and voice quality. The neurologist evaluates the
affected-person for signs of other muscle movement disorders.
The excessive strain and misuse of muscle tension dysphonia, the harsh
strained voice of certain neurological conditions, the weak voice symptoms
of Parkinson's disease, certain psychogenic voice problems, and voice
tremors are often confused with spasmodic dysphonia.