Spasmodic dysphonia can be difficult to diagnose because the anatomy of the larynx is normal. SD has no objective pathology that is evident through x-rays or imaging studies like a CT or MRI scan, nor can a blood test reveal any particular fault. In addition, several other voice disorders may mimic or sound similar to it. The excessive strain and misuse of muscle tension dysphonia (MTD), the harsh strained voice of certain neurological conditions, the weak voice symptoms of Parkinson’s disease, certain psychogenic voice problems, acid reflux, or voice tremor are often confused with SD. Therefore, the best way to diagnose the problem is to find an experienced clinician with a good ear.
Who Treats Spasmodic Dysphonia?
Usually an otolaryngologist, a physician that specializes in diseases of the ears, nose, and throat (ENT), diagnoses SD. Some otolaryngologists, called laryngologists, have additional postgraduate training and specialize in voice disorders. Many otolaryngologists work with a speech pathologist, a clinician who has expertise in the evaluation and non-medical treatment of voice disorders. A neurologist may also be part of the diagnostic team to evaluate a patient for other forms of dystonia or other neurological conditions.
After taking the medical history, the physician and speech pathologist listen carefully to the person’s speech to subjectively identify specific signs of SD, such as voice breaks. To help differentiate the condition and subtype, they ask the patient to read and speak specific sentences loaded with certain sounds. While additional evaluations may help to support or refute the conclusion, the experienced clinician’s expert perceptual analysis usually serves as the basis for making the SD diagnosis.
The physical examination continues by looking at the larynx in action. Even though the person with SD often has normal anatomy, the physician should look at the larynx to rule out other common laryngeal disorders that can result in a hoarse voice. These include conditions such as vocal nodules or chronic laryngitis.
One way to view the larynx is to insert a rigid endoscope, a straight, narrow metal rod containing a camera, through the mouth and toward the back of the throat while the person is saying “eeeee.” In this manner, the otolaryngologist can obtain a close-up view of the structures of the larynx and the movement of the vocal folds. Another approach to viewing the vocal folds involves the use of a flexible endoscope. In this method, a very narrow, flexible tube is inserted through one nostril and down through the throat, which allows the doctor to evaluate the movements of the larynx while the person is speaking or singing. Often, these endoscopic examinations are performed with a specialized flickering light called a stroboscope which allows the clinician to further evaluate the rapid fine movement of the vocal folds.
The otolaryngologist may recommend a laryngeal electro-myography (EMG) test to obtain specific information about the muscles involved. EMG involves inserting a thin needle electrode through the neck into the muscles of the larynx and evaluating the electrical activity of the muscles at rest and during speaking. With a confirmed diagnosis, the doctor and patient can find an appropriate course of treatment.