Spasmodic Dysphonia

Lisa Lee and Keith M. Wilson

History

A 46-year-old white woman has had chronic hoarseness of several years’ duration. She describes her voice as breaking often and “going in and out.” The patient first noticed the hoarseness after a sore throat during a particularly stressful time in her life. Her voice is worse when talking on the phone and during stressful situations. Intermittently her voice cannot be understood by others. She notes that her voice gets better after an alcoholic beverage. Her voice causes her great personal distress. Her medical history is remarkable only for mild anxiety. She denies smoking, heartburn, hemoptysis, throat clearing, and allergy problems. She has seen several health professionals about her chronic hoarseness, including her primary care physician, two otolaryngologists, a psychiatrist, and a speech therapist. Prior treatments included speech therapy, antibiotics, and reflux medication with minimal improvement.

During the conversation, the patient’s voice is noted to have a strained and strangled quality with abrupt cessation and return of phonation. At times there is a notable tremulousness to her voice. Although she cannot count to 10 without intermittent stoppages, she is able to sing her favorite song smoothly. Her head and neck examination is otherwise unremarkable; there is no evidence of abnormal tongue or palate mobility. Her neurologic examination is notable only for a fine hand tremor. Flexible laryngoscopy shows normal-appearing, fully mobile vocal cords without any masses or sulci. No evidence of supraglottic erythema or edema is seen. During speech, the patient’s vocal cords abruptly adduct forcefully corresponding to phonatory stoppages.

Differential Diagnosis—Key Points

2. Essential laryngeal tremor. Essential tremor causes shaking of the head, hands, and voice. The tremor is typically not present at rest and is worse with emotional stress or fatigue. Essential laryngeal tremor manifests as a regular, 4- to 12-Hz tremor seen in the vocal cords during speech and respiration. In contrast, the tremor found in SD is irregular. Vocal tremor can be the only symptom in some patients. The vocal tremor represents rhythmic laryngeal movement, presenting as rhythmic pitch and loudness alterations during speech. Essential tremor can be seen concomitantly with SD.

3. Muscle tension dysphonia. Affected individuals are usually unable to sing or whisper without voice breaks. The dysphonia is worse under stressful situations. Unlike SD, intraword phonatory breaks are infrequent. Patients are more likely to exhibit excessive contraction of the intrinsic and extrinsic laryngeal muscles, with an over-adduction of the true or false vocal cords or even the supraglottis. Muscle tension dysphonia is most commonly treated with voice therapy. Occasionally botulinum toxin type A (Botox) is used in conjunction with voice therapy to release the abnormal muscle activation patterns.

4. Neurologic disorders. Although not likely to be the initial or sole manifestation, systematic neurologic diseases must be considered during the initial evaluation. Movement disorders such as Parkinson disease, Huntington disease, tardive dyskinesia, and cerebellar disorders need to be excluded with a complete neurologic examination. Other neurologic diseases to consider include myoclonus and Meige syndrome. Oculopalatal myoclonus presents as an involuntary movement of the head and neck region, including the soft palate, pharynx, larynx, and eyes. Laryngeal involvement presents as broken speech. Indirect laryngoscopy would show that the vocal cords have a slow, rhythmic adduction and abduction at the same frequency as the other myoclonic tics. Meige syndrome consists of myoclonic spasms of the eyelids, pharynx, tongue, floor of the mouth, and larynx.

Test Interpretation

When no overt laryngeal pathology is found, physiologic tests are indicated to further investigate the cause of the hoarseness.

Speech Evaluation