Differences in Patient Characteristics between Spasmodic Dysphonia and Vocal Tremor

ABSTRACT

Spasmodic dysphonia, essential tremor, and vocal tremor related with Parkinson’s disease are different disorders showing fairly similar symptoms such as difficulty in the speech onset, and tremble in the voice. However, the cause and the resulting treatment of these diseases are different. Spasmodic dysphonia is a vocal disorder characterized by spasms of the laryngeal muscles during a speech, invoking broken, tense, forced, and strangled voice patterns. Such difficult- to-treat dysphonia disease is classified as central-origin-focal dystonia, of a yet unknown etiology. Its symptoms arise because of intermittent and involuntary muscle contractions during speech. Essential tremor, on the other hand, is characterized by a rhythmic laryngeal movement, resulting in alterations of rhythmic pitch and loudness during speech or even at rest. Severe cases of tremor may cause speech breaks like those of adductor spasmodic dysphonia. In the case of hyper-functional tension of vocal folds and accompanying tremors, it is necessary to distinguish these disorders from muscular dysfunction. A diversified assessment through the performance of specific speech tasks and a thorough understanding for the identification of the disorder is necessary for accurate diagnosis and effective treatment of patients with vocal tremors.