Diseases presenting withh voice tremor are rare in Japan. Much less frequent is essential tremor imputed to a central nervous disturbance and spastic dysphonia of unknown etiology. Furthermore, it is often extreme by difficult to differentiate these diseases.
Two patients with voice tremor, one with essential tremor and one with spastic dysphonia, were recently examined with various tests mainly of voice. When the patient with spastic dysphonia used her voice without the intent of communication had tremble was only to slight, and the symptom responded temporarily to superficial anesthesia with lidocaine. Furthermore, auditory feedback shut-off resulted in symptom mitigation. None of these changes could be induced in the patient with essential tremor. These findings may be of help in differentiating the two diseases.
