Biofeedback therapy for spastic dysphonia.

Spastic dysphonia is a disorder of phonation which is characterized by a strained, creaking, and choked vocal attack, a tense and squeezed voice sound. Spastic dysphonia in a functional voice disorder can be classified into two types from the viewpoint of activities of the extrinsic and intrinsic laryngeal muscle groups. A functional voice disorder pertaining to abnormal activities of the intrinsic and extrinsic laryngeal muscles results in spastic dysphonia. The adductor spastic dysphonia may be due to abnormal actions of the intrinsic laryngeal muscles as such is relieved by sectioning of the recurrent nerve, while spastic dysphonia mainly dealing with the extrinsic laryngeal muscles is relieved by relaxation on monitoring an electromyographic feedback system. Within 3 months we encountered two patients whose extrinsic laryngeal muscles were hyperactive on phonation. A trial on injection of lidocaine into extrinsic laryngeal muscles made their muscles relax. So, biofeedback therapy of relaxation was began using a monitoring system of EMG burst regarding to hypertonicity of the extrinsic laryngeal muscles. Normal vocal abilities were recovered using a biotrainer as a monitoring device of electromyographic feedback.