Spastic dysphonia is presumably a voice disorder with pressed hoarse voice, when the phonation mechanismis executed by spastic contractions of internal as well as external cervical muscles. The enhanced phonation effort results in organic changes on vocal cords and vestibular folds, which further deteriorate the disorder. This kind of dysphonia has been considered of predominantly functional, mostly of psychogenic nature for many years. In the recent years several authors expressed the opinion that, in many cases, there is an organic-based dystonia in a way similar go blepharospasm, hemifacial spasm or torticollis. In the same way as in these kinds of dystonia, botulotoxin was also administered into internal pharyngeal muscles also in spastic dystonias. Botulotoxin is produced by the bacteria Clostridium botulinum, causing muscular paralysis by blocking presynaptic cholinergic terminals. A systemic administration induces a serious, life-threatening disease characterized by paralysis of skeletal muscles including respiratory muscles. When administered locally in suitably selected doses botulotoxin causes a local decreased of muscular tension producing a favorable effect in dystonias.The authors administered botulotoxin into both thyreoarytenoideus muscles at the dose of 10 - 20 units of Botox or Dysport in 11 patients, affected by spastic dystonia. In all these patients there was an improvement of voice in that the spastic mechanism of phonation was suppressed, the voice was easier, but remained dimmed due to insufficiency of phonation closure, which originated after the administration. The authors performed a laryngostroboscopic analysis of the phonation mechanism and revealed that the basic feature of laryngoscopic picture of phonation before the administration is an increased tension of vocal cords with completely absent verticalcomponent of oscillation (a shift of the edgewas not apparent). After the administration of botulotoxin the vertical component reappeared and gradually became more evident being most prominent at the peak of botulotoxin effect on quality of voice and then gradually disappeared. This symptom, which has not been described in literature yet, is considered as a highly important diagnostic tool, making the evaluation of the dynamics of botulotoxin effect of phonation mechanism possible.

        Key words: spastic dysphonia, therapy by botulotoxin.