Our Experience in the Treatment of Spastic Dysphonia with Botulotoxin

Overview

Spastic dysphonia is presumably a voice disorder with pressed hoarse voice, whenthe phonation mechanismis executed by spastic contractions of internal as well as external cervicalmuscles. The enhanced phonation effort results in organic changes on vocal cords and vestibularfolds, which further deteriorate the disorder. This kind of dysphonia has been considered ofpredominantly functional, mostly of psychogenic nature for many years. In the recent years severalauthors expressed the opinion that, in many cases, there is an organic-based dystonia in a waysimilar go blepharospasm, hemifacial spasm or torticollis. In the same way as in these kinds ofdystonia, botulotoxin was also administered into internal pharyngeal muscles also in spasticdystonias. Botulotoxin is produced by the bacteria Clostridium botulinum, causing muscularparalysis by blocking presynaptic cholinergic terminals. A systemic administration induces a serious,life-threatening disease characterized by paralysis of skeletal muscles including respiratorymuscles. When administered locally in suitably selected doses botulotoxin causes a local decreasedof muscular tension producing a favorable effect in dystonias.The authors administered botulotoxininto 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 thespastic mechanism of phonation was suppressed, the voice was easier, but remained dimmed due toinsufficiency of phonation closure, which originated after the administration. The authors performeda laryngostroboscopic analysis of the phonation mechanism and revealed that the basic featureof laryngoscopic picture of phonation before the administration is an increased tension of vocalcords with completely absent verticalcomponent of oscillation (a shift of the edgewas not apparent).After the administration of botulotoxin the vertical component reappeared and gradually becamemore evident being most prominent at the peak of botulotoxin effect on quality of voice and thengradually disappeared. This symptom, which has not been described in literature yet, is consideredas a highly important diagnostic tool, making the evaluation of the dynamics of botulotoxin effectof phonation mechanism possible.

Key words:
spastic dysphonia, therapy by botulotoxin.