Glottic physiology after Botox treatment of adductor spasmodic dysphonia, abductor spasmodic dysphonia and vocal tremor

The action of botulinum toxin type A (Botox) on glottic phonatory biomechanics was studied stroboscopically, acoustically, and aerodynamically in a series of adductor spasmodic dysphonia (ADD SD) patients, abductor spasmodic dysphonia (ABD SD) patients, patients who had vocal tremor (VT) and ADD SD, and patients who had VT only. After chemodenervation, glottic gap size, which narrowed from its initial maximum as a function of delayed reinnervation/recovery, was a primary physiologic element responsible for symptom elimination in ADD SD. Breathiness;Is well as pitch and loudness control were reflected by glottic gap size. Mucosal vibratory wave (MVW) asymmetry accounted for aperiodicity (hoarseness). Symptoms were eliminated for a mean of 4 months in ADD SD. Drug dosage criteria did not correlate well with physiologic and acoustic findings. Voice therapy appeared to prolong interinjection interval. Shifting of the vocal fold toward the midline after denervation of the posterior cricoarytenoid (PCA) muscle to reduce the posterior glottic gap produced variable results in ABD SD. Although glottic physiology in VT was similar to that in ADD SD, results in VT were also variable. Resultant data are used to construct a typical phonatory profile after Botox treatment, which can be used to explain the results of this treatment method for all patients.