title: Efficacy of repeated botulinum toxin injections as a function of timing.
abstract: This pilot study was designed to determine if the interval between repeated botulinum toxin injections influenced physiologic and histologic effects on laryngeal muscles in a rat model. The physiologic measurements included digitized videomicroscopic recording of vocal fold movement and electromyography. The histologic measurements included muscle fiber size and digitized optical density of laryngeal muscles after glycogen depletion by electrical stimulation. The results demonstrated that the effect of timing of the second injection was strongly correlated to laryngeal changes. Most notable were results in the subjects that underwent injections 6 weeks apart. We hypothesize that these findings might be related to terminal axonal sprouting with reinnervation. The results from this study help confirm and expand the validity of using the rat laryngeal model to understand the effect of botulinum toxin. Moreover, we believe that the data might be extrapolated to prove useful in predicting human responses to botulinum toxin treatment for functional dystonias such as spasmodic dysphonia.
authors.affiliation: Department of Surgery, University of Wisconsin Medical School, Madison, USA.
authors.forename: K
authors.initials: K
authors.lastname: Inagi
authors.forename: C N
authors.initials: CN
authors.lastname: Ford
authors.forename: A A
authors.initials: AA
authors.lastname: Rodriquez
authors.forename: E
authors.initials: E
authors.lastname: Schultz
authors.forename: D M
authors.initials: DM
authors.lastname: Bless
authors.forename: D M
authors.initials: DM
authors.lastname: Heisey
mesh_terms: D000818:Animals; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D004195:Disease Models, Animal; D004334:Drug Administration Schedule; D004353:Drug Evaluation, Preclinical; D016903:Drug Monitoring; D004576:Electromyography; D006801:Humans; D007267:Injections / Q000379:methods; D008297:Male; D018715:Microscopy, Video; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D010865:Pilot Projects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013035:Spasm; D013997:Time Factors; D014827:Vocal Cords / Q000503:physiopathology; D014832:Voice Disorders / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A