Botulinum toxin injection and airflow stability in spasmodic dysphonia.
OBJECTIVE
The aim of this study was to analyze the effects of botulinum toxin (BT) injection on airflow stability, by measuring mean phonatory oral airflow and its coefficient of variation (CV), in subjects with adductor spasmodic dysphonia (SD).


METHODS
Twenty-four subjects with SD (aged 31-78 years) and 23 controls (aged 29-63 years) were evaluated for mean airflow and its CV during sustained phonation. Fifteen of the subjects with SD were also evaluated within 3 weeks after BT injection.


RESULTS
BT increased airflow in subjects (P = 0.0130) but neither the preinjection nor postinjection values differed significantly from those of controls. Conversely, airflow CV was invariably higher in subjects than in controls (P < 0.0001). In 13 subjects in whom phonation perceptually improved, including 3 in whom airflow did not increase, airflow CV decreased significantly after BT treatment (P = 0.0232).


CONCLUSIONS
Subjects with SD have highly unstable phonatory airflow; its CV is a valid measure for assessing the outcome of a BT injection. A reduced airflow CV probably does not depend solely on increased airflow due to thyroarytenoid muscle paresis, and may indicate a change in laryngeal motoneuronal activity.


METHODS
B-3b.
Cantarella
Giovanna
G
Department of Otolaryngology, Fondazione Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, IRCCS, Pad. Alfieri, Via Commenda 10, 20122 Milan, Italy. giovanna.cantarella@policlinico.mi.it
Berlusconi
Alessandra
A
Maraschi
Barbara
B
Ghio
Alain
A
Barbieri
Sergio
S
D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007821:Laryngeal Muscles / Q000187:drug effects; D007828:Laryngoscopy; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D010699:Phonation / Q000187:drug effects / Q000502:physiology; D012123:Pulmonary Ventilation / Q000187:drug effects* / Q000502:physiology; D016896:Treatment Outcome; D014741:Video Recording; D014826:Vocal Cord Paralysis / Q000188:drug therapy / Q000503:physiopathology; D014832:Voice Disorders / Q000188:drug therapy*
D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A