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Use of botulinum toxin type A for chronic cough: a neuropathic model.

OBJECTIVE
To review the experience and outcomes of a novel use of botulinum toxin type A (BtxA) in the treatment of chronic cough.


DESIGN
Retrospective case series.


SETTING
Academic referral center.


PATIENTS
A total of 438 patients were diagnosed as having laryngeal spasm and chronic cough, and 6 were documented as having chronic cough treated with BtxA injections. Two patients were excluded from the study because of a history of tracheostomy or concurrent laryngeal and voice dysfunction.


INTERVENTION
Electromyography-guided BtxA injections of the thyroarytenoid muscles.


MAIN OUTCOME MEASURES
Patient demographics (age and sex), voice-related quality-of-life scores, postprocedure complications, number of BtxA units used, number and length of treatments, and voice outcomes are reviewed.


RESULTS
Three of the 4 patients (75%) were women, and the mean patient age was 55.6 years (range, 38-64 years). All patients had significant relief of cough after BtxA injection, with complete resolution after a median of 7 injections (range, 4-16), using a mean dose of 4.0 U (range, 1.0-10.0 U) per treatment session for a mean duration of 25.7 months (range, 7.2-42.9 months).


CONCLUSIONS
To our knowledge, this is the first reported series in the literature of the use of BtxA in the treatment of chronic cough in adults. In this small case series, we report a neuropathic model for chronic cough caused by neuroplastic changes and laryngeal hyperactivity as an explanation for the effectiveness of BtxA treatment. Further research and long-term follow-up are warranted, but BtxA is effective in directly decreasing laryngeal hypertonicity and possibly reducing neurogenic inflammation and neuropeptide-mediated cough. Botulinum toxin type A can be considered for the treatment of chronic cough refractory to other medical therapies.