RHINORRHEA IS DECREASED IN DOGS AFTER NASAL APPLICATION OF BOTULINUM TOXIN

At this time no effective long-term therapy exists for the excessive s ecretion of vasomotor rhinitis. Because rhinorrhea is under parasympat hetic control, it was theorized that botulinum toxin - a powerful and long-acting cholinergic blocker that has been successful in the treatm ent of dystonia - might be useful in blocking the cholinergic control of rhinorrhea. Four male mongrel dogs were studied. Fifty units of typ e A botulinum toxin was soaked into sterile gauze, which was then pack ed into the left nasal cavity of each dog for 1 hour. Saline-soaked ga uze was similarly introduced into the right nasal cavity to serve as c ontrol. Six days later, rhinorrhea was produced by inserting a bipolar needle electrode into the sphenopalatine ganglion and electrically st imulating for 10 minutes (6 mA, 50 Hz). Nasal secretions were collecte d with a suction catheter placed in the nasal vestibule. Three of four dogs exposed to the toxin showed a 41% average decrease in rhinorrhea (specifically 53%, 41%, and 30%). One dog showed a 10% increase in se cretion after exposure to the toxin, We conclude that topically applie d botulinum toxin reduced neurally evoked rhinorrhea by an average of 41%. Because some secretion is mediated by noncholinergic neurotransmi tters such as vasoactive intestinal peptide, topical application of an anticholinergic substance has limitations. However, because all the n asal parasympathetic nerves appear to originate from cholinergic synap ses in the sphenopalatine ganglion, direct injections of toxin into th is ganglion may possibly allow complete blockade of all cholinergicall y mediated rhinorrhea.