Topical papaverine and facial nerve dysfunction in cerebellopontine angle surgery

Hypothesis: Topical application of 3% papaverine hydrochloride in the cereb ellopontine angle (CPA) produces reversible conduction block of the facial nerve. Background: A case of loss of spontaneous and evoked facial muscle activity , and transient postoperative facial paralysis, after topical application o f papaverine in the CPA during surgery for an acoustic neuroma using intrao perative cranial nerve monitoring is reported. Other cases of transient neu rologic dysfunction after use of this drug have been reported. Methods: A rabbit model of CPA surgery via suboccipital craniectomy, with i ntraoperative monitoring of the facial nerve, was used in this experiment. Results: No significant difference in facial muscle stimulation thresholds was identified after application of varying concentrations of papaverine to the facial nerve in the CPA. Conclusion: Although the intraoperative event described in the report is su ggestive of an effect of papaverine on facial nerve function, this effect c ould not be reproduced in an established animal model of CPA surgery.