Retrograde degeneration of the facial nerve after acute traction on parotid gland: an experimental investigation.

The parotid gland of the cat underwent traction for 2 hours (group A) or until the facial nerve was broken (group B). The cats survived postoperatively for 1 day, 2 weeks, 1 month, and 3 months, respectively. Each cat underwent an electroneurography session before they were killed. The facial nerve was harvested and underwent histologic examination. The present study demonstrated that, in group A, the degree of facial nerve degeneration indicated with evoked electroneurography was 100% at 1 day and 2 weeks and 85% and 35%, respectively, at 1 and 3 months after damage. In group B, no electric response was recorded, epineurium of extratemporal segment was broken. This study also showed that the pronounced alteration of the facial nerve following acute traction on the parotid gland was retrograde degeneration; it involved up to its internal acoustic meatus segment. Furthermore, pronounced damage was noted in its stylomastoid foramen and extratemporal segment.