The facial ridge and the discharging mastoid cavity.

This study evaluates the causes for a persistently discharging mastoid cavity and attempts to weight the importance of each identified factor. It consists of a temporal bone dissection to evaluate the anatomy of the facial nerve and a clinical prospective study measuring the factors that contribute to a wet cavity. The factors measured were height of the facial ridge, the size of the meatus, state of the tympanic membrane, and size of the mastoid cavity. The height of the facial ridge and the kidney shape of the cavity were found to be the most significant factors contributing to the state of the cavity. The tympanic membrane and size of the meatus were also found to significantly influence the state of the cavity, whereas the size of the cavity was not significant. These results illustrate the importance of the facial ridge in mastoid surgery and that most poor results in mastoid surgery are due to the surgeon, not the disease.