The pressure exerted by mucoceles in the frontal sinus. An experimental study in the cat.

The pathophysiologic process that results in bone erosion from frontal sinus mucoceles has long been a mystery. Traditionally, bone erosion has been attributed to pressure. However, no scientific evidence has yet been presented to support this hypothesis. To answer this question, seven cats had a mucocele created in one frontal sinus, with the other sinus left as a control. A manometer was inserted into each frontal sinus. Pressure readings were taken over a 7-month period. Pressures on the mucocele side were higher than on the control side and were sufficient to erode bone. Bone was thicker on the mucocele side than on the control side. This study established that mucoceles exert sufficient pressure to erode bone, and that such erosion may be part of a two-stage process.