Pyramidal eminence and subpyramidal space: an endoscopic anatomical study.

OBJECTIVES/HYPOTHESIS To describe retrotympanic endoscopic anatomy, especially the pyramidal eminence and contiguous spaces. STUDY DESIGN This was an anatomical study on a prospective case series. METHODS The anatomy of the retrotympanum was studied by endoscopy in nine patients affected by cholesteatoma who underwent tympanomastoid surgery and in six temporal bone dissections. RESULTS Pneumatization of the sinus tympani and posterior tympanic sinus or both, noted in 12 ears out of 15, may give rise to a recess beneath the pyramidal eminence, which we have called the subpyramidal space. This space can manifest with a variable degree of depth, shape, or extent depending on the shape and dimensions of the pyramidal eminence. CONCLUSIONS Endoscopic exploration of the middle ear may guarantee a very good exposure of retrotympanic structures, allowing detailed anatomical descriptions of hidden areas. Improvement in our knowledge of the anatomy may decrease the possibility of residual disease during cholesteatoma surgery.