The Petrosquamous Stalactite: Anatomic Characterization and Mastoid Surgical Implications

Abstract

Objective To define the presence and relationship of the petrosquamous stalactite (PsS)—a condensation of the trabecular Korner’s septum into a bony plate of the petrosquamous suture—to surrounding structures and understand its surgical implications. Study Design Series of cadaver dissections. Setting University of Missouri Alumni Temporal Bone and Microvascular Laboratory. Subjects and Methods Anatomic dissections were conducted on 15 consecutive formalin-preserved and frozen adult human temporal bones. A calibrated Dino-Lite Premier Digital Microscope was used to photograph dissections of each bone. Measurements were conducted with DinoCapture 2.0 software, with measurement agreement between 2 authors. Results The PsS was present in all specimens. A conserved vascular structure courses within the structure, and the superior malleolar ligament inserts on it. The mean ± SEM distances from the PsS to the tegmen tympani and incus buttress were 2 ± 0.24 mm and 4.23 ± 0.14 mm, respectively. The shortest distance from the PsS to the posterior body of the incus was 1.25 ± 0.13 mm, while the greatest distance from the posterior prominence of the PsS to the posterior body of the incus was 4.58 ± 0.25 mm. Conclusion The PsS is a consistently identifiable structure that may facilitate identification of the tegmen tympani and guide the otologic surgeon from the mastoid antrum to the incus. It is important to recognize the contribution of the PsS to the division of the epitympanic space when cholesteatoma involves the region, to avoid leaving a nidus for future disease.