Classification of the Suprameatal Tubercle and Morphometric Analysis with Surgical Approach to the Temporal Bone

Abstract: The temporal bone is a valuable structure in the approach of intracranial pathologies to the middle and posterior fossa, sometimes requiring the performance of anterior, posterior, or combined approaches for resection of tumors in these regions. The purpose of this study is to perform morphometric analysis with a surgical approach to the temporal bone, in adult skulls, with emphasis on the suprameatal tubercle (SST) taking into account their anatomical relationships.

Material and Methods: The present study was developed in the facilities of the Faculty of Medicine of the National Autonomous University of Mexico (UNAM). A total of 200 temporal bones from 100 adult human skulls were analyzed. The TSM was emphasized according to its location and size, classifying it as: middle or posterior anterior and type I (0–1 mm), type II (2–3 mm), and type III (>3mm). In addition, measurements were made with a surgical approach of the petrosal portion of the temporal bone and the supramastoid crest.

Results: The SST was observed in 171 specimens studied (85.5%). Among them, the posterior position was the most frequent 85 of 171 (49.70%), followed by the average position 43 (25.14%), and finally the previous position 43 (25.14%). In terms of size, type II was more frequently found in 99 of the specimens (49.5%), type I in 82 specimens (41%), and type III were found in 19 (9.5%). The asterion was reflected within the impression of the breasts in the majority 48.5%; the union of the supramastoid crest with squamous suture was reflected in 98.5% of the cases to the middle fossa.

Discussion: In our search for information there is no data to make a comparison with that obtained in this study of the suprameatal tubercle, the findings found seems to indicate that there is a direct relationship with the presence of the impression of the groove of the upper petrosal sinus. The distribution according to its position is important when it is in grade III, since it poses a technical difficulty in approaches such as petrosectomies or Meckel's cavum from a retrosigmoid approach.

Conclusion: The anatomical observation and classification that we perform of the suprameatal tubercle, a very poorly evaluated structure, gives us preoperative and transoperative considerations when we perform an approach that involves the posterior aspect of the petrosal portion of the temporal bone.