Anatomical variations of the frontal sinus and its relationship with the orbital cavity

Abstract

INTRODUCTION: The anatomy of the frontal sinus is highly variable and its variations affect the occurrence/course of pathological processes. We investigated its size and relationship to the orbit, searching for patterns that would allow it to be classified anatomically.

MATERIAL AND METHODS: Cone beam computed tomography was applied to 91 skulls (age range 21-86 years) to determine sinus height, width, length, and length of contact with the orbit in the coronal and sagittal planes. In addition, orbital roof pneumatization in the coronal plane was categorized as: none; only medial part pneumatized; the medial and a portion of the central part pneumatized; roof predominantly pneumatized.

RESULTS: Sinus dimensions varied widely (mm): height 6.2-50.0; width 3.7-54.0; length 2.4-45.0; frontal orbital contact 4.0-41.6; sagittal orbital contact 0.0-41.2. Pneumatization of the orbital roof (coronal plane) mostly affected the medial and a portion of the central part (50%), or the roof was predominantly pneumatized (32%). Three 'types' of sinus (cluster analysis) were distinguished by the extent of pneumatization of the orbital roof in the coronal plane: 'small', pneumatization absent or only of the medial part; 'medium-sized', pneumatization of the medial and a portion of the central part; 'large', roof predominantly pneumatized. All dimensions were significantly different among the types (P<0.001). Sinus type was fairly predictive of the extent of contact with the orbit in the sagittal plane (not routinely assessed clinically).

CONCLUSIONS: The data confirm the variability of frontal sinus anatomy and suggest a simple and straightforward classification with potential clinical relevance. This article is protected by copyright. All rights reserved.

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