A novel perspective on geniculate ganglion fossa: Cone beam computed tomography analysis of pneumatization and dehiscence

Abstract

Objective

This study aimed to analyze the prevalence and patterns of geniculate ganglion fossa (GGF) pneumatization, as well as the dehiscence and thickness of its tegmen, while evaluating their anatomical correlations. The assessment was conducted using two coronal planes aligned with the histological division of the GGF.

Methods

Seventy cone-beam computed tomography (CBCT) scans (140 sides) were analyzed. Two coronal planes through the GGF were used, based on its histology: an anterior plane through the ganglion and a posterior plane through the facial nerve fibers. Pneumatization was assessed by identifying air cells within a 2 mm range of the GGF, examining its superior, lateral, medial, and inferior walls, and classifying the pneumatization patterns. The GGF tegmen dehiscence was evaluated in both planes and categorized as intact, partial, or total. Based on combined findings, five dehiscence types were defined, ranging from type 1 (no dehiscence) to type 5 (complete dehiscence in both coronal planes). The classification reflects the progressive extent of tegmen dehiscence across these planes.

Results

Type 1 (intact GGF tegmen) was the most common, observed in 47.1 % of cases, while partial dehiscence (types 2–4) and complete dehiscence (type 5) were found in 39.3 % and 13.6 % of cases, respectively. Pneumatization was predominantly lateral (95 %), corresponding to the epitympanum, while superior pneumatization within the GGF tegmen occurred in 33.6 % of cases. Circumferential pneumatization, involving all GGF walls, was very rare (1 case, left side). Superior pneumatization correlated with a significantly greater mean GGF tegmen thickness compared to non-pneumatized cases (2.6 ± 1.3 mm vs. 1.2 ± 0.7 mm). GGF tegmen dehiscence did not significantly influence tegmen tympani dehiscence (prevalence of 72.9 %), indicating no clear association.

Conclusion

Assessing GGF morphology in anterior and posterior planes, thus correlated with the histological division of its neural content, can enhance preoperative planning and help predict and minimize surgical risks in this complex and delicate region.