Association of the superior semicircular canal and tegmen tympani dehiscences and its relationship with the pneumatisation of the temporal bone

PURPOSE

To analyse the degree of pneumatisation of the temporal bone when there is an association between dehiscence of the superior semicircular canal and dehiscence of the tegmen tympani.

MATERIALS AND METHODS

We analysed a retrospective CT study of 124 selected cases. A single inclusion criterion was applied: the presence of a dehiscence of the tegmen tympani. On the other hand, the degree of temporal pneumatisation was assessed by axial and coronal planes, and has been divided into the following grades O, I, II and III, according to the status and relationship of the mastoid, the bony labyrinth, the petrous segment of the carotid canal and sigmoid sinus.

RESULTS

Of the 124 cases studied, 35 (28.2%) presented both dehiscences. In 26 of the 35 (47.3%), grade II pneumatisation, 4 (14,8%), grade I, and 5 (11,9%) grade III was observed, with a statistically significant relationship (p < 0.001). On the other hand, we did not find a significant relationship when relating both dehiscences in any age or sex group. However, when relating the degree of pneumatisation to sex, among those with grade III pneumatisation, the proportion of men (52.4%) was significantly higher than that of women (47.6%) (p = 0.017).

CONCLUSION

We have detected a statistically significant relationship between the coexistence of grade II pneumatisation and the presence of both dehiscences in the temporal bone.

Alveolar Recess Cell (ARC): A Newly Described Intra Maxillary Sinus Cell with Variable Pneumatisation of Alveolar Process of Maxilla

Anatomical variations in the maxillary sinus pneumatisation are limited unlike the ethmoids. We present rare variations of the maxillary sinus along its floor other than septations and includes wide pneumatisation of alveolar and palatal recess with cell formation. An intra-maxillary cell that opens into the maxillary infundibulum well within the sinus is described here and our senior author has coined the new term-alveolar recess cell. Its involvement in the sinus pathologies and additional surgical approaches for the disease clearance is discussed here.

Is the pneumatisation of the maxillary sinus following tooth loss a reality? A retrospective analysis using cone beam computed tomography and a customised software program

OBJECTIVES

To compare the dimensions of maxillary sinuses in dentate and edentulous patients using cone beam computed tomography (CBCT) scans and a customised software program.

MATERIALS AND METHODS

This study comprised CBCTs of 50 dentate and 50 edentulous posterior maxillae. The observers drew two planar curves in all included sinuses in the frontal, sagittal and axial planes of the respective CBCT scans. The volume (mm³), surface (mm²) and maximum diameter (mm) of the sinuses were calculated using a custom-made software program. The variables analysed were the influence of the state of dentition on sinus dimensions (primary outcome) and the influence of age, gender and side on sinus dimensions; the time needed for analysis; and the intra- and inter-observer agreement (secondary outcomes).

RESULTS

There was no difference in sinus dimensions between dentate and edentulous posterior maxillae. Males had significantly (p < 0.05) greater volume, surface and diameter than females. Strong intra- and inter-observer agreement (Pearson correlation) was found for the calculated sinus dimensions. The time needed per analysis was less than 4 min for both observers.

CONCLUSIONS

Being edentulous did not have an impact on the sinus dimensions, suggesting that there is no ongoing pneumatisation in the sinus after tooth loss. Males had larger sinuses than females in a population older than 30 years.

CLINICAL RELEVANCE

Following tooth loss in the posterior maxilla, vertical bone height is primarily lost due to resorption of the alveolar crest, and not due to pneumatisation of the maxillary sinus. The customised software program was found to be user-friendly and efficient.

Carotid canal and optic canal at sphenoid sinus

In the present study, we investigated the relationship between sphenoid sinus, carotid canal, and optic canal on paranasal sinus computed tomography (PNSCT). This study was performed retrospectively. PNSCT images of 300 adult subjects (159 male, 141 female). Sphenoid sinus (pneumatisation, dominancy, septation, inter-sinus septa deviation), anterior clinoid process pneumatisation, Onodi cell, carotid and optic canals (width, dehiscence, classification) were measured. In males, type 3 pneumatised sphenoid sinus (in both sides) and in females type 2 pneumatised sphenoid sinus (right side) and type 3 pneumatised sphenoid sinus (left side) were detected more. Anterior clinoid pneumatisation was present 47.2% in males and 39.7% in females. In male group, more septation (i.e. 22.6%, ≥ 3 septa) in sphenoid sinus were detected. Onodi cell was present 26.6 and 19.1% in males and females, respectively. Carotid canal protrudation to the sphenoid sinus wall was present 23.9-32.1% in males and 35.5-36.2% in females. Dehiscence in carotid canal was detected more in females (34%) compared to males (22%). Optic canal protrudation was 33.3 and 30.5% in males and females. Type 4 optic canal was detected more in both gender. Optic canal dehiscence was detected 11.3 and 9.9% in males and females. Carotid and optic canal diameters were higher in males. In pneumatised sphenoid sinuses and in females, type 3 carotid canal (Protrudation to SS wall) (bilaterally) and type 1 optic canal type (No indentation) (ipsilateral side) were detected more. In elderly patients, carotid and optic canal width increased. When carotid canal protrudation was detected, there was no indentation in optic canals In pneumatised SS, carotid canal protrudation was observed with a greater risk in surgery. However, type 1 (non indentation) optic canal was present in highly pneumatised SS with lower risk for the surgery. In women, the risk of carotid canal protruding (about 1/3) is greater than that of males, and carotid canal dehiscence rates are also higher in females. Therefore, physicians should be very careful during the preparatory stages of the sphenoid sinus surgery. Otherwise, it may not be possible to prevent lethal carotid artery bleeds.