The imaging anatomy of ethmomaxillary sinus and its impact on chronic rhinosinusitis

The Ethmomaxillary Sinus-A False Duplicate Maxillary Sinus

Functional endoscopic sinus surgery consistently benefits from good anatomical knowledge and modern imaging techniques. Ethmoid air cells migrate in specific topographical sites near the ethmoid. Posterior ethmoid air cells that descend into the maxillary sinus (MS) are ethmomaxillary sinuses (EMSs) that into the superior nasal meatus. Few previous studies found EMSs in 0.68% to 16.48% of cases. An EMS differs from a Haller's infraorbital cell nearing the ethmoidal infundibulum. A posterior ethmoid air cell intercalated between the ethmoid, MS and sphenoidal sinus is a Sieur's cell, but it could also be regarded as an EMS. An EMS should be discriminated from a maxillary recess of the sphenoidal sinus. An EMS could determine Onodi's maxillary bulla into the MS. The false duplicate MS described by Zuckerkandl consists of a MS draining into the middle nasal meatus adjoined by an EMS draining into the superior nasal meatus. These are separated by the ethmomaxillary septum. The latter may be confused with an intrasinus septum of the MS if the drainage pathways are not adequately documented. Therefore, a case-by-case anatomic identification of the pneumatic spaces nearing the MS should be performed before surgical endoscopic approaches of the nose and sinuses.

Anatomical Variations of the Maxillary Sinus – A Cone Beam Computed Tomography Study

Objectives: The knowledge of the normal morphology of the maxillary sinuses and their variations is important for maxillofacial radiologists to achieve a better evaluation and delineation of pathologies and for pre-implant evaluation of the maxilla.

The aim of our study was to evaluate anatomical variations of maxillary sinuses using Cone Beam Computed Tomography (CBCT).

Materials and methods: 150 CBCT images where bilateral maxillary sinuses were scanned were included in the study following the inclusion and exclusion criteria. 75 CBCT scans each of males and females were studied using the Planmeca Romexis software (Version 4.6.2). Multiplanar images were searched for the presence of anatomical variations such as septae, haller cells and ethmomaxillary sinus. The data were subjected to Chi square test using SPSS software to compare and relate gender and site based differences in the occurrence of the anatomical variations.

Results: Sinus septa was the predominant variation in both males and females with significantly higher prevalence in females and on the right side. An ethmomaxillary sinus was seen significantly more often in males, while Haller cells did not show any gender based differences in their occurrence. Ethmomaxillary sinus and Haller cells showed no difference in occurrence on the right and left side.

Conclusions: Anatomic variations of the maxillary sinuses are a common finding. It necessary for the clinicians to be familiar with these variations to avoid clinical complications especially in cases of implant placements.

[Anatomical variations of the ethmomaxillary sinus]

OBJECTIVE

To establish the prevalence and individual variations of the ethmomaxillary sinus (EMS) using cone beam computed tomography (CBCT).

MATERIAL AND METHODS

CBCT images from 553 dental and ENT patients (1106 sides), presenting to treatment at Minsk outpatient clinics, Belarus, were used in this study. The maximum vertical diameter of ethmomaxillary sinus in the coronal plane was measured. Anatomical variations of the ostiomeatal complex and mucosal diseases of paranasal sinuses were recorded.

RESULTS

Ethmomaxillary sinus - is posterior ethmoidal cell extending to the posterior superior part of the maxillary sinus (MS) while draining into superior meatus. It was present in 13 of 553 patients (2.4%). The age of patients with EMS ranged from 12 to 60 years, including 8 males and 5 females. A total of 5 patients had unilateral EMS and 8 patients - bilateral EMS. Ethmomaxillary sinus was extended to the alveolar bone in five cases. Moreover, in two cases, the roots of the upper third molars protruded into its lumen.

CONCLUSION

The enlarged posterior ethmoidal air cell can occupy the posterior superior portion of the maxillary sinus and even reach the alveolar bone. Such a cell is called the ethmomaxillary sinus and, as a rule, its presence is accompanied by excessive pneumatization of other cranial bones. Inflammation of the mucous membrane of the ethmomaxillary sinus is most often not combined with the radiographic signs of maxillary sinusitis, and a direct communication of the EMS and MS was detected in only one patient.