Anatomical variations in the human paranasal sinus region studied by CT

Risky anatomic variations of sphenoid sinus for surgery

We searched for the surgically risky anatomic variations of sphenoid sinus and aimed to compare axial and coronal tomography in detection of these variations. Fifty-six paranasal tomography images (112 sides) were evaluated for coronal, axial and both coronal and axial images. Tomographic findings including bony septum extending to optic canal or internal carotid artery; protrusions and dehiscences of the walls of internal carotid artery, optic nerve, maxillary nerve and vidian nerve; extreme medial course of internal carotid artery; patterns of aeration of the anterior clinoid process; and Onodi cells were evaluated. The results were classified as "present, absent, suspicious-thin (only for dehiscence) or no-consensus". The results of each plane were compared with that of the result of the both planes together. Kappa coefficient and Chi-square tests were used to compare both planes. Twelve cadaveric dissections were performed to reveal the proximity of sphenoid sinus to surgically risky anatomic structures. Endoscopy was applied to five cadavers. 18 evaluations were classified as 'no-consensus'. We detected 34, 35, 34 and 40 protrusions of internal carotid artery, optic nerve, maxillary nerve, vidian nerve, respectively. Dehiscences were present in 6, 9, 4 and 8, and suspicious-thin in 8, 10, 16 and 25 in canals of internal carotid artery, optic nerve, maxillary nerve and vidian nerve, respectively. Bony septum to internal carotid artery and optic nerve was observed in 30 and 22 cases. We observed 9 extreme medial courses of internal carotid artery, 27 aerated clinoid process and 9 Onodi cells. Axial images were superior in detection of bony septum to internal carotid artery and Onodi cells; while the coronal images were more successful in detection of protrusion of optic nerve and vidian nerve, and dehiscense of maxillary nerve and vidian nerve (P<0.05). In cadaveric dissections, the septa were inserted into the bony covering of the carotid arteries in two sinuses (8.3%). Detailed preoperative analysis of the anatomy of the sphenoid sinus and its boundaries is crucial in facilitating entry to the pituitary fossa and reducing intraoperative complications. Coronal tomography more successfully detects the sphenoid sinus anatomic variations.

The incidence of concha bullosa and its relationship to nasal septal deviation and paranasal sinus disease

BACKGROUND AND PURPOSE

The incidence of middle turbinate pneumatization, or concha bullosa, has been well described in the literature. However, to our knowledge, no study has evaluated concha bullosa in relation to nasal septal deviation. We sought to analyze the incidence of concha bullosa and any correlation with nasal septal deviation and paranasal sinus disease.

METHODS

Three neuroradiologists retrospectively reviewed findings of 1095 consecutive paranasal sinus CT studies conducted between 2001 and 2002. All examinations were performed for evaluation of a symptom referable to the sinonasal region. Paranasal sinus inflammatory disease was identified and graded as mild, moderate, or severe. Sphenoid, ethmoid, maxillary, and frontal sinuses were each graded separately on both sides. If a concha bullosa was present, it was graded in size as small, moderate, or large. If bilateral concha were present, sizes were compared and when one was larger, it was identified as dominant. When nasal septal deviation was present, it was graded as mild, moderate, or severe. The direction of nasal septal deviation was identified as the face of the convex surface.

RESULTS

There was a clear association between the presence of a unilateral concha, or a dominant concha (in the case of bilateral concha), and the presence of nasal septal deviation (P < .0001). Moreover, there was a significant relationship between the presence of concha bullosa and deviation of the nasal septal to the contralateral side (P < .0001). This inverse association was present regardless of the size of the concha bullosa or degree of septal deviation. In every case, there was some preservation of air channels between the dominant concha and the nasal septum. Seventy-three percent of patients with concha bullosa had paranasal sinus inflammatory disease; 78% of patients without concha bullosa also had some form of inflammatory disease.

CONCLUSION

Concha bullosa is a common anatomic variant. There is a strong association between the presence of a concha bullosa and contralateral deviation of the nasal septum. Nasal septal deviation away from the dominant concha, with preserved adjacent air channels, suggests that the deviation is not a direct result of mass effect from the concha. No increased incidence of paranasal sinus disease exists in patients with concha bullosa.

The Utility of Radiologic Studies in the Diagnosis and Management of Rhinosinusitis

The past two decades have seen the development of computed tomography scanning as the principal investigation for paranasal sinus disease. This article describes the benefits and limitations of computed tomography scanning in the assessment of rhinosinusitis. It also discusses the role of magnetic resonance imaging as a further diagnostic tool in the assessment of rhinosinusitis and in particular its complications. Other imaging modalities such as plain radiographs and ultrasound have limited use in this field. The introduction of image guidance techniques as an aid to surgical treatment and possible future developments are outlined.