[Osseous variations in the coronary CT of the paranasal sinuses].

Bony variations in the anterior ethmoids may, if severe, play an important role in the development of chronic sinusitis and present the surgeon with added risks during operation. We have, therefore, analysed 390 preoperative CT examinations of the sinuses performed in the coronary plane with respect to the frequency of bone variations. Concha bullosa, increased pneumatisation of the agger nasi, large ethmoidal bullae, Haller's cells and increased pneumatization of the sphenoid were found with equal frequency in about 20%. The most common variants occurred in the uncinate process (31.5%), less common were paradoxical curve of the middle turbinates (13.3%) and very rare were Onodi cells (1.3%).