The sagittal grooves of the middle nasal turbinate determine paradoxical curvatures and bifidities.

Abstract

Paradoxical curvature of the middle nasal turbinate (MT) is a common anatomic variant, usually found and reported on coronal CT slices. However, less attention has been paid to the sagittal groove (SG) which is determining it. The study aimed to determine paradoxical curvatures and bifidities in the sagittal groves of middle nasal turbinate. A retrospective CBCT study on the archived files of 52 adult patients was performed. Different patterns of MT bifidity were found: (1) unilateral bifid MTs; (2) bifid and trifid MTs and "wandering" single SGs; (3) bilateral bifid middle turbinates and double SGs, (4) bilateral false bifid appearance due to middle and superior turbinates fusion and (5) bifid concha bullosa media. Digital "dissections" of patients' files allowed us to conclude that paradoxical curvature as well as bifidity of MTs relate to the placement and number of the SGs on the MTs. Such SGs were previously documented in prenatal MTs since the 14th week, as well as in pædiatric patients. It seems reasonable to speculate that paradoxical curvature, as well as bifidity of MT, this later being previously undocumented, are just adult vestiges of the primitive MT morphology. Nevertheless, documentation of the MT morphology should not rely exclusively on coronal CTs, as combined morphologies of that turbinate could occur.