The advances in CT scanning and the wide spread of endoscopic sinus surgery increased the detection of MT variations. MT variations include CB, PMT, and secondary and accessory MT. These variations and their relationship to DS may be a source of obstruction of the middle meatal and subsequent headache and rhinosinusitis [9].
CT represents the gold standard diagnostic tool for the nasal and PNS pathologies, and multiple advanced techniques [10] are utilized now in pre-management of different nasal and PNS pathologies. Knowing detailed knowledge of the anatomical variants of the nasal turbinates is critical for effective and safe surgical procedures especially during functional endoscopic sinus surgery.
In current study, MT variations were studied using MSCT in asymptomatic adults with pathology-free nose and paranasal sinuses. The most frequent MT variation was concha bullosa (51.1%), followed by PMT (33.7 %), while the least frequent reported MT variation was bifid MT in one adult. The CB incidence was previously reported to range from 14 to 53% [11] and reaches up to 73% [12]. In current study, the incidence of frequency of types of CB was determined as 20.9% for bulbous concha, 11.6% for lamellar Concha, and 8.1% for total conchae. San et al. [11] have reported higher frequency of CB types such as 46.95% for total conchae, 32.17% for bulbous concha, and 20.86% for lamellar Concha. The differences could be attributed to racial difference and the analytical methods used. Frequencies of pneumatized MT and PMT in previous reports were 28% and 25% for Japanese [13], 24.5% and 10% in Spain [14], 29% and 11% in Italian [15], 18.2% and 14.3% in Pakistani [16], and 31.1% and 7.5% in Nigerian subjects [17]. Environmental factors and genetics seem to be the attributed explanation for these variations.
In present study, prevalence of PMT was 33.7%, and it was bilateral in 76% of the affected sides. Riello and Boasquevisque [12] and Fikre et al. [18] noted lower prevalence rate of 29% and 26.1%, respectively.
Association of multiple MT anatomical variations was more with bilateral PMT and CB. Fifty-nine percent of the reported bilateral PMT was associated with pneumatized MT, while 35.7% of unilateral PMT were associated with pneumatized MT with non-significant difference. Some reports have suggested a relationship between the presence of a CB and DS, Tiwari et al. [19] found a strong relationship between the presence of a concha (a dominant or unilateral concha) and DS; in the other side, Vincent and Gendeh [20] disproved that DS is associated with CB in its development and pathogenesis of chronic rhinosinusitis.
Our study also showed no significant association between the most common MT anatomical variation as CB and PMT and the presence of ipsilateral or contralateral DS, so our study considered that CB and DS are coincidental variations.
The presence of these variations in our study in normal adult without rhinosinusitis may mean that no specific association of anatomic variations of MT and rhinosinusitis. This supports the hypothesis that local, systemic, environmental factors or intrinsic mucosal disease may be more significant in the pathogenesis of rhinosinusitis.
We used 64 MDCT, and application of such high multi-detector CT scanners or with higher detectors improve the image qualities [21, 22]. The effective radiation dose used during sinus MDCT is 0.5–0.9 mSv [23]. But, the familiarity with scanning parameters affecting the radiation dose and increased radiologists awareness are mandatory to achieve the highest image quality with the least exposure.
To the best of our knowledge, this is the first work describing the anatomical variations of the MT in Egyptian asymptomatic adult. Further studies are needed to compare such MT variation in different nasal pathologies and to compare between symptomatic and asymptomatic patients to assess the actual effect of these anatomical variants upon the clinical manifestation of the patients.