Symmetry of external auditive meatus. A pilot study on human skulls.

OBJECTIVES. To evaluate the perpendicularity of the line connecting external auditive meatus to the midsagital plane and the palatal suture as a midsagittal symmetry reference line. Setting and Sample Population - 62 randomly chosen human skulls from osteological collection (Vilnius University). MATERIAL AND METHODS. The skulls were photographed (Nikon 40 D, Nikkor lens 50 mm) from basal, frontobasal and frontal views. Photos were analysed with Adobe Photoshop CS5 (Adobe). The first line connected frontal points of external auditive meatus and the angle to the midsagittal plane was measured. The second line (the palatal suture) was compared to the median sagittal plane. Data was analysed with SPSS 17 (IBM). RESULTS. The mean value for the angles of the line between the external auditive meatus and the midsagittal plane in basal views was 90.12° (SD=1.48°) and in frontobasal 90.36° (SD=2.25°). No statistically significant differences were found between groups of age and sex. The inter-rater agreement for evaluation of the adequacy of palatal suture with the midsagital plane was high (Cohen's Kappa 0.702 (p<0.05)) as well as the coincidence of both lines in basal and frontobasal views (90.3% and 85.5% respectively). CONCLUSION. Considering the limits of this study the angle between external auditive meatus and midsagital skull plane has a characteristic fluctuating asymmetry. The congruence of palatal suture and midsagital plane is debatable.