Abnormalities of lateral cartilaginous lamina and lumen of eustachian tube in cases of cleft palate.

Development of the lateral lamina (LL) of the eustachian tube (ET) cartilage was investigated in cleft palate (CP) cases and controls by measuring the areas of the LL and medial lamina (ML) of the ET cartilage in histologic cross section, and comparing the ratio of the area of LL to that of ML (LL/ML) in CP cases and controls. The degree to which the ET lumen appeared straight or C-shaped in cross section was also measured. Thirty temporal bones with the entire ET--10 CP cases and 20 controls--were studied. The ratio of the areas of the ET cartilage was significantly smaller (t = 2.903, p less than .01) and the curvature of the ET lumen was significantly less (t = 2.080, p less than .05; chi 2 = 3.936, p less than .05) in CP cases than in controls. In addition, in all 30 CP cases and controls, the ratio of the areas of cartilage was significantly less in specimens with straight ET lumens than in those with C-shaped lumens (t = 2.713, p less than .02). The results appear to show that the ET cartilages and lumens are anomalous in CP cases. These anomalies are considered to be important factors in active ventilatory dysfunction of the ET.