Temporal bone histopathological findings in trisomy 13 syndrome.

This study reports the histopathological findings of 14 temporal bones from infants with trisomy 13 syndrome. The most primitive anomalies in the structures of the inner and middle ears in the present series are those of the semicircular canals, particularly of the horizontal canals: flattened horizontal canal cristae, absence or opening of the utricular endolymphatic valve, small facial nerve, and obtuse angle of the geniculate area of the facial nerve. Each ear demonstrated more than one of those anomalies. The anomalies present features similar to those found in the structures of the normal six to ten-week fetus. Many other mild anomalies observed appear to demonstrate features similar to those seen in the same structures in later fetal life. Reviewing these findings, most of the anomalies that were found in the inner and middle ears appear to be the result of poor development of the structures for reasons which are now unclear. In addition, middle ear infection was found in all cases.