Temporal bone and brain stem histopathological findings in Cornelia de Lange syndrome.

The temporal bone and the brain stem of an infant with Cornelia de Lange syndrome, aged 9 months, were studied histopathologically. Abnormalities in the inner ear included short cochlea, dilated vestibule, and mesenchyme-filled perilymphatic spaces of the vestibule and semicircular canals. The inner and outer hair cells were normal. Many spiral ganglion cells, which normally would be located in the canal of Rosenthal, were seen in the internal auditory meatus. Some of the vestibular ganglion cells intruded into the facial nerve. The facial nerve formed a loose curve and the geniculum was difficult to recognize. The middle ear was filled with mesenchyme, and there was marked dehiscence of the facial canal. The brain stem, particularly the pons, was smaller than normal, while the fourth ventricle was dilated. The microscopic observation of the pons revealed weak staining with Luxol Fast Blue and decreased number of oligodendroglia. These findings suggested the malformation of the myelin of transverse fibers.