CONGENITAL DEAFNESS 403 microtia and meatal stenosis or atresia with malformation of the middle and/or inner ears. iv. Van der Hoeve^s syndrome in which there is osteogenesis imperfecta, blue sclerotics and conductive deafness. Fig. 213. Congenital deaf-mutism due to faulty development of membranous cochlea. Hori- zontal section through upper part of left basal coil. 1, Dilated cochlear duct; 2, Split in bony capsule (artefact); 3, Adhesion between membrana tectoria and stria vascularis; 4, Rudimentary Corti's organ. Fig. 215. Same case as Figs. 213, 214, 216. Vertical section through upper part of right basal coil. 1, Reissner's membrane depressed and attached to malformed Corti's organ; 2, Position of stria vascularis, which is absent; 3, Position of spiral prominence; 4, Basilar membrane; 5, Membrana tectoria tucked into spiral sulcus. It will be seen that there is a complete malformation of the epithelium lining the cochlear canal. Fig. 214. Same case as Figs. 213, 215, 216. Horizontal section through lower part of left middle coil. 1, Dilated cochlear duct; 2. Membrana tectoria lying on the apex of the limb us; 3, Rudimentary Corti's organ. The spiral ligament shows oedematous degeneration. The stria vascularia appears to be well formed. Fig. 216. Same case as Figs. 213, 214, 215. Vertical section through lower part of right middle coil. 1, Membrana tectoria, which lies between the origin of Reissner's membrane and the limbus; 2, Rudimentary Corti's organ; 3, Great proliferation of stria vascularis, which occupies the outer third of the narrow cochlear canal. v. Dyostosis cleidocranialis which consists of absence of the clavicles and abnormalities of the skull, spine and pelvis. There may be stenosis of the bony meatus with hearing loss. vi. Hunter's syndrome is a recessive type of gargoylism associated with progressive deafness.