COCHLEAR DYSPLASIA AND MENINGITIS

Congenital dysplasias of the labyrinth of the inner ear are associated with varying degrees of hearing loss. There is a risk of a fistulous communication between the subarachnoid space and the middle ear cavity in some cases that present either as cerebrospinal fluid otorhinorrhe a or as recurrent attacks of meningitis. The types of deformity where such a fistula is likely have not been clearly defined. The authors co rrelated the hearing state with the imaging assessment in 20 patients with congenital malformation of the labyrinth and, in particular, the cochlea. In addition the postmortem histologic findings from one patie nt with severe cochlear dysplasia who died from otogenic meningitis ar e described. The key to the assessment is the basal turn of the cochle a. If the basal turn is present and of normal caliber then some hearin g is possible and there is no risk of a major fistula. However, if the basal turn is wider than normal or replaced by an undeveloped sac the n there is anacusis and very real risk of fistula. In such cases the d eformed labyrinth needs to be packed with fibrofatty tissues after jus t one attack of meningitis.