Unilateral Atresia of the Internal Auditory Meatus, confirmed by Radiography

Abstract

Labyrinthine anomalies constitute an unexplored field in the study of deafness. Only a very few pathological investigations of such cases have been published. These anomalies may consist in a total absence of the labyrinth, but this appears to be extremely rare, only two definite cases being on record (Saissy, 1819; Michel, 1863). Both were bilateral. A less common anomaly is a partial, visible defect of the labyrinthine skeleton, called Mondini's defect, in which the modiolus and septa of the superior cochlear coil are absent. This defect has been described in detail by Guffarth (1936) and Albrecht (1940) who considered it to be the pathological basis of dominant inherited deafness. It is represented by several examples in the “Ibsen-Macke-prang collection of temporal bones from deafmutes” (described by Mygind in 1893 and still kept at the University Ear Clinic, Rigshospitalet, Copenhagen). Special labyrinthine anomalies have recently been reported by Everberg (1960, 1961), who demonstrated, by polytomography of the inner ear in certain individuals with unilateral total deafness, two types of inner-ear abnormality: one—called Type I—was characterised by total or partial obliteration of the semicircular canal system, while in the other—called Type II—the vestibule and lateral semicircular canal made up one large cavity; the cochlea was absent and the superior semicircular canal partially obliterated.