An Unusual Case of Unilateral Cochlear Nerve Agenesis with Bilateral Lateral Semicircular Canals Aplasia

Imaging of the inner ear structures is becoming essential nowadays as the increasing number of cases of cochlear implants being performed globally. We report here a case of a 19-year-old boy who had congenital hearing loss and was being evaluated in our service for possible cochlear implantation. Audiometry showed profound mixed sensorineural hearing loss of the right side and mild to moderate conductive hearing loss in the left side. The magnetic resonance imaging revealed only two nerves in the narrowed right inner auditory canal: one in the anterior superior quadrant, identified as the facial nerve, and one on the posterior quadrants, representing the incomplete separation of the superior and inferior vestibular nerves which is an anatomical variant. Bilateral lateral semicircular canals were not visualized and there is dysplastic vestibules morphology. The diagnosis for the patient was right cochlear nerve agenesis with bilateral lateral semicircular canals aplasia.