Internal auditory canal duplication with facial and cochlear nerve dysfunction: A case report

Internal auditory canal duplication is a rare anomaly of the temporal bone. The condition is diagnosed on performing High-Resolution Computed Tomography of the temporal bone and magnetic resonance imaging for sensorineural hearing loss. A bony septum divides the internal auditory canal into dual compartments. Duplication may be either unilateral or bilateral and vestibulocochlear nerve may be aplastic or hypoplastic. Rarely, patient may present with facial nerve palsy. A 26-year-old female presented with right grade IV lower motor neuron facial nerve palsy for 12 years and right-sided hearing loss for 9 years. Pure tone audiogram revealed 45 dB of moderate degree sensorineural hearing loss on the right ear. On High-Resolution Computed Tomography of the temporal bone, an incomplete bony septum was visualized in the right internal auditory canal, dividing it into two compartments. Internal auditory canal on the left side was normal. Other inner and middle ear structures were normal. On magnetic resonance imaging, both the vestibulocochlear and facial nerves were well visualized with normal calibers.