Unilateral enlargement of the internal auditory canal: a developmental variant.

Marked asymmetry of the petrous pyramids as seen on plain skull roentgenograms is reported in 3 patients with no clinical findings related to the region of the cerebellopontine angle. Polytomograms of the enlarged internal auditory canal in these patients demonstrated in intact crista falciformis and absence of cortical destruction. These roentgenographic features suggest that the asymmetry represents a developmental variant. When contrast enchanced computed tomography fails to demonstrate an abnormality in asymptomatic patients with an enlarged internal auditory canal, it is unnecessary to proceed with further neuroradiological study.