Pontine tegmental cap dysplasia with a duplicated internal auditory canal.

Pontine tegmental cap dysplasia (PTCD) is a rare neurological syndrome that results in a hypoplastic ventral pons, tegmental cap at the dorsal pons, and cranial nerve dysfunction. The most common symptoms are hearing loss and speech problems. We present a case of a 9-month-old male who presented with developmental delay and hypotonia. Magnetic resonance imaging revealed ectopic dorsal transverse pontine fibers and a cap-like protrusion of the dorsal pons. Diffusion tensor imaging showed that the ventral pontine fibers were absent. The cause of PTCD is undiscovered, but proposed hypotheses include dysfunction in axonal guidance, neuronal migration, and ciliary protein function. PTCD is a rare neurological disorder, but the diagnosis can be suggested with MRI using diffusion tensor imaging as an aid.