Pontine tegmental cap dysplasia: the role of diffusion tensor imaging.

Pontine tegmental cap dysplasia (PTCD) is a rare hindbrain malformation syndrome. Recurrent aspiration pneumonia is a major cause of death during a first year of life. We report the case of month-old child with an inability to suck milk since birth and multiple convulsions. PTCD was identified using tractography and MRI. This case report describes the imaging findings, the role of diffusion tensor imaging in PTCD and its differentiating features from Joubert syndrome and related disorders (JSRDs). The constellation of imaging features in PTCD includes a midbrain appearance resembling a molar tooth, a flattened anterior pontine belly, hypoplastic middle cerebellar peduncles and dorsal pontine tegmental cap. 'Tegmental cap' is a transversely oriented abnormal bundle of fibres with absent superior cerebellar peduncle decussation. Accurate diagnosis with MRI and tractography and differentiating PTCD from JSRD would help the clinician for appropriate genetic counselling and prognosis.