[The clinical and imaging presentations of the pontine tegmental cap dysplasia]

Objective: To summarize the clinical and imaging presentations of the pontine tegmental cap dysplasia (PTCD). Methods: The clinical, high resolution CT(HRCT) and MRI materials of 4 patients with PTCD between August 2007 to December 2024 were retrospectively analyzed. Among these, there were 2 males and 2 females, their ages ranged from 10 months to 16 years. Results: Of 4 PTCD patients, severe or profound severe hearing loss (n=8 ears), developmental delay, hypotonia and severe facioplegia (n=3 cases) were found. On HRCT, all of 4 cases were associated with temporal anomalies [including a narrow bony cochlear nerve canal (n=8 ears), duplicated (each n=4 ears) or narrow (n=1 ear) internal auditory canal, enlarged vestibular aqueduct (n=2 ears), enlarged vestibules and dysplastic lateral semicircular canals (n=3 ears), ossicular deformation(n=2 ears). The stenosis of the labyrinthine segments of the facial nerve canal (n=3 ears) and facial nerve canal ectopia(n=6 ears)], atrial or ventricular septal defect (each n=1 case), thoracic or lumbar vertebral anomalies and ribs fusion (n=3 cases). On the brain MRI, the variable flattening of the ventral pons and dysmorphism of the dorsal upper pons cap-like bulging and protruding in the fourth ventricle were shown in all cases, the vermian and cerebellar peduncles hypoplasia gave rise to a molar tooth appearance. The dysplastic (n=3 ears), aplastic(n=5 ears) cochlear nerves and dysplastic facial nerves (n=3 ears) were found. Conclusion: The PTCD patients usually present severe hearing loss, developmental delay, hypotonia, and facioplegia. The flattening of the ventral pons and the dorsal upper pons cap-like bulging usually with duplicated internal auditory canal and severe facial and auditory nerves dysplasia are its imaging features.