Infratentorial Magnetic Resonance Imaging Evaluation of Joubert Syndrome

Abstract

Introduction: Joubert syndrome is rare autosomal recessive/X-linked disorder involving the posterior fossa structures. It is often missed clinically and radiologically. However, vermian hypoplasia and ‘molar tooth’ sign on axial Magnetic Resonance Imaging (MRI) are key to the diagnosis of Joubert syndrome. Aim: To identify and characterize the classical and associated brain, brainstem and cerebellar imaging findings in the patients of Joubert syndrome. Materials and Methods: Clinical details and MRI details of 7 Joubert syndrome patients were collected from hospital medical record department and Picture Archiving and Communicating System (PACS). Existing images were evaluated retrospectively by two qualified radiologists. Results: Vermian hypoplasia was seen in 85.7% of patients. Asymmetric thickening of bilateral superior cerebellar peduncles measuring more than 2 mm was seen in all the patients. Enlargement with distortion of the fourth ventricle with rounded roof and widening of foramina Magendie were seen in all patients. Conclusion: Identification of hallmark findings-classic molar tooth sign and other posterior fossa abnormalities on MR imaging along with the clinical features can help to establish the diagnosis and to plan genetic counselling and prenatal screening for future pregnancies.

Keywords

• bat-wing appearance
• buttock sign
• molar tooth sign
• posterior fossa malformation
• vermian hypoplasia