Clinical and Imaging Profile of Patients with Joubert Syndrome

Abstract

Objective: Joubert syndrome (JS) is a rare syndrome characterized by ataxia and the molar tooth sign (MTS) on imaging. The present study aims to explore the clinical and radiological features in a cohort of patients with JS.

Methods: This was a retrospective chart review of patients with JS evaluated by movement disorder specialists.

Results: Nine patients were included in the study. All patients had facial dysmorphism and ocular abnormalities, and 4 patients had dystonia. Ocular tilt reaction and alternate skew deviation (66%) were the most common ocular abnormalities. Horizontally aligned superior cerebellar peduncles were observed in all four patients with diffusion tensor imaging, with a lack of decussation in three. Exome sequencing performed in four patients revealed novel variants in the MKS1, CPLANE1, and PIBF1 genes.

Conclusion: Facial dysmorphism, ocular abnormalities and classical imaging findings were observed in all patients with JS. Apart from ataxia, dystonia and myoclonus are other movement disorders observed in JS.

Keywords: Ataxia; Facial dysmorphism; Joubert syndrome; Molar tooth sign; Movement disorders; Vermis hypoplasia.

Figure 1.

Facial dysmorphisms seen in Joubert syndrome. Broad nasal bridge (A), frontal bossing (C, D), trapezoid mouth (A, D), everted lower lip (C, D), dolichocephaly (C), elongated face (B, D), and head tilt (B, D). A: Patient 1. B: Patient 6. C, D: Patient 7.

Figure 2.

Magnetic resonance imaging findings in Joubert syndrome. (A) Molar tooth sign (thick arrow) and deep interpeduncular fossa (thin arrow). (B) Color coded fractional anisotropy map showing horizontally oriented superior cerebellar peduncles (thin arrow) and the absence of normal decussating horizontal fibers, (C) superior cerebellar (thin arrow) and vermian hypoplasia, (D) callosal atrophy (thin arrow), (E) frontal cerebral atrophy and (F) diffuse pachygyria. A-C: Patient 4. D: Patient 1. E: Patient 2. F: Patient 7.