Learning objectives
The posterior fossa malformations are a widely diverse group of disorders with significant overlap in many of the findings.The constellation of episodic hyperpnoea, developmental delay, and cerebellar vermian dysgenesis with ataxia was initially described by Joubert et al in 1969.
Joubert syndrome (JS) is a rare, autosomal-recessive condition. Early recognition isimportant for management and counseling. Magnetic resonance imaging (MRI) can help indiagnosis. Therefore, we sought to evaluate clinical presentation and MRI findings in Joubertsyndrome and related disorders.
Background
A retrospective review of genetically proven cases of Joubert syndromes and relateddisorders were reviewed for their clinical presentation, demographic information, andmagnetic resonance imaging findings in a period of the last 10 years. Two radiologistsdocumented magnetic resonance imaging (MRI) findings. The presence of hypoplasia of thecerebellar vermis with hypoplasia of the superior cerebellar peduncle resembling the “MolarTooth Sign” in the mid-brain was documented [Fig.1].
Findings and procedure details
Out of 12 genetically proven JS cases, most were females (9/12), and nearly all presentedwith hypotonia, ataxia, developmental delay, intellectual impairment, and speech disorders.5/12 children presented at age of 1 or below. The molar tooth sign was seen in 10/12 cases [Table 1].Most of the cases were found associated with consanguineous marriage
Conclusion
The molar tooth sign is a frequent and reliable sign of JS and related disorders.Genes related to defective cilia result in malfunctioning in the retina, renal tubule, andneural cell migration thus producing heterogeneous syndrome complexes known as“ciliopathies.” Other ciliopathies like Senior-Loken syndrome, Bardet Biedl syndrome, andisolated nephronophthisis must be considered as the differential diagnosis of JS.The main imaging findings are the partial or complete absence of the cerebellar vermis,hypoplastic cerebellar peduncles (giving MTS), and (bat-wing appearance) fourth ventriculardeformity.
Traditionally, all patients with the molar tooth...
Personal information and conflict of interest
A. Al Orf :
Nothing to disclose
K. B. Waheed:
Consultant: King Fahad Military Medical Complex
M. A. Albassam:
Nothing to disclose
A. A. Alshehri:
Nothing to disclose
References
1.Joubert M, Eisenring JJ, Robb JP, Andermann F. Familial agenesis of the cerebellar vermis. A syndrome of episodic hyperpnea, abnormal eye movements, ataxia, and retardation.Neurology. 1969;19: 813–825.
2. Radha Rama Devi A, Naushad SM, Lingappa L. Clinical and Molecular Diagnosis of Joubert Syndrome and Related Disorders. Pediatr Neurol. 2020 May;106:43-49. doi: 10.1016/j.pediatrneurol.2020.01.012. Epub 2020 Feb 4. PMID: 32139166.
3. Gana S, Serpieri V, Valente EM. Genotype-phenotype correlates in Joubert syndrome: A review. Am J Med Genet C Semin Med Genet. 2022 Mar;190(1):72-88. doi: 10.1002/ajmg.c.31963. Epub...