NEURORADIOLOGY


 
Case 2 
Diagnosis please!

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Diagnosis
Joubert’s syndrome

Introduction
It is a rare developmental defect of the cerebellar vermis, with autosomal recessive inheritance. The phenotype is highly variable and may include episodic hyperpnea, abnormal eye movements, hypotonia, ataxia, developmental delay, and mental retardation.

A recent report suggests that the anomaly is genetically heterogeneous and that one locus maps to the telomeric region of chromosome 9q, close to the marker D9S158, with a multipoint LOD score of Z=+3.7

MRI Features
The recently described “molar tooth” sign on axial sections results from a combination of midbrain, vermian, and superior cerebellar peduncle abnormalities. Other findings include thinned optic tracts, abnormal embryonic vessels associated with the dysplastic folia of the cerebellar hemispheres, dilatation of the fourth ventricle with some appearing bat-wing shaped enlarged temporal horns in the absence of hydrocephalus, high-signal of the cerebral periventricular white matter, abnormal signal in the decussation of the superior cerebellar peduncles, elongation and stretching of the superior cerebellar peduncles, dysplasia of the vermis, and widening of the foramen of Magendie and the posterior cistern.

References

http://www.thefetus.net/sections/articles/Central_nervous_system/Joubert_syndrome_Jeanty.html

Dr. Ashok Raghavan, Manipal Hospital, Bangalore