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
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