Joubert Boltshauser Syndrome (Congenital Vermian Hypoplasia)
In this anomaly, there is inherited hypoplasia or aplasia of cerebellar vermis (Figure ). Fourth ventricle is enlarged and has a typical “bat-wing” or “umbrella” appearance. Isthmus (area of pontomesencephalic junction) is narrow. Midbrain has the typical “molar tooth” appearance 10, 11, 12. Associated abnormalities include holoprosencephaly, frontonasal dysplasia, pituitary hypoplasia. Abnormal signal may be noted in periventricular white matter. Renal cysts, hepatic fibrosis and cardiac anomalies may be associated, for which abdominal ultrasound may be advisable.
Figure : Joubert syndrome. A, Axial T1 weighted MR image. Fourth ventricle is enlarged and has a typical “umbrella” appearance (Arrow). B, Note the typical “molar tooth” appearance of midbrain (Black arrows), small vermis (Arrowhead) and narrow isthmus (White long arrow) on this T1 weighted image. C, Sagittal T1 image. Fourth ventricle is enlarged with vermian hypoplasia and abnormal folial pattern. Note that isthmus is abnormally narrow (Arrow).
In this anomaly, there is inherited hypoplasia or aplasia of cerebellar vermis (Figure ). Fourth ventricle is enlarged and has a typical “bat-wing” or “umbrella” appearance. Isthmus (area of pontomesencephalic junction) is narrow. Midbrain has the typical “molar tooth” appearance 10, 11, 12. Associated abnormalities include holoprosencephaly, frontonasal dysplasia, pituitary hypoplasia. Abnormal signal may be noted in periventricular white matter. Renal cysts, hepatic fibrosis and cardiac anomalies may be associated, for which abdominal ultrasound may be advisable.
Figure : Joubert syndrome. A, Axial T1 weighted MR image. Fourth ventricle is enlarged and has a typical “umbrella” appearance (Arrow). B, Note the typical “molar tooth” appearance of midbrain (Black arrows), small vermis (Arrowhead) and narrow isthmus (White long arrow) on this T1 weighted image. C, Sagittal T1 image. Fourth ventricle is enlarged with vermian hypoplasia and abnormal folial pattern. Note that isthmus is abnormally narrow (Arrow).
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(C)Reference:The Internet Journal of Radiology™ ISSN: 1528-8404
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