The Center for Cerebellar Malformations
Cerebellar Vermis Hypoplasia
General Information
Cerebellar
vermis hypoplasia occurs with a wide variety of genetic disorders, including
nonprogressive autosomal recessive disorders (see table below) as well as in sporadic
cases.
|
Syndromes with cerebellar vermis hypoplasia |
|
Joubert
|
Absent cerebellar
vermis, molar tooth abnormality, ataxia, oculomotor apraxia, mental
retardation |
Meckel
|
Polycystic kidney
disease, encephalocele, hepatic ductal dysplasia, polydactyly |
Vici
|
Agenesis of the corpus
callosum, cutaneous hypopigmentation, cataracts, cleft lip, combined
immunodeficiency |
Bardet-Biedl
|
mental retardation,
pigmentary retinopathy, polydactyly, obesity, hypogenitalism, diabetes |
|
|
Congenital blindness,
autosomal recessive Leber congenital amaurosis |
Smith-Magenis |
brachycephaly, midface
hypoplasia, prognathism, hoarse voice, and speech delay, hearing loss,
psychomotor and growth retardation, and behavioral problems, Chr. 17
deletions |
Cogan
|
Oculomotor apraxia,
ataxia |
|
Congenital
disorders of glycosylation |
pontocerebellar
hypoplasia, hypotonia, dysmorphic facies, inverted nipples, lipodystrophy,
hepatic fibrosis |
Cerebellar
Vermis Hypoplasia & The Molar Tooth Malformation
Cerebellar vermis
hypoplasia associated with the molar tooth malformation of the brainstem
including Joubert syndrome
Cerebellar vermis hypoplasia may be
encountered in several conditions, but additional brain malformations or
systemic malformations may help differentiate these various conditions. Among the most helpful sign is the
molar tooth malformation of the midbrain-hindbrain junction. The molar tooth malformation is a
radiographic hallmark consisting of three key components that together result
in the midbrain-hindbrain junction taking the appearance of a molar-tooth on
axial brain MRI (Maria et al., 1999a). These features include: 1. cerebellar vermis hypoplasia/
aphasia/ dysplasia that produces enlargement of the 4th ventricle.
2. a deep interpeduncular fossa. 3. upwardly-rotated and malformed superior
cerebellar peduncles.
Radiographic appearance of Joubert
syndrome. (A) Diminished volume of cerebellar vermis (short arrows) and
horizontally-oriented superior cerebellar peduncle (long arrow). (B) Hypoplasia of the cerebellar vermis
(arrow shows residual tissue). The
midbrain-hindbrain junction takes the shape of a molar-tooth (circle) giving rise
to the terminology molar-tooth malformation.