Arnold Chiari malformation is characterized by all except
Ans. is 'a' i.e., Hypoplasia of cerebellar vermis Arnold-chiari malformation* Arnold-Chiari malformation consists of herniation of the cerebellum and fourth ventricle into the foramen magnum, flattening of the base of the skull, and spina bifida with meningomyelocele.* Chiari malformation is divided intoi) Type I: Produce symptoms during adolescence or adulthood is usually not associated with hydrocephalus. The deformity consists of displacement of cerebellar tonsils into the cervical canal,ii) Type II: It is characterized by progressive hydrocephalus with a myelomeningocele in newborns. There is a failure of pontine flexure during embryogenensis, which results in elongation of 4th ventricle; kinking of brainstem and breaking of quadrigeminal plate (tectum); along with displacement of inferior vermis, pons and medulla into cervical canal. This causes widening of cervical canal (syringomyelia),iii) Type III: Usually associated with occipital encephalocele and causes abundant neurological deficit,iv) Type IV: Characterised by lack of cerebeller development and usually not compatible with life.
Hypoplasia of cerebellar vermis
Herniation of cerebellum
Flattened base of skull
Adulthood syndrome not associated with hydrocephalus
Central Nervous System