Arnold-Chiari (Chiari II) Malformation Arnold-Chiari malformation = herniation of cerebellar tissue and the medulla downwards through the foramen magnum into the upper cervical spinal canal causing compression of the upper segments of the spinal cord. Two distinct ages are identified with Chiari II malformations: infants and adolescents ==> Infants often present with Respiratory Distress, Inspiratory Stridor, and/or apnea. -- These herald impeding brainstem compromise. ==> Older children more often present with syncopal episodes or muscle weakness. Chiari Malformation needs to be considered in all children with myelomeningocele, Down s Syndrome, Hydrocephalus, Sacral Dimple, or other neurologic abnormalities presenting with respiratory distress. ==> Myelomeningocele is associated with Chiari Malformation and hydrocephalus in 80-90% of cases. Recognition is critical, since movement of the head and neck can lead to further compression of the CNS structures. Rath GP, Bithal PK, Chaturvedi A: Atypical Presentations in Chiari II Malformation. Pediatric Neurosurgery 2006;42:379-382
