Chiari II Malformation
CM-II, Arnold-Chiari malformation, congenital abnormalities, neural tube defects
Congenital, Hereditary, and Neonatal Diseases and Abnormalities | Nervous System Diseases
Chiari II malformation (CM-II), commonly known as Arnold-Chiari malformation, is a relatively common congenital malformation characterized by beaked midbrain, downward displacement of the tonsils, and cerebellar vermis, and spinal myelomeningocele. This malformation is frequently misunderstood as a more severe version of Chiari I malformation (CM-I). However, these are two distinct diseases with overlapping imaging findings. Interestingly, most patients who have myelomeningocele also have CM-II and are typically associated with hydrocephalus. There are many additional findings associated with CM-II, including cerebellar dysplasia, elongation of the lower pons and the medulla, and the fourth ventricle displacing into the cervical canal. The diagnosis is primarily based on the patient’s neuroanatomy on MRI. The treatment is typically centered upon surgical interventions. Prognosis is dependent on the extent of the malformations and the symptoms of the patient.
Publisher or Conference
Kuhn J, Emmady PD. Chiari II Malformation. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2020.