Chiari malformation type II

Chiari malformation type II, also known as Arnold-Chiari malformation type II, is a rare congenital condition that affects the central nervous system. In this condition, parts of the brain such as the cerebellum, pons, medulla, and fourth ventricle are displaced downward through the foramen magnum into the spinal canal. This downward shift is often seen together with a condition called myelomeningocele, a neural tube defect that is present at birth. In addition to the downward displacement of the brain structures, people with this condition may have other central nervous system abnormalities. These include differences in the development of the corpus callosum, a smaller than usual fourth ventricle, potential issues with the falx and tentorium, and sometimes obstructive hydrocephalus or polygyria. The full reason why these changes occur is not fully explained in the provided sources, and the condition can vary from person to person.

Symptoms may include low muscle tone (hypotonia), breathing interruptions such as apnea with cyanosis (bluish skin), difficulty swallowing (dysphagia), abnormal body posturing (opisthotonus), rapid or irregular eye movements (nystagmus), muscle stiffness or spasticity, problems with balance (ataxia), and headaches at the back of the head (occipital headache). Not every person experiences all of these symptoms, and the severity can vary.

Chiari malformation type II is a congenital condition, which means it is present at birth. It is typically associated with myelomeningocele, a neural tube defect where the spinal cord and its coverings do not form properly. The exact mechanisms leading to the downward displacement of brain structures are not fully detailed in the provided sources.

Information about treatment is currently limited for this condition.

Information about prognosis is currently limited for this condition.

Information about current research is currently limited for this condition.