Arnold-Chiari malformation- type 2




Chiari malformation type 2 (CM type II) is a type of Chiari malformation in which both the cerebellum and brain stem tissue extend into the foramen magnum (the hole at the skull base for passing of the spinal cord). This form is often accompanied by a type of spina bifida called myelomeningocele, and can also be accompanied by syringomyelia, hydrocephalus, or other abnormalities. In this malformation where the base of the brain enters into the upper spinal canal. The extent of the deformity is greater in type 2 than type 1 and hence the symptoms are more severe and are often associated with a myelomeningocele (opening of the spine and spinal cord). The term Arnold-Chiari malformation is technically specific to type II but may sometimes be used to describe other types of Chiari malformations.


Symptoms in infants;

  • Stridor (wheezing sound)
  • Difficulty swallowing (dysphagia)
  • Feeding difficulties
  • Hypotonia
  • Weak cry

Symptoms in children and/or adults;

  • Headache
  • Fatigue
  • Loss of vision
  • Tingling extremities
  • Nausea
  • Dysphagia
  • Dizziness
  • Muscle weakness
  • Ataxia

Adults and adolescents who previously had no symptoms may begin to have symptoms later in life.

Other symptoms include;

  • Hydrocephalus
  • Myelomeningocele
  • Respiratory complications


Chiari malformation type 2 typically occurs sporadically (in individuals with no history of the condition in the family). However, the exact cause of Chiari malformation type 2 is not known. Genes may play a role in predisposing an individual to the condition, but environmental factors (such as lack of proper vitamins or nutrients in the maternal diet during pregnancy) may also contribute to the condition. Because the cause is unclear, it is not currently possible to estimate what the recurrence risk for family members may be.

There have been reports in the medical literature of families in which more than one family member was affected with a Chiari malformation. However, a search of the available medical literature yields limited information specific to familial cases of Chiari malformation type 2. One article written by Lindenberg and Walker in 1971 describes the Arnold-Chiari malformation in 2 sisters; both also had hydrocephalus and meningomyelocele.


  • Magnetic resonance imaging (MRI)
  • Computerized tomography (CT) scan


  • Reducing pressure by surgery


  • NIH
  • Mayo Clinic