Chiari malformation

Older African American woman recovering from Chiari Malformation syndrome.

​Chiari malformation (CM) is a condition where a person’s brain sits lower than normal at the base of the skull. Normally, the entire brain sits completely in the skull. With this condition, the lower part of the brain (cerebellum) hangs down through an opening at the bottom of the skull and bulges into the top of the spine. This puts pressure on parts of the brain and spinal cord, and can cause mild to severe symptoms. In most cases, Chiari malformation is congenital (present at birth). It often worsens with time and causes first symptoms for patients in their 20s to 30s.

Types of Chiari malformation

CM is caused by structural defects in the brain and spinal cord that occur during fetal development. There are three types of Chiari malformation:

Type I (CM-I)—is the most common type. Part of the cerebellum (lowest part of the brain) extends through the bottom of the skull. It is most often present at birth and often not found until a child is a teen or young adult. In rare cases, CM-I may also develop later in life. This is called acquired or secondary CM. It may happen with a loss of spinal fluid due to an injury, contact with harmful substances or an infection. 

Type II (CM-II or Arnold-Chiari malformation)—is when part of the lower brain and the brainstem extend through the bottom of the skull. This most often happens in babies born with spinal myelomeningoceles, or spina bifida. Myelomeningocele is when a part of the spinal cord and spine develop outside the body. A common problem with Type II CM is too much fluid on the brain or hydrocephalus. The excess fluid puts pressure in the brain to increase and the skull bones to expand beyond normal size.

Chiari malformation symptoms

Common symptoms are headaches or pain in the back of the head or neck, especially after sudden coughing, sneezing or straining. Other symptoms may include:

  • Abnormal reflexes

  • Balance problems

  • Difficulties with hand coordination and fine motor skills

  • Hoarseness or trouble speaking

  • Muscle weakness or abnormal movements

  • Noisy breathing

  • Rapid eye movements (nystagmus) 

  • Sleep apnea (interrupted breathing during sleep)

  • Scoliosis (abnormal shape of the spine)

  • Tinnitus (ringing in the ears)

  • Trouble swallowing

  • Vomiting

There may be no symptoms for some persons and symptoms may change over time.

Why choose The Christ Hospital Health Network

Children and adults get advanced diagnosis and treatment for Chiari malformation from our team of experienced neurologists, neurosurgeons, neurosurgery nurses and other healthcare professionals.

Chiari malformation patients also have access to support services like physical therapy and interventional pain management.

Learn more about Chiari malformation care at The Christ Hospital Health Network.