Chiari Malformation

Chiari Malformations (CMs) are structural defects in the cerebellum, the part of the brain that controls balance. When the indented bony space at the lower rear of the skull is smaller than normal, the cerebellum and brain stem can be pushed downward. The resulting pressure on the cerebellum can block the flow of cerebro spinal fluid (the liquid that surrounds and protects the brain and spinal cord)


  • CMs are classified by the severity of the disorder and the parts of the brain that protrude into the spinal canal
  • Dizziness
  • Headache
  • Muscle weakness
  • Numbness
  • Other conditions sometimes associated with CM include hydrocephalus, syringomyelia (a fluid-filled cyst in the spinal cord), and spinal curvature
  • Partial or complete paralysis below the spinal opening
  • Problems with balance and coordination
  • Symptoms may change for some individuals depending on buildup of CNS and any resulting pressure on tissue and nerves
  • Type I, which may not cause symptoms and is often found by accident during an examination for another condition. (most common)
  • Type II (also called Arnold-Chiari malformation) is usually accompanied by a myelomeningocele-a form of spina bifida that occurs when the spinal canal and backbone do not close before birth, causing the spinal cord to protrude through an opening in the back
  • Type III is the most serious form of CM, and causes severe neurological defects
  • Vision problems




  • More than one surgery may be needed to treat the condition
  • Medications may ease certain symptoms, such as pain
  • Some CMs have no noticeable symptoms and do not interfere with the person’s activities of daily living
  • Surgery is the only treatment available to correct functional disturbances or halt the progression of damage to the central nervous system

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