World Arnold Chiari Malformation Association
Chiari and Syringomyelia Research



   The Center for Human Genetics, in collaboration with Dr. Thomas
   Milhorat and colleagues, the American Syringomyelia
   Alliance Project, and the Canadian Syringomyelia Network is
   investigating the hereditary basis of Chiari type I malformations with
   or without syringomyelia.

What are Chiari malformations?
   Chiari malformations occur in the region where the brain and spinal
   cord join. The lowerportions of the brain (cerebellar and/or
   brainstem) are located lower than normal, penetrating out of the skull
   or protruding into the spinal canal.
   Chiari malformations were first described in the 1890's by Professor
   Chiari, a German pathologist. He assigned a grade to the malformations
   beginning with Type I, the mildest form, classification today. Chiari
   malformations are also known by the following medical terms:
   herniation of the cerebellar tonsils, cerebellar ectopia, hindbrain
   herniation, and Arnold-Chiari malformations, with Arnold-Chiari
   malformations being specific to type II malformations. Scientists and
   physicians further define Chiari malformations by the exact millimeter
   of brain stem that extends into the neck.
   Chiari type I malformations are a result of the smallest degree of
   herniation and are not associated with spina bifida. Chiari type II
   malformations are almost exclusively associated with a type of spina
   bifida known as a myelomeningocele, an opening of the spine and spinal
   cord on the lower back. Chiari type III and IV malformations are very

What other disorders can occur with Chiari malformations?
   Chiari malformations can occur with other conditions. Some are:
     * hydrocephalus (excessive fluid in the brain)
     * spina bifida (opening of the spine usually associated with an
       abnormality of the spinal cord)
     * syringomyelia (excessive fluid in the spinal cord, leading to a
       cavity detectable by MRI).
     * other conditions, including some inherited conditions like
       achondroplasia (a type of dwarfism), Hajdu-Cheney syndrome,
       Albright hereditary osteodystrophy (pseudohypoparathyroidism), or
       other rarer syndromes.
   Many individuals with Chiari malformations do not have any other
   associated medical problems.

How common are Chiari malformations?
   There are no data describing the incidence of Chiari malformations.
   However, malformations of the cervico-medullary junction, the
   connection between the brain and spine, are present in approximately 1
   percent of live newborns. The most common cervico-medullary junction
   malformations are Chiari malformations.

What are the symptoms of a Chiari malformation?
       Some patients with Chiari malformations are without symptoms. When
       symptoms are present, headache and neck pain are the most common

       The affected regions of the brain are the lower brainstem and
       cerebellum. The lower brainstem controls breathing, swallowing,
       balance, the vocal cords, eye movements, and sensation and
       movement of the arms and legs. The cerebellum's most important
       function is to coordinate body movements. Symptoms of a Chiari
       malformation are often vague and many times diagnosis of a Chiari
       malformation is delayed.

       Some individuals with Chiari malformations report vertigo
       (dizziness), headaches caused by coughing, weakness in their arms,
       a burning-like pain in the arms, severe curvature of the spine and
       other symptoms.

       The severity of symptoms is often associated with the degree of
       pressure on this portion of the brain. Therefore an individual
       with a "small Chiari malformation" may have very mild symptoms or
       no symptoms at all. Some individuals with Chiari malformation
       never develop symptoms.

What causes Chiari malformations?
   Scientists do not know the cause of Chiari malformations. Still, there
   are several hypotheses. One theory suggests that the base of the skull
   is too small in some individuals and this forces the cerebellar region
   lower than it should be. Another theory suggests that the growth of
   the cerebellar region is thrown off and overgrowth occurs resulting in
   the cerebellar region of the brain being compressed lower than it
   should be. Research studies are ongoing to learn how Chiari
   malformations occur.

How is syringomyelia associated with Chiari malformations?
   Syringomyelia (sear-IN-go-my-EEL-ya) is a disorder where abnormal
   collection of fluid occurs the spine. This collection of fluid,
   composed of cerebral spinal fluid (CSF), is referred to as a "syrinx"
   or a "cyst." Syringomyelia can be occur as a res ult of a car accident
   or other trauma. Syringomyelia can also occur with Chiari
   malformations or spinal tumors. The symptoms and signs of this
   disorder are often vague and may include weakness, fatigue, stiffness,
   or loss of ability to feel hot or cold.
   Syringomyelia can be diagnosed with a magnetic resonance imaging (MRI)

Are Chiari malformations inherited?
   There are several families reported in medical literature in which
   more than one family member has a Chiari malformation. However, no
   research study has ever been done to prove or disprove whether Chiari
   malformations are inherited. If more than one person in your family
   has a Chiari malformation or a spinal cord problem, please contact
   Medical Genetics's toll free telephone number (800) 283-4316.

   Participation in the study involves answering questions about
   family and medical history, allowing Medical Genetics researchers to
   review medical records to confirm the diagnosis of Chiari
   malformation, and in some instances PROVIDING A BLOOD SAMPLE to the

Resources for Families

   - American Syringomyelia Alliance Project (ASAP)
      National network founded in 1988. Offers support, networking &
   information for individuals with syringomyelia.
   P.O. Box 1586
   Longview, TX 75606-1586
   tel (903) 236-7079
   fax (903) 757-7456.

   - World Arnold-Chiari Malformation Association (WACMA)
   31 Newtown Woods Road,
   Newtown Square
   Philadelphia, PA 19073 

   - Canadian Syringomyelia Network
   69 Penny Crescent Markham,
   Ontario L3P5X7
   (905) 471-8278

   - National Organization for Rare Disorders (NORD)
    P.O. Box 8923
   New Farfield, Connecticut 06812-8923
   (203) 746-6518
   (800) 999-6673

   - National Institute of Health NIH-NINDS
   Federal Bldg, Room 814
   7550 Wisconsin Avenue
   Bethesda, MD 20892
   Ph: (301) 496-5821
   Fax: (301) 402-0302

   - Center for Human Genetics
   Duke University Medical Center
   P.O. Box 2900
   Durham, N.C. 27710

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