World Arnold-Chiari Brain Malformation (ACM) Association (WACMA)
31 Newtown Woods Road, Newtown Square
Philadelphia, PA 19073
UNITED STATES OF AMERICA
Free, not-for-profit support group for patients/parents and source of
updated information for Doctors (mainly Neurologists and Neurosurgeons)
and other Medical Professionals (RNs, PTs, GPs, etc)
Ms. Darlene Long-Thompson, RN, MHSc.
Mr. Bernard H. Meyer
Free membership and free support/information E-Mailing Lists.
Information available English, Spanish.
Chiari Malformations and Syringomyelia
The CSIND, in collaboration with Dr. Thomas Milhorat and colleagues of
SUNY-Brooklyn, 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 followi ng 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.
* 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
* 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
CSIND. CSIND's toll free telephone number (800)283-4316.
Participation in the study involves answering questions about
family and medical history, allowing CSIND rese archers to review
medical records to confirm the diagnosis of Chiari malformation, and
in some instances providing a blood sample to the CSIND.
* 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 Brain Malformation Association (WACMA)
Free, not-for-profit support group for Arnold-Chiari Malformation and
Syringomyelia patients/parents and source of updated information for
Doctors (mainly Neurologists and Neurosurgeons) and other Medical
Professionals (RNs, PTs, GPs, etc.) - international network Founded
31 Newtown Woods Road, Newtown Square
Philadelphia, PA 19073
Contact person: Mr. Bernard Meyer, Philadelphia, (610)353-4737
Arnold-Chiari Family Network
International network founded in 1985. Informal network of families
affected by symptomatic Arnold-Chiari malformation with spina bifida.
Provides phone support, newsletter & networking of multiplex families.
c/o Maureen & Kevin Walsh
67 Spring Street
Weymouth, MA 02188
Canadian Syringomyelia Network
69 Penny Crescent Markham,
National Organization for Rare Disorders (NORD)
P.O. Box 8923
New Farfield, Connecticut 06812-8923
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 the Study of Inherited and Neurological Disorders (CSIND)
Duke University Medical Center
P.O. Box 2900
Durham, N.C. 27710
(800) 283-4316 toll free
Outside the United States please call collect (919) 684-6515
1. Introduction: Arnold-Chiari Malformations (ACM) and Syringomyelia (SM)
Current nomenclature recognizes three different types of Chiari Malformations
consisting of various degrees of herniation of the cerebellar tonsils and
medulla below the foramen magnum. Type I malformation is characterized
primarily by caudal displacement of the cerebellar tonsils below the
foramen magnum with absent of minimal descent of the medulla. The fourth
ventricle is always in a normal position. Syringomyelia (or Hydromyelia)
often accompanies Chiari-1 Malformations: it has been noted in 30-75% of
Type II malformation is a more extensive anomaly with elongation and caudal
displacement of the cerebellar tonsils, inferior vermis, fourth ventricle,
choroid plexus and medulla. These structures descend into the cervical
spinal canal, often extending to the level of the fourth or fifth cervical
vertebra. It is almost invariably a component of myelodysplasia and the
associated hydrocephalus. Type III (ACM-3) malformation is a form of high
cervical meningocele with displacement of the cerebellum and lower brainstem
into the dysplastic sac. Over the years, the terms syringomyelia and
hydromyelia have been applied to a variety of diseases that have as the end
result an intramedullary cyst associated with progressive neurological
2. Major Neurosurgery
There is general agreement that patients presenting with moderate or severe
neurological deficits fare much worse suggesting that early intervention may
improve prognosis. Neonatal Chiari II malformations continue to have
significant morbidity and mortality. Most series describe between 23 and 50%
long term mortality. Tracheostomy (creation of a new airway outlet through
the neck) and gastrostomy (creation of a new food inlet through the
abdominal wall) or nasogastric (a tube through the nose, down the throat to
the stomach) feedings are often required for months after decompression.
Intervention prior to the onset of bilaterall vocal cord paralysis is
associated with early improvement and eventual complete recovery.
Operative mortality for Chiari 1, Chiari II in older children and
hydromyelia ranges from 0 to 15% with recent series reporting near zero
mortality. There were no deaths among 70 consecutive patients treated by
the author over the past 9 years. The predominant cause of death in the
literature was respiratory failure followed by postoperative hematoma,
acute hydrocephalus and medullary (see Anatomy - S4.2) infarction from
damage to the posterior inferior cerebellar artery (P.I.C.A.). Morbidity
includes aseptic meningitis, bradycardia, and respiratory dysfunction with
apnea. When myelotomy has been performed, proprioceptive loss or
dysesthesias may rarely occur. Whether or not morbidity is increased with
more extensive procedures remains unclear.
Note: paragraphs (c)Rick Abbott, M.D. Pediatric Neurosurgeon -
"Your child and Neurosurgery: Arnold-Chiari Malformations", 1996,
practice: New York Beth Israel Medical Center, http://www.bethisraelny.org
Please visit (free, not-for-profit organizations...):
Thank you for your interest.
John A. MacDonald, Ph.D.
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