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Chiari malformation type 1

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Not a rare disease Not a rare disease
Other Names:
Chiari type I malformation; Chiari malformation type I; Arnold Chiari malformation type I; Chiari type I malformation; Chiari malformation type I; Arnold Chiari malformation type I; Arnold-Chiari malformation type 1; Arnold-Chiari malformation type I See More
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This disease is grouped under:
Chiari malformation type 1 is a structural abnormality of the cerebellum, the part of the brain that controls balance, and the skull. The malformation occurs when the lower part of the cerebellum extends below the foramen magnum (the large hole at the base of the skull which allows passage of the spinal cord), without involving the brainstem. Normally, only the spinal cord passes through the foramen magnum. Type 1 is the most common type of Chiari malformation and may not cause any symptoms.[1] It is usually first noticed in adolescence or adulthood, often by accident during an examination for another condition. Symptoms, when present, may include headache, neck pain, unsteady gait, poor hand coordination, numbness and tingling of the hands and feet, dizziness, difficulty swallowing, and vision and speech problems.[1][2][3] Depending on the symptoms present and severity, some individuals may not require treatment while others may require pain medications or surgery.[1][4]
Last updated: 8/11/2017

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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HPO ID
100% of people have these symptoms
Arnold-Chiari type I malformation 0007099
80%-99% of people have these symptoms
Neck pain 0030833
Recurrent paroxysmal headache 0002331
Small posterior fossa 0040010
30%-79% of people have these symptoms
Abnormality of the clivus 0010558
Abnormality of the eleventh cranial nerve 0010825
Abnormality of the twelfth cranial nerve 0010826
Abnormality of the vestibulocochlear nerve 0009591
Anteriorly placed odontoid process 0004608
Areflexia of upper limbs 0012046
Cervical C2/C3 vertebral fusion 0004602
Cranial nerve compression 0001293
Cranial nerve paralysis 0006824
Distal peripheral sensory neuropathy 0007067
Dysesthesia 0012534
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty
[ more ] 		0002015
Gait ataxia
Inability to coordinate movements when walking
0002066
Increased intracranial pressure
Rise in pressure inside skull
0002516
Lower limb hyperreflexia
Overactive lower leg reflex
0002395
Myelopathy 0002196
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Progressive cerebellar ataxia 0002073
Scoliosis 0002650
Sensory impairment 0003474
Stiff neck
Neck stiffness
0025258
Syringomyelia
Fluid-filled cyst in spinal cord
0003396
Tinnitus
Ringing in ears
Ringing in the ears
[ more ] 		0000360
Vertigo
Dizzy spell
0002321
Vocal cord paralysis
Inability to move vocal cords
0001605
5%-29% of people have these symptoms
Abnormality of the musculature of the lower limbs 0001437
Adult onset sensorineural hearing impairment 0008615
Babinski sign 0003487
Basilar impression 0005758
Basilar invagination 0012366
Brain stem compression 0002512
Central sleep apnea 0010536
Diplopia
Double vision
0000651
Fatigable weakness of swallowing muscles 0030195
Photophobia
Extreme sensitivity of the eyes to light
Light hypersensitivity
[ more ] 		0000613
Urinary incontinence
Loss of bladder control
0000020
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance 0000006
Dysarthria
Difficulty articulating speech
0001260
Headache
Headaches
0002315
Hearing impairment
Deafness
Hearing defect
[ more ] 		0000365
Hyperacusis 0010780
Limb muscle weakness
Limb weakness
0003690
Lower limb spasticity 0002061
Paresthesia
Pins and needles feeling
Tingling
[ more ] 		0003401
Small flat posterior fossa 0005759
Unsteady gait
Unsteady walk
0002317
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Last updated: 7/1/2020
Primary or congenital Chiari malformations are caused by structural defects in the brain and spinal cord that occur during fetal development. The underlying cause of the structural defects are not completely understood, but may involve genetic mutations or lack of proper vitamins or nutrients in the maternal diet.[5]

Less frequently, Chiari malformation type 1 is acquired after birth. Causes of acquired Chiari malformation type 1 involve the excessive draining of spinal fluid from the lumbar or thoracic areas of the spine as a result of injury, exposure to harmful substances, or infection.[5] Click here to view a diagram of the spine.

Last updated: 8/11/2017
Some individuals with Chiari malformation type 1 do not have symptoms and do not require treatment.[1] People who have mild symptoms, without syringomyelia, can typically be treated conservatively. Mild neck pain and headaches can usually be treated with pain medications, muscle relaxants, and the occasional use of a soft collar.[4]

People with more severe symptoms may need surgery.[4] Surgery is the only treatment available to correct functional disturbances or stop the progression of damage to the central nervous system.[1] The goals of surgical treatment are decompression of the point where the skull meets the spine (the cervicomedullary junction) and restoration of normal flow of cerebrospinal fluid in the region of the foramen magnum (the hole in the bottom of the skull where the spinal cord passes to connect to the brain).[4] Prognosis after surgery for the condition is generally good and typically depends on the extent of neurological deficits that were present before the surgery. Most people have a reduction of symptoms and/or prolonged periods of relative stability. More than one surgery may be needed to treat the condition.[1][4]
Last updated: 8/11/2017
The prognosis for someone diagnosed with Chiari malformation type 1 is often unknown. Many people with this condition do not have any symptoms, and it is not possible to predict if symptoms will develop in the future.[5] Other people with Chiari malformation may experience dizziness, muscle weakness, numbness, vision problems, headache, or problems with balance and coordination.[5] In these people, it is not always known if symptoms will get worse over time. It is important for people with Chiari malformation type 1 to receive regular medical care so they can be monitored by a physician for any new symptoms.

There are some treatments that may help reduce or eliminate the symptoms of Chiari malformation type 1. Medications may ease certain symptoms, such as pain. Surgery is another treatment option, but it is typically reserved for people with severe symptoms. Many patients who have had surgery see a reduction in their symptoms and/or prolonged periods of relative stability.[5]

 

Last updated: 8/11/2017

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The Centers for Mendelian Genomics program is working to discover the causes of rare genetic disorders. For more information about applying to the research study, please visit their website.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Chiari malformation type 1. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Chiari Malformation Fact Sheet. NINDS. 2016; http://www.ninds.nih.gov/disorders/chiari/detail_chiari.htm#194173087.
  2. Questions about Chiari. Conquerchiari.org. http://conquerchiari.org/education/chiari-faqs.html.
  3. Chiari Malformation Symptoms and Cause. Mayo Clinic. 2017; http://www.mayoclinic.org/diseases-conditions/chiari-malformation/symptoms-causes/dxc-20249662.
  4. Pakzaban P. Chiari Malformation. Medscape Reference. 2016; http://emedicine.medscape.com/article/1483583-overview.
  5. Chiari Malformation Fact Sheet. National Institute of Neurological Disorders and Stroke Web site. http://www.ninds.nih.gov/disorders/chiari/detail_chiari.htm.