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Disease Profile

Chiari malformation type 1

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

Unknown

Age of onset

#N/A

ICD-10

#N/A

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

Chiari type I malformation; Chiari malformation type I; Arnold Chiari malformation type I;

Categories

Nervous System Diseases

Summary

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]

Symptoms

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.

Medical Terms Other Names
Learn More:
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

Cause

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.

Treatment

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]

Organizations

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

    Learn more

    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.

        References

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

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