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Arnold-Chiari Malformation II occurs in almost all children born with both [[spina bifida]] and [[hydrocephalus]], but ACM I is typically seen in children and adults without spina bifida. The scale of severity is rated I - IV, with IV being the most severe. <ref>Barkovich AJ, Wippold FJ, Sherman JL, Citrin CM. [http://www.ajnr.org/cgi/content/abstract/7/5/795 Significance of cerebellar tonsillar position on MR.] AJNR Am J Neuroradiol. 1986 Sep-Oct;7(5):795-9.</ref> <ref>Haughton VM, Korosec FR, Medow JE, Dolar MT, Iskandar BJ. [http://www.ajnr.org/cgi/content/abstract/24/2/169 Peak systolic and diastolic CSF velocity in the foramen magnum in adult patients with Chiari I malformations and in normal control participants.] AJNR Am J Neuroradiol. 2003 Feb;24(2):169-76.</ref> <ref>Elster A, Chen M. [http://radiology.rsnajnls.org/cgi/content/abstract/183/2/347 Chiari I malformations: clinical and radiologic reappraisal.] Radiology. 1992; 183:347-353.</ref>
Arnold-Chiari Malformation II occurs in almost all children born with both [[spina bifida]] and [[hydrocephalus]], but ACM I is typically seen in children and adults without spina bifida. The scale of severity is rated I - IV, with IV being the most severe. <ref>Barkovich AJ, Wippold FJ, Sherman JL, Citrin CM. [http://www.ajnr.org/cgi/content/abstract/7/5/795 Significance of cerebellar tonsillar position on MR.] AJNR Am J Neuroradiol. 1986 Sep-Oct;7(5):795-9.</ref> <ref>Haughton VM, Korosec FR, Medow JE, Dolar MT, Iskandar BJ. [http://www.ajnr.org/cgi/content/abstract/24/2/169 Peak systolic and diastolic CSF velocity in the foramen magnum in adult patients with Chiari I malformations and in normal control participants.] AJNR Am J Neuroradiol. 2003 Feb;24(2):169-76.</ref> <ref>Elster A, Chen M. [http://radiology.rsnajnls.org/cgi/content/abstract/183/2/347 Chiari I malformations: clinical and radiologic reappraisal.] Radiology. 1992; 183:347-353.</ref>
==Classification==
The Austrian pathologist Hans Chiari in the late 19th century described seemingly related anomalies of the hindbrain, the so called Chiari malformations I, II and III. Later, other investigators added a fourth (Chiari IV) malformation. The scale of severity is rated I - IV, with IV being the most severe. Types III and IV are very rare.<ref name="urlArnold Chiari Malformation">{{cite web|url=http://neurosurgery.ucla.edu/body.cfm?id=109 |title=Arnold Chiari Malformation |work= |accessdate=}}</ref>


==Cause==
{| class="wikitable"
The [[cerebellar tonsils]] are elongated and pushed down through the opening of the base of the [[skull]] (see [[foramen magnum]]), blocking the flow of [[cerebrospinal fluid]] (CSF).  
|-
! Type
! Presentation
! Other notes
|-
| I
| A congenital malformation. Is generally asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms. Herniation of [[cerebellar tonsil]]s.<ref name="pmid19246872">{{Cite journal|author=Kojima A, Mayanagi K, Okui S |title=Progression of pre-existing Chiari type I malformation secondary to cerebellar hemorrhage: case report |journal=Neurol. Med. Chir. (Tokyo) |volume=49 |issue=2 |pages=90–2 |year=2009 |month=February |pmid=19246872 |doi= 10.2176/nmc.49.90|url=http://joi.jlc.jst.go.jp/JST.JSTAGE/nmc/49.90?from=PubMed |format=}} {{Dead link|date=May 2009}}</ref><ref name="pmid16509477">{{Cite journal|author=O'Shaughnessy BA, Bendok BR, Parkinson RJ, ''et al.'' |title=Acquired Chiari malformation Type I associated with a supratentorial arteriovenous malformation. Case report and review of the literature |journal=J. Neurosurg. |volume=104 |issue=1 Suppl |pages=28–32 |year=2006 |month=January |pmid=16509477 |doi=10.3171/ped.2006.104.1.28 |url=http://thejns.org/doi/abs/10.3171/ped.2006.104.1.28?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dncbi.nlm.nih.gov}}</ref>
| The most common form.
|-
|Syndrome of occipitoatlantoaxial hypermobility
|An acquired Chiari I Malformation in patients with hereditary disorders of connective tissue.<ref name="Milhorat-2007"/> Patients who exhibit extreme joint [[hypermobility]] and connective tissue weakness as a result of [[Ehlers-Danlos syndrome]] or [[Marfan Syndrome]] are susceptible to instabilities of the craniocervical junction and thus acquiring a Chiari Malformation. This type is difficult to diagnose and treat.<ref name="Conquer Chiari, Connective Tissue Disorders">{{cite web|url=http://www.conquerchiari.org/subs%20only/volume%204/issue%204(10)/bland%20connective%20tissue%204(10).asp |title=Dr. Bland Discusses Chiari & EDS 4(10) |publisher=Conquerchiari.org |date=2006-11-20 |accessdate=2011-11-04}}</ref>
|
|-
| II
| Usually accompanied by a [[lumbar]] [[myelomeningocele]]<ref name="urlNeuroradiology - Chiari malformation (I-IV)">{{cite web|url=http://www.mir.wustl.edu/neurorad/internal.asp?NavID=123 |title=Neuroradiology - Chiari malformation (I-IV) |work= |accessdate=}}</ref> leading to partial or complete paralysis below the spinal defect. As opposed to the less pronounced tonsillar herniation seen with Chiari I, there is a larger cerebellar vermian displacement. Low lying [[torcular herophili]], tectal beaking, and hydrocephalus with consequent clival hypoplasia are classic anatomic associations.<ref>{{cite web|url =http://www.cchs.net/pediatricradiology/imagegallery/default.asp|title =Pediatric Radiology Image Gallery|accessdate = June 14, 2010|year = 2010|title = Cleveland Clinic Children's Hospital Pediatric Radiology Image Gallery|accessdate = June 14, 2010|publisher = [[Cleveland Clinic]]| archiveurl= http://web.archive.org/web/20100627053310/http://www.cchs.net/pediatricradiology/imagegallery/default.asp| archivedate= 27 June 2010 <!--DASHBot-->| deadurl= no}}</ref> The position of the torcular herophili is important for distinction from [[Dandy-Walker syndrome]] in which it is classically upturned. This is important because the hypoplastic cerebellum of Dandy-Walker may be difficult to distinguish from a Chiari malformation that has herniated or is ectopic on imaging. [[Colpocephaly]] may be seen due to the associated neural tube defect.
|
|-
| III
| Causes severe neurological defects. It is associated with an [[occiput|occipital]] [[encephalocele]].<ref name="Mesh">{{MeshName|Arnold-Chiari+Malformation}}</ref>
|
|-
| IV
| Characterized by a lack of [[cerebellar]] development.<ref name="urlChiari Malformations - Department of Neurological Surgery">{{cite web|url=http://www.cumc.columbia.edu/dept/nsg/ct/chiari_malformation.html |title=Chiari Malformations - Department of Neurological Surgery |work= |accessdate=}}</ref>
|
|}
[[File:Neck MRI 130850-dichromatic t1-t2-t2.png|thumb|200px|Syringomiyelia associated with Chiari malformation]]
Other conditions sometimes associated with Chiari Malformation include [[hydrocephalus]],<ref name="urlNeuropathology For Medical Students">{{cite web|url=http://www.pathology.vcu.edu/WirSelfInst/neuro_medStudents/devdis.html |title=Neuropathology For Medical Students |work= |accessdate=}}</ref> [[syringomyelia]], [[spinal curvature]], [[tethered spinal cord syndrome]], and connective tissue disorders<ref name="Milhorat-2007">{{Cite journal|author=Milhorat TH, Bolognese PA, Nishikawa M, McDonnell NB, Francomano CA |title=Syndrome of occipitoatlantoaxial hypermobility, cranial settling, and chiari malformation type I in patients with hereditary disorders of connective tissue |journal=[[Journal of Neurosurgery|Journal of Neurosurgery: Spine]] |volume=7 |issue=6 |pages=601–9 |year=2007 |month=December |pmid=18074684 |doi=10.3171/SPI-07/12/601 |url=http://thejns.org/doi/full/10.3171/SPI-07/12/601}}</ref> such as [[Ehlers-Danlos syndrome]] and [[Marfan Syndrome]].


The [[brainstem]], cranial nerves, and the lower portion of the [[cerebellum]] may be stretched or compressed.
==Pathophysiology==


Therefore, any of the functions controlled by these areas may be affected. The blockage of CSF flow may also cause a [[syrinx (medicine)|syrinx]] to form, eventually leading to [[syringomyelia]].  Many sufferers turn to the Chiari Institute in Long Island, NY for specialized medical attention and medication.
*The most widely accepted pathophysiological mechanism by which Chiari Type 1 Malformations occur is by a reduction or lack of development of the [[posterior fossa]] as a result of either congenital or acquired disorders.
*The [[cerebellar tonsils]] are elongated and pushed down through the opening of the base of the [[skull]] (see [[foramen magnum]]), blocking the flow of [[cerebrospinal fluid]] (CSF).
*The [[brainstem]], cranial nerves, and the lower portion of the [[cerebellum]] may be stretched or compressed.
*Therefore, any of the functions controlled by these areas may be affected. The blockage of CSF flow may also cause a [[syrinx (medicine)|syrinx]] to form, eventually leading to [[syringomyelia]].  Many sufferers turn to the Chiari Institute in Long Island, NY for specialized medical attention and medication.
==Causes==


==Presentation==
In [[infant]]s, the most common symptoms are [[stridor]] and swallowing difficulties. In older children, upper (and lower as age marches on) limb weakness and breathing difficulties may occur. Patients may experience no symptoms or remain asymptomatic until early adulthood, at which point they will often experience quick onset severe headaches and neck pain. Fatigue, dizziness, vertigo, neuropathic pain, pain at the point of tethering, visual disturbances, difficulty swallowing, ringing in the ears, sleep apnea, impaired fine motor skills, muscle weakness, and palpitations and excessive clearing of the throat with no obstructions are other common symptoms. Because of the complex combination of symptoms and the lack of experience with ACM1 had by many, even outstanding neurologists and neurosurgeons, many patients are frequently misdiagnosed.


Some patients may go an entire lifetime without having noticeable symptoms. Or, symptoms can be minimal, then turn severe suddenly due to head trauma which alters the condition of the spine, brain, or cerebellar tonsils and begins to cause more difficulties...
Congenital causes are


==Diagnostic Studies==
[[craniosynostosis]] (especially of the lambdoid suture)


*'''Radiographs''' may demonstrate associated abnormalities of the skull base.
[[hyperostosis]] (ex. craniometaphyseal dysplasia
*'''CT''' may demonstrate hydrocephalus, herniated cerebellar tonsils, and a flattened spinal cord. Rarely will CT show a syrinx.
 
*'''MRI''' is the imaging modality of choice to evaluate for a Chiari I malformation. MRI findings:
[[osteopetrosis]]
 
[[X-linked vitamin D-resistant rickets]]
 
[[neurofibromatosis type I]]
 
Acquired disorders include space occupying lesions due to one of several potential causes ranging from brain tumors to hematomas.<ref name="pmid21882908">{{Cite journal|author=Loukas M, Shayota BJ, Oelhafen K, Miller JH, Chern JJ, Tubbs RS, Oakes WJ |title=Associated disorders of Chiari Type I malformations: a review |journal=Neurosurg Focus |volume=31 |issue=3 |pages=E3 |year=2011 |pmid=21882908 |doi=10.3171/2011.6.FOCUS11112 |url=http://thejns.org/doi/abs/10.3171/2011.6.FOCUS11112}}</ref>
 
 
==Historical Perspective==
An Austrian [[pathologist]], [[Hans Chiari]], first described these hindbrain malformations in the 1890s.  A colleague of Professor Chiari, Dr. Julius Arnold later contributed to the definition of the condition, and students of Dr. Arnold suggested the term "Arnold-Chiari malformation" to henceforth refer to the condition.<ref>{{WhoNamedIt|synd|1154|Arnold-Chiari malformation}}</ref>
 
 
==Diagnosis==
 
In [[infant]]s, the most common symptoms are
* [[stridor]]
* [[Swallowing]] difficulties
 
 
In older children
* Upper (and lower as age marches on) limb weakness
* Breathing difficulties may occur
* Patients may experience no symptoms or remain asymptomatic until early adulthood at which point they will often experience severe headaches and neck pain
* Fatigue
* Dizziness
* Vertigo
* Neuropathic pain
* Pain at the point of tethering
* Visual disturbances
* Difficulty swallowing
* Ringing in the ears
* Sleep apnea
* Impaired fine motor skills
* Muscle weakness
* Palpitations
* Excessive clearing of the throat with no obstructions 
* Because of the complex combination of symptoms and the lack of experience with ACM1 had by many, even outstanding neurologists and neurosurgeons, many patients are frequently misdiagnosed.
* Some patients may go an entire lifetime without having noticeable symptoms. Or, symptoms can be minimal, then turn severe suddenly due to head trauma which alters the condition of the spine, brain, or cerebellar tonsils and begins to cause more difficulties...
 
 
===physical Examination===
 
===Vitals===
 
====Pulse====
 
====Rate====
 
[[Tachycardia]] may be present.
 
===Eye===
 
*[[Nystagmus]] (irregular eye movements) may be present.
 
*[[pupillary dilatation]]
 
====Neurologic====
 
*Impaired [[gag reflex]]
 
*Impaired [[coordination]]
 
===X ray skull===
 
May demonstrate associated abnormalities of the skull base.
 
===CT===
 
May demonstrate hydrocephalus, herniated cerebellar tonsils, and a flattened spinal cord. Rarely will CT show a syrinx.
===MRI===
 
[[MRI]]is the imaging modality of choice to evaluate for a Chiari I malformation. MRI findings:
**Cerebellar tonsillar herniation
**Cerebellar tonsillar herniation
**Wedge shaped tonsils
**Wedge shaped tonsils
Line 273: Line 375:
==Treatment==
==Treatment==


===Surgery===
Once these "onset of symptoms" occurs, the most frequent treatment is decompression surgery, in which a neurosurgeon seeks to open the base of the skull and through various methods unrestrict CSF flow to the spine.
Once these "onset of symptoms" occurs, the most frequent treatment is decompression surgery, in which a neurosurgeon seeks to open the base of the skull and through various methods unrestrict CSF flow to the spine.


Line 284: Line 387:


{{Congenital malformations and deformations of nervous system}}
{{Congenital malformations and deformations of nervous system}}
{{SIB}}
 


[[Category:Overview complete]]
[[Category:Overview complete]]
[[Category:Neurology]]
[[Category:Neurology]]
[[Category:Needs patient information]]
[[Category:Needs patient information]]
 
[[Category:Disease]]
[[ca:Malformació d'Arnold-Chiari]]
[[ca:Malformació d'Arnold-Chiari]]
[[de:Chiari-Malformation]]
[[de:Chiari-Malformation]]

Revision as of 18:22, 25 July 2012

Arnold-Chiari malformation
An uncollapsed syrinx (before surgery).
ICD-10 Q07.0
ICD-9 741.0
OMIM 207950
DiseasesDB 899
MeSH D001139

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Arnold-Chiari malformation, sometimes referred to as Chiari malformation or ACM, is a congenital anomaly of the brain.

Arnold-Chiari Malformation II occurs in almost all children born with both spina bifida and hydrocephalus, but ACM I is typically seen in children and adults without spina bifida. The scale of severity is rated I - IV, with IV being the most severe. [1] [2] [3]

Classification

The Austrian pathologist Hans Chiari in the late 19th century described seemingly related anomalies of the hindbrain, the so called Chiari malformations I, II and III. Later, other investigators added a fourth (Chiari IV) malformation. The scale of severity is rated I - IV, with IV being the most severe. Types III and IV are very rare.[4]

Type Presentation Other notes
I A congenital malformation. Is generally asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms. Herniation of cerebellar tonsils.[5][6] The most common form.
Syndrome of occipitoatlantoaxial hypermobility An acquired Chiari I Malformation in patients with hereditary disorders of connective tissue.[7] Patients who exhibit extreme joint hypermobility and connective tissue weakness as a result of Ehlers-Danlos syndrome or Marfan Syndrome are susceptible to instabilities of the craniocervical junction and thus acquiring a Chiari Malformation. This type is difficult to diagnose and treat.[8]
II Usually accompanied by a lumbar myelomeningocele[9] leading to partial or complete paralysis below the spinal defect. As opposed to the less pronounced tonsillar herniation seen with Chiari I, there is a larger cerebellar vermian displacement. Low lying torcular herophili, tectal beaking, and hydrocephalus with consequent clival hypoplasia are classic anatomic associations.[10] The position of the torcular herophili is important for distinction from Dandy-Walker syndrome in which it is classically upturned. This is important because the hypoplastic cerebellum of Dandy-Walker may be difficult to distinguish from a Chiari malformation that has herniated or is ectopic on imaging. Colpocephaly may be seen due to the associated neural tube defect.
III Causes severe neurological defects. It is associated with an occipital encephalocele.[11]
IV Characterized by a lack of cerebellar development.[12]
File:Neck MRI 130850-dichromatic t1-t2-t2.png
Syringomiyelia associated with Chiari malformation

Other conditions sometimes associated with Chiari Malformation include hydrocephalus,[13] syringomyelia, spinal curvature, tethered spinal cord syndrome, and connective tissue disorders[7] such as Ehlers-Danlos syndrome and Marfan Syndrome.

Pathophysiology

  • The most widely accepted pathophysiological mechanism by which Chiari Type 1 Malformations occur is by a reduction or lack of development of the posterior fossa as a result of either congenital or acquired disorders.
  • The cerebellar tonsils are elongated and pushed down through the opening of the base of the skull (see foramen magnum), blocking the flow of cerebrospinal fluid (CSF).
  • The brainstem, cranial nerves, and the lower portion of the cerebellum may be stretched or compressed.
  • Therefore, any of the functions controlled by these areas may be affected. The blockage of CSF flow may also cause a syrinx to form, eventually leading to syringomyelia. Many sufferers turn to the Chiari Institute in Long Island, NY for specialized medical attention and medication.

Causes

Congenital causes are

craniosynostosis (especially of the lambdoid suture)

hyperostosis (ex. craniometaphyseal dysplasia

osteopetrosis

X-linked vitamin D-resistant rickets

neurofibromatosis type I

Acquired disorders include space occupying lesions due to one of several potential causes ranging from brain tumors to hematomas.[14]


Historical Perspective

An Austrian pathologist, Hans Chiari, first described these hindbrain malformations in the 1890s. A colleague of Professor Chiari, Dr. Julius Arnold later contributed to the definition of the condition, and students of Dr. Arnold suggested the term "Arnold-Chiari malformation" to henceforth refer to the condition.[15]


Diagnosis

In infants, the most common symptoms are


In older children 
  • Upper (and lower as age marches on) limb weakness
  • Breathing difficulties may occur
  • Patients may experience no symptoms or remain asymptomatic until early adulthood at which point they will often experience severe headaches and neck pain
  • Fatigue
  • Dizziness
  • Vertigo
  • Neuropathic pain
  • Pain at the point of tethering
  • Visual disturbances
  • Difficulty swallowing
  • Ringing in the ears
  • Sleep apnea
  • Impaired fine motor skills
  • Muscle weakness
  • Palpitations
  • Excessive clearing of the throat with no obstructions
  • Because of the complex combination of symptoms and the lack of experience with ACM1 had by many, even outstanding neurologists and neurosurgeons, many patients are frequently misdiagnosed.
  • Some patients may go an entire lifetime without having noticeable symptoms. Or, symptoms can be minimal, then turn severe suddenly due to head trauma which alters the condition of the spine, brain, or cerebellar tonsils and begins to cause more difficulties...


physical Examination

Vitals

Pulse

Rate

Tachycardia may be present.

Eye

  • Nystagmus (irregular eye movements) may be present.

Neurologic

X ray skull

May demonstrate associated abnormalities of the skull base.

CT

May demonstrate hydrocephalus, herniated cerebellar tonsils, and a flattened spinal cord. Rarely will CT show a syrinx.

MRI

MRIis the imaging modality of choice to evaluate for a Chiari I malformation. MRI findings:

    • Cerebellar tonsillar herniation
    • Wedge shaped tonsils
    • Syringohydromyelia
    • Small posterior fossa
    • Obstructive hydrocephalus
    • Brainstem anomalies
  • Tonsillar displacement is measured from the basion-opisthion line on a sigittal image.
  • Herniation is usually at least 5mm, though patients with 3-5mm herniation may also have the malformation.
  • MRI CSF flow studies may prove to be helpful and are currently under investigation.

Patient #1

Images shown below are courtesy of RadsWiki and copylefted

Patient #2

Images shown below are courtesy of RadsWiki and copylefted


Other Radiologic Findings









Pathological Findings












Treatment

Surgery

Once these "onset of symptoms" occurs, the most frequent treatment is decompression surgery, in which a neurosurgeon seeks to open the base of the skull and through various methods unrestrict CSF flow to the spine.

This treatment is under observation and review. Decompression is a very taxing surgical procedure and is now, in some circles, disdained in lieu of tethered cord detachment at the base of the spine. Some neurological surgeons find that detethering the spinal cord relieves the compression of the brain against the skull opening (foramen magnum) obviating the need for decompression surgery and associated trauma. It should be noted that the alternative spinal surgery is not without risk.

History

An Austrian pathologist, Hans Chiari, first described these hindbrain malformations in the 1890s. A colleague of Professor Chiari, Dr. Julius Arnold later contributed to the definition of the condition, and students of Dr. Arnold suggested the term "Arnold-Chiari malformation" to henceforth refer to the condition.[16]

References

  1. Barkovich AJ, Wippold FJ, Sherman JL, Citrin CM. Significance of cerebellar tonsillar position on MR. AJNR Am J Neuroradiol. 1986 Sep-Oct;7(5):795-9.
  2. Haughton VM, Korosec FR, Medow JE, Dolar MT, Iskandar BJ. Peak systolic and diastolic CSF velocity in the foramen magnum in adult patients with Chiari I malformations and in normal control participants. AJNR Am J Neuroradiol. 2003 Feb;24(2):169-76.
  3. Elster A, Chen M. Chiari I malformations: clinical and radiologic reappraisal. Radiology. 1992; 183:347-353.
  4. "Arnold Chiari Malformation".
  5. Kojima A, Mayanagi K, Okui S (2009). "Progression of pre-existing Chiari type I malformation secondary to cerebellar hemorrhage: case report". Neurol. Med. Chir. (Tokyo). 49 (2): 90–2. doi:10.2176/nmc.49.90. PMID 19246872. Unknown parameter |month= ignored (help)[dead link]
  6. O'Shaughnessy BA, Bendok BR, Parkinson RJ; et al. (2006). "Acquired Chiari malformation Type I associated with a supratentorial arteriovenous malformation. Case report and review of the literature". J. Neurosurg. 104 (1 Suppl): 28–32. doi:10.3171/ped.2006.104.1.28. PMID 16509477. Unknown parameter |month= ignored (help)
  7. 7.0 7.1 Milhorat TH, Bolognese PA, Nishikawa M, McDonnell NB, Francomano CA (2007). "Syndrome of occipitoatlantoaxial hypermobility, cranial settling, and chiari malformation type I in patients with hereditary disorders of connective tissue". Journal of Neurosurgery: Spine. 7 (6): 601–9. doi:10.3171/SPI-07/12/601. PMID 18074684. Unknown parameter |month= ignored (help)
  8. "Dr. Bland Discusses Chiari & EDS 4(10)". Conquerchiari.org. 2006-11-20. Retrieved 2011-11-04.
  9. "Neuroradiology - Chiari malformation (I-IV)".
  10. "Cleveland Clinic Children's Hospital Pediatric Radiology Image Gallery". Cleveland Clinic. 2010. Archived from the original on 27 June 2010. Retrieved June 14, 2010.
  11. Arnold-Chiari+Malformation at the US National Library of Medicine Medical Subject Headings (MeSH)
  12. "Chiari Malformations - Department of Neurological Surgery".
  13. "Neuropathology For Medical Students".
  14. Loukas M, Shayota BJ, Oelhafen K, Miller JH, Chern JJ, Tubbs RS, Oakes WJ (2011). "Associated disorders of Chiari Type I malformations: a review". Neurosurg Focus. 31 (3): E3. doi:10.3171/2011.6.FOCUS11112. PMID 21882908.
  15. Template:WhoNamedIt
  16. Template:WhoNamedIt

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