Name = Arnold-Chiari
Caption = A T2-weighted sagittal MRI scan, from a patient with Chiari-like symptomatology, demonstrating tonsillar herniation less than 3 mm
DiseasesDB = 899
ICD10 = ICD10|Q|07|0|q|00
ICD9 = ICD9|741.0
OMIM = 207950
MeshID = D001139
Arnold-Chiari malformation is a malformation of the
brain. It consists of a downward displacement of the cerebellar tonsilsand the medullacite web |url=http://www.urmc.rochester.edu/neuroslides/slide169.html |title=urmc.rochester.edu |format= |work= |accessdate=] through the foramen magnum, sometimes causing hydrocephalusas a result of obstruction of CSF outflow.cite book | last=Rosenbaum
first=RB | coauthors=DP Ciaverella | title=Neurology in Clinical Practice | publisher=Butterworth Heinemann | date=2004 | pages=2192-2193 | isbn=0-7506-7469-5 ]
Some sources use "Chiari malformation" to describe four specific grades of the condition, reserving the term "Arnold-Chiari" for type II only.cite web |url=http://www.mercksource.com/pp/us/cns/cns_hl_dorlands_split.jsp?pg=/ppdocs/us/common/dorlands/dorland/nine/100011880.htm |title=Dorlands Medical Dictionary:Chiari malformation |format= |work= |accessdate=] Other sources use "Arnold-Chiari" for all four types.cite web |url=http://www.hawaii.edu/medicine/pediatrics/pedtext/s18c16.html |title=Case Based Pediatrics Chapter |format= |work= |accessdate=] This article uses the latter convention.
One advantage of using "Arnold-Chiari" is that the term "Chiari's syndrome" can refer to
Budd-Chiari syndrome,cite web |url=http://www.icd9data.com/2008/Volume1/390-459/451-459/453/453.0.htm |title=2008 ICD-9-CM Diagnosis 453.0 - Budd-Chiari Syndrome |format= |work= |accessdate=] a hepatic condition also named for Hans Chiari.
The average age at diagnosis is about 34Fact|date=July 2008 and it is more common in women.
Some characteristics are visible prenatally.cite web |url=http://www.bidmc.harvard.edu/content/bidmc/departments/radiology/files/fetalatlas/brain/chiari/chiari.html |title=Fetal MRI: Arnold-Chiari Malformation |format= |work= |accessdate=]
incidenceof Arnold-Chiari Malformation (Chiari I malformation) defined as tonsilar herniations of 3 to 5 mm or greater is approximately 1 in 1,200.Fact|date=July 2008 The incidence of symptomatic Chiari is less but unknown.
prevalenceof approximately 1 in 1000 has been described.cite web |url=http://www.uscneurosurgery.com/Disorders_includes/arnchiari.html |title=Arnold Chiari Malformation |format= |work= |accessdate=]
Average age at presentation is 41 years (range : 12 - 73 years). Slight female preponderance (f:m = 1,3:1). Average duration clearly related to Chiari malformation is 3,1 years (range 1 month to 20 years).
History and classification
The Austrian pathologist Hans Chiari in the late 1800s 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.cite web |url=http://neurosurgery.ucla.edu/body.cfm?id=109 |title=Arnold Chiari Malformation |format= |work= |accessdate=]
* The most common form of Arnold-Chiari Malformation is Type I, which is generally asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms.
* Type II is usually accompanied by a
myelomeningocelecite web |url=http://www.mir.wustl.edu/neurorad/internal.asp?NavID=123 |title=Neuroradiology - Chiari malformation (I-IV) |format= |work= |accessdate=] leading to partial or complete paralysis below the spinal defect. Abnormal development of the cerebellar vermis and medulla occur, and they both descend into the foramen magnum. Hydrocephalus is also nearly always present.
* Type III causes severe neurological defects. It is associated with an
* Type IV involves a failure of brain development.cite web |url=http://www.cumc.columbia.edu/dept/nsg/ct/chiari_malformation.html |title=Chiari Malformations - Department of Neurological Surgery |format= |work= |accessdate=]
Other conditions sometimes associated with Chiari Malformation include
hydrocephalus,cite web |url=http://www.pathology.vcu.edu/WirSelfInst/neuro_medStudents/devdis.html |title=Neuropathology For Medical Students |format= |work= |accessdate=] syringomyelia, spinal curvature, and connective tissue disorderscite 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. 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/abs/10.3171/SPI-07/12/601?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dncbi.nlm.nih.gov] such as Ehlers-Danlos syndromeand Marfan Syndrome.
brainstem, cranial nerves, and the lower portion of the cerebellummay be stretched or compressed. Therefore, any of the functions controlled by these areas may be affected. The blockage of Cerebro-Spinal Fluid (CSF) flow may also cause a syrinx to form, eventually leading to syringomyelia. Chiari is often associated with major headaches, sometimes mistaken for migraines. Chiari headaches usually include intense throbbing in the back of the head. Chiari also includes extreme muscle soreness and low energy levels. It also can cause insomnia cycles of sleep deprivation followed by inabilities to remain awake cycling between them. 15 - 30 % of patients with adult Chiari malfomation are asymptomatic.
Once symptomatic onset occurs, a common treatment is decompression surgery,cite journal |author=Guo F, Wang M, Long J, "et al" |title=Surgical management of Chiari malformation: analysis of 128 cases |journal=Pediatr Neurosurg |volume=43 |issue=5 |pages=375–81 |year=2007 |pmid=17786002 |doi=10.1159/000106386 |url=http://content.karger.com/produktedb/produkte.asp?typ=fulltext&file=000106386] in which a neurosurgeon usually removes the first and part of the second and sometimes third
cervical vertebraeand part of the occipital boneof the skullto allow the flow of spinal fluid and may be accompanied by a shunt. This treatment is well recognized and accepted with many studies published (involving a total of hundreds of patients) in well-respected peer-reviewed medical journals showing that about 80% of patients obtain improvement.Some authors advocate performing a transoral clivus-odontoid resection in cases with ventral brain-stem compression, as they feel these patients may potentially deteriorate with posterior fossa decompression alone.
A small number of neurological surgeons believe that detethering the spinal cord as an alternate approach relieves the compression of the brain against the skull opening (foramen magnum), obviating the need for decompression surgery and associated trauma. However, this approach is significantly less documented in the medical literature, with reports on only a handful of patients. It should be noted that the alternative spinal surgery is also not without risk.
Austrian pathologist, Hans Chiari, first described these hindbrain malformations in the 1890s. [Chiari, H. Uber Veranderungen des Kleinhirns infolge von Hydrocephalie des Grosshirns. Dtsch. Med. Wochenschr. 17: 1172-1175, 1891.] A colleague of Professor Chiari, Dr. Julius Arnold, later contributed to the definition of the condition, [Arnold, J. Myelocyste, Transposition von Gewebskeimen und Sympodie. Beitr. Path. Anat. 16: 1-28, 1894.] and students of Dr. Arnold (Schwalbe and Gredig)cite book |author=Ashwal, Stephen |title=The Founders of child neurology |publisher=Norman Pub. in association with the Child Neurology Society |location=San Francisco |year=1990 |pages=195 |isbn=0-930405-26-9 |oclc= |doi= |accessdate=] suggested the term "Arnold-Chiari malformation" to henceforth refer to the condition. [WhoNamedIt|synd|1154|Arnold-Chiari malformation] cite journal |author=Bejjani GK |title=Definition of the adult Chiari malformation: a brief historical overview |journal=Neurosurg Focus |volume=11 |issue=1 |pages=E1 |year=2001 |pmid=16724811 |doi=10.3171/foc.2001.11.1.2 |url=http://thejns.org/doi/abs/10.3171/foc.2001.11.1.2?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dncbi.nlm.nih.gov]
Some sources credit the characterization of the condition to Clelandcite journal |author=Susman J, Jones C, Wheatley D |title=Arnold-Chiari malformation: a diagnostic challenge |journal=Am Fam Physician |volume=39 |issue=3 |pages=207–11 |year=1989 |month=March |pmid=2923030 |doi= |url=http://findarticles.com/p/articles/mi_m3225/is_n3_v39/ai_7621931] cite journal |author=Cleland |title=Contribution to the Study of Spina Bifida, Encephalocele, and Anencephalus |journal=J Anat Physiol |volume=17 |issue=Pt 3 |pages=257–92 |year=1883 |month=April |pmid=17231474 |pmc=1310092 |doi= |url=] or Cruveilhier.cite journal |author=Pearce JM |title=Arnold chiari, or "Cruveilhier cleland Chiari" malformation |journal=J. Neurol. Neurosurg. Psychiatr. |volume=68 |issue=1 |pages=13 |year=2000 |month=January |pmid=10601393 |doi= |url=http://jnnp.bmj.com/cgi/pmidlookup?view=long&pmid=10601393]
* [http://www.conquerchiari.org/ Conquer Chiari]
* [http://www.pressenter.com/~wacma/info.htm/ World Arnold Chiari Malformation Association]
* [http://www.asap.org/chiari-malformation.html American Syringomyelia Alliance Project]
* [http://www.theannconroytrust.org.uk/info.htm The Ann Conroy Trust] (ACT)
* [http://www.huffingtonpost.com/joel-schwartzberg/head-trip-who-do-you-trus_b_116145.html An insightful Huffington Post blog] from a father whose son suffered from Chiari Malformation and the emotional roller coaster it created.
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