Arnold-Chiari malformation

From Wikipedia, the free encyclopedia

This article does not cite any references or sources. (May 2008) Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed.

Arnold-Chiari Classification and external resources
ICD-10	Q07.0
ICD-9	741.0
OMIM	207950
DiseasesDB	899
MeSH	D001139

Arnold-Chiari malformation, sometimes referred to as Chiari I malformation or ACM, is a malformation of the brain. It consists of a downward displacement of the cerebellar tonsils and the medulla through the foramen magnum, sometimes causing hydrocephalus as a result of obstruction of CSF outflow.^[1]

The incidence of Arnold-Chiari Malformation (Chiari I malformation) defined as tonsilar herniations of 3 to 5 mm or greater is approximately 1 in 1,200. The incidence of symptomatic Chiari is less but unknown. The average age at diagnosis is about 24 and it is more common in women. It occurs in many children born with both spina bifida and hydrocephalus. 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.

Contents 1 Symptoms 2 Presentation 3 Treatment 4 History 5 References 6 External links

[edit] Symptoms

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 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 a hoarseness in the voice.

[edit] Presentation

In infants, 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 may experience quick onset severe headaches and neck pain. Fatigue, dizziness, vertigo, neuropathic pain, pain at the point of tethering, visual disturbances, difficulty swallowing, tinnitus, sleep apnea, impaired fine motor skills, muscle weakness, 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 the malformation by many neurologists and neurosurgeons, patients are frequently misdiagnosed. Common misdiagnoses include clinical depression, fibromyalgia, chronic fatigue syndrome, and multiple sclerosis.

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.

A Chiari malformation may be congenital or acquired. Research is still being done to determine its causes. In some cases it may be hereditary, and numerous cases exist of multiple members of one family having the condition.

[edit] Treatment

Once symptomatic onset occurs, the most frequent treatment is decompression surgery, in which a neurosurgeon usually removes the first and part of the second cervical vertebrae and part of the occipital bone of the skull to 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.

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.

[edit] 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.^[2]

[edit] References

[edit] External links

• Conquer Chiari
• Chiari Connection International
• World Arnold Chiari Malformation Association
• American Syringomyelia Alliance Project
• The Ann Conroy Trust (ACT)
• AFACPA Association for Arnold Chiari Malformation Patients. In Spanish.

v • d • e Congenital malformations and deformations of nervous system (Q00-Q07, 740-742) Brain Anencephaly (Acephaly, Acrania, Iniencephaly) - Encephalocele - Microcephaly - Congenital hydrocephalus (Dandy-Walker syndrome) - other reduction deformities (Holoprosencephaly, Lissencephaly, Pachygyria, Hydranencephaly) - Septo-optic dysplasia - Megalencephaly - Congenital cerebral cysts (Porencephaly, Schizencephaly) - Congenital brain tumors Brain stem Arnold-Chiari malformation Spinal cord Spina bifida - Currarino syndrome - Sacrococcygeal teratoma - Diastematomyelia - Syringomyelia see also non-congenital CNS and PNS (G, 320-359)