User:Mr. Ibrahem/Chiari malformation

Not to be confused with Budd–Chiari syndrome.

Chiari malformation
Other names	Arnold–Chiari malformation
A sagittal FLAIR MRI scan, from a patient with an Arnold-Chiari malformation, demonstrating tonsillar herniation of 7 mm.
Pronunciation	/kiˈɑːriː/
Specialty	Neurosurgery
Symptoms	Headaches, neck pain, vision problems, world spinning, hearing loss, poor coordination, no symptoms
Complications	Cerebellar tonsillar herniation, hydrocephalus, syrinx
Usual onset	Generally present at birth
Types	0, I, II, III, IV
Causes	Unknown
Diagnostic method	Medical imaging
Differential diagnosis	Intracranial hypotension, increased intracranial pressure, normal variant
Treatment	Observation, decompressive surgery
Frequency	0.5 to 3.5%

Chiari malformation (CM), also known as Arnold–Chiari malformation, is a group of deformities that involves the back of the skull and brain. Symptoms may include headaches, neck pain, vision problems, world spinning, hearing loss and trouble with coordination, though some may have no symptoms. Complications can include cerebellar tonsillar herniation, hydrocephalus, and syrinx.

The cause is unknown, though a number of theories have been proposed. The specific part of the brain involved are the cerebellum, pons, and medulla oblongata. It is classified as type 0, I, II, III, or IV. Diagnosis is suspected based on symptoms and confirmed by medical imaging.

People with no symptoms may not require specific treatment. Otherwise the primary treatment is decompressive surgery. Pain may be managed with NSAIDs or a cervical collar. Chiari I generally has a good prognosis while Chiari II has a 15% risk of death by age 3.

Chiari I affects bout 0.5 to 3.5% of people, Chiari II occurs in about 0.4 per 1,000 births, and other types are less common. Females may be affected more often than males. It is named after the Austrian pathologist Hans Chiari who first described the condition in 1891 and the German pathologist Julius Arnold who further elaborated on it.