Chiari Malformation - An Overview
Information and Resources About This Rare Neurological Disorder
Oct 7, 2009
Wider use of MRI scans and changing definitions may lead to more people being diagnosed who have classic symptoms of Chiari. Early diagnosis and treatment may help prevent serious damage to the spinal cord and give relief for some of the symptoms.
Chiari is a Brain Disorder
Normally the cerebellum, the rear portion of the brain, is contained in a small bony space in the back of the skull. In Chiari, the rear section of the cerebellum, called cerebellar tonsils because of their shape, are compressed and forced out of their usual position. They protrude into the upper end of the spinal canal blocking the flow of cerebral spinal fluid. Chiari is often congenital (present at birth), but many people do not develop symptoms until much later in life.
Types of Chiari Malformation
Chiari malformations are classified into four types:
- Chiari Type I - The rear portion of the cerebellum, the cerebellar tonsils, are pushed through the foramen magnum, the area at the base of the skull where the spinal cord meets the brain and into the spinal canal. This is the more common type and the only kind of Chiari found in adults.
- Chiari Type II - This is the form of Chiari that is most often seen in children with spina bifida
- Chiari Type III - In this very rare form of Chiari, the cerebellum and brain stem protrude through the foramen magnum and into the spinal canal.
- Chiari Type IV - Like Type III, this form is quite rare. In Type IV, the cerebellum is not fully developed, and children who are born with it have a low survival rate.
Diagnosis:
Chiari malformations are usually diagnosed by MRI scans of the brain and spinal cord. They are often noticed incidentally while scanning for another reason. Once a Chiari is identified, other tests may be needed to look for possible related conditions including tethered cord and syringomyelia.
Changing Views On Diagnosis:
Historically, Chiari was defined as a herniation of at least 3-5 mm in size, but there is no consensus on this. Research indicates that there is not a strong relationship between the size of the malformation and the symptoms a patient experiences.
In Milwaukee, Wisconsin, specialists at the Wisconsin Chiari Center put the problem in a wider context, "At the Wisconsin Chiari Center, we have come to view the problem as a result of the compression of the brain stem or spinal cord at the base of the skull." they state on their website. They find that symptoms of Chiari may occur in patients whose herniation is as small as one millimeter.
Nor are the symptoms always due to Chiari. According to a review on the Wisconsin Center's website, "Our studies have shown us that the neurological symptoms of Chiari malformation may also occur because of other disorders such as cervical spinal stenosis, tethered cord syndrome and syringomyelia."
They note that some patients may have both Chiari and one of these other disorders.
Symptoms:
Chiari can cause a wide range of symptoms in many while others may be free of them altogether. A study reported in the Journal of American Nurse Practitioners showed at least half of all Chiari patients show the following symptoms:
- Headache
- Dizziness
- Difficulty sleeping
- Weakness in arms/hands
- Neck pain
- Numbness/tingling in arm, hand
- Fatigue
- Nausea
- Shortness of breath
- Blurred Vision
- Tinnitus
- Difficulty swallowing
- Leg weakness
Source: Conquer Chiari: (J Am Acad Nurse Pract. 2004 Mar;16(3):134-8.)
Scoliosis (curved spine), hydrocephalus (too much fluid build-up around the brain), and syringomyelia (cyst in the spinal cord) are also common in those with Chiari.
Treatment for Chiari
Managing symptoms and surgery when needed are the only known treatments for Chiari. Physical therapy, pain management, and treatment for headaches may offer some relief. Surgery may help prevent further injury and improve some symptoms, but has risks and limitations also.
When surgery is necessary, the purpose is to decompress the spinal cord and brain stem. Surgery is done to create more space in the rear of the skull for the brain and spinal cord. During the operation some of the skull bone may be removed permitting the tonsils to move back into their normal position. More than one surgery may be needed to manage the symptoms related to Chiari.
Sources:
American Syringomyelia and Chiari Alliance Project
Conquer Chiari (Chiari and Syringomyelia Patient Education Foundation)
The Wisconsin Chiari Center (Chiari Malformation and Beyond)
Related Links:
ASAP - Resource for Two Rare Disorders
Resources:
Conquer Chiari
2311 N. Prospect Ave., Suite 2B
Milwaukee, WI 53211
Phone: (414) 319-3017
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