- By sahlhealth
- May 18, 2021
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Chiari malformation (kee-AH-ree mal-for-MAY-shun) is a condition in which brain tissue extends into your spinal canal. It occurs when part of your skull is abnormally small or misshapen, pressing on your brain and forcing it downward.
Chiari malformation is uncommon, but increased use of imaging tests have led to more frequent diagnoses.
Doctors categorize Chiari malformation into three types, depending on the anatomy of the brain tissue that is displaced into the spinal canal, and whether developmental abnormalities of the brain or spine are present.
Chiari malformation type I develops as the skull and brain are growing. As a result, signs and symptoms may not occur until late childhood or adulthood. The pediatric forms, Chiari malformation type II and type III, are present at birth (congenital).
Treatment of Chiari malformation depends on the form, severity and associated symptoms. Regular monitoring, medications and surgery are treatment options. In some cases, no treatment is needed.
Many people with Chiari malformation have no signs or symptoms and don't need treatment. Their condition is detected only when tests are performed for unrelated disorders. However, depending on the type and severity, Chiari malformation can cause a number of problems.
The more common types of Chiari malformation are:
In Chiari malformation type I, signs and symptoms usually appear during late childhood or adulthood.
Chiari malformation type II is usually noted by ultrasound during pregnancy. It may also be diagnosed after birth or in early infancy.
Although these types are less serious than the more rare pediatric form, type III, signs and symptoms still can be life disrupting.
Chiari malformation type I
Headaches, often severe, are the classic symptom of Chiari malformation. They generally occur after sudden coughing, sneezing or straining. People with Chiari malformation type I can also experience:
Unsteady gait (problems with balance)
Poor hand coordination (fine motor skills)
Numbness and tingling of the hands and feet
Difficulty swallowing, sometimes accompanied by gagging, choking and vomiting
Vision problems (blurred or double vision)
Speech problems, such as hoarseness
Less often, people with Chiari malformation may experience:
Ringing or buzzing in the ears (tinnitus)
Slow heart rhythm
The curvature of the spine (scoliosis) related to spinal cord impairment
Abnormal breathing, such as central sleep apnea, characterized by periods of breathing cessation during sleep
Chiari malformation type II
In Chiari malformation type II, a greater amount of tissue extends into the spinal canal compared with Chiari malformation type I.
The signs and symptoms can include those related to a form of spina bifida called myelomeningocele that nearly always accompanies Chiari malformation type II. In myelomeningocele, the backbone and the spinal canal haven't closed properly before birth.
Symptoms may include:
Changes in breathing pattern
Swallowing problems, such as gagging
Quick downward eye movements
Weakness in arms
Chiari malformation type III
In one of the most severe types of the condition, Chiari malformation type III, a portion of the lower back part of the brain (cerebellum) or the brainstem extends through an abnormal opening in the back of the skull. This form of Chiari malformation is diagnosed at birth or by ultrasound during pregnancy.
This type of Chiari malformation has a higher mortality rate and may also cause neurological problems.
Treatment for Chiari malformation depends on the severity and the characteristics of your condition.
If you have no symptoms, your doctor likely will recommend no treatment other than monitoring with regular examinations and MRIs.
When headaches or other types of pain are the primary symptoms, your doctor may recommend pain medication.
Reducing pressure by surgery
Doctors usually treat symptomatic Chiari malformation with surgery. The goal is to stop the progression of changes in the anatomy of your brain and spinal canal, as well as ease or stabilize your symptoms.
When successful, surgery can reduce pressure on your cerebellum and spinal cord, and restore the normal flow of spinal fluid.
In the most common surgery for Chiari malformation, called posterior fossa decompression, your surgeon removes a small section of bone in the back of your skull, relieving pressure by giving your brain more room.
In many cases, the covering of your brain, called the dura mater, may be opened. Also, a patch may be sewn in place to enlarge the covering and provide more room for your brain. This patch may be an artificial material, or it could be tissue harvested from another part of your body.
Your doctor may also remove a small portion of the spinal column to relieve pressure on your spinal cord and allow more space for the spinal cord.
The surgical technique may vary, depending on whether a fluid-filled cavity (syrinx) is present, or if you have fluid in your brain (hydrocephalus). If you have a syrinx or hydrocephalus, you may need a tube (shunt) to drain the excess fluid.
Surgical risks and follow-up
Surgery involves risks, including the possibility of infection, fluid in your brain, cerebrospinal fluid leakage or problems with wound healing. Discuss the pros and cons with your doctor when deciding whether surgery is the most appropriate alternative for you.
The surgery reduces symptoms in most people, but if nerve injury in the spinal canal has already occurred, this procedure won't reverse the damage.
After the surgery, you'll need regular follow-up examinations with your doctor, including periodic imaging tests to assess the outcome of surgery and the flow of cerebrospinal fluid.