What Is Chiari Malformation?
Arnold-Chiari Malformation is a
condition in which the cerebellum portion of the brain protrudes into the spinal
canal. It may or may not be apparent at birth. Arnold-Chiari I type malformation
usually causes symptoms in young adults and is often associated with
syringomyelia, in which a tubular cavity develops within the spinal cord.
Arnold-Chiari II type malformation is associated with myelomeningocele (a defect
of the spine) and hydrocephalus (increased cerebrospinal fluid and pressure
within the brain), which usually are apparent at birth. Myelomeningocele usually
causes paralysis of the legs and, less commonly, the arms. If left untreated,
hydrocephalus can cause mental impairment. Either type of Arnold-Chiari
Malformation can cause symptoms of headache, vomiting, difficulty swallowing and
hoarseness.
Adults and adolescents who are unaware they have
Arnold-Chiari I type malformation may develop headache that is predominantly
located in the back of the head and is increased by coughing or straining.
Symptoms of progressive brain impairment may include dizziness, an impaired
ability to coordinate movement, double vision, and involuntary, rapid, downward
eye movements.
Is There Any Treatment?
Infants and children
with myelomeningocele may require surgery to repair protrusion of the meningeal
sac into the spinal cord. Hydrocephalus may be treated with surgical
implantation of a shunt to relieve increased pressure on the brain. Some adults
with Arnold-Chiari Malformation may benefit from surgery in which the existing
opening in the back of the skull is enlarged.
What Is the
Prognosis?
Infants with very severe malformations may have
life-threatening complications. Most patients who have surgery experience a
reduction in their symptoms. Some patients may experience prolonged periods of
relative stability.
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