Filed under: Brain & Nervous System
Chiari malformation (kee-AHR-ee mal-for-MAY-shun) is a condition in
which brain tissue protrudes 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 improved
imaging tests have led to more frequent diagnoses.
The adult form, called 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 most common pediatric form,
called Chiari malformation type II, is 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.
Doctors categorize Chiari malformation into four 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
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:
* Type I (adult)
* Type II (pediatric)
In Chiari malformation type I, signs and symptoms usually appear during
late childhood or adulthood. Chiari II malformation is usually noted by
ultrasound during pregnancy or at birth or early infancy. Although these
types are less serious than the more rare pediatric forms, types III
and IV, signs and symptoms still can be life disrupting.
Chiari malformation type I
Headaches, often severe, are the classic symptom of Chiari malformation.
They're typically precipitated with sudden coughing, sneezing or
straining. People with Chiari malformation type I can also experience:
* Neck pain (running down the shoulders at times)
* 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)
* Slurred speech
Less often, people with Chiari malformation may experience:
* Ringing or buzzing in the ears (tinnitus)
* Poor bladder control
* Chest pain, in a band-like pattern around the chest
* Curvature of the spine (scoliosis) related to spinal cord impairment
* Abnormal breathing — specifically, sleep apnea, characterized by periods of breathing cessation during sleep
Chiari malformation type II
In Chiari malformation type II, a greater amount of tissue protrudes
into the spinal canal compared with type I. The signs and symptoms can
include those related to a form of spina bifida, called
myelomeningocele, that always accompanies Chiari II malformation. In
myelomeningocele, the backbone and the spinal canal have not closed
properly before birth.
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 obvious at birth or by
Chiari malformation type IV
In people with the even more severe Chiari malformation type IV, the
brain itself has never developed normally. This form also is obvious at
birth or by intrauterine ultrasound.
When to see a doctor
If you or your child has any of the signs and symptoms that may be
associated with Chiari malformation, see your doctor for an evaluation.
Because many symptoms of Chiari malformation can also be associated with
other disorders, a thorough medical evaluation is important. Head pain,
for example, can be caused by migraines, sinus disease or a brain
tumor, as well as Chiari malformation. Other signs and symptoms overlap
with other conditions, such as multiple sclerosis.
Chiari malformation occurs when the section of the skull containing the
cerebellum is too small or is deformed, thus putting pressure on and
crowding the brain. The lowermost portion, or tonsils, of the cerebellum
are displaced into the upper spinal canal. The pediatric form, Chiari
II malformation, is always associated with a myelomeningocele. The adult
form, Chiari I malformation, results primarily from a too small back
portion of the skull.
When the cerebellum is pushed into the upper spinal canal, it can
interfere with the normal flow of cerebrospinal fluid (CSF) that
protects your brain and spinal cord. This impaired circulation of CSF
can lead to the blockage of signals transmitted from your brain to your
body, or to a buildup of spinal fluid in the brain or spinal cord.
Alternatively, the pressure from the cerebellum upon the spinal cord or
lower brainstem can cause neurological signs or symptoms.
There's some evidence that Chiari malformation runs in some families.
However, research into a possible hereditary component is still in its
In some people, Chiari malformation can become a progressive disorder
and lead to serious complications. In others, there may be no associated
symptoms, and no intervention is necessary. The complications
associated with this condition include:
* Hydrocephalus. This accumulation of excess fluid within the brain
may require placement of a flexible tube (shunt) to divert and drain the
cerebrospinal fluid to another area of the body.
* Paralysis. This may occur because of the crowding and pressure on
the spinal cord. Paralysis tends to be permanent, even after surgical
* Syringomyelia. Some people with Chiari malformation also develop a
condition called syringomyelia, in which a cavity or cyst (syrinx)
forms within the spinal column. Although the mechanism connecting Chiari
malformation with syringomyelia is unclear, it may be associated with
injury or displacement of nerve fibers in the spinal cord. When a cavity
forms, it tends to be filled with fluid and can additionally impair the
function of the spinal cord.
* Death. When a child is born with Chiari malformation type IV, death is common, usually early in infancy.
Preparing for your appointment
You're likely to start by seeing your family doctor or a general
practitioner. However, in some cases when you call to set up an
appointment, you may be referred to a doctor who specializes in
disorders of the brain and nervous system (neurologist).
Because appointments can be brief, and because there's often a lot of
ground to cover, it's a good idea to be well prepared for your
appointment. Here's some information to help you get ready for your
appointment, and what to expect from your doctor.
What you can do
* Be aware of any pre-appointment restrictions. At the time you make
the appointment, be sure to ask if there's anything you need to do in
* Write down any symptoms you're experiencing, including any that
may seem unrelated to the reason for which you scheduled the
appointment. For example, even though your primary complaint may be
headache, your doctor will want to know about any changes you may have
noticed in your vision, speech or coordination.
* Write down key personal information, including any major stresses and recent life changes.
* Make a list of your key medical information, including other
conditions you're being treated for and the names of the medications
that you're taking.
* Take a family member or friend along, if possible. Sometimes it
can be difficult to soak up all the information provided to you during
an appointment. Someone who accompanies you may remember something that
you missed or forgot.
* Write down questions to ask your doctor.
Prepare a list of questions so that you can make the most of your
limited time with your doctor. List your questions from most important
to least important in case time runs out. For Chiari malformation, some
basic questions to ask your doctor include:
* What is likely causing my symptoms or condition?
* Other than the most likely cause, what are possible causes for my symptoms or condition?
* What kinds of tests do I need?
* Do I need treatment?
* If you don't think I need to be treated now, how will you monitor me for changes in my condition?
* If you recommend surgery, what should I expect from my recovery?
* What is the risk of complications from surgery?
* What is my long-term prognosis following surgery?
* I have these other health conditions. How can I best manage them together?
* Are there any restrictions that I need to follow?
* Should I see a specialist? What will that cost, and will my insurance cover seeing a specialist?
* Are there any brochures or other printed material that I can take home with me? What Web sites do you recommend visiting?
In addition to the questions that you've prepared to ask your doctor,
don't hesitate to ask questions during your appointment at any time that
you don't understand something.
What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to
answer them may reserve time to go over any points you want to spend
more time on. Your doctor may ask:
* When did you first begin experiencing symptoms?
* Have your symptoms been continuous, or occasional?
* If you experience head and neck pain, is it made worse by sneezing, coughing or straining?
* How severe is your head and neck pain?
* Have you noticed any change in your coordination, including problems with balance or with hand coordination?
* Do your hands and feet feel numb or do they tingle?
* Have you developed any difficulty swallowing?
* Do you experience episodes of dizziness or faintiness? Have you ever passed out?
* Have you developed any problems with your eyes and ears, such as blurred vision or a ringing or buzzing in your ears?
* Have you had problems with bladder control?
* If your share a bed or bedroom with someone else, have they commented on changes in your breathing while you sleep?
* Have you been taking pain relievers or using other approaches to relieve your discomfort? Does anything seem to work?
* Do you have any additional symptoms, such as hearing loss, fatigue, or changes in your bowel habits or appetite?
* Have you been diagnosed with any other health conditions?
* Has anyone in your family been diagnosed with Chiari malformation?
What you can do in the meantime
To ease your discomfort while you wait to see your doctor, try taking a
nonsteroidal anti-inflammatory drug (NSAID) such as ibuprofen (Advil,
Motrin, others). Acetaminophen (Tylenol, others) also may relieve mild
to moderate pain.
Tests and diagnosis
Exam and medical history
The diagnostic process begins with your doctor taking your medical
history and giving you a complete physical examination. Your doctor will
ask whether you're having symptoms such as head and neck pain, and will
ask you to describe them. He or she will also check your fine motor
skills and swallowing ability.
If you have symptoms such as head pain, and the exact cause isn't
apparent to your doctor, you'll likely undergo a magnetic resonance
imaging (MRI) scan of your skull, which is the definitive diagnostic
tool for Chiari malformation. Your doctor might also use computerized
* MRI. This test is a safe and painless test that produces 3-D,
high-resolution images of structural abnormalities that may be
contributing to your symptoms. It can provide pictures of the cerebellum
and determine whether it extends into the spinal canal. An MRI can be
repeated and, over time, can be used to monitor the progression of this
* CT. Your doctor may recommend other imaging techniques such as a
CT scan. A CT scan uses X-rays in conjunction with a computer to produce
precise, sectional images of the bone tissue that surrounds the spinal
Treatments and drugs
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
When headaches or other types of pain are the primary symptom, your
doctor may recommend pain medication. Some people experience symptom
relief with anti-inflammatory or pain-relieving agents, such as
indomethacin (Indocin). This approach may prevent or delay the need for
Reducing pressure by surgery
Surgery is the approach doctors use most often to treat symptomatic
Chiari malformation. The goal is to stop the progression of changes in
the anatomy of the brain and spinal canal, as well as ease or stabilize
symptoms. When successful, surgery can reduce pressure on the cerebellum
and the spinal cord, and restore the normal flow of spinal fluid.
In the most common operation for Chiari malformation — called posterior
fossa craniectomy or posterior fossa decompression — your surgeon
removes a small section of bone in the back of the skull, relieving
pressure by giving the brain more room. The covering of the brain,
called the dura, is then opened, and a patch is sewn in place to enlarge
the covering and provide more room for the brain. This patch may be an
artificial material, or it could be tissue harvested from your own leg
or neck. The exact technique may vary, depending on whether a
fluid-filled cavity is present, or if you have hydrocephalus. The
operation takes about two to three hours, and recovery in the hospital
usually requires two to four days.
Surgical risks and follow-up
The use of surgery carries risks — the possibility of infection or
problems with wound healing. Discuss the pros and cons with your doctor
when deciding whether surgery is the best alternative for you. The
operation reduces symptoms in most people, but if nerve injury in the
spinal canal has already occurred, this procedure won't reverse the
After the operation, 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.