What is Arnold Chiari Malformation?
Arnold-Chiari Malformation is a pathological condition in which some tissues of brain tend to extend into the spinal canal. This usually happens if the skull is extremely small and out of shape pressurizing the brain to move in a downward direction. Arnold-Chiari Malformation is quite rare but with advancement of medical science and the technology available these days this disease is diagnosed more frequently and easily. There are two types of Arnold-Chiari Malformations, type I and type II. Arnold-Chiari Malformation Type I develops when the child is growing and the child may not experience any symptoms until late childhood or early adolescence. Arnold-Chiari Malformation Type II which is the more common form of Arnold-Chiari Malformation is congenital and is present at the time of the birth of the child. Treating Arnold-Chiari Malformation depends on the severity of the malformation and the type of malformation with observation, medications and surgery being the preferred choice of treatment.
What Causes Arnold Chiari Malformation?
Causes of Arnold-Chiari Malformation Type I: This form of malformation occurs when the section of the brain which contains the cerebellum is misshapen or deformed thus pressurizing the brain. In this malformation the lower part of the cerebellum moves into the spinal canal.
Arnold-Chiari Malformation Type II: This is most commonly caused due to a medical condition called as myelomeningocele.
Now the question is what happens when the cerebellum is pushed into the top part of the spinal canal. When this happens, it tends to interfere with the flow of the CSF or cerebrospinal fluid which protects the brain and the spinal cord. This impaired flow of CSF causes signals transmitted from the brain to other parts of the body to get blocked or accumulation of CSF into the brain or the spinal cord resulting in symptoms.
What are the Risk Factors for Arnold Chiari Malformation?
Some studies point to a genetic link to development of Arnold-Chiari Malformation even though this is still a matter of ongoing research and investigations.
What are the Symptoms of Arnold Chiari Malformation?
As stated, Arnold-Chiari Malformation is classified into two main types and the symptoms caused by them are mentioned below.
Symptoms of Arnold-Chiari Malformation Type I: In this type the child may not experience any symptoms until late childhood or early adolescence and this malformation is usually an incidental finding on imaging studies conducted to rule out some other disorder. Some of the symptoms experienced by the patient of Arnold-Chiari Malformation Type 1 are:
- Persistent Headaches which begin all of a sudden after a bout of coughing, sneezing, or doing any strenuous activity
- Persistent pain in the neck
- Gait imbalance
- Problems with fine motor skills
- Numbness and paresthesias in the extremities
- Frequent dizziness
- Speech impediment
- In rare cases tinnitus.
Symptoms of Arnold-Chiari Malformation Type II: As stated, this type of malformation usually occurs with a medical condition called as myelomeningocele. Some of the symptoms that the child with Arnold-Chiari Malformation Type II may experience are:
- Changes in breathing
- Frequent gagging during feeding
- Weakness of the arms.
How is Arnold Chiari Malformation Diagnosed?
To begin with the treating physician will take a detailed history of the patient as to when the symptoms started and how severe the symptoms are. A physical examination will also be conducted to look for certain reproducible neurological symptoms. If Arnold-Chiari Malformation is suspected then imaging studies will be ordered to include MRI scan of the brain and spinal cord which will give three dimensional images of the brain and spinal cord and clearly show a misshapen skull and the cerebellum going into the spinal canal. Once Arnold-Chiari Malformation is confirmed, repeated MRIs may be taken so as to check the status of the condition.
How is Arnold Chiari Malformation Treated?
The treatment options for treating Arnold-Chiari Malformation are dependent on the type of the malformation and the severity of it. In case if the malformation produces no symptoms at all then the physician may just plain observation of the condition with serial MRIs looking for any changes in the malformation and no specific treatment is rendered. Pain medications may be given for symptoms of frequent headaches and other pains which may be experienced by the patient. For more severe forms of Arnold-Chiari Malformation surgery is the preferred route to go. The procedure that is done is to relieve the pressure that is put on the brain and the spinal cord due to the malformation and thus stop progression of the disease and relieve the symptoms. Once the procedure is completed successfully then the pressure on the brain and spinal cord is significantly reduced and there is relief from the lot of the symptoms. The most common surgical procedure performed for Arnold-Chiari Malformation is known as posterior fossa decompression where the surgeon will remove a small portion of the bone behind the skull to make more room for the brain to expand an thus relieving the pressure from the brain. The surgeon may also remove a part of the spinal column to relieve pressure being put on the spinal cord. As is the case with all surgical procedures, there are inherent risks in this surgery as well to include risks of infection, accumulation of fluid in the brain, CSF leakage, and delayed wound healing. Almost all of the symptoms of Arnold-Chiari Malformation are relieved after successful completion of the surgery but in case of there is a nerve injury in the spinal cord then surgery may not be able to reverse the damage already done. Postprocedure, the patient will require regular checkups in the form of serial MRIs and other imaging tests to look at the status of the brain and spinal cord and check the status of Arnold-Chiari Malformation.