Everyone gets a headache once in awhile. Sometimes we ride it out. Other times we take medication for pain relief. Either way, we take for granted that it will go away, and we take comfort in the fact that headaches don’t occur too often.
But for people with Chiari type 1 malformations, the headache may not go away. If it does, it will certainly come back. Affected individuals may also experience breathing or swallowing difficulties, weakness, numbness or radiating pain, or other rare neurological issues.
Chiari malformations involve improper development of the base of the skull. The opening in the skull between the brain and the spinal cord is called the foramen magnum, and it is this opening and the surrounding tissue that are affected by the condition.
People are born with Chiari malformations, but symptoms may not be present at birth depending on the severity of the malformation. They are broken down into 4 types based on severity. Most people affected by the disorder are affected by Type 1, which is fortunately the least severe.
In Chiari type 1 malformations, the cerebellum (the lowest part of the brain) protrudes into the opening at the base of the skull. Patients may develop symptoms as adolescents or young adults. In some cases they come later or not at all.
Treatment for a type 1 Chiari malformation depends on the patient’s symptoms (a patient without symptoms may never need treatment).
For those patients whose symptoms interfere with their lives, the most common course of treatment involves surgery to relieve pressure on the area. In this procedure, a neurosurgeon will decompress the affected area by removing some of the bone at the base of the skull and sometimes the lamina from the upper vertebrae – the bone that surrounds and protects the spinal cord. This can relieve the pressure on the surrounding tissue and nerves and thus reduce symptoms.
In addition, the dura is traditionally opened in surgery for Chiari type 1 malformations. The dura is a thick, tough tissue that surrounds the brain and spinal cord and helps protect them. In addition, the dura contains the cerebrospinal fluid, which cushions the brain, bathes it with nutrients, and carries waste away. Like decompressing the vertebrae, opening the dura and patching it creates more space for the brain, nerves and fluid.
But opening the dura is associated with possible complications, including infection and persistent spinal fluid leakage.
Fortunately, Dr. Neil A. Feldstein, of the Pediatric Neurosurgery Center at Columbia University Medical Center/NewYork-Presbyterian Hospital finds that many, if not most, patients – children and adults alike – with Chiari type 1 malformations do get sufficient relief of symptoms from removal of bone without opening the dura. Avoiding this step dramatically reduces complications and recovery time.
However, a small number of patients may not get adequate relief from removing only bone and require a second surgery to open the dura. A surgeon must identify the best approach for each individual based on the characteristics of the patient’s disease and symptoms.
Dr. Feldstein has performed hundreds of Chiari type 1 surgeries in which the dura was left in tact. His extensive experience has yielded reliable criteria for determining which patients will do well without opening the dura. He uses the position of the cerebellum, the part of the brain that sits just above the opening in the skull, as a yardstick to determine which type of surgery a patient will require.
Patients whose cerebellum protrudes less than eight millimeters through the base of the skull do well without having the dura opened during surgery. The complication rate is a very low; 2.6 percent compared to 15-25 percent for patients whose dura is opened. Only a small percent will require a second surgery to open the dura for further relief of symptoms.
However, when the cerebellum protrudes more than eight millimeters through the base of the skull, to the second vertebra or further, the need for a second surgery is higher if the dura is not opened initially. For these patients, it may be the best approach to open the dura during the initial surgery since the need for a second surgery would be high otherwise.
Dr. Feldstein’s approach to minimizing risk in Chiari type 1 surgery is representative of the work done at Columbia Neurosurgery, aimed at individualizing treatments for children and adults with Chiari and other neurosurgical disorders. This individualized approach minimizes risk while improving outcomes.
Image credit: [© Nevit Dilmen]/Wikimedia Creative Commons
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