In many infants who become symptomatic from a Chiari II malformation, the symptom onset and progression are severe and rapid, and this requires an urgent or emergency approach. Surgical treatment of these malformations depends on the type of malformation. The goal of surgery is to relieve the symptoms or stop the progression of the syrinx or symptoms.
Chiari I malformations may be treated surgically with only local decompression of the overlying bones, decompression of the bones and release of the dura a thick membrane covering the brain and spinal cord or decompression of the bone and dura and some degree of cerebellar tissue resection. Occasionally some patients will also require cervical spinal fusion. Decompression is performed under general anesthesia. It consists of removing the back of the foramen magnum and often the back of the first few vertebrae to the point where the cerebellar tonsils end.
This provides more space for the brainstem, spinal cord and descended cerebellar components. A tissue graft is often spliced into this opening to provide even more room for the unimpeded passage of CSF. In some patients the descended cerebellar components are debulked or removed. Occasionally, the cavity within the spinal cord resulting from hydromyelia can be drained with a diverting shunt tube.
This tube can divert the fluid from inside the spinal cord to outside the cord, or be directed to either the chest or abdominal cavity. These procedures can be done together or separately. Chiari II decompression is treated similarly, but is usually restricted to decompressing the tissues in the spinal canal and leaving the back of the skull alone. The benefits of surgery should always be weighed carefully against its risks.
Although some patients experience a reduction in their symptoms, there is no guarantee that surgery will help every individual. Nerve damage that has already occurred usually cannot be reversed.
Some surgical patients need repeat surgeries, while others may not achieve symptom relief. Central canal : A small tubular cavity in the center of the spinal cord which is normally not dilated.
Cerebellum : The portion of the brain which is in the posterior fossa. It is involved in coordination of movements. Dysraphism : Developmental abnormalities in the midline region of the back, with incomplete fusion or malformation of a seam, such as in all forms of spina bifida.
Foramen magnum : The opening at the base of the skull through which the spinal cord passes. Hydrocephalus : A condition in which excess cerebrospinal fluid CSF builds up within the ventricles fluid-containing cavities of the brain and may increase pressure within the head. Medulla oblongata : Lowest part of the brainstem, located just above the spinal cord, at the exit from the skull. Provides control for breathing and heart function. Pons : Band of nerve fibers linking the medulla oblongata and the cerebellum with the midbrain.
Posterior fossa : The cavity in the back part of the skull which contains the cerebellum, brainstem and cranial nerves Suture : The saw-like edge of a cranial bone that serves as joint between bones of the skull. Syrinx syringomyelia, hydromyelia : These terms all refer to a fluid filled cavity in the spinal cord.
Tonsils : The portion of the cerebellum that protrudes into the spinal canal, which may become elongated. Vallecula of cerebellum : The longitudinal hollow on the inferior surface of the cerebellum, between the hemispheres, in which the medulla oblongata rests. Ventricles : Fluid-filled cavities within the brain. The spinal fluid is produced by a gland in the ventricle about two pints each day and circulates through the ventricles and over the surface of the brain into the veins.
If there is a block in the system, the fluid can build up and cause hydrocephalus. Vermis : The narrow middle zone between the two hemispheres of the cerebellum; the portion projecting above the level of the hemispheres on the upper surface is called the superior vermis; the lower portion, sunken between the two hemispheres and forming the floor of the vallecula, is the inferior vermis.
The AANS does not endorse any treatments, procedures, products or physicians referenced in these patient fact sheets. This information is provided as an educational service and is not intended to serve as medical advice. If you've been diagnosed with a Chiari malformation, you should contact your doctor for advice if you develop any new symptoms or your symptoms worsen.
Treatment for Chiari I malformation depends on whether you have any symptoms and how severe they are. You might not need any treatment if you do not have any symptoms.
If your headaches are severe or you have problems caused by the pressure on your spinal cord such as movement difficulties , surgery may be recommended.
Under general anaesthetic a cut is made at the back of your head and the surgeon removes a small piece of bone from the base of your skull. They may also remove a small piece of bone from the top of your spine. This will help reduce the pressure on your brain and allow the fluid in and around your brain and spinal cord to flow normally. The aim of surgery is to stop existing symptoms getting any worse. Some people also experience an improvement in their symptoms, particularly their headaches.
However, surgery sometimes results in no improvement or symptoms getting worse. There's also a small risk of serious complications, such as paralysis or a stroke.
Since appropriate gene expression is crucial for normal brain development, variations in chromodomain genes have been linked to neurodevelopmental conditions such as autism spectrum disorders, developmental delays, and unusually large or small heads.
The association between chromodomain genes and head size inspired Haller and colleagues to measure the heads of children with Chiari malformations, comparing them to age-matched controls and to population averages provided by the Centers for Disease Control and Prevention. Children with Chiari tended to have larger than average heads. The findings suggest that children with larger heads or people with other neurodevelopmental disorders linked to chromodomain genes may benefit from screening for Chiari malformation.
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