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Arnold chiari malformation with syrinx
Carrie Lee
Chiari malformation is a condition in which brain tissue protrudes into the spinal canal.
They affect the area in the lower back of the skull where the brain and spinal cord connect. They are named after Hans Chiari, an Austrian pathologist, who first identified types I-III in 1891.
Julius Arnold further expanded the definition of Chiari malformation type II and some medical sources began using the name Arnold-Chiari malformation. They have also been known as congenital tonsillar herniation, tonsillar ectopia or tonsillar descent. Doctors categorize the malformations in to 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 present. Type I is the most common type in older children. The lower part of the cerebellum – but not the brain stem – extends into an opening at the base of the skull. The opening is called the foramen magnum. Normally, only the spinal cord passes through this opening. Type I is also the only type of the malformation that can be acquired. Severe headaches are a common symptom that are usually precipitated with sudden coughing, sneezing, or straining. Other symptoms include: Neck pain, problems with balance, poor hand coordination, numbness and tingling of the hands and feet, vision problems, and slurred speech. Symptoms that are uncommon include tinnitus, poor bladder control, chest pain, and scoliosis. It occurs more often in females than males. Scientists once believed that Chiari
Malformations occurred in only 1 in every 1000 births, but the increased use of diagnostic imaging techniques such as CT scans and MRIs suggests that the condition may be much more common. Most defects develop during fetal development due to genetic mutations or a maternal diet that lacked certain nutrients. The indented bony space at the base of the skull is abnormally small and as a result, pressure is placed on the cerebellum which blocks the flow of cerebrospinal fluid.
Chiari type I is the least severe of the four. The rear displacement of peglike cerebellar tonsils below the level of the foramen magnum is the trademark sign. The result of impaction of the foramen magnum, pressure of the cervicomedullary junction by the ectopic tonsils, and the interference of the flow of CSF (cerebrospinal fluid) through the area produce this syndrome. Chiari type II is not as common and more severe. Because of this, it becomes evidential in infancy or early childhood. Its indication is caudal displacement of the lower brainstem through the foramen magnum. The problems arise from dysfunction of the brainstem and lower cranial nerves. Chiari types III and IV are very rare and are usually not compatible with life. They have little clinical significance. In type III, it is the herniation of the cerebellum into a high cervical myelomeningocele. Type IV refers to the failure of development of the cerebellum. A genetic basis for Chairi I has been suggested based on an analysis of familial aggregation. There have been recent studies that suggest linkage to chromosomes nine and fifteen.
Syringomyelia is the formation of a fluid-filled cyst (syrinx) within the spinal cord.3
This is associated with Chairi Malformation because it is one type of congenital brain defect. If the flow of cerebrospinal fluid is blocked and has to start flowing again itself, syrinx may form within the tissue. The cyst can be small at the beginning. Some think that the differences in pressure between the brain and the spinal cord slowly force CSF into the cyst, therefore making it larger and presses on the surrounding nerves of the spinal cord, which causes damage to the nerves. Symptoms of Syringomyelia may occur rapidly due to straining and coughing. Some complications include syringobulbia, which include difficulty swallowing, involuntary flickering of the eyes, and speech problems due to tongue atrophy.
