Arnold-Chiari Malformation

A structural malformation in the brain, which leads to the displacement of the cerebellar tonsils and medulla, is known as Arnold-Chiari malformation. In this disorder, the cerebellar tonsils shift downwards through the foramen magnum. The malformation may also cause hydrocephalus, which results in the accumulation of cerebrospinal fluid (CSF) in the brain cavities. Due to the displacement of the cerebellar parts of the brain, the balance between the inflow and outflow of blood in the brain gets disturbed. It results into the blockage of the CSF.

Symptoms
The person affected by such a malformation may suffer from dizziness, vision problems, numbness and headache. Arnold-Chiari malformation, is one of the forms of Chiari malformation and is also known as type II malformation. In this type, the person may suffer from 'Spina bifida cystica' or 'myelomenigocele'. Myelomeningocele is condition in which the spinal cord remains underdeveloped.

The person affected by the malformation suffers from headaches. This headache is sometimes confused with migraine. Intense pressure in the back of the head is the main reason behind the headache in Arnold-Chiari malformation.

Related Symptoms
Along with the cerebellar displacement, the Arnold-Chiari malformation may show the following symptoms.

• Syringomyelia: A disorder, in which a cavity is formed inside the spinal cord. The cavity which is also referred to as a 'syrinx', elongates in course of time, damaging the spinal cord. It causes various back problems such as stiffness, pain and weakness.
• Spinal Curvature: It is the state in which the spinal cord is deformed and deviates from its normal curvature.
• Ehlers-Danlos Syndrome: A type of disorder in the connective tissues, the Ehlers-Danlos syndrome results from a problem in collagen synthesis. Collagen is a kind of protein found in connective tissues.
• Marfan Syndrome: This syndrome is characterized by aortic root dilation, dislocation of lenses and constellation of long limbs. Marfan syndrome is hereditary in nature.

Diagnosis
Magnetic Resonance Imaging (MRI) scan is used in the diagnosis of Arnold-Chiari malformation. If the displacement of the cerebellar parts is more then 5mm below its normal position, the person diagnosed with the malformation. The problem is generally detected by the age of 27; however, some of the characteristics of the malformation may also be found in prenatal stages.

Treatment
Surgery is the only treatment to deal with Arnold-Chiari malformation. The type of surgery performed on the patient is the 'decompressed surgery'. The purpose behind surgically operating the patient is to remove the excess spinal fluid. During the operation, the neurosurgeon may have to temporarily separate the first three cervical vertebrae from the patient's body. The occipital bone too is removed. This action allows the fluid to flow by means of a 'shunt', a surgical tube made of rubber or plastic, which helps in draining body fluids.

History
Hans Chiari, a pathologist from Austria, first brought to light the information about this malformation. The definition of the malformation was, however, provided by Dr. Julius Arnold, a colleague of Mr. Chiari. Thus, the malformation was known as the Arnold-Chiari malformation, thereafter.

Advanced Research
The research carried out regarding the malformation is mostly about improving the diagnostic techniques. The presently used method of checking the dislocation of the cerebellar parts may not be fruitful in some cases. Research pertaining to the diagnostic techniques is carried out with respect to following areas.

• Velocities of the cerebrospinal fluid.
• The geometric parameters of the cranium.
• Studying the importance of the spinal canal and cranium in relation to the Arnold-Chiari malformation.
• Studying the 'filum terminale' - a filament present in the brain.

The 'World Arnold-Chiari Malformation Association' acts as a communication bridge between the patients, doctors and the scientists carrying out research. The need of the hour, however, is to create awareness about this malformation in the medical community.