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Chiari malformation is a congenital condition. Rarely, it has been reported later. It is divided into 1, 2, 3 and 4 types according to the degree of the disease. Chiari 2 malformation is called Arnold Chiari malformation and is often accompanied by syringomyelia and hydromyelia.

The cerbellum (cerebellum) is located in the lower part of the skull (back pit) and provides coordination of movement. Under the cerebellum, there are two small projections called tonsils that hang bilaterally. All these structures are located on the foramen magnum (big hole) under the skull bone, and through this large hole, the spinal cord comes down after connecting with the brain stem. This malformation often occurs while the child is in the womb and is diagnosed when the tonsils descend more than 4 mm from the foramen magnum to the spinal cord. This downward slide can block the CSF circulation between the spinal cord and the intracranial. In this way, it can cause fluid accumulation in the spinal cord called syringomyelia or hydromyelia. Skull base developmental anomaly may accompany in 30-50% of Chiari type 1 cases.

Frequency of the disease

The incidence of the disease is less than 1 per thousand. There are no complaints or findings in most of the cases. A Chiari malformation is usually discovered by chance as a result of an MRI showing that area for another reason.

Complaints and findings

Many patients with Chiari 1 malformation do not have any complaints. Complaints are severe head and neck pain, pain in the neck that increases with coughing, sneezing and straining, loss of pain and temperature sensation in the arms (seen in those with syrinx cavity), loss of muscle strength in the hands and arms (seen in those with syrinx cavity), falling attacks due to muscle weakness. There may be slouching, spasticity, dizziness, balance problems, double or blurred vision, and increased sensitivity to bright lights. Some of the complaints are related to the development of the syrinx (fluid-filled cavity in the spinal cord).

Other types of chiari are rarer and present with more severe findings.


  • There are many tests to be done to diagnose Chiari malformation. Brainstem Evoked Responses (BAEP) (It is an electrical test for the control of the hearing system, including the brain stem connection. It is revealed whether the brain stem is working properly.)

  • Computerized Brain Tomography (CT) (Shows the inside of the skull and bone structures well)

  • Magnetic Resonance Imaging (MRI) (It is important for obtaining a complete anatomical image, and it has no side effects as it uses a magnetic field. Information about the prevalence of the malformation can be obtained by imaging both the brain, the cerebellum, the brain stem  and the spinal cord. )

  • Somatosensory evoked responses (SSEP) (It gives information about its function by controlling the passage of the stimulus from the cerebrospinal cord and nerves by giving an electrical stimulus.)


The type of treatment depends on the type of malformation and the anatomy being affected. 
Chari 1 malformations that do not cause complaints should not be handled. Here, prophylactic surgery is not appropriate. If the disease is complaining or if there is a syrinx, surgery should be performed to stop its progression. Chari 2 malformation should also be treated if the patient has complaints. If there is progression, surgery can be applied.

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