Chiari malformation

What is Chiari Malformation?

Chiari malformation is also known as Arnold-Chiari or Kiari, Arnold-Kiari malformation. However, the term “Arnold-Chiari malformation” specifically refers to Type II of this condition.

Chiari malformation is a structural defect of the occipital bone in the skull, which develops either during childhood growth (Type I) or is congenital (Types II and III). This condition is characterized by the descent of the cerebellum and other brain structures into the spinal canal, often due to a smaller or deformed posterior skull cavity.

Depending on which brain structures extend into the spinal canal, Chiari malformations are classified into three types, with Types I and II being the most common.

How common is Chiari malformation?

Chiari malformation occurs in approximately 1 in 1,000 individuals. Chiari Type I malformation is frequently diagnosed incidentally, often when imaging is performed for unrelated symptoms in children, adolescents, or adults. Other types of Chiari malformation are typically diagnosed via ultrasound before birth or identified soon after birth.

Characteristics of Chiari Type I Malformation

In Chiari I malformation, the cerebellar tonsils descend more than four millimeters into the foramen magnum (the large opening at the skull base). This can disrupt cerebrospinal fluid (CSF) circulation, leading to hydrocephalus or syringomyelia, as well as symptoms specific to this malformation.

Symptoms of Chiari Type I Malformation

Many individuals with Chiari I malformation do not experience any symptoms. However, symptoms may appear individually or in combination and may also be associated with syringomyelia (fluid-filled cavities in the spinal cord).

Common symptoms include:

• Severe headaches and neck pain
• Occipital (back of the head) pain, worsened by coughing or sneezing
• Nausea and vomiting
• Sudden falls due to muscle weakness
• Dizziness, balance issues, and coordination difficulties
• Blurred or double vision 
• Increased sensitivity to bright light
• Sleep apnea 
• Numbness or muscle weakness in arms and legs

How is Chiari I Malformation Diagnosed?

MRI is the gold standard for evaluating both brain and spinal cord abnormalities. If Chiari malformation is confirmed and there are no additional findings such as hydrocephalus or syringomyelia, an MRI CSF flow study can assess whether the malformation disrupts cerebrospinal fluid circulation.

If you or a loved one has been diagnosed with or suspected of having Chiari malformation, consulting a neurosurgeon is essential. Our team is available to provide expert consultation and recommend the best possible treatment plan.

If an in-person consultation is not feasible, we also offer remote consultations via video call. You can schedule an appointment online, by phone, or via email. Remote consultations should be arranged by contacting us directly.

Treatment Options for Chiari I Malformation

Treatment depends on associated symptoms and structural changes. Surgical intervention is recommended in cases of neurological complications or CSF circulation disturbances.

• Posterior Fossa Decompression – This is the most common surgical procedure for Chiari malformation, in which a small portion of the occipital bone (sometimes including part of the first cervical vertebra) is removed. This relieves pressure on the brain and restores cerebrospinal fluid circulation.
• Careful Surgical Evaluation – Since Chiari I malformation symptoms resemble many other neurological conditions, decisions regarding surgery should be made after thoroughly evaluating symptoms, imaging results, and potential benefits versus risks.

Where is Surgery Performed?

Our clinical center for surgeries and procedures is Aiwa Clinic.

Preparing for surgery often raises many questions—you can find answers to frequently asked questions about surgery preparation [here].

If you are considering surgery, feel free to read reviews about our Latvian and international patient experiences [here].