Arnold Chiari malformation

Arnold Chiari Malformation Arnold Chiari Malformation (ACM) is a structural defect in the cerebellum, the part of the brain that controls balance. It involves the downward displacement of the cerebellar tonsils through the foramen magnum, which can lead to a variety of neurological symptoms.

Classification

Arnold Chiari Malformation is classified into several types based on the severity and anatomical features:

• Chiari Malformation Type I: This is the most common form and often diagnosed in adulthood. It involves the extension of the cerebellar tonsils into the foramen magnum without involving the brainstem.
• Chiari Malformation Type II: Also known as Arnold-Chiari Malformation, this type is usually associated with myelomeningocele, a form of spina bifida.
• Chiari Malformation Type III: This is a rare and severe form involving herniation of the cerebellum and brainstem through the foramen magnum and into the spinal canal.
• Chiari Malformation Type IV: This involves an underdeveloped cerebellum and is the most severe form.

Symptoms

The symptoms of Arnold Chiari Malformation can vary depending on the type and severity. Common symptoms include:

• Headaches, often severe and worsened by coughing or straining
• Neck pain
• Balance problems
• Muscle weakness
• Numbness or tingling in the arms or legs
• Difficulty swallowing
• Dizziness
• Vision problems

Diagnosis

Diagnosis of Arnold Chiari Malformation typically involves:

• Magnetic Resonance Imaging (MRI): This is the most common imaging test used to diagnose ACM, as it provides detailed images of the brain and spinal cord.
• Computed Tomography (CT) Scan: Sometimes used to assess bone abnormalities in the skull and spine.
• Neurological Examination: To assess symptoms and neurological function.

Treatment

Treatment options for Arnold Chiari Malformation depend on the severity of symptoms and may include:

• Observation: For mild cases with no symptoms, regular monitoring may be sufficient.
• Medications: To manage symptoms such as pain.
• Surgery: The most common treatment for symptomatic ACM is decompression surgery, which involves removing a small section of bone at the back of the skull to relieve pressure.

Prognosis

The prognosis for individuals with Arnold Chiari Malformation varies. Some people may have no symptoms and require no treatment, while others may experience significant neurological impairment. Early diagnosis and treatment can improve outcomes.

See Also

• Syringomyelia
• Spina Bifida
• Hydrocephalus
• National Institute of Neurological Disorders and Stroke. "Chiari Malformation Fact Sheet."
• Mayo Clinic. "Chiari Malformation."

NIH genetic and rare disease info

• NIH info on Arnold Chiari malformation

Arnold Chiari malformation is a rare disease.