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  • Writer's picturePietro D'Urso

Foramen magnum decompression

Updated: Mar 15, 2021

At the base of the skull there is an oval shaped opening that is called the foramen magnum. In this opening the spinal cord links to the brain.

Foramen magnum decompression is one of the procedures that can be used to treat Chiara malformation. Chiari malformation occurs when the spinal cord is put under pressure from the cerebellum (lower part of the brain). A foramen magnum decompression involves removing a small part of the base of the skull and sometimes the top of the spine to relieve the pressure that is on the cerebellum.

The cerebellum, which means ‘little brain’ in Latin is responsible for a range of voluntary movement and physical activities, such as walking or cycling.

Chiari Malformation

There are different types of Chiari malformation, however foramen magnum decompression is used to treat Chiari I.

As mentioned before, Chiari I malformation occurs when part of the brain (cerebellum) pushes into the spinal cord and brainstem. This can cause a number of different symptoms such as headaches and neck pain.

Cerebrospinal fluid (CSF) is found in the brain and spinal canal. CSF is like a cushion between the brain and skull, it aids basic mechanical and immunological functions in the brain. Chiari I malformation can disturb the flow of CFS to the brain and therefore cause a build-up of fluid. When this occurs the ‘cyst like’ obstruction is known as a syringomyelia.

Chiari malformation can be caused by a structural malfunction in the spinal cord and brain during foetal growth. A bad diet during pregnancy can be a factor. If the skull is not large enough for the brain then this can be diagnosed as a Chiari malformation.


Many people that are diagnosed with Chiari malformation will not display and symptoms and will not need to undergo any treatment.

However, some of the most common symptoms include:

  • Altered vision (blurry)

  • Headaches (often felt in the back of the head)

  • Neck pain

  • Muscle weakness

  • Problems with balance and coordination

A Chiari malformation can be diagnosed by x-rays, CT scans or MRI scans (these are some of the more common methods)

Surgery and recovery

Serious complications with foramen magnum decompression surgery are very uncommon, however it is important that you understand all the possible risks before you go ahead with any surgery. Before the surgery, your doctor will go through your medical history and explain the benefits and risks to the surgery.

Patients that are having foramen magnum decompression will be put under general anaesthetic; meaning that they will not be awake during the surgery. The head is anchored to ensure that there is no movement during the surgery. An incision is made in the back of the head, usually 5-10cm. surgery is done to relieve pressure on the brain and spinal cord. This procedure usually takes around 3 hours.

It is quite common to experience mild discomfort after the surgery, so appropriate medication will be given to aid recovery. Once you have recovered you should notice a reduction in the symptoms that you were experiencing.

If you would like to find out more about Chiari malformation please read our previous blog or contact our team if you wish to have a consultation.

This article is intended to inform and give insight but not treat, diagnose or replace the advice of a doctor. Always seek medical advice with any questions regarding a medical condition.

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