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​Basilar Invagination Causes, Symptoms, and Treatment Options 

Basilar invagination is a health problem that affects your spine, neck, and — in some cases — your brain. It may be due to spine-related accidents, issues due to bone diseases and arthritis, or defects with which you are born. A person with severe basilar invagination often has neck or head pain, hand weakness, trouble walking, and other symptoms.

It's crucial to see a doctor right away if you think you have basilar invagination, though symptoms usually come on slowly.

Basilar invagination can be mild or severe. Severe cases may need surgery. Other treatments include medication and physical therapy.

Learn about the treatment options for Basilar Invagination at the UPMC Center for Skull Base Surgery.

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To schedule a visit with the UPMC Department of Neurosurgery or ask a question:

  • Call us at 412-647-3685 or 1-877-320-8762 (international calls).
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What is Basilar Invagination?

Doctors define basilar invagination as a defect or injury to the vertebrae (neck bones) that connect the head to the neck and puts pressure on the spinal cord and/or brainstem. It occurs when the peg in the front of the second neckbone (the C2 vertebra) moves slowly upward through the opening at the bottom of the skull. It can lead to issues with the brain, spine, or nerves.

Basilar invagination is not common. It may:

  • Be present from birth and get worse over time.
  • Happen as a result of an accident.
  • Form in people with a bone or joint disease like arthritis.

You may also hear the term basilar impression. The terms are often used interchangeably. Basilar impression is a milder form of basilar invagination.

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What Causes Basilar Invagination?

Some people are born with abnormally formed vertebrae at the top of the spine, which can lead to basilar invagination. Doctors often don't know why, but it may sometimes be related to other diseases like Chiari syndrome, Klippel-Feil syndrome, and even Down syndrome.

Basilar invagination also happens in people with health problems that cause their bones to soften or joints erode. This can include:

Others may get basilar invagination as a result of a fall, car, bike, or diving accident. For instance, someone diving into a too-shallow pool may hit their head on the bottom, causing a fracture which, if undiagnosed or poorly healed, can lead to basilar invagination.

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Symptoms of basilar invagination

Those with basilar invagination may have symptoms including:

  • Headache.
  • Dizziness.
  • Swallowing problems.
  • Numbness or tingling in the limbs.
  • Weakness or difficulty moving or coordinating your arms or legs.

Symptoms of basilar invagination can worsen when the person bends their head toward the chest. This action drapes the brainstem or spinal cord over the top of the backbone. The body may react with pain or muscle spasm to prevent damage from this motion.

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Diagnosing Basilar Invagination

UPMC doctors diagnose basilar invagination through doing an exam and imaging tests. They will ask about symptoms and take a health history. If they suspect basilar invagination, they'll confirm it by ordering imaging tests.

Imaging and radiology tests for diagnosing basilar invagination

Doctors use imaging studies — such as spine and skull X-rays, CT scans, and MRI scans — to confirm basilar invagination.

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Basilar Invagination Treatments

People with minor symptoms due to basilar invagination often don't need surgery. When basilar invagination does not put pressure on the spinal cord, treatments include:

  • Physical therapy.
  • Non-steroidal anti-inflammatory drugs.
  • A cervical collar.

People with symptoms that don't get better with these treatments may need spinal surgery. The surgeon will remove the bone that is putting pressure on the spine and/or fuse the vertebrae to prevent further pressure.

If you need surgery, UPMC surgeons often use the endoscopic endonasal approach. Surgeons use this less-invasive option to treat basilar invagination, which was first performed and described at UPMC.

Endoscopic endonasal surgery uses the nose and nasal cavities as an entryway. It gives the surgeon access to hard-to-reach areas they couldn't operate on before. Previously, surgery for this area required an incision in the back of the mouth, with increased risk of infection, prolonged healing, and worsening of swallowing.

The less-invasive surgical option means:

  • No cuts to heal.
  • No scarring.
  • Faster recovery.

As part of endoscopic endonasal surgery for basilar invagination, people will usually need a second surgery, performed at the same time, to fuse the involved spinal bones. This helps stop the invagination from coming back and stabilizes the neck joints, which are often already unstable.

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