Basilar invagination (BI) is when the top of the spine pushes into the base of the skull. This causes pinching and pressing on the brain stem, the thick bundle of nerves that connects the brain to the spinal cord.
Basilar invagination (BA-zih-ler in-vaj-ih-NAY-shin) that is very mild is called basilar impression.
The condition is caused by either an unusual flattening of the bottom of the skull (called platybasia), and/or problems with the bones in the neck.
The neck is a stack of separate bones called vertebrae :
Basilar invagination can cause different symptoms depending on which part of the brain stem is pinched or pressed. Common symptoms include:
Symptoms can get worse when the neck bends forward.
A child can be born with the condition (congenital basilar invagination) or develop it over time.
The cause of congenital basilar invagination isn't known. There's nothing the parents could have done to prevent it.
BI that develops over time can happen because of:
Children with symptoms of BI are checked by health care providers who specialize in:
The provider will ask about symptoms and do an exam, checking muscles and nerves all over the body.
X-rays or a computer tomography (CT) scan can help them reach a diagnosis. An MRI is the best test to look at the brain stem and spinal cord.
Health care providers might just do regular checkups for a child with basilar invagination who has mild or no symptoms.
Some symptoms can be treated with:
If symptoms include nerve problems or if the neck isn't stable, a child might need surgery. The surgeon may do an operation through the nose, the mouth, or at the back of the head and neck. Sometimes a child needs halo-gravity traction for a few weeks before surgery to help the skull and neck get into a better position.
As a child with BI grows, be sure to:
Neck injuries in children with basilar invagination are more likely to be severe or fatal than in most children. So they should avoid activities that put them at risk for neck injuries, such as contact sports, diving, and gymnastics.
Reviewed by: Suken A. Shah, MD;Alicia McCarthy, APRN
Date Reviewed: 01-04-2019