Small foramen magnum

What it means

An abnormal narrowing of the foramen magnum.

The foramen magnum is the aperture through which the medulla oblongata enters and exits the skull. Stenosis of the foramen magnum can represent a risk for compression to the spinal cord.

Rare diseases that can present with this2

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Foramen magnum stenosis · Hypoplasia of foramen magnum · Narrow foramen magnum · Stenosis of foramen magnum