Disc extrusion: Meaning in a Radiology Report

Disc extrusion

Also written as: extruded disc, extruded disc herniation, disk extrusion

A disc extrusion is a disc herniation in which the pushed-out part is wider than its base or reaches above or below the disc. Many shrink over time.

Seen on: MRI

How it reads in a report

L4-L5: A right paracentral disc extrusion extends 8 mm inferiorly and compresses the traversing right L5 nerve root.

What it means

In an extrusion, material from the disc's soft center has pushed out through its tough outer ring. What sets it apart is shape. The escaped part is wider than the narrow neck joining it to the disc, a bit like toothpaste squeezed from a tube, or it extends above or below the disc. If a piece breaks off completely, reports call it a sequestered or free fragment.

When it matters

Extrusions are more likely than protrusions to press on a nerve root and cause pain, numbness or weakness in a leg or arm. Even so, many shrink on their own over weeks to months as the body clears the material, and symptoms often improve. Doctors weigh the level and side against your exam. A repeat MRI is usually considered if symptoms persist, worsen or include new weakness.

Questions to ask your doctor

Is the extrusion pressing on a nerve root that fits my symptoms?
Has any piece broken off from the disc as a free fragment?
Which symptoms would mean I should seek care urgently?

General information, not medical advice. What a finding means for you depends on your symptoms, your history and the images themselves, so talk your results through with a doctor.