Hi, this is Sagar Wagle, one of the musculoskeletal radiology fellows at Stanford University. We have a case of a 19 year old male with low back pain and right-sided sciatica after a squat. There's a clinical concern for herniated disc. In the radiographs, which include extension and flexion views, we see that the vertebral bodies have a grossly normal height and alignment and there's an anterior osteophyte at the anterior superior L4. Before we go into the MRI, let's look at a few disc pathologies. This is an example of a normal disc. There is nucleus pulposus centrally and annulus fibrosus peripherally, and the disc normally has this reinforced shape posteriorly. In disc protrusion, which is a type of disc herniation, the disc focally herniates out. The neck of the herniation is wider than the apex of the herniation. And this is how it looks like on the sagittal view. In case of disc extrusion, the neck of herniation is narrower than the apex. And this is how it looks like on the axial view. In case of disc bulge, the disc never focally herniates out and the bulge involves more than 25% of the disc circumference. And classically the posterior normal reinforced shape of the disc is lost in case of a disc bulge. So here we have our normal disc, here a disc bulge, here extrusion, and here protrusion. Let's take a look at a case of a 25 year old male with acute onset left sided sciatica during a deadlift. As we scroll through the images and come to this image, you can see a focal disc herniation. The neck is narrower than the apex. So we're going to call this a disc extrusion. And on the axial slices, we can see the disc herniation right here. So as long as the neck is narrower than the apex on either the sagittal or the axial view, we are going to call this an extrusion and not a protrusion. MRI can help us identify when nerve roots are displaced or compressed. This dotted line shows where the image on the right is taken. And we can see that this herniated disc, it compresses and displaces the nerve root which are traversing down. Whereas the L5 nerve root at this level has exited already. Now let's go back to our original case. Here the disc has focally herniated out at L4 L5 level. And when you compare the neck to the apex, the neck looks slightly wider than the apex. So we're going to call this a disc protrusion. And this case of disc protrusion is easier to see on the sagittal than it is to see on the axial view. So we have a case of a disc protrusion at L4 L5 level. The patient was treated with epidural steroid injection at right-sided L4 L5 and L5 S1 levels. Thank you for watching the video.

3rd Edition, CASE 55

3rd Edition

Spine

disc herniation

MRI images

sciatica

epidural steroid injections

nerve root compression