Radiology/Extruded disc


My question is how to determine if the disc has migrated or is simply extruded.
Below is my MRI results.
"There is an elliptical extradural lesion at level of L1-L2 disc space in the right paramedical posterior aspect. It measures up to 1.5 cm in width and 6.5 mm in AP dimension and extends towards the right neural foraminal recess without entering it. The cranioclaudal extent is 1.8 cm and extends almost halfway down the L2 vertebral wall. The signal intensity is similar to the disc material adjacent. However, no obvious communication with the disc is seen and there is an acute angle with the adjacent vertebral body.
The lesion causes indentation of the thecal sac and approaches the descending right L2 nerve root without contact or displacement. No evidence of nerve root compression or displacement or significant central canal stenosis."
I interpret the 1.8 cm downward direction to indicate migration though my Dr. said that was not the case. [injury is from two years ago, MRI is recent and may be related to chronic pelvic nerve problems].
How does the radiologist determine if the extrusion has migrated from original site?
Many thanks

ANSWER: Hi Kathy,

You would make a great detective as such details are very important to you :)

What report describes is a disc material that is extruded into the spinal canal but still sits adjacent to the "mother" disc from which it came.  in fact, if we are going to talk details then the report suggests that the disc material is not only extruded but also separated from the mother disc - that separation we term sequestration.  Now, if the disc will move away some significant distance from the place of origin then it may be described as a migrated disc material (which is also sequestered from the mother disc).  If it sits next to the disc of origin we do not say migrated.

Hope this helps.

Michael K.

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QUESTION: Thanks for your response and astute personality description!
I expect that without an earlier MRI for comparison it cannot be stated that a disc has migrated?
After reading the Radiologist description of "no obvious communication with the disc" I also wondered why it was not described as sequestered.
The initial acute injury 2 years ago has been a bit "tweeky", but recently have had significant L1-L2 related issues....pubic/abdominal/lower rib pain over last 5 months. This MRI is the only positive finding other than gyne infections [GAS].
I've been advised to have surgery/not have surgery, L2 epidural nerve block, Ilioinguinal nerve block....just want to correlate these findings with my symptoms so I can proceed to a better place with the least treatment risk.
Your comments are much appreciated.
Thank you.

ANSWER: If you read my many prior answers regarding lumbar spine when appropriate I always caution people about surgery being absolutely the last resort unless you can't live your life. Yes surgery may be helpful but your back will never be the same.  So, from what I understand, I would probably stay away from it as much as possible within reason.  Also, I am not sure how this finding correlates to your symptoms. As you may already know there are many disc protrusions, extrusions etc...that are completely asymptomatic.  I think you need a very good neurologist or a spine surgeon to correlate your symptoms and figure out if they are caused by L2 nerve.  If it is possible that these correlate I would suggest an nerve block to see if your symptoms would go away and hence prove that your symptoms are from the nerve displacement. Sometimes disc extrusions, sequestrations etc.. slowly get resorbed. Your disc material is pretty prominent and it may not or may not completely.
So there are doctor whose whole practice revolves around spine pain. I think you should go see one of them. If you live in the area with a large medical center / referral center, I would suggest you go there as oppose to private practice solo doc. They are great people but given current medical fiscal environment they may push limits on what it means to correlate pain with MRI findings.  Do not do anything drastic without second opinions. See different specialists like neurologist vs neurosurgeon vs anestesiologist (pain management).  They will all have slightly different approach and tools they use; so you will be much better informed.
Like buying a car by walking into a first dealership you see. You wouldn't do that. So don't do it with your body either.

Good luck!

---------- FOLLOW-UP ----------

QUESTION: I should have added this question last night but forgot. Second MRI with contrast material was performed....
"There is no enhancement of the extradural lesion with it's signal intensity consistent with disc material therefore proving disc extrusion rather than extradural mass. There is enhancement of the posterior longitudinal ligament and surrounding soft tissue structures along the posterior adjacent vertebral bodies indicating inflammation of these structures".
I understand this rules out tumors and such, but does this also mean the disc is not sequestered as suggested in the first report which stated "no obvious communication with disc"?
Thanks, this info really helps me to understand the issues. I believe a sequestered disc is at greater danger of migrating?


There is really no clinical significance of the disc is extruded or sequestered; and there is really nothing dangerous about the disc material migrating. The only thing that matters is whether or not you have symptoms related to that disc material. If it moves any significant distance either along the  canal or into the foramina, you may notice it IF you will have new symptoms that would also need to be correlated with a new position of the disc.

Regarding enhancement: I am not sure if the ligament enhances or not; what usually happens is that body tries to "heal" the site of injury and increases blood flow to the region, so small vessels, usually veins, become bigger in caliber which shows as enhancement. Also sometimes extruded or sequestered disc material becomes vascularized (if new vessels grow around and into the surface of the extruded/sequestered disc). This is a body's response to take care of trauma and sometimes this helps to resorb the disc material which would be great for you.

Hope this clarifies the issues further.


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Michael K.


Almost any kind of questions regarding any types of radiology exams, procedures, meaning of radiology reports etc...


12 year experience in the field of radiology

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