What is compression of the thecal sac?

Answer 1

from what I understand by reading the results of my MRI, and I am no expert at all, but it seems like l4 l5 and s1 verterbraes surround the thecal sac, and if the protrude out or are bulging, that would compress the thecal sac...That is on the anterior side...hope that helps someone

Thecal sac is also known as the lumbar cistern, and is the space below the termination of the spinal cord (L1/L2). It is covered by dura and arachnoid mater, and contains CSF (cerebrospinal fluid). A compression can result from vertebral disc herniation, edematous tissue in the surrounding epidural space, tumors, or anything that can invade the surrounding area (meningiomas, etc). If it's a disc herniation, since it's below the level of the spinal cord, it will compress nerve roots, typically compressing the transversing root below the level of the disc herniation. ie.-an L4/L5 herniation will compress nerve root L5 and you will get dysfunction according to that root and functional distribution. It can also impinge on lower roots, however this is uncommon. Hope that helps.

Answer 2

That depends inherently on the specific location, and severity of the condition.

But first I'd like to divulge upon you my rationale of "severity" as it pertains to the all too common lumbar injury.

The one caveat that I have always had with the current imaging technology used today in radiology for the aid in diagnostics of lumbar spine etiologies is not in and of the actual technology itself, but the testing technique used to employ it.

Lying prone and completely flat removes most of the anatomical load from the spine and thus most of the patients symptoms with it. With exception for the extreme of cases whereas a fellow Back pain sufferer feels no relief whatsoever such as even when lying down on their back, symptoms are most often dependent on positions that produce load upon the injury. Those positions are when it would be most suitable for any approach to diagnostic accuracy; i.e., as just it's most accurate when only visually inspecting how flat your car's tire is while the car is on the ground. In a perfect world, such as with the MRI, testing could be done this way if it were practical but it then would in effect turn an MRI machine into a virtual torture chamber. Radiologists and neurologists need only to consider this limitation of the radiology technique and allow for a standard margin of error to better assess how bad a herniated nucleus pulposus is effecting a patient in an actual occupational nature. Just maybe then, we will here a little less about how someone's doctor is "ignoring their symptoms."

When the thecal sac, or sometimes called the dural sac, is compressed enough to displace the nerve roots of the cauda equina, it begins causing symptoms. The nerve roots of this area are somewhat distributed and firmly "wrapped" in tissues similarly to what you'd find inside a very large guage wire. Compressing these nerve roots disrupts the chemical flow of "communications" and a variance of symptoms depending on which actual nerves they happen to will be experienced such as pain, tingling, burning, specific muscle weakness and even bowel and bladder problems such as incontinence.