As I mentioned in my first post, you need to use the right tool for the job. When it comes to evaluation of soft tissues, in general, MRI reigns supreme. In the case of low back pain, MRI is essential for detection of disc herniation. However, most low back pain is attributable to muscle strain and pain. That is why most medical society recommendations recommend against immediate imaging. Moreover, the general recommendations are to wait 6 weeks and then perform X-rays even before considering MRI. In fact, most insurance companies will not approve payment for an MRI until this step wise process is followed. The exception to this general rule includes red flag symptoms. Examples of red flags include a history of cancer, motor or sensory deficits like foot drop, and bowel and/or bladder incontinence.
When an MRI is performed, it provides a detailed view of the lumbar anatomy. A radiologist should comment on the curvature and alignment of the spine. When a vertebral body closer to the head is anterior to the immediately lower vertebral body near the buttock it is called anterolisthesis. If the above vertebral body is posterior to the lower vertebral body it is called retrolisthesis. The bone marrow is evaluated for edema/inflammation or suspicious lesions/cancer. It is important to note that only the marrow of the vertebrae is well-appreciated. Cortical bone appears as a black line and is not as clearly seen, hence a CT scan may be necessary to fully evaluate bone spurs. Lastly, the tip of the spinal cord (conus) is evaluated and the descending nerve roots (cauda equina = horses tail).
Then each disc space may be evaluated level by level. A disc herniation (protrusion), extrusion (protrusion that may go up or down in the canal and be larger at its tip than at its base), or sequestered free fragment (broken off and migrated piece of disc) may be characterized. Additionally, the posterior facet joints (joints that allow you to bend forward and backward) are evaluated for degeneration. This combination of findings can determine spinal canal stenosis and neuroforaminal narrowing (tunnels where nerve roots from your spinal canal exit a bone tunnel to innervate your body). Compression of any of these nerve roots can lead to symptoms.
Take a look at my video to get an idea of what I’m talking about. It has been a while, but I hope to be back posting monthly so stay tuned. Let me know what you think and give me a shout out on the comments. Thanks!