You should definitely get a second opinion from another orthopedic surgeon that specializes in spines only.
The fact that your present ortho never looked at the MRI pics is very telling. He based his diagnosis on someone else's "opinion" and not his own.
The reading of the MRI that your doctor looked at is really nothing more than that, an opinion.
You could take those MRI images to another MRI radiologist to read or another doctor and get different opinions.
Essentially what you are doing know is following the medical advise given to you by a doctor who has based his diagnosis on someone else's opinion and never formed one of his own.
Not a good way to diagnose a patient.
Lots of things go into reading an MRI and in some things, such as how the vertebrae are counted, there is no standard that is used.
If you have a really "normal looking spine" then there may not be a problem in how the vertebrae are counted.
On the other hand, if you have some fusion at the base of your spine, which many people do, then that area may or may not be counted as a vertebrae. Then when the vertebrae are counted, what is really L3/L4, can be counted as L4/L5.
Believe me, I know about this one as I have that problem and several second opinions that I saw before my surgery, did not count correctly and disagreed with the radiology report.
Even my own daughter, who was in college at the time and majoring in biology/anatomy and physiology/genetics and microbiology, could see by looking at my MRI films that some of the second opinion docs where wrong as was one radiologist that gave another opinion.
Another thing as well, hemangiomas can appear on MRI pics with one MRI and when another one is done, they will be gone. I had that happen with a second MRI a year after my surgery. One appeared in the pics.
Subsequent MRIs a year after that one and 2 years later, never showed the hemangioma again and the MRIs where all done at the same facility and read by the same radiologist and the views where all seen and examined by my spine surgeon.
Physical therapy might help, but you should get a second opinion and specifically go over all that the views of the MRI show with a spine surgeon.
If a spine surgeon isn't willing to look at the MRI pics and go over them with you to point out where problems are and what is causing or may be causing your pain, you need to leave the spine surgeon and get another one right away.
What is considered slight narrowing of the lateral recess by one radiologist, can be seen as moderate by another.
Also, just because the opinion is slight, doesn't mean that it isn't causing you specifically pain.
Lateral recess narrowing and nerve compression in that area is the leading cause of failed spine decompression because many spine surgeons ignore that area of the vertebrae when doing surgery.
Get another opinion as fast as you can.
Good luck and keep us posted.
Fran