Was the injection done under fluoroscopy? Many times there is overlapping of nerve distribution and although the peroneal nerve coincides with the L5 nerve root it would be interesting to consider a selective S1 transforaminal block as the dermatomal distribution is more related clinically to this segment. Many MRI's are negative as they are read from a surgical point of view.But definitely with the finding in the NCS it does validate your situation.
Thanks for the links and the info, NaniKai. I appreciate it.
http://en.wikipedia.org/wiki/Tibialis_anterior_muscle
that's a link that you can read more about the anterior tibialis muscle...
In human anatomy, the tibialis anterior is a muscle in the shin that spans the length of the tibia. It originates in the upper two-thirds of the lateral surface of the tibia and inserts into the medial cuneiform and first metatarsal bones of the foot. Its acts to dorsiflex and invert the foot.
paraspinal muscles
http://www.allaboutbackpain.com/html/files_links/spine_anatomy_muscle.html
The muscles next to the spine are called the paraspinal muscles. They support the spine and are the motor for movement of the spine. Joints allow flexibility, and muscles allow mobility. There are many small muscles in the back. Each controls some part of the total movement between the vertebrae and the rest of the skeleton. These muscles can be directly injured, such as when you have a pulled muscle or muscle strain. They can also cause problems indirectly, such as when they are in spasm after injury to other parts of the spine.
follow the above link for a more definitive explanation and I hope that this has helped you some.
Good Luck in your running and marathons
NaniKai
http://images.google.com/images?q=peroneal+nerve&hl=en&ie=UTF-8&um=1&sa=X&oi=images&ct=title
the link above will show you some really great images of how this nerve is connected and amazingly, it shows the leg and foot images so it will serve as a visual explanation for you to follow.
Be sure to copy and paste the links that I gave you into your browser (the spot where you type webpages that you want to visit) so that you can read the information. :)
NaniKai
Thanks NaniKai. Pinched nerve makes sense to me but I have no idea where it is being pinched (and apparently neither do any of the doctors I've seen). The MRI on my back (Lumbar region) showed no disc bulges or herniations so there is no pinching at the spine (according to the Radiologist who read my MRI). Nerves are a tough one, I'm finding out.
Pinched Nerve maybe...I'm not a doc by any stretch of the imagination (not licensed and I've only worked in the medical field in hospitals and as an EMT... but it seems from what I'm reading that you have a pinched nerve somewhere ...I'm going by the terminology though, Quix would be the one to give you a more elaborate diagnosis because SHE IS A PHYSICIAN...
NaniKai