I think, with the EMG, they will be looking at the peroneal nerve specifically -- this is the nerve that runs on the outside of the knee -- and with injury or inflammation -- this can cause weakness in the foot and toes, as well as pain or numbness which involves the outside of the lower leg and shin and top fo the foot.
Another potenial reason for this would be a "pinched" nerve in the lower back - the lumbar spine - but a MRI of the lumbar spine would have ruled this possibility out.
Yes MRI revealed nothing in her spine. Is this something serious? Everything I read is scary and says either MS or ALS, I'm so concerned.