It's hard to see from one slice without being able to change contrast, magnify, etc...
With all the "I'm not a doctor" qualifiers, it looks somewhat stenotic, like there is not much room around the cauda equina (what seems like the spinal cord in your lumbar spine). Note that these types of issues can be comnpletely asymnptomatic in a high percentage of patients. The symptoms you described don't sound like typical L4-5 problems.
I'll be interested to hear what the EMG says.
Have you had a hernia surgery or other abdominal surgery? Read this:
http://www.ispine.org/forum/ispine/4...diagnosis.html