Lower back and peroneal nerve

I have a symptom that has my neurologist baffled.  When heat is applied to my lumbar area, via hot shower or a hot surface, it triggers a sharp pain in my left calf, the peroneal nerve.  That is the only pain, completely localized to my left calf.  He had an MRI done of my middle back to check for MS but that came up negative.  He doesn't believe anything in my lower back can trigger the peroneal nerve exclusively.  He wants to wait a month and then do a spinal fluid test.  I think he should do a lumbar MRI but he disagrees.  Have these symptoms been seen before?

[Dr. A. Srivastava]

Hi, Thank you for your question. It sounds like slipped disc condition. In slipped disc or disc prolapse conditions symptoms may originate due to nerve root pressure, pressure on the spinal cord and pressure on the tail bone. Common symptoms could be paralysis of muscles, pain radiating to the legs/thigh, numbness, tingling, or weakness. Warning symptoms can include loss of control of the bladder function, paralysis & spasticity of both the legs. If you are suffering continuous weakness and notice reduced strength of muscle bulk in left leg, please arrange an appointment with a neurologist right away. Further referral to a physiotherapist for spinal exercises could be beneficial and may produce relief of symptoms. Hope this helps. Take Care & Stay Healthy!!!