I've had pain in my knee and calf - doctor performed surgery to remove a tear in the medial meniscus - now I have pain in the hip, knee, calf and instep - extruciating pain - vicodin does not even help; I had an EMG which showed possible stenosis in the back and an MRI should compression of L5S1 - I had the knee and calf pain before the surgery; the hip and instep is post surgery; I'm taking the films to a radiologist to review and getting a second opinion. The MRI of the knee post surgery showed a cyst and some inflammation - docs told me not to worry about that.
I had leg pain for 15 years with no diagnosis because all the doctors wanted to do was look at my lumbar. Turns out I have a Chiari Malformation and Syringomyelia - problem with the brain and spinal cord. These did not show up on countless lumbar mris. If you haven't had any tests further up, I'd insist on them. The logical place for leg pain is the lumbar - but it's not the only area that could have a problem that is causing your pain.
1. I'm assuming you mean the disc was at L5-S1. At that level, the disc would theoretically have to be pushing out laterally to catch the L5 nerve root as it exits on one side. I agree it would be unusual to have a disc problem at only one level that is actually protruding out centrally and catching both L5 roots without touching the S1 roots.
2. Neurological complications of habitual leg crossing tend to result from peroneal nerve compression, which manifests as foot drop, not sciatic nerve (too far up). You can get sciatic nerve problems with prolonged sitting in the lotus position (as in yoga - with your legs flexed and hips abducted), especially on a hard floor.
3.Depends on exactly what nerve (s) are involved, to what extent/degree the injury was, and your height (length of nerve in you). More details needed for prognostication, but typically at least several months.
4.Not enough info from the EMG for an accurate opinion. Also, EMGs are very subjective and dependent on the person who performed them. What I can say is that we routinely do sural nerve sensory responses as well as tibialis anterior and abductor hallucis motor studies in addition to the ones you mentioned when looking for a sciatic problem. The needle examination is also very important here, but again is operator dependent and should be done by someone who was formally trained in EMG.
5.You're mixing up terms. Lumbosacral plexus refers to a group of nerves that is situated higher than the sciatic nerve (not the same thing). If it's a plexus lesion, the sensory responses would be gone or reduced in the leg. To cause bilateral symptoms, the lesion would be rather extensive. The majority of cases we saw in our lab doing this were due to cancer related causes like a large mass or radiation injury. Gunshot wounds/trauma from pelvic fracture, diabetes, and maternal injuries during childbirth were also major causes that we found. MRI/CT of the lumbosacral plexus (if this is what is suspected) can be done looking for a mass and has been helpful for some cases in our experience.