I agree with David on this one.
A trapped nerve at L4/5 woud confine pain to the leg, buttock or lower back. In most cases the symptoms from disc related problems can usually be eased by addopting a diferent position. If a trapped nerve was the cause then by releasing the nerve the symptoms would vanish.
I think people are getting confused about cause and trigger when it comes to BFS/NMT. A simple example of this would be, pain in leg, CAUSE, broken bone, TRIGGER, bad tackle playing football or a bullet fired from a gun CAUSES the damage and to inflict the damage you pull the TRIGGER.
People think stress might be the cause of their BFS, if this was the case then in order to cure the symptoms, all you would have to do is lower your stress levels to normal and the symptoms would disappear completely. Stress is not the cause, it might be the trigger, personally I don't think it is.
When I enquired with Hart about what could have triggered it in my case, he did mention that the site of my back injury, which was a trapped nerve way back in 75 as a posible source, but this was purely guess work. Hart believes the cause is a voltage gated potassium channel defect and I would tend to go along with this.
When the sodium and potassium channels are working properly, at the resting state the two are more or less balanced. When a signal comes in, say to move the arm, the sodium channel gate opens and sodium is released. Then the potassium gate opens and potassium flows through in the opposite direction to replace the sodium. Meanwhile the sodium gate closes, when this exchange has taken place, which takes ml/secs, the potassium gate closes and the sodium gate opens at which point the resting state returns. This process is all to do with chemically produced electrical signals that cause muscle activity.
Evidience sugest that the fault lies at the potassium gate, with it either not closing or staying open, therefore, the resting state is not reached and the electrical signals are constantly being sent to the muscle fibres, which results in the twitching and the rest of the symptoms that we experience. Its kind of like a faulty switch on a torch where you can't turn the light off.
At least this is how I understand it.
Steve.