Hi and welcome back,
To be honest i'm perplexed at what would of prompted you to get your GP to specifically check you for the Babinski sign......a positive Babinski added to measurable weakness and a non psychological tremor should of gotten your GP to send you for tests looking for the more common medical explanations eg structural spinal issues etc, when the patient is potentially an MSer then that would prompt a spinal MRI looking for spinal cord lesion(s).
I'm unaware of a connection with migraine, there could be an association with the medication you take for your migraines and or when combined with your other medications, though it wouldn't be the oral prednisone because that basically reduces inflammation and would of been prescribed because it can often brake the migraine cycle, but i think you need to keep in mind that if this is the same GP who has been focused on the conversion disorder and functional aspects, it's possible he was just saying a porkie pie as a way to dismiss it.
It's actually possible it was a false positive Babinski, it's one of the tests that relies on more experience than most GP's would have, proper assessment of the
plantar reflex should involve not only toe movements, but also observing simultaneous contraction of other flexor muscles in the leg, the toes can go down and it makes the big toe look like it went up and it can be mistaken for a positive result....
"The Babinski - This test is harder to perform and interpret than it looks. It takes lots (LOTS) of practice. It is supposed to be a "noxious stimulus" applied to the bottom of the ffot along the outside edge and then across under the toes. The doc looks for an initial flaring upward (may be very subtle) of the great toe. Sometimes all the toes will also flare out. Normal is an initial downward movement of the toe or sometimes no movement at all.
If the examiner does it too harshly, causing pain, the patient will withdraw the foot and the toes may go up (sometimes when the patient tries to pull away from the doc they will pull their toes up in the effort to get away from the discomfort. That's what 'Zilla was talking about with false positives) , BUT if the examiner is watching very closely and the Babinski is +, the toes will have already made a tiny motion upward. Conversely, if the examiner is harsh and causes pain, and the Babinski is "negative" there will be a brief downward motion, before the foot withdraws (Most examiners will hold the foot in place so that you can't withdraw it. Someone who is trying to fake a "positive" will invariably time it wrong and this will be obvious to the experienced doc." Written by Quix back in 08 (
http://www.medhelp.org/posts/Multiple-Sclerosis/Babinski-sign-of-pyramidal-dysfunction/show/408700)
Hope that helps..........JJ