What is your foot SUPPOSED to do?!

Hello,

Yes, this is the test where the doctor draws a (blunt) pointed object across the sole of the foot, from the heel along the side of the foot, and then across to under the big toe? Is this what you mean, (click) http://www.adinstruments.com/solutions/i…

In normal people the big toe curls downwards, a so-called "down-going" plantar reflex.

If the big toe reacts by curling upwards, that is indicative of nerve damage, somewhere in the "central nervous system," between the brain's motor cortex and the bottom end of the spinal cord. Technically the damage is somewhere in the "cortico-spinal tract," also known as the "pyramidal tract." I'm afraid nerve anatomy is fiendishly complicated.

He was looking to make your big toe curl upwards, - i.e. go the wrong way. This would have shown that your cortico-spinal tract was damaged by MS. Clearly he was disappointed, your big toe must have curled downwards, or not moved at all. This is good (from your point of view).

If the big toe curls upwards, this abnormality is called any of the following: an up-going plantar reflex, or Babinski's sign, or a Babinski response, or Koch's sign. Theis doesn't mean that these patients had the problem, - it means that a Dr. Babinski and also a Dr. Koch, were the two doctors who first discovered this reflex, and also what it meant.

The most common illness which causes an up-going plantar reflex, is a stroke, (i.e. bleeding or clotting damage to the motor-cortex in the brain), but MS can also cause it if it happens to target the cortico-spinal tract.

It is nearly always one-sided, - I mean that usually the plantar reflex is only up-going on one side, (the paralyzed side, in a stroke). The other big toe goes downwards as normal.

If the nerve damage is below the bottom-end of the spinal cord, - - say, for example, someone sat on their tail-bone so long that one of their legs went to sleep, - then the plantar reflex in the asleep-leg, if it was present, would be normal, (downwards). That is because the "lower" nerve, and not the "upper" nerve, would be involved.

The "upper" nerve is <brain to spinal-connection>; the "lower" nerve is <spinal-connection to muscles>. An up-going plantar reflex is a sign of damage to the "upper" nerve.

Here is a picture which may make this clearer, (or just be more confusing <g>) A "synapse" is a nerve connection point (click) http://www.clinicalexams.co.uk/images/mo…

I hope this helps.

Best wishes,

Belliger
retired uk gp