There are 2 indicators of MS they look for in a spinal tap. My first spinal tap showed one and ruled out other similar diseases.

Because of the way my MS was progressing my neuro wanted another spinal tap to look for the 2nd indicator of MS (which did show up) and yet to rule out other possible diseases.

I've had 3 spinals in my life and never a problem with any of them.

Take care.