My MS neuro who diagnosed me said that LP's are not necessary, or at least it wasn't in my case. I had lesions on the brain, and a history of two relapses with classic symptoms as well as other lingering symptoms.

The previous neuro I saw did do the LP, and it turned out negative. He however, was not an MS specialist, so maybe that's why he wanted the additional tests to be sure.

My current doctor is familiar enough with MS that he didn't need the LP.