As I recall, Alan has psoriasis, right? He had a high ESR at one time, and an equivocal ANA. Based on that, I'd think that what he needs is NOT a spinal tap, but a more exhaustive work up for all the tests listed under connective tissue diseases. Does he have dry eyes and mouth? There were a lot of tests he had never had, and there are connective tissue diseases associated with neuropathy (just ask Silverlady, for instance). If he has a neuropathy associated with a connective tissue disease, he could qualify for IVIG without ever having a spinal tap. Spinal tap is usually to look for specific inflammatory neuropathies. He's had a 20 year history of this already. More likely connective tissue. Also, I forgot--does he have diabetes? Does he take statins for his cholesterol?
I just pulled up the labs you'd sent me, and it says, after ANA "Interpretive note: The above results suggest the possibility of clinically significnt autoimmune antibodies
that may be detected by ENA (Sm RNP, SS A, SS-B, Sch1-70, Jo-1) antibody assay or a dsDNA antipody assay antibody assay or a dsDNA antipody assay'

Did he ever get these tests? Please, Melody, before getting all worried about the spinal tap, make sure he gets the simple blood tests he should have had back then.