First, they will be looking for autoimmune markers both in the spinal tap and in the other blood tests that were ordered. (The immunofixation and SPEP--serum protein electrophoresis--tests both look for rogue antibodies.) Even if they don't find excess immunglobulins or banding in Alan's spinal fluid, he may still have autoimmune issues--there's a lot we still don't know about how the immune system works, and there may well be autoantibodies unique to Alan that could not be picked up by standard testing. Indeed, it is speculated that many "idiopathic" small-fiber neuropathies, and some larger fiber ones, are autoimmune in nature, but we have not yet progressed to the point of being able to identify the antibodies responsible. Even the KNOWN autoantibodies to nerve, such as anti-MAG (myelin associated glycoprotein), the anti-sulfatides, and the various others, have only been isolated/identified in the last few decades.
In my conversations with Drs. Latov and Chin, they've mentioned they believe we will find others that may explain many more neuropathies (and their lab, of course, has been at the forefront of doing that research).

Dr. Latov is a major outspoken advocate of using IVIg for neuropathy, and Dr. Goldfarb knows him well, so I'm sure if she thinks there's an indication for it in Alan's case, she will make a case to any insurance company, and will have a lot of research material available to back it up. In fact, consider this excerpt from Angela Macropoulos' article on neuropathy--one of the ones I, and some other people I'm sure would be familiar to you, were interviewed for; the whole article can be seen at--

http://jscms.jrn.columbia.edu/cns/20...los-neuropathy


Neurologists who specialize in the disease are frustrated that health insurance plans increasingly rely on evidence from blinded controlled medical trials before they will cover treatment. With peripheral neuropathy, there aren’t enough blinded controlled trials to draw evidence from. Dr. Norman Latov, also of Cornell University, has diagnosed several patients with demyelinating polyneuropathy but their insurance would not cover treatment.
“’Evidence-based’ guidelines is doublespeak because guidelines use evidence selectively,” Latov said. “Clinical treatment develops through experimentation and observation. We need to do what we need to to help patients.”

This fight to get IVIg for patients has been going on a while, primarily because it is a very expensive blood product. Nevertheless, should it come to that, I'm sure you'll have good advocacy. (That includes us here.)