Archie here:

When I first had my pump implanted in 2007 in DC, I also had an infection which resolved into a large seroma (fluid filled sack) around the pump. The surgeon was apologetic as he removed many 100.s of cc's from my body., but it solved the issue. I'm now 80, and my Adhesive Arachnoiditis has progressed and for whatever reason is more active right now. I have a 40ML PUMP, SO PLENTY OF ROOM FOR MEDICATION. I get over 6.8 on continuous flow daily (I'll look ups exactly if you need it) but also have the choice of 5 boluses /day. This flexibility precludes the necessity of oral meds. Bottom line, I'm very happy with the Medtronic 40 that I have.

As an aside, I recently had a consult with the head of Neurology at Mayo's in Jacksonville, and he told me again the AA is progressive and that it was UNREASONABLE for me to expect the pump to cover all the pain issues I am having, That was a real kick in the butt, and he recommended getting a spinal cord stimulator as an adjunct to the pump. For me, that has been a big mistake. I've gone through months of healing, testing various treatment protocols--all to no avail--it just doesn't help me. So be aware that it may not be for everyone. I've had AA since 1978, so I do have some perspective on the disease and treatment modalities.. I wish you good luck.
Best, Archie