I think the most important thing, regardless of what technique you choose, comes before you take him back to the OR -- the interview! Make sure when you consent him you tell him he is clearly at higher risk for intraoperative awareness than your average patient. Talk to him about his prior experiences. Does he have PTSD? Was he distressed by the prior surgical experiences? Was he intubated and felt like he couldn't move or breathe during the surgery? All of these answers become extraordinarily important, and will likely influence how you approach the anesthetic (as an example, if he felt like he was choking and couldnt breathe, maybe you want to avoid muscle relaxation). Obviously, obtaining prior records would be very valuable as well.
But, going off of what we have available to us, and assuming the idea of being awake during a surgery doesn't totally freak him out (he was already awake for two prior ones, right?) I would plan on doing a spinal and maybe giving him a little sedation. That way, he truly is awake and isn't gagging on a tube or LMA, and I can easily assess whether the local anesthetic "isn't working" in him. Maybe throw some ear plugs in him if he doesn't like the sound of hammering, or have him borrow my iPhone and throw on some jams. I find it hard to believe having bupivacaine bathing his nerve roots in a spinal "wouldn't work." Though there are some people who have mutations that can render local anesthetics ineffective, he apparently just "needs more" according to the dentist. Anyway, that would be plan A. Plan B is intubate him and run him super deep, probably one of the rare times I would use a BIS, load him with a benzodiazepine, and hope for the best.
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