Understanding Opioid Induced Hyperalgesia

The existence of opioid induced hyperalgesia has been debated, but I believe that it does. It’s when a patient uses an opioid and over time develops not just tolerance but super tolerance. Tolerance is normal. You take a medicine, your body adjusts to that dose. The side effects will usually go away and you might need more medicine over time, stretched out over a long period of time to achieve the desired effect. Opioid-induced hyperalgesia (OIH) is different. Not only is there tolerance but there’s actually an anti-analgesic effect. In other words, the pain medicines that you take actually create more pain. There is an imbalance. The functional term is allostasis; it’s an opponent process. The more medicine you take for pain, the more the anti-analgesic process continues and that’s the theory behind opioid-induced hyperalgesia. So someone on a moderate to high dose of opioids presents with the complaint “I still hurt. Not only do I hurt but I hurt all over.” On exam the physician often finds psychiatric comorbidity, but typically they’ll also find diffuse pain which is worse with stimulation. A painful response for me is much worse for a hyperalgesic patient. So these patients are notoriously intolerant of needle injections, surgical procedures or any type of noxious stimuli that you might do even an aggressive physical examination, and it’s due to the opioids. It’s not due to an underlying process.

When you reverse the opioids, when you bring the dosage down, typically what you’ll see is that this phenomena will regress and disappear. So, the easiest thing for the primary care practitioner to do is to wean the patient. The problem with that--and we find this in our practice--is it doesn’t always work immediately. So patients are really frustrated. We found especially with high dose opioid patients, weaning them takes a long time. They have to come in for several visits. It’s cumbersome, but a primary care physician could certainly do that. There are various algorithms to do that, and it’s well within their training. When it comes to adding adjuvants and NMDA receptor antagonists and maybe detoxification, I think that gets out of their realm. I don’t think many primary cares would be particularly comfortable with that unless they are really doing a lot of pain management. In general, my opinion is that anyone who’s on opioids for more than 30 days for a chronic condition probably should get a second opinion with a pain specialist. I think from a medical legal point of view that’s prudent, for the patient as well as the provider.