Diagnosing Hyperalgesia to Limit Care

Misuse of Hyperalgesia to Limit Care | Practical Pain Mgmt | By Donald C. Harper, MD, BSc March 2011

John (not his real name) is a 51-year-old chronic pain patient that I have been seeing since 2003. I had begun carefully titrating him on oxycodone, Oxycontin® and Dilaudid®, which had been started by another doctor and, ultimately, settled on a dose of Oxycontin 640mg B.I.D., 32mg hydromorphone q 4 hrs prn breakthrough pain and Xanax® 1 to 1.5mg q.i.d. prn muscle spasms and anxiety. On these medicines, he was content and functional and denied any deficits or side-effects due to his medicine.

His insurance company was concerned about the expenses of his medicine and asked me to arrange for a second opinion. Given the complicating factor of his end-stage lung cancer, I arranged for an evaluation by the pain clinic of a major cancer center.  

The report stated that his opiate daily intake was “very variable” and that “he would likely benefit from establishing a scheduled long-acting or extended-release dos-age and rely on the use of a short acting pain medication for breakthrough pain and/or variability in his pain.”

This was, in fact, exactly what we had been doing for years.

My opioid use is also “very variable” and can fluctuate by a factor of three, depending on how well my body is aligned and what hormones are rising or falling and who knows what other kinds of influences.  My body is always “under the influence” of pain.

Further, the report stated “given his high doses, the patient is likely suffering from opiate-induced hyperalgesia and would actually benefit from weaning his daily opiate intake.”

My patient contacted me on a Friday afternoon and told me the insurance company was refusing to pay for his medicines until I gave them a report on my plan to take him off his medicines.

So Dr. Harper decided to do some of his own research and investigate hyperalgesia. He what he found can be summarized in the following:

“Opioid-induced hyperalgesia
seems to be a well-established rat phenomenon,
but remains controversial in humans.”

Fishbain et al did an evidence-based structured review of 504 articles on OIH in humans and animals.2 They addressed ten hypo-theses that had been utilized to test for the possibility of OIH in humans. Only studies performed on opioid naïve, pain-free volunteers that were given opioid infusions met criteria for quality evidence—and even those studies showed inconsistent results.

A study by D. Andrew Tompkins, MD and colleagues at Johns Hopkins School of Medicine compared the effects of repeated alfentanil and diphenhydramine injections on normal opioid naïve, pain-free volunteers.Evidence of “OIH” developed in the antihistamine group, but not in the opioid group.

Another study by Robert Edwards, PhD and colleagues at Harvard Medical School and Brigham and Women’s Hospital prospectively studied 204 patient with chronic spinal pain and recorded their responses to pain tests. They found individuals with lower thresholds and decreased tolerance to pain in approximately 65% of both opioid and non-opioid exposed patients. There was no significant difference in tolerance and pain thresholds to punctuate or pressure stimuli be-tween the two groups.

I agree with Gavril Pasternak, MD, PhD, the distinguished opiate researcher at Memorial Sloan Sloan-Kettering Cancer Center who has stated, in reference to hyperalgesia:

“There is little question that it exists. The animal models can reliably detect it and, if you look closely enough, you might be able to detect it in human subjects. However, in the clinical setting it rarely, if ever, has a sufficiently robust effect to become a significant issue in the absence of metabolic abnormalities including hypercalcemia or renal insufficiency.”

I have been practicing Pain Medicine for thirty years and remember the struggles we went through to establish the reasonableness of chronic opioid therapy in the ethical treatment of chronic non-malignant pain patients.

I am afraid that our concern with the laboratory curiosity of OIH will end up feeding opiophobia and will be used as an excuse by clinicians to avoid the complexities of opioid analgesia or by insurance companies to limit access to care for “expensive” chronic pain patients.

Ethical concerns have disappeared now. The authorities who are deciding the fate of pain patients no longer consider it an ethical imperative to treat pain when possible. How is that even possible?

In our attempts to optimize therapy for chronic pain patients, we must be careful not to “throw out the baby with the bathwater.”  

See also: Why Some Patients Require High Dose Opioid Therapy

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