Opioid-Induced Hyperalgesia

Patients with chronic pain being treated with opioids can commonly be expected to develop tolerances to the drug with longer-term pain management treatment, but the emergence of certain, uniquely sensitive pain characteristics can be red flags for a potential differential diagnosis of hyperalgesia.

 

What is Opioid-Induced Hyperaglesia?

"Opioid-induced hyperalgesia (OIH) is defined as a state of nociceptive sensitization caused by exposure to opioids. The condition is characterized by a paradoxical response whereby a patient receiving opioids for the treatment of pain could actually become more sensitive to certain painful stimuli. The type of pain experienced might be the same as the underlying pain or might be different from the original underlying pain. OIH appears to be a distinct, definable, and characteristic phenomenon that could explain loss of opioid efficacy in some patients". Source.

Hyperalgesia is not an easy condition to diagnose. When a chronic pain patient isn't getting better, a clinician should asks: is the patient developing a tolerance and needs more opioid or does he have opioid-induced hyperalgesia?

Importantly, clinicians should rule out other factors, including the progression of a disease, such as cancer, or a new injury causing new pain.

Additionally, hyperalgesia should not be mistaken for allodynia. Whereas hyperalgesia is characterized as a painful response to painful stimuli, allodynia involves oversensitized, increased pain in response to even non-painful stimuli, such as just brushing against the skin.