71-year-old with worsening diffuse pain
A 71-year-old retired transit dispatcher presents with two weeks of worsening, diffuse pain. He has chronic lumbar spondylosis and takes amlodipine. Three weeks ago, his extended-release morphine dose was increased for persistent back pain. Since the adjustment, his discomfort has intensified and spread to his chest, abdomen, and thighs. His spouse notes he cannot tolerate the touch of bedsheets or his flannel shirt. Vitals and complete blood count are normal. Neurologic examination reveals normal motor strength and intact reflexes. Light stroking of his abdomen and extremities with a cotton swab produces severe pain. Which of the following is the most likely diagnosis?
See the answer and explanation below:
Post-Call Recovery Reads
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B
Explanation
Clinical Pearl:
Opioid-induced hyperalgesia presents as a paradoxical intensification and diffuse spread of pain beyond the original site, accompanied by cutaneous allodynia, following opioid dose escalation. Unlike opioid tolerance, increasing the opioid dose worsens the pain, whereas gradual dose reduction or opioid rotation alleviates it.
Explanation:
This patient has opioid-induced hyperalgesia, evidenced by paradoxical worsening and anatomical spread of pain beyond his initial lumbar region following an increase in his morphine dose, coupled with prominent cutaneous allodynia. Opioid-induced hyperalgesia represents a state of neuroplastic nociceptive sensitization driven by central glutamatergic pathways and N-methyl-D-aspartate receptor activation, where opioid exposure paradoxically lowers pain thresholds. Opioid tolerance manifests as a diminished analgesic response to a constant opioid dose over time, but pain remains confined to the original anatomical distribution, lacks cutaneous allodynia, and improves rather than worsens when the dose is escalated. Lumbar radiculopathy follows a specific dermatomal distribution with corresponding sensory loss, motor weakness, or asymmetric tendon reflexes, which are absent here. Opioid withdrawal can produce myalgias and hyperalgesia, but it occurs after dose reduction or missed doses and is accompanied by prominent autonomic signs such as diaphoresis, mydriasis, tachycardia, and rhinorrhea. Polymyalgia rheumatica produces bilateral aching and morning stiffness primarily localized to the shoulder and pelvic girdles rather than widespread cutaneous allodynia to light touch, and its onset does not correlate with opioid dose escalations.
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