Hyperalgesia & Opioid Induced Hyperalgesia: Causes, Treatment

If you have continuous pain for more than 6 months then you are suffering with chronic pain.

Chronic pain may be secondary to cancer or non-cancer illnesses. Almost all cancer pain results in hyperalgesia. Most common chronic non-cancer illnesses causing hyperalgesia are failed back syndrome, degenerative disk disease, disk herniation, spinal stenosis, facet joint disease, fibromyalgia, hip or knee joint arthritis, intercostal neuralgia, post-herpetic neuralgia (shingles), diabetic neuropathy and peripheral neuropathy. Prolonged chronic pain becomes neuropathic pain. Neuropathic pain causes hyperalgesia.

Neuropathic pain is described as hyperalgesia and allodynia. Description of hyperalgesia is distinct from symptoms of allodynia. Hyperalgesia is increased feeling of pain after painful stimuli and allodynia is increased feeling of pain following non-painful stimuli like touch or pressure over skin.

Yes, prolonged back pain causes hyperalgesia. The cause of hyperalgesia pain is neuropathic pain. Initial back pain is nociceptive pain and become neuropathic pain when symptoms of hyperalgesia become predominant.

• Cancer pain.
• Non- cancer pain.

• Hyperalgesia Caused Due To Failed Back Syndrome: Hyperalgesia is caused by irritation of spinal nerve following back surgery. Scar tissue following surgery often irritates or pinches spinal nerve resulting in hyperalgesia.
• Peripheral Neuropathy Causing Hyperalgesia: Peripheral Neuropathy most often causes hyperalgesia in late stages. Peripheral neuropathy is caused by medications, chemotherapy, radiation treatment, vitamin deficiency and alcohol.
• Hyperalgesia Caused Due To Diabetic Neuropathy– Hyperalgesia is associated with diabetic neuropathy.
• Inflammatory Diseases that Can Cause Hyperalgesia- Joint pain, arthritis, and joint injury causes nociceptive pain and if not adequately treated results in hyperalgesia.
• Hyperalgesia Caused Due To Pinched Nerve-Scar tissue, disk herniation, disk fragments and entrapped neuropathy causes continuous irritation or pinch of spinal or peripheral nerve, which results in hyperalgesia.
• Complex Regional Pain Syndrome (CRPS) Resulting in Hyperalgesia– CRPS is described as type 1 and 2 CRPS. CRPS is caused by amputation resulting in hyperalgesia also known as Phantom pain.
• Hyperalgesia Caused Due To Trigeminal Neuralgia– Trigeminal neuralgia causes hyperalgesia spread over all three branches of trigeminal nerve or one of the three branches of trigeminal nerve.
• Multiple Sclerosis– Multiple sclerosis causes irritation of spinal nerve and results in wide spread hyperalgesia.
• Shingles or Post-Herpetic Neuralgia– Hyperalgesia pain is along the nerve, which is affected by viral infection. Nerve is irritated by viral spread through the nerve.

You may feel hyperalgesia induced by opioids. The prolonged opioid treatment often causes physiological changes in pain receptors and synapses resulting in hyperalgesia.

You may be suffering with Opioid Induced Hyperalgesia (OIH).

Opioid induced hyperalgesia (OIH) is escalation of sensation of residual pain following both noxious and non-noxious stimuli. Opioid induced hyperalgesia is increased pain following taking opioid pills. Symptoms of Opioid induced hyperalgesia (OIH) were thought to be more common in long-term opioid therapy.^1,2

Yes. Opioid-induced hyperalgesia is also known as “Medication-Overuse Pain”. Opioid-induced hyperalgesia (OIH) was often observed in patients taking high dosage of opioid. Hyperalgesia induced by opioid is different than hyperalgesia caused by neuropathic pain.

Recent evidence indicates that chronic opioid administration activates pain receptor-4 on glial cells.¹ Activation of glial cells results in a pro-inflammatory state of pain receptors, which results in magnification of pain impulses expressing hyperalgesia.¹ Opioids are known to induce chronic hyperalgesia following long–term opioid treatment.

Tolerance is one of the opioid side effects. Tolerance is a resistance to analgesics effects of opioids, which is seen in patients after long-term use. Patient feels continuation of pain at same intensity or very little reduction of pain intensity after taking opioid medications. Obviously ineffective dosage and continuation of pain follows increased demand for pain medications.

If you have developed tolerance, you will get some pain relief after taking opioid pills and your pain will not be more than residual pain as in hyperalgesia.

Opioid-induced hyperalgesia is often mistaken for increased tolerance to opioids.³ Microbiological dissimilarity between Opioid induced hyperalgesia (OIH) and opioid tolerance is at receptor level. Pain receptors of patient suffering with Opioid induced hyperalgesia (OIH) are hypersensitive to noxious and non-noxious stimuli, while pain receptors of patients who have tolerance to opioid do not respond to opioid medications as expected.

Once you develop opioid induced hyperalgesia, you will get more pain after taking opioid. Hyperalgesia is caused by molecular changes in pain receptors. Pain receptors are hypersensitive to any stimulation and results in hyperalgesia following continuous ingestion of high dosage of opioids. Pain receptors of patient suffering with opioid induced hyperalgesia become hypersensitive to noxious and non-noxious stimuli after ingestion of opioid pills. Hypersensitive receptors following taking opioid pills respond to any noxious or non-noxious stimuli with expression of severe pain.

Demand for increased dosage of opioids to achieve hyperalgesia pain relief is extremely high. Opioid Addiction and Opioid Induced Hyperalgesia (OIH) both leads to increased demand for pain medications. Opioid induced hyperalgesia is often not recognized by treating physician. Literature and published scientific papers suggests Opioid Induced Hyperalgesia is observed following opioid treatment in normal patient⁷ and in patients abusing opioid.⁴ Opioid induced hyperalgesia is often mistaken and diagnosed as addiction. Your primary care physician may have thought you may be suffering with opioid addiction.

Addiction is an illness seen in individuals taking opioid for recreational reason and not for pain. Chronic pain patients with history of opioid addiction often request additional pain medications and early refill. The behavior of opioid addict patient and Opioid Induced Hyperalgesia patient is similar to obtain additional pain medication than prescribed dosage.⁵

You should be treated at multidisciplinary pain clinic. You may need physical therapy and interventional pain therapy to reduce intensity of pain. You need a pain physician who can monitor your pain and treat your hyperalgesia with different medications. You may need adjuvant treatments like physical therapy and interventional pain treatment.

Hyperalgesia is treated with rotation of different opioids. If symptoms subside then rotations are continued as long as analgesic effects are seen with opioid therapy. If rotation treatment is not helpful then addition of ketamine, dextromethorphan, and/or nonsteroidal anti-inflammatory drugs (NSAIDs) with opioid may alleviate the symptoms. Finally if symptom of hyperalgesia does continue then opioid is switched to buprenorphine, or methadone.^5,6,7

Physical therapy is prescribed to strengthen your back muscles and facet joint injection treatment like epidural injection for radicular pain and facet joint injection for facet joint pain may also be useful.

Pain following back surgery is diagnosed as failed back syndrome. Failed back syndrome is secondary to pinch nerve or facet joint pain. If pain is reduced to tolerable level then you should consider a treatment of prevention of hyperalgesia.

Rotating different opioids after 3 to 6 months of continuous exposure to same opioid can be used as a preventive treatment.⁸ Addition of NMDA receptor antagonist like dextromethorphan, methadone or ketamine with opioids also helps to prevent hyperalgesia.^8,9

Also Read:

• Hyperalgesia: Symptom Caused By Fibromyalgia and Opioid Therapy
• Morphine Induced Hyperalgesia-Is It Real? History Of Morphine As A Pain Medication