Chronic Pain Syndrome
What Is Chronic Pain?
Chronic pain is a syndrome involving either ongoing pain that lasts beyond the resolution of an injury or pain that recurs as a result of a long-standing condition. Criteria for chronic pain includes pain that lasts for at least a month beyond what would be expected from the illness or injury; pain that recurs on and off for at least three months; and pain that accompanies a long-standing condition. The common sources of chronic pain are damage or inflammation affecting joints, muscles and/or nerves.
Pain syndromes related to joint injury include osteoarthritis, which is the most common cause of chronic joint pain, and rheumatoid arthritis, which occurs when the body’s own defense mechanism attacks the joints. Pain related to nerve injury includes postherpetic neuralgia, the vexing pain that may follow shingles; tic douloureux (trigeminal neuralgia), a condition that involves intense facial pain; diabetic neuropathy, which results in painful feet; and phantom limb or post-amputation pain, which may occur following the removal of a limb.
Because the organs inside the body don’t have pain fibers like the joints, skin, or muscles, organ damage may be signaled by a chronic, aching or ill-defined discomfort. This is referred to as visceral pain. Inflammation or cancer of an organ, for example, the liver, kidney, or bowel, can cause chronic visceral pain.
Another type of chronic pain, psychogenic or psychophysiological pain, is not related to an injury or illness. People with psychogenic pain have real discomfort, but no source of pain can be identified or the level of discomfort exceeds any possible cause. Fibromyalgia and chronic headache may fall into this pain category.
Persistent, debilitating pain is the common feature of pain syndromes. The location and type of the pain depends on the nature of the injury when present.
Causes for chronic pain can vary greatly. Risk factors for chronic pain include recovering from injury, ongoing infection, and living with long-term or degenerative illness. Pain linked to a muscle, bone, or joint is typically caused by damage or injury to tissue that activates nerve endings called nociceptors, which respond by transmitting pain signals to the brain.
- Injuries. Sprains, muscle strains, and under- and overuse like back pain,Achilles tendonitis, andheel pain may develop into chronic pain.
- Nociceptive pain is usually localized, constant, and often has an aching or throbbing quality. Visceral pain stemming from damage to an internal organ is a subtype of nociceptive pain.
- Neurogenic pain is pain of caused by damage to the central nervous system and includes neuralgias, such as phantom limb pain, and peripheral neuropathies, such as that caused by diabetes—may also involve tissue damage initially, but the pain persists as a result of an injury or malfunction in the peripheral or central nervous system.
- Psychogenic pain has no known physical cause.
- Trigeminal neuralgia, also called tic douloureux, is a condition caused by damage to the fifth cranial nerve called the trigeminal nerve. This condition is characterized by severe, stabbing pain on one side of the jaw or cheek, typically lasting a few seconds and recurring throughout the day. Talking, brushing the teeth, touching the face, chewing, or swallowing may trigger an attack. Trigeminal neuralgia may persist for days or months, disappear, and recur months or years later.
Long-term illnesses that may result in chronic pain include the following:
Cancer. Cancerpatients often experience chronic pain caused by tumors that infiltrate and compress organs or bones and by treatment such as radiation and chemotherapy that causes tissue swelling.
Degenerative diseases such as osteoarthritis or osteoporosis.
Inflammatory disease such as rheumatoid arthritis.
Multiple sclerosis. Central pain syndrome is a neurological condition caused by damage to the central nervous system. It may occur in patients who have experienced spinal cord injury, brain injury, or strokeand in patients with multiple sclerosis. It is characterized by steady pain usually described as a burning, aching, or cutting sensation, and brief bursts of sharp pain. Central pain syndrome may develop years after damage to the central nervous system occurs.
Vascular conditions that reduce blood flow to an area of the body can cause pain. Vascular headache is one of the most common types of headache.
What If You Do Nothing?
Mild to moderate cases of pain may clear up on their own, depending on the cause. For example, many cases of back pain resolve without treatment. However, pain associated with chronic conditions may worsen over time, impair daily functioning, and have a negative impact on emotional well-being.
Finding a root cause for chronic pain can take time and follow-up. The diagnosis is based on the patient's history of symptoms, underlying conditions, physical and neurological examination, and diagnostic tests. Patients may be referred to several medical practitioners, including neurologists or orthopedists for diagnosis and treatment.
- A physical examination and taking the patient's history are necessary to determine the degree of pain (on a scale of 1 to 10, for instance), to identify a possible source of pain, and to uncover the degree of impairment.
- Blood and urine tests to evaluate for potential infection or abnormalities.
- Imaging tests include x-rays, computed tomography scans, magnetic resonance imaging scans and bone scans.
- Spinal tap such as a lumbar puncture, may used to diagnose infection, multiple sclerosis or other conditions.
- Electrophysiological studies of the nerves and muscles or electromyography (EMG) are used to rule out or diagnose conditions that affect the nerves or muscles.EMGrecords electrical activity in muscle tissue, andnerve conduction velocity studies record the speed at which impulses travel through nerves and measure electrical responses.
- Thermographymeasures the temperature of surface tissue as a function of blood flow. This test may be used to detect altered blood flow to a painful area, which may indicate a vascular condition.
A variety of medical and nondrug therapies are available for treating chronic pain. Patients with
chronic pain may be referred to a pain clinic, where clinicians take a multidisciplinary approach, prescribing a variety of methods to customize a treatment plan that meets the individual’s needs.
- Over-the-counter pain relievers, which include acetaminophen, and the nonsteroidal anti-inflammatory drugs (NSAIDS) aspirin, ibuprofen, ketoprofen, and naproxen sodium, are commonly used to treat chronic pain. NSAIDS are most useful when pain involves an inflammatory component; if inflammation is not present, acetaminophen is preferred.
- Tricyclic antidepressants may be prescribed to treat the neuropathic pain associated with postherpetic neuralgia, diabetic neuropathy, phantom limb pain, and central pain which follows a stroke. These antidepressants are effective even in the absence of depression.
- Anticonvulsant drugs are commonly used to treat seizures, may be prescribed for pain associated with trigeminal neuralgia, postherpetic neuralgia, neuroma, diabetic neuropathy, multiple sclerosis, and migraines.
- Antiarrhythmic drugs treat heart arrhythmias and may be prescribed to treat diabetic neuropathy and central pain.
- Topical anesthetics and capsaicin may be helpful for patients with diabetic neuropathy, postherpetic neuralgia, or neuroma pain.
- Opioids, such as oxycodone, fentanyl, and morphine, may be prescribed for intractable pain. Because of concerns regarding addiction, ongoing opioid use for the treatment of chronic pain is controversial controversial.
Lifestyle and Behavior
- Hot and cold applications can provide temporary relief for muscle and joint conditions.
- Exercise can help keep the joints and connective tissue strong and limber, improve sleep, and fight depression. Exercise may also reduce the need for pain relievers.
- Cognitive behavior therapy teaches patients skills to cope with pain and may help relieve the anxiety that accompanies chronic pain.
- Acupuncture is a centuries-old Asian remedy that involves the insertion of tiny needles into key points of the body, may be beneficial for those with osteoarthritis, headache, and low back pain.
- Stress management techniques, such as relaxation therapy, biofeedback, and self-hypnosis, help patients learn to influence their physical response to pain.
- Electrical stimulation, including transcutaneous electrical stimulation and spinal cord stimulation, involves the delivery of brief electrical pulses to the nerve endings to provide pain relief.
There is no way to prevent chronic pain, but precautions may help reduce the risk of injuries that can cause pain, and proper pain management can minimize chronic pain symptoms.
When To Call A Doctor
Call a doctor if you experience pain that persists beyond the expected course of an illness or injury if you experience recurrent pain that accompanies a chronic condition, or if pain impairs your ability to function daily. You may also want to ask your doctor about referral to pain clinics that specialize in pain management.
Reviewed by James Cyriac, M.D., Assistant Clinical Professor of Anesthesiology and Pain Medicine, UC Irvine Health, Orange County, CA. Review provided by VeriMed Healthcare Network.