Chronic Pain in America

Chronic pain is a silent epidemic in the United States. According to the National Institutes of Health, the overall costs associated with pain in the United States are estimated at $100 billion a year in healthcare, compensation, and litigation. Studies suggest that more than one third of the American population will suffer from chronic pain in their lifetime.¹

The Two Faces of Pain: Acute and Chronic

Pain is an unpleasant sensation localized to a specific part of the body and is often described in tissue-destructive terms (e.g., stabbing, burning, twisting, tearing, squeezing) and/or, emotional terms (e.g., terrifying, nauseating, sickening).² In this sense, there is a duality to pain, it is both a sensation and an emotion.²  Pain can be divided into two general types: acute and chronic pain. Acute pain usually results from disease, inflammation, or injury to tissues, generally comes on suddenly, such as after trauma or surgery, and is confined to a relatively short period of time. In some instances, acute pain becomes chronic pain; postoperative and severely ill patients with poorly controlled pain may be at high risk for developing chronic pain.^3-4

Chronic pain is defined as pain that persists or recurs for greater than 3 months, that persists for greater than 1 month after the resolution of an acute tissue injury, or accompanies a non-healing lesion.⁶ Causes include chronic disorders (e.g., cancer, arthritis, diabetes) and injuries (e.g., herniated disk, torn ligament), and many primary pain disorders (e.g., neuropathic pain, fibromyalgia, chronic headache).⁶

Sometimes, even mild injury may lead to long-lasting changes (sensitization) in the nervous system that may produce persistent pain, even after the injury has healed. With sensitization, discomfort that is due to a nearly resolved disorder and that one would otherwise be perceived as mild, is instead perceived as significant pain. In some cases, as with chronic back pain after injury, the original cause of pain is obvious; in others (e.g., chronic headache, atypical facial pain, chronic abdominal pain), the cause is not readily identified.⁶

Uncontrolled or inadequately controlled pain also has a dramatic impact on the quality of life of a patient. Some chronic pain patients suffer physical deterioration in addition to disturbances in sleep, depression, and emotional changes.⁶ Some patients whose pain cannot be adequately controlled with oral medications may considerer having their pain medication injected directly into the spinal fluid. Many of these patients are resistant or intolerant to the use of narcotic medications and have few treatment options available to them.⁷

Nociceptive Pain

This is the type of pain we have all experienced from time to time as a result of injury -- a paper cut, a broken bone, burns, and appendicitis, among other things.³  In nociceptive pain, the nerves are responding to tissue injury from parts of the body that are damaged, and when the damage heals, the pain usually stops. In some cases, nociceptive pain may persist for months or years.³

Neuropathic Pain

Neuropathic pain can result from injury to the nerves, either in the peripheral or central nervous system.² When the pain results from damage to central nervous system, especially spinothalamic pathway or thalamus, the pain is often severe and notoriously difficult to treat.²

Neuropathic pain is frequently described as unusual burning, tingling, or electric shocklike and can be triggered by very light touch.²  The unremitting presence of these unusual painful sensations can be devastating to the patient with neuropathic pain. It can result from diseases that affect nerves (such as diabetic neuropathy or herpes zoster, shingles) or without direct injury to nerves (e.g., complex regional pain syndrome, also known as
reflex sympathetic dystrophy – causalgia).²

Evolution of Intrathecal (Intraspinal) Therapy

For centuries, opioid (narcotic) medications have been regarded as the universal treatment for acute and chronic pain, and today, 90% of patients with chronic pain receive opioids.⁸ However, opioid therapy does not provide adequate pain relief for everyone. Therefore, there is a continued need for alternative treatment options for patients. In the past 20 years, a great deal of progress has been made in the treatment of severe chronic pain, including the widespread use of intrathecal pain medications.^8,9 The side effects for specific pain medications should be considered. Non-opioid medications, delivered directly into the spine via a pump (intrathecal delivery), may provide another option for patients who do not respond well to their previous treatments. The only medications that are FDA approved for intrathecal pain management are morphine and PRIALT® (ziconotide intrathecal infusion).⁹

Please see accompanying full prescribing information including boxed WARNING and important safety information.

1. National Institutes of Health. NIH Guide: New Directions in Pain Research I. September 4, 1998. Available from http://grants.nih.gov/grants/guide/pa-files/PA-98-102.html
2. Pain: Pathophysiology and Management. In: Hauser SL, ed. Harrison’s Neurology in Clinical Medicine. New York: McGraw-Hill; 2006: Chapter 4.
3. Taylor DR. Improving outcomes in acute pain management: optimizing patient selection. Pharmacologic Management of Pain Expert Column. Available at http://www.medscape.com/viewarticle/489495_print. Accessed January 14, 2009.
4. Kehlet H. Acute pain control and accelerated postoperative surgical recovery. Surg Clin North Am. 1999;79(1):431-443.
5. Fortner BV, Okon TA, Portenoy RK. A survey of pain-related hospitalizations, emergency department visits, and physician office visits reported by cancer patients with and without history of breakthrough pain. J Pain. 2002;3(1):38-44.
6. Pain. In Beers MH, ed. The Merck Manual of Diagnosis and Therapy: Eighteenth Edition. Whitehouse NJ: Merck Research Laboratories; 2006: 1769-1781.
7. Hassenbuch SJ, Garber J, Buchser E, et al. Alternative intrathecal agents for the treatment of pain. Neuromodulation. 1999;2(2):85-91.
8. Benyamin R, Truscott Am, Data S. et al. Opioid complications and side effects. Pain Physician. 2008;11:S105-S120.
9. PRIALT® (ziconotide intrathecal infusion) Prescribing Information.