Chapter 012. Pain: Pathophysiology and Management (Part 9) docx

Pain: Pathophysiology and Management Part 9 Treatment of Neuropathic Pain It is important to individualize treatment for patients with neuropathic pain.. Several general principles sh

Chapter 012 Pain:

Pathophysiology and Management

(Part 9)

Treatment of Neuropathic Pain

It is important to individualize treatment for patients with neuropathic pain Several general principles should guide therapy: the first is to move quickly to provide relief; a second is to minimize drug side effects For example, in patients with postherpetic neuralgia and significant cutaneous hypersensitivity, topical lidocaine (Lidoderm patches) can provide immediate relief without side effects Anticonvulsants (gabapentin or pregabalin, see above) or antidepressants can be used as first-line drugs for patients with neuropathic pain Antiarrhythmic drugs such as lidocaine and mexiletene can be effective (see above) There is no consensus on which class of drug should be used as a first-line treatment for any chronically painful condition However, because relatively high doses of

anticonvulsants are required for pain relief, sedation is very common Sedation is also a problem with the tricyclic antidepressants but is much less of a problem with serotonin/norepinephrine reuptake inhibitors (SNRIs, e.g., venlafaxine and duloxetine) Thus, in the elderly or in those patients whose daily activities require high-level mental activity, these drugs should be considered as the first line In contrast, opioid medications should be used as a second- or third-line drug class While highly effective for many painful conditions, opioids are sedating, and their effect tends to lessen over time, leading to dose escalation and, occasionally, a worsening of pain due to physical dependence Drugs of different classes can be used in combination to optimize pain control.It is worth emphasizing that many patients, especially those with chronic pain, seek medical attention primarily because they are suffering and because only physicians can provide the medications required for pain relief A primary responsibility of all physicians is

to minimize the physical and emotional discomfort of their patients Familiarity with pain mechanisms and analgesic medications is an important step toward accomplishing this aim

Further Readings

Craig AD: How do you feel? Interoception: The sense of the physiological condition of the body Nat Rev Neurosci 8:655, 2002

Fields HL: Should we be reluctant to prescribe opioids for chronic nonmalignant pain? Pain 129:233, 2007 [PMID: 17449177]

Keltner JR et al: Isolating the modulatory effect of expectation on pain transmission: A functional magnetic resonance imaging study J Neurosci 26:4437, 2006 [PMID: 16624963]

Macintyre PE: Safety and efficacy of patient-controlled analgesia Br J Anaesth 87:36, 2001 [PMID: 11460812]

Wager TD et al: Placebo-induced changes in FMRI in the anticipation and experience of pain Science 303:1162, 2004 [PMID: 14976306]

Bibliography

Baliki MN et al: Chronic pain and the emotional brain: Specific brain activity associated with spontaneous fluctuations of intensity of chronic back pain

J Neurosci 26:12165, 2006 [PMID: 17122041]

Baron R et al: Causalgia and reflex sympathetic dystrophy: Does the sympathetic nervous system contribute to the generation of pain? Muscle Nerve

22:678, 1999 [PMID: 10366221]

Gebhart GF (ed): Visceral Pain Seattle, IASP Press, 1995

Gilron I et al: Morphine, gabapentin, or their combination for neuropathic pain N Engl J Med 352:1324, 2005 [PMID: 15800228]

Julius D, Basbaum AI: Molecular mechanisms of nociception Nature 413:203, 2001 [PMID: 11557989]

Kearney PM: Do selective cyclo-oxygenase-2 inhibitors and traditional non-steroidal anti-inflammatory drugs increase the risk of atherothrombosis? Meta-analysis of randomized trials BMJ 332:1302, 2006 [PMID: 16740558]

McMahon SB, Koltzenburg M (eds): Wall and Melzack's Textbook of Pain,

5th ed Philadelphia: Elsevier/Churchill Livingstone, 2006

Rush AM et al: A single sodium channel mutation produces hyper- or hypoexcitability in different types of neurons Proc Nat Acad Sci U.S.A 103:8245, 2006 [PMID: 16702558]

Wallace MS: Diagnosis and treatment of neuropathic pain Curr Opin Anaesthesiol 18:548, 2005 [PMID: 16534291]