Showing papers by "Ian Gilron published in 2006"

Neuropathic pain: a practical guide for the clinician

Abstract: Neuropathic pain, caused by various central and peripheral nerve disorders, is especially problematic because of its severity, chronicity and resistance to simple analgesics. The condition affects 2%-3% of the population, is costly to the health care system and is personally devastating to the people who experience it. The diagnosis of neuropathic pain is based primarily on history (e.g., underlying disorder and distinct pain qualities) and the findings on physical examination (e.g., pattern of sensory disturbance); however, several tests may sometimes be helpful. Important pathophysiologic mechanisms include sodium-and calcium-channel upregulation, spinal hyperexcitability, descending facilitation and aberrant sympathetic-somatic nervous system interactions. Treatments are generally palliative and include conservative nonpharmacologic therapies, drugs and more invasive interventions (e.g., spinal cord stimulation). Individualizing treatment requires consideration of the functional impact of the neuropathic pain (e.g., depression, disability) as well as ongoing evaluation, patient education, reassurance and specialty referral. We propose a primary care algorithm for treatments with the most favourable risk-benefit profile, including topical lidocaine, gabapentin, pregabalin, tricyclic antidepressants, mixed serotonin-norepinephrine reuptake inhibitors, tramadol and opioids. The field of neuropathic pain research and treatment is in the early stages of development, with many unmet goals. In coming years, several advances are expected in the basic and clinical sciences of neuropathic pain, which will provide new and improved therapies for patients who continue to experience this disabling condition.

Chronobiological characteristics of painful diabetic neuropathy and postherpetic neuralgia: diurnal pain variation and effects of analgesic therapy.

Abstract: Clinical impressions suggest that neuropathic pain is often worse at night and significantly impairs sleep. However, the temporal pattern of neuropathic pain during waking hours has not been clearly characterized. Using clinical trial data, we have evaluated the diurnal variation of pain intensity before and during analgesic treatment in patients with diabetic neuropathy (DN) and postherpetic neuralgia (PHN). Pain intensity (0-10) measures throughout the day from a placebo-controlled trial of around-the-clock administration of gabapentin, morphine and a gabapentin-morphine combination in neuropathic pain patients were examined. Baseline data in untreated patients revealed no effect of day of week but a significant effect of time of day in both DN (P < 0.001) and PHN (P < 0.001) such that pain intensity progressively increases throughout the day. This temporal pattern is essentially preserved during treatment with gabapentin, morphine and their combination. Neuropathic pain intensity progressively increases throughout the day and this temporal profile appears to be unaffected by treatment with gabapentin and/or morphine. Advancing our understanding of the chronobiology of neuropathic pain may shed new light on various neurohormonal and neurophysiologic influences and lead to the identification of novel therapeutic targets. Furthermore, recognizing diurnal pain patterns may guide treatment strategies such as the targeted timing of analgesic therapies.

Gabapentin and Pregabalin for the Treatment of Neuropathic Pain: A Review of Laboratory and Clinical Evidence

Abstract: 1Clinical Pain Research, Departments of Anesthesiology and Pharmacology & Toxicology, Queen’s University, Kingston, Ontario; 2Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA Correspondence: Dr Ian Gilron, Clinical Pain Research Departments of Anesthesiology and Pharmacology & Toxicology, Queen’s University, 76 Stuart Street, Kingston, Ontario K7L 2V7. Fax 613-548-1375, e-mail gilroni@post.queensu.ca I Gilron, SJL Flatters. Gabapentin and pregabalin for the treatment of neuropathic pain: A review of laboratory and clinical evidence. Pain Res Manage 2006;11( Suppl A):16A-29A.

Review article: the role of anticonvulsant drugs in postoperative pain management: a bench-to-bedside perspective.

Abstract: Anticonvulsant drugs are effective in the treatment of chronic neuropathic pain but were not, until recently, thought to be useful in more acute conditions such as postoperative pain. However, similar to nerve injury, surgical tissue injury is known to produce neuroplastic changes leading to spinal sensitization and the expression of stimulus-evoked hyperalgesia and allodynia. Pharmacological effects of anticonvulsant drugs which may be important in the modulation of these postoperative neural changes include suppression of sodium channel, calcium channel and glutamate receptor activity at peripheral, spinal and supraspinal sites. The purpose of this article is to review preclinical evidence and clinical trial data describing the efficacy and safety of anticonvulsant drugs in the setting of postoperative pain management. A Medline search was performed to retrieve available literature on the basic and clinical pharmacology of anticonvulsant drugs as they pertain to postoperative pain management. Numerous laboratory studies have described analgesic effects of different anticonvulsant drugs in experimental pain models. Furthermore, several recent clinical trials have shown that anticonvulsants may reduce spontaneous and movement-evoked pain, as well as decrease opioid requirements postoperatively. Some early findings suggest further that anticonvulsant drugs may alleviate postoperative anxiety, accelerate postoperative functional recovery and reduce chronic postsurgical pain. Given the incomplete efficacy of currently available non-opioid analgesics, and the identified benefits of opioid sparing, anticonvulsant medications may be useful adjuncts for postoperative analgesia. Further research in this field is warranted.

The impact of therapy on quality of life and mood in neuropathic pain: what is the effect of pain reduction?

Abstract: Mood and quality of life (QOL) outcomes vary widely in neuropathic pain trials. This may be a result of variable analgesia and other treatment effects. We evaluated the relationship between pain reduction and mood/QOL in neuropathic pain. Pain, side effects, QOL, and mood from a trial of morphine, gabapentin, and a morphine-gabapentin combination were examined. Baseline QOL was impaired according to Short Form Health Survey (SF-36) scores. Baseline mood, according to Profile of Mood States scores, was comparable to that of a nondepressed population. Pain reduction with all three active trial treatments correlated with improved QOL. Pain reduction with morphine and with gabapentin correlated with improved mood. Pain reduction with a morphine-gabapentin combination correlated with improvement in only one of several domains of the Profile of Mood States. Severity of sedation, constipation, and dry mouth during any treatment did not correlate with mood/QOL changes. These results can be interpreted to imply that larger analgesic treatment effect sizes lead to more substantial improvements in QOL and/or mood. However, other beneficial or adverse treatment-related side effects may also affect mood/QOL. Therefore, future studies are needed to also evaluate the impact of treatment-related side effects on mood/QOL in analgesic trials.