Articles: neuralgia.
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Anesthesia and analgesia · Dec 1998
The anti-allodynic effects of amitriptyline, gabapentin, and lidocaine in a rat model of neuropathic pain.
The management of patients with neuropathic pain is challenging. There are only a few reports regarding the acute effects of the commonly used adjuvant drugs amitriptyline (AMI), gabapentin (GBP), and lidocaine (LDC) on neuropathic pain behaviors in animal models. Thus, the purpose of this study was to investigate the acute effects of AMI, GBP, and LDC on behavioral signs of mechanical allodynia and the site of action of these drugs using a rat model of neuropathic pain. Under general anesthesia with halothane, neuropathic injury was produced in rats by tightly ligating the left L5 and L6 spinal nerves. In Experiment 1, baseline mechanical allodynia data were recorded, and the animals were randomly divided into five groups: Group 1 received saline intraperitoneally (IP), Group 2 received AMI (1.5 mg/kg IP); Group 3 received GBP (50 mg/kg IP), Group 4 received an IV saline infusion for 10 min, and Group 5 received LDC (10-mg/kg IV infusion) for 10 min. Measurements of mechanical allodynia were repeated 0.5, 1, 2, and 4 h and 1, 3, and 7 days after treatment. In Experiment 2, rats were prepared similarly to the first experiment, and a single unit activity of continuous discharges of injured afferent fibers was recorded from the left L5 fascicles before and until 1 h after treatment. All animals developed neuropathic pain behavior within 7 days after surgery. All three tested drugs were effective in increasing the threshold for mechanical allodynia as early as 30 min after treatment, and the effect lasted for at least 1 h. Furthermore, AMI and LDC reduced the rate of continuing discharges of injured afferent fibers, whereas GBP did not influence these discharges. Our findings clearly demonstrate an attenuation of neuropathic pain behavior in rats treated with AMI, GBP, or LDC. Finally, the site of action of LDC seems to be primarily in the periphery, and that of GBP is exclusively central, whereas that of AMI seems to have both peripheral and central components. ⋯ In the present study, we examined the effectiveness of three drugs commonly used for the treatment of neuropathic pain. Systemic injections of amitriptyline, gabapentin, or lidocaine produced pain-relieving effects in this established model for neuropathic pain in rats, which supports their clinical use in managing patients with neuropathic pain syndromes.
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Randomized Controlled Trial Multicenter Study Clinical Trial
Postherpetic neuralgia: impact of famciclovir, age, rash severity, and acute pain in herpes zoster patients.
New and previously reported analyses of the data from a placebo-controlled trial of famciclovir are reviewed in light of recently proposed recommendations for the analysis of pain in herpes zoster trials. The analyses examined the effect of famciclovir treatment on the duration of postherpetic neuralgia (PHN), which was defined as pain persisting after rash healing, pain persisting > 30 days after study enrollment, or pain persisting > 3 months after study enrollment; the baseline characteristics of patients in the famciclovir and placebo groups who developed PHN; the impact of famciclovir treatment on the duration of PHN, while controlling for significant covariates; and the prevalence of PHN at monthly intervals from 30 to 180 days after enrollment. The results of these analyses indicated that greater age, rash severity, and acute pain severity are risk factors for prolonged PHN. In addition, they demonstrated that treatment of acute herpes zoster patients with famciclovir significantly reduces both the duration and prevalence of PHN.
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Comparative Study
Mesh inguinodynia: a new clinical syndrome after inguinal herniorrhaphy?
Chronic inguinodynia or neuralgia after conventional inguinal herniorrhaphy is rare, and diagnosing the exact cause is difficult. Treatment has ranged from local injection to remedial surgery with variable results. The increasing popularity of prosthetic mesh repairs (tension free, plug, or laparoscopic) has not eliminated these pain syndromes from occasionally occurring. Recommended management in these situations is extremely difficult. ⋯ Remedial inguinal exploration and mesh removal with or without neurectomy resulted in favorable outcomes in 60% of patients with mesh herniorrhaphy chronic inguinodynia (neuralgia). It appears that coincident neurectomy affords better results than mesh removal alone. Relief with nerve block did not predict favorable outcomes. Despite the popularity and favorable outcomes of prosthetic mesh repairs, persistent postoperative pain still occurs in a small cohort of patients. This may become more evident with the rising interest in laparoscopy. Correcting this problem once presented can be a formidable task. Remedial inguinal surgery with mesh removal and neurectomy will cure selected patients.
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Moderate to severe pain is a common feature of central and peripheral demyelinating disorders. Pain in multiple sclerosis tends to occur when the disease is well-established and usually lingers infinitely. ⋯ Pain syndromes are well-defined in each disorder based on the underlying pathophysiology. Treatment involves a variety of pharmacologic and nonpharmacologic approaches individualized for each specific pain syndrome.
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Comparative Study Clinical Trial Controlled Clinical Trial
Effects of gabapentin on the different components of peripheral and central neuropathic pain syndromes: a pilot study.
Anticonvulsants are widely used in the treatment of neuropathic pain, and are assumed to act preferentially on lancinating, shooting pain. In the present study, the effects of gabapentin, a novel anticonvulsant, were evaluated systematically on both spontaneous and evoked pain in 18 patients with peripheral nerve injuries or central lesions. Gabapentin was administered orally in gradually increasing doses up to a maximum of 2,400 mg/day. ⋯ In contrast, no effects were observed on detection and pain thresholds to static mechanical and hot stimuli. Side effects were generally minor and did not interfere with everyday activities. The present study suggests that gabapentin has preferential antihyperalgesic and/or antiallodynic effects, and is equally effective in pain due to peripheral nerve injuries and central lesions.