Background: Chemotherapy-induced neuropathic pain is a disabling condition following cancer treatment. Vincristine has more neurotoxicity than other vinca alkaloid agents. This study evaluated the correlation of different doses of nefopam with antiallodynic effects in a mouse vincristine neuropathy model. Methods: A peripheral neuropathic mouse model was made by intraperitoneal injection of vincristine (0.1 mg/kg/day; 5-day-on, 2-day-off schedule over 12 days). After the development of allodynia, mice were injected intraperitoneally with 0.9% normal saline (NS group) or various doses (10, 30, 60 mg/kg) of nefopam (Nefopam group). We examined allodynia using von Frey hairs pre-administration and at 30, 60, 90, 120, 180, 240 mins, and 24 hrs after drug administration. We also measured the neurokinin-1 receptor concentrations in the spinal cord to confirm the antiallodynic effect of nefopam after drug administration. Results: The peripheral neuropathic mouse model showed prominent mechanical allodynia. Intraperitoneal nefopam produced a clear dose-dependent increase in paw withdrawal threshold compared with pre-administration values and versus the NS group. The concentration of neurokinin-1 receptor was significantly decreased in the Nefopam group (P< 0.05). Conclusion: Intraperitoneally administered nefopam yielded a dose-dependent attenuation of mechanical allodynia and decreased neurokinin-1 receptor concentration, suggesting that the neurokinin-1 receptor is involved in the antiallodynic effects of nefopam in vincristine neuropathy.

Transforaminal epidural injection is used to treat radicular pain. However, there is no objective method of assessing pain relief following transforaminal injection. Perfusion index is a metric for monitoring peripheral perfusion status. This study evaluates the correlation between perfusion index change and analgesic efficacy in transforaminal blocks for lumbosacral radicular pain. We retrospectively analyzed data of 100 patients receiving transforaminal block for lumbosacral radicular pain. We assessed perfusion index before treatment and at 5, 15, and 30 min following the block. We defined responders (group R) and non-responders (group N) as those with ≥50% and <50% pain reduction, respectively, 30 min following block. Clinical data and perfusion index of the groups were analyzed. Ninety-two patients were examined, of whom 57 (61.9%) and 35 (38.0%) patients reported ≥50% and <50% pain reduction, respectively. Group R had a significantly higher perfusion index change ratio 5 min following the block (p = 0.029). A perfusion index change ratio of ≥0.27 was observed in group R (sensitivity, 75.4%; specificity, 51.4%; AUC (area under the curve), 0.636; p = 0.032). A perfusion index change ratio of ≥0.27 at 5 min after block is associated with, but does not predict improvement in, pain levels following lumbosacral transforaminal block.

Trigeminal neuralgia (TN) is a unilateral disorder characterized by electric shock-like pain, abrupt onset and termination, and limited to one or more branches of the trigeminal nerve. Various therapeutic modalities for TN have been introduced. We searched for literature indexed in PubMed, Medline, and the National Library of Medicine and reviewed all relevant articles on non-surgical treatments for TN. Published studies were reviewed with no restrictions on date; reviews, clinical trials, animal studies, retrospective studies, and cases were included. Carbamazepine and oxcarbazepine are the recommended first-line pharmacotherapies. Interventional treatments should be considered when pharmacotherapy is insufficient or withdrawn because of adverse effects.

Although there are various drugs for Neuropathic pain (NP), the effects of single drugs are often not very satisfactory. The analgesic effects of different combinations of pregabalin, duloxetine, and tramadol or the combination of all three are still unclear. Mixtures of two or three drugs at low and high concentrations (7.5, 10, 15, and 20 mg/kg pregabalin; 7.5, 10, 15, and 30 mg/kg duloxetine; 5 and 10 mg/kg tramadol) were administered to chronic postischemic pain (CPIP) and spinal nerve ligation (SNL) model mice. The effects of these combinations of drugs on mechanical allodynia were investigated. The expression of the glial fibrillary acidic protein (GFAP) in the spinal cord and dorsal root ganglia (DRGs) was measured. The combination of pregabalin, duloxetine, and tramadol significantly alleviated mechanical hyperalgesia in mice with CPIP and SNL. After the administration of this drug combination, the expression of GFAP in the spinal cord and DRGs was lower in the CPIP and SNL model mice than in control mice. This result suggests that the combination of these three drugs may be advantageous for the treatment of NP because it can reduce side effects by preventing the overuse of a single drug class and exert increased analgesic effects via synergism.

Despite rapid advancements in laparoscopic surgical devices and techniques, pain remains a significant issue. We examined the efficacy of preemptive transversus abdominis plane (TAP) block for acute postoperative pain in patients undergoing laparoscopic colorectal cancer surgery. We retrospectively analyzed 153 patients who underwent laparoscopic colorectal cancer surgery with or without TAP block; among them, 142 were allocated to the TAP or non-TAP group. We performed between-group comparisons of demographic, clinical, and anesthetic data and pain scores at a postoperative anesthesia care unit (PACU) and at postoperative days 1, 3, and 5. There were no significant between-group differences in demographic and clinical characteristics. The mean arterial pressure, heart rate, and minimum alveolar concentration (MAC) were significantly lower in the TAP group at the start and end of surgery. The post-extubation bispectral index was significantly higher in the TAP group. There were no significant between-group differences in the pain scores and opioid consumption at the PACU or at postoperative days 1, 3, and 5, or in the time to pass flatus, the hospital stay length, and postoperative complications. Preemptive TAP block showed an intraoperative, but not postoperative, analgesic effect, characterized by a low mean arterial pressure, heart rate, and MAC.