Pain
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Spinal NMDA receptors (NMDA R) are important in neuropathic sensitisation and acute administration of antagonists can provide temporary attenuation of sensitisation. If establishment of the chronic pain state could be prevented by brief administration of such agents at or around the time of nerve injury (pre-emptive analgesia) it might be possible to avoid many of the unacceptable side effects associated with repeated administration of these or other antagonists. Several reports describe aspects of effective pre-emptive analgesia from NMDA R antagonists in animal models of neuropathic pain. ⋯ These changes were attenuated following NMDA receptor antagonist pre-treatment. Thirdly, we investigated the pharmacological properties of residual mechanical allodynia and cold allodynia that remained after pre-emptive treatment and revealed a greater sensitivity to NMDA R antagonists. These findings indicate that in addition to a marked suppression of thermal hyperalgesia and cold allodynia, pre-emptive treatment with NMDA R antagonist causes a lasting change in spinal NMDA R complexes such that remaining mechanical allodynia should be more effectively targeted by NMDA R antagonists.
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Comparative Study
Spinal-supraspinal serotonergic circuits regulating neuropathic pain and its treatment with gabapentin.
Not all neuropathic pain patients gain relief from current therapies that include the anticonvulsant, gabapentin, thought to modulate calcium channel function. We report a neural circuit that is permissive for the effectiveness of gabapentin. Substance P-saporin (SP-SAP) was used to selectively ablate superficial dorsal horn neurons expressing the neurokinin-1 receptor for substance P. ⋯ This circuit is therefore a crucial determinant of the abnormal neuronal and behavioural manifestations of neuropathy and importantly, the efficacy of gabapentin. As this spino-bulbo-spinal circuit contacts areas of the brain implicated in the affective components of pain, this loop may represent a route by which emotions can influence the degree of pain in a patient, as well as the effectiveness of the drug treatment. These hypotheses are testable in patients.
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Comparative Study
Anatomy of the cervical intervertebral foramina: vulnerable arteries and ischemic neurologic injuries after transforaminal epidural injections.
Cervical transforaminal epidural steroid injections are performed for the treatment of radicular pain. Multiple recent case reports have raised safety concerns regarding neurologic deficits such as anterior spinal artery syndrome and cerebellar injury after these injections. To investigate the potential causes of these injuries, an anatomic study was conducted. ⋯ Variable anastomoses between the vertebral and cervical arteries were found. Therefore, it is possible to introduce steroid particles into the vertebral circulation via the cervical arteries. Critical arteries are located in the posterior aspect of the intervertebral foramen and may be vulnerable to injection or injury during transforaminal epidural steroid injection.
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Randomized Controlled Trial Comparative Study Clinical Trial
Effects of intradermal foot and forearm capsaicin injections in normal and vulvodynia-afflicted women.
Cutaneous response to capsaicin has been used to assess central sensitization in pain research. This study compared the response to intradermal capsaicin in the forearm and foot of vulvar vestibulitis (vestibulodynia)-afflicted cases and controls. We hypothesized that cases will experience greater spontaneous pain, larger cutaneous areas of punctate hyperalgesia and dynamic allodynia, and greater vascular flow than controls. ⋯ VVS cases had higher resting pulse rates and lower resting systolic blood pressures than in controls. Conclusion. VVS patients show enhancement of post-capsaicin pain response extending far beyond the anatomic location of the primary complaint.
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In this systematic review effectiveness of analgesics for pain after tonsillectomy in children was evaluated and trial methodology of the included studies explored. Databases were searched for randomised, controlled studies on systemic paracetamol, NSAIDs and opioids. Eighty-four studies were evaluated for inclusion. ⋯ Because of highly variable methodology and lack of sensitivity only limited conclusions on clinical efficacy of analgesics investigated can be drawn. No analgesic in single prophylactic dose provided analgesia for day of operation. Further studies are needed to find the optimal analgesic(s) for pain after tonsillectomy in children.