Articles: neuralgia.
-
Patients with an implanted spinal cord stimulation (SCS) system for pain management present an opportunity to study dynamic changes in the pain system in a situation where patients are not stimulated (ie, experiencing severe pain) compared with a situation in which patients have just been stimulated (ie, pain free or greatly reduced pain). The aims of this study were (1) to determine if there are differences in nociceptive withdrawal reflex thresholds (NWR-T) and electrical pain thresholds (EP-T) before and after SCS; and (2) to establish if these differences are related to psychological factors associated with chronic pain. ⋯ The results of this study suggest that pain relief after SCS is partially mediated by a decrease in the excitability of dorsal horn neurons in the spinal cord.
-
Patients with neuropathic pain commonly present with spontaneous pain, in addition to allodynia and hyperalgesia. Although evoked responses in neuropathic pain models are well characterized, determining the presence of spontaneous pain is more challenging. We determined whether the chronic constriction injury (CCI) model could be used to measure effects of treatment of spontaneous pain, by evaluating dorsal horn neuron (DHN) spontaneous activity and spontaneous pain-related behaviors. ⋯ The median rate of spontaneous activity in the CCI group (12.6 impulses per second) was not different from the sham group (9.2 impulses per second). Also, there was no change in DHN spontaneous activity after sciatic nerve block with bupivacaine. Our findings suggest that CCI as a neuropathic pain model should not be used to measure effects of treatment of spontaneous pain driven by the peripheral input.
-
Loss of calcineurin (protein phosphatase 3) activity and protein content in the postsynaptic density (PSD) of spinal dorsal horn neurons was associated with pain behavior after chronic constriction injury (CCI) of the rat sciatic nerve, and intrathecal administration of the phosphatase provided prolonged analgesia (Miletic et al. 2013). In this study, we examined whether one consequence of the loss of calcineurin was the persistent phosphorylation of the GluA1 subunit of α-amino-3-hydroxy-5-methyl-4-isoxazolepropioinic acid (AMPAR) receptors in the PSD. This would allow continual activation of AMPAR receptors at the synapse to help maintain a long-lasting enhancement of synaptic function, ie, neuropathic pain. ⋯ This was associated with phosphorylation of GluA1 in the ipsilateral PSD at Ser831 (but not Ser845) by PKCγ and not by PKA or CaMKII. Intrathecal treatment with calcineurin provided prolonged analgesia, and this was accompanied by GluA1 dephosphorylation. Therapy with calcineurin may prove useful in the prolonged clinical management of well-established neuropathic pain.
-
The mechanism of neuropathic pain (NP) and osteoarthritic (OA) pain, although different, are both defined as chronic pain, and combinations are possible. In this study, the awareness of both types of chronic pain was investigated among patients and doctors. This prospective study was planned and coordinated by the orthopedic and internal medicine clinics and included 100 patients with a diagnosis of knee OA evaluated with the DN4 questionnaire. ⋯ It was observed that in these two knee OA patient groups, NP had a statistically significant enhancing effect on the WOMAC pain score and the VAS (p < 0.001). As underlying pathophysiological mechanism of pain caused by OA is complex, and OA is considered to have a component of NP, it has been proven to be useful to use drugs apart from conventional treatments for NP. We believe that, as a source of pain that is not relieved after arthroplasty, awareness level of NP among orthopedists should be increased and multidisciplinary studies are required on this topic.
-
To determine the association of self-report use of metformin and pain intensity. ⋯ In a clinic sample of patients with diabetes, the use of metformin at an average dose of 1,432 mg (SD = 596 mg) was not associated with lower pain scores. Given the anti-nociceptive effects of metformin in the animal models of pain, and the relative safety of metformin, future research should evaluate the effect of the higher dose of metformin as a potential analgesic.