Pain
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Comparative Study
Differentiating sensory and affective-sensory pain descriptions in patients undergoing magnetic resonance imaging for persistent low back pain.
The study design is a cross-sectional survey with psychometric analysis. The objective is to determine the validity of a modified version of the Short-Form McGill Pain Questionnaire (SF-MPQ). The SF-MPQ has been widely used to differentiate between reports of sensory and affective pain. ⋯ Correlations with measures of pain intensity and the RM were significant, but slightly lower, for the subscales of the modified 2-factor solution (0.26-0.40) than for the subscales of the previously described 2-factor solutions (0.34-0.45). The MSF-MPQ can be used as a brief tool to differentiate the language used to describe pain in patients who are undergoing lumbar MRI. The evidence indicates that this clinical tool can be used to categorize how these patients describe their pain and potentially may be very valuable in determining the optimal course of treatment.
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Comparative Study
Mechanical allodynia and thermal hyperalgesia upon acute opioid withdrawal in the neonatal rat.
Upon withdrawal from opioids many patients experience a heightened sensitivity to stimuli and an exaggerated pain response. We present evidence that neonatal rats exhibit allodynia and hyperalgesia on acute opiate withdrawal. Postnatal 7 and 21 day rats were used to approximately model a full term human infant and a human child, respectively. ⋯ Spontaneous and precipitated withdrawal from a single acute administration of morphine produced mechanical allodynia and thermal hyperalgesia in postnatal day 7 rats and mechanical allodynia in postnatal day 21 rats. A higher dose of morphine was required to produce mechanical allodynia in postnatal day 21 versus 7 rats but this increase was independent of the analgesic efficacy of morphine at these two ages. The present work illustrates the need to examine the phenomenon of hypersensitivity upon opioid withdrawal in the human pediatric population.
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Comparative Study
Sensitization to bradykinin B1 and B2 receptor activation in UV-B irradiated human skin.
Bradykinin B1 and B2 receptors contribute to nociceptor sensitization under inflammatory conditions. Here, we examined the vascular inflammatory responses and nociceptive effects resulting from activation of B1 and B2 receptors in healthy and UV-B irradiated skin in human volunteers. The B1 receptor agonist des-Arg(10)-Kallidin (10(-6)-10(-3)M) and the B2 receptor agonist bradykinin (10(-9)-10(-4)M) were administered by dermal microdialysis to the ventral thigh. ⋯ In normal skin, both B1 and B2 receptor activation dose-dependently evoked pain, vasodilatation and protein extravasation. In UV-B irradiated skin, pain sensation and axon reflex vasodilatation were enhanced by both B1 and B2 agonists, whereas local vasodilatation was increased only following B1 receptor activation. The UV-B irradiation did not enhance B1 and B2 receptor-induced protein extravasation indicating a differential sensitization of the neuronal, but not the vascular response.
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Comparative Study
Exaggerated nociceptive responses on morphine withdrawal: roles of protein kinase C epsilon and gamma.
On withdrawal from opioids many patients experience a heightened sensitivity to stimuli and an exaggerated pain response. The phenomenon has been little studied in infants. We present evidence that in postnatal day 7 rats an exaggerated nociceptive ventral root response of spinal cords in vitro and withdrawal-associated thermal hyperalgesia in vivo are dependent on protein kinase C (PKC), and we document the roles of PKC and gamma isozymes. ⋯ In contrast, thermal hyperalgesia during spontaneous withdrawal was inhibited by both PKC and gamma inhibitors. The consistency between the in vivo and in vitro findings with respect to naloxone-precipitated withdrawal provides further evidence that the sVRP reflects nociceptive neurotransmission. In addition the difference between naloxone-precipitated and spontaneous withdrawal in vivo suggests that in postnatal day 7 rats, morphine exposure produces an early phase of primary afferent sensitization dependent upon PKC translocation, followed by a later phase involving spinal sensitization mediated by PKC gamma.
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Comparative Study
Complex regional pain syndrome-like symptoms during herpes zoster.
Complex Regional Pain Syndrome (CRPS) associated with herpes zoster (HZ) was first reported by Sudeck in 1901 (Sudeck, 1901) and is recognized clinically. However, only 13 cases have been published in the literature, and nothing is known about the incidence, prevalence, or natural history (Chester, 1992; Foster et al., 1989; Grosslight et al., 1986; Ketz and Schliack,1968; Kishimoto et al., 1995; Querol and Cisneros, 2001; Sudeck, 1901; Visitsunthorn and Prete, 1981). The aim of the present study was to determine the prevalence of CRPS-like symptoms in a prospectively gathered cohort of subjects with HZ and to follow the natural history of their pain and sensory disturbance during the first 6 months after onset of HZ. ⋯ Development of PHN is common in subjects who have experienced CRPS-like symptoms. More aggressive preventive treatments may be justified in this high-risk subset of HZ subjects to prevent development of PHN. Prospective randomized controlled studies are needed to determine which subjects are most likely to benefit and when treatment should begin.