The journal of pain : official journal of the American Pain Society
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Comparative Study
Comparison of Fos expression within the ferret's spinal trigeminal nuclear complex evoked by electrical or noxious-thermal pulpal stimulation.
Fos-like immunoreactivity (Fos-LI) was used as a marker of trigeminal neurons that responded to tooth pulp stimulation. The activation of intradental afferents was produced by electrical stimulation of the ferret's intact canine tooth, whereas natural stimuli that activate predominantly Adelta (5 mol/L CaCl2 applied to dentin) or C fibers (slow heating of the intact tooth) were used to stimulate the 2 populations of afferents selectively. Electrical stimulation evoked Fos-LI in ipsilateral dorsomedial of the trigeminal subnucleus caudalis (Vc), dorsomedial and ventrolateral of the transition zone between subnucleus interpolaris and caudalis (Vi/Vc), and the the paratrigeminal nucleus (Pa5). Osmotic stimulation evoked Fos-LI in the ipsilateral dorsomedial Vc and Vi/Vc. The spatial distribution of Fos labeling after heat stimulation was dependent on the duration and location of the stimulus application. Repeated heating of the maxillary canine for 30 minutes evoked labeling bilaterally in ventrolateral Vi/Vc. Stimulation of the maxillary and mandibular canines with heat pulses for 1 hour produced labeling in the ipsilateral dorsomedial Vc, dorsomedial Vi/Vc, and the Pa5. None of the stimulating procedures did evoke Fos expression in regions rostral to Vi/Vc. Regardless of the pulpal stimulation procedures, a similar number of Fos-positive neurons was found in the nucleus of solitary tract and the ventrolateral medulla. Although Fos expression does not reveal all neurons that respond to noxious pulpal stimulation, it marks many neuronal regions that contain neurons that respond to pulpal stimulation and injury. Our results suggest that a population of neurons in Vc and Vi/Vc contribute to painful sensations originating from the dentition. ⋯ We demonstrated that the trigeminal nucleus caudalis and the transitional zone between trigeminal interpolaris and caudalis mediate painful sensation in the dental pulp. Both trigeminal regions might be therapeutic targets for dental pain in the future.
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The aim of this study was to investigate the associations among 4 measures of pain induction procedures in 244 healthy women. The procedures were (1) pressure pain threshold assessed over the temporalis muscles, masseter muscles, temporomandibular joints, and the wrists; (2) C fiber-mediated heat pain threshold/tolerance assessed on the skin over the forearm, cheek, and dorsal aspect of the foot; (3) temporal summation of C fiber-mediated heat pain; and (4) ischemic pain threshold/tolerance. Strong associations among pressure pain thresholds at the 4 sites examined (rho = 0.7 to 0.8, P values < or = .001) and among heat pain threshold/tolerance values at the 3 sites examined (rho = 0.6 to 0.9, P values < or = .001) were observed. Pressure pain threshold was moderately correlated with each of the heat pain threshold/tolerance values (rho = 0.2 to 0.4, P values < or = .001). Ischemic pain threshold/tolerance was moderately associated with each of the pressure and heat pain measures (rho = 0.2 to 0.3, P values < or = .05 to .001). Derived measures of the temporal summation of heat pain did not correlate strongly with threshold or tolerance measures of pressure, ischemic, or heat pain. We concluded (1) that for a specific pain modality, the correlation between threshold and tolerance values across anatomic sites is high, and (2) that measures of pressure, ischemic, and thermal pain threshold/tolerance are significantly correlated, although the strength of these associations is moderate. These findings demonstrate that a battery of pain-assessing procedures is required to determine an individual's pain sensitivity profile or phenotype. ⋯ By investigating the relationship between pain sensitivity produced by different forms of stimuli, this study demonstrates that a battery of tests should be used to assess an individual's pain sensitivity and one should be careful in making inferences about an individual's sensitivity to pain by using only one pain modality.
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The idiopathic sensorial disturbances of burning mouth syndrome (BMS), taste disturbances (dysgeusia), and dry mouth (xerostomia) have recently been recognized as one entity and given the generic name of oral sensorial complaints (OSC). However, not all patients with OSC complain of all three disturbances, and the underlying mechanism of OSC has not yet been elucidated. This study sought to determine whether OSC was associated with the alteration of oral sensory perception, salivary profile and/or personality traits. It examined 35 patients with OSC and 19 controls. Sensory perception was assessed by Quantitative Sensory Testing (QST) applied to the tongue, including thresholds for thermal sensations and pain, and the magnitude estimation of tonic suprathreshold heat pain stimuli. The salivary profile included flow rate and compositional analysis. Personality traits were examined by both state and trait anxiety and somatization scoring. Results showed significantly elevated thermal sensory thresholds and decreased pain scores for tonic heat pain. In addition, there was an increased level of somatization in the OSC group as compared to the control group (15.1 +/- 1.5 vs. 6.6 +/- 2.1, respectively; P = .003). Concomitantly, altered salivary composition (elevated Na, K, Cl, Ca, IgA, and amylase concentrations)-but not salivary flow rate reduction-was observed in those patients despite their complaints of oral dryness. All parameters were similar among the patients with OSC regardless of their type of complaint. Linear regression analysis revealed that an elevated warm sensory threshold was associated with higher levels of salivary K and Cl concentrations in the patients with OSC. These findings may be attributed to a regional small fiber idiopathic neuropathy affecting oral sensation and salivary secretion in OSC. Alternatively, a primary idiopathic salivary dysfunction might cause sensory neural dysfunction at the receptor level by changing the oral cavity milieu. ⋯ Based on the salivary, psychophysical, and personality traits analysis currently presented, as well as on the available literature, we hypothesize that a comprehensive mechanism for OSC is based on a regional neuropathy, which is expressed by complaints of BMS, taste disturbances, and/or xerostomia. All are clearly distinguishable from similar conditions with established organic/therapeutic-related etiologies.
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The present study examined the interactive effects of state and trait anxiety on pain threshold and subjective pain intensity. State anxiety was manipulated in 15 low trait anxious (LTA) individuals and 17 high trait anxious (HTA) individuals, who rated their anxiety level and subjective pain intensity in response to noxious electrical experimental pain stimuli. A difference in pain threshold between HTA and LTA participants was not found; however, higher state anxiety led to an increase in reported pain intensity for all participants. Furthermore, HTA individuals reported significantly higher levels of anxiety and pain intensity than LTA individuals across all pain and anxiety conditions. There was no interaction between state and trait anxiety on pain perception and anxiety ratings. These findings show an additive rather than synergistic effect between state-trait anxiety and subjective pain intensity. ⋯ Use of anxiety-reducing techniques for individuals experiencing pain might reduce the perceived severity/intensity of pain. Furthermore, individuals with higher trait anxiety (a greater disposition to experience anxiety) might benefit from these techniques because higher trait anxious individuals tend to exacerbate perceived pain stimulations more than lower trait anxious individuals.
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This study assessed the influence of medication beliefs, symptom severity, disability, mood, and psychiatric history on opiate medication misuse behaviors in 288 chronic pain patients. Data were gathered by questionnaires and systematic reviews of electronic medical records. The results demonstrate that patients with a history of substance abuse, compared to those without, showed greater medication misuse despite similar dosages and self-rated opiate effectiveness. Misusers believed more strongly in the potential for opiate addiction and that they required higher doses than others, but also had greater belief in opiate effectiveness and the importance of free access. Although both anxiety and substance abuse history are related to medication misuse, a multivariate analysis indicated that these factors can be seen as mediated by medication beliefs. These data suggest important roles for historical, affective, and cognitive variables in understanding medication misuse. Patients with a history of substance abuse report stronger beliefs in opiate effectiveness while simultaneously showing awareness of their addiction potential. Providers may help patients by addressing these issues prior to prescribing opiates. ⋯ History of substance abuse is associated with increased opiate medication misuse independent of differences in reported opiate effectiveness. Self-attributions regarding opiate treatment related to need for higher doses, dose control, and addiction potential, may be important mediators of this relationship and interact with anxiety to produce heightened risk of opiate misuse.