Pain
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Clinical Trial Controlled Clinical Trial
The effects of auricular transcutaneous electrical nerve stimulation (TENS) on experimental pain threshold and autonomic function in healthy subjects.
The present study examines the effects of auricular transcutaneous electrical nerve stimulation (TENS) on electrical pain threshold measured at the ipsilateral wrist and autonomic functions including skin temperature, blood pressure and pulse rate in 24 healthy subjects. TENS was administered as low frequency trains of pulses delivered at a 'strong but comfortable' intensity to 1 of 3 auricular points to be examined: (i) autonomic effects (autonomic point), (ii) pain threshold effects (wrist point), and (iii) placebo effects at an unrelated point (face point). A fourth untreated group was designated as a situation control. ⋯ However, pain threshold was found to increase by over 50% of its pretreatment baseline in 4 subjects and by 30% in 6 subjects. This rise was not dependent upon the site of auricular TENS. The possible mechanisms of such changes are discussed.
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Comparative Study
Stress-related electromyographic responses in patients with chronic temporomandibular pain.
Surface electromyographic (EMG) recordings from the right and left masseter and the left biceps muscle during stress and non-stress imagery were obtained from patients with temporomandibular myofascial pain and dysfunction syndrome (MPDS), temporomandibular joint disorder (TMJD), chronic low back pain (CBP) and healthy controls (HC). Both the MPDS and the TMJD groups displayed significantly more masseter EMG reactivity to the stressful imagery than the CBP and HC groups. ⋯ The MPDS patients indicated more life stress and gave higher aversiveness ratings during the experiment. These findings are discussed with respect to the validity of the TMJD and MPDS distinction.
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In patients with unexplained pain after cholecystectomy, morphine often induces pain and may increase plasma aspartate aminotransferase (AST) activity because of exaggerated or prolonged rises in pressure within the biliary system. These anomalous effects of morphine may be mediated by activation of autonomic or related afferent nuclei. In this study, 16 patients with pain and increases in AST after morphine were further studied after pre-treatment with dexamethasone and hydrocortisone. ⋯ Serial changes in plasma concentrations of catecholamines were determined in 8 patients and showed that pre-treatment with dexamethasone, but not hydrocortisone, was associated with lower concentrations of norepinephrine and epinephrine with overall reductions of 53% and 67%, respectively. These observations are consistent with a role for sympatho-adrenomedullary activation in abdominal pain induced by morphine. The different effects of dexamethasone and hydrocortisone raise the possibility that sympatho-adrenomedullary activation after morphine is influenced by the interaction of cortisol with type I glucocorticoid receptors which have a low affinity for dexamethasone and a high affinity for cortisol.
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Patients' beliefs about chronic pain, such as how long it will last and whether it is a mysterious experience, have been shown to be related to compliance with treatment programs. The present study examined whether these pain beliefs related to a specific component of pain management, namely the frequency of use and the perceived effectiveness of cognitive and behavioral coping strategies. One hundred twenty chronic pain patients were administered the Pain Beliefs and Perceptions inventory (PBAPI) and the Coping Strategies questionnaire (CSQ). ⋯ Multivariate analysis of variance was used to detect whether the use of cognitive-behavioral pain coping strategies differed in patients in the 3 pain beliefs subgroups. The results indicated that patients belonging to the group characterized by the belief that pain was enduring and mysterious were less likely to use cognitive coping strategies (e.g., reinterpretation of pain sensation), more likely to catastrophize, and less likely to rate their coping strategies as effective in controlling and decreasing pain than patients believing their pain to be understandable and of short duration. The implications of these results for understanding the patient's choice of and compliance with treatment and coping efforts is discussed.
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One hundred and fifty-six patients with moderate to severe postherpetic neuralgia (PHN) were followed for up to 11 years. Nearly half of all patients were doing well at the final assessment (median 2 years) and more than half of these were on no therapy at this time. ⋯ More of these patients were noted to be using some form of treatment at follow up. A group of patients seemed to follow a progressive course and were refractory to all treatments used in this study.