Pain
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Nociceptive flexion reflexes of the lower limbs (RIII responses) have been studied in 21 patients undergoing either epidural (DCS, n = 16) or transcutaneous (TENS, n = 5) analgesic neurostimulation (AN) for chronic intractable pain. Flexion reflex RIII was depressed or suppressed by AN in 11 patients (52.4%), while no modification was observed in 9 cases and a paradoxical increase during AN was evidenced in 1 case. In all but 2 patients, RIII changes were rapidly reversible after AN interruption. ⋯ Recording of RIII reflexes is relatively simple to implement as a routine paraclinical procedure. It facilitates the objective assessment of AN efficacy and may help to choose the most appropriate parameters of neurostimulation. In addition, RIII behavior in patients could be relevant to the understanding of some of the mechanisms involved in AN-induced pain relief.
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Case Reports
Post-herpetic neuralgia: the relation of pain complaint, sensory disturbance, and skin temperature.
Twelve otherwise healthy patients with longstanding postherpetic neuralgia (PHN) were prospectively studied using clinical examination, infrared thermography and response to local anesthetic skin infiltration. All had at least 2 of 3 possible components to their PHN pain: continuous, neuralgic, or allodynic. In patients with allodynia, maximal reported pain and the location of maximal allodynia on sensory examination were largely overlapping and were often warm thermographically. ⋯ These results suggest that PHN patients can be divided into at least 2 clinical groups: those with predominantly continuous pain localized to a region of significant sensory loss and those in whom allodynia is the most prominent sensory disturbance. The latter group has pain localized to areas with relatively preserved sensation. The differences in clinical features and response to lidocaine suggest that there are at least 2 different mechanisms contributing to the pain of PHN.
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Four studies are presented testing the validity and reliability of pressure pain thresholds (PPTs) and of examination parameters believed to be important in the clinical assessment of sites commonly used for such measures in patient samples. Forty-five patients with a myogenous temporomandibular disorder were examined clinically prior to PPT measures. Criteria for history and examination included functional aspects of the pain, tissue quality of the pain site, and the type of pain elicited from palpation. ⋯ Referred pain had a poor association with the pain pattern and physical findings, which may suggest a need to reevaluate part of the theory regarding referred muscle pain. The reliability of PPT measures was better overall than the reliability of the signs and site-specific symptoms, suggesting that pressure pain thresholds may be an important tool in clinical studies of pain. PPT measures demonstrate a high within-subject variability in pain patient subjects as well as non-pain subjects.(ABSTRACT TRUNCATED AT 400 WORDS)
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The efficacy of transcutaneous electrical nerve stimulation (TENS) in producing analgesia in cold-induced pain was assessed using a range of 5 stimulating frequencies (10 Hz, 20 Hz, 40 Hz, 80 Hz and 160 Hz) in 83 normal healthy subjects. TENS significantly elevated ice pain threshold when compared with sham and control groups. ⋯ Measurement of ice pain tolerance was found to be unreliable under the present conditions. No significant relationships were observed between personality variables as measured by Eysenck Personality Questionnaires and the degree of TENS response.