Pain
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Of 113 patients treated in a 2-year period, for whom complete data were available, 29 who received surgery for pain relief were compared with 84 who did not, both groups receiving psychological treatment and rehabilitation. Using an analysis of covariance to eliminate pre-treatment differences, the surgery patients showed significantly greater reductions on the MMPI Hysteria and Hypomania scales, and on the invalidism scale of a Health Index, and this was associated with a significantly greater reduction of pain. These differences obtained despite a greater increase in activity levels by the non-surgery patients at the time of testing. The results support the hypothesis that the neuroticism associated with chronic pain is the result of it, and may be reversible when the pain is reduced or abolished.
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An electrophysiological analysis has been made of 82 L7 dorsal horn neurons antidromically activated from the contralateral C1 anterolateral quadrant (ALQ) of unanesthetized rhesus monkeys (bilateral carotid ligation). This analysis was made to compare refractory periods and antidromic activation thresholds with these same parameters of ALQ stimulation required to produce pain in conscious humans. Refractory periods of laminae IV-VI cells that were optimally but not exclusively responsive to noxious skin stimulation ranged from 0.8 to 2.8 msec (m = 1.5) and were briefer than those of lamina I cells. ⋯ Unlike lamina I cells, refractory periods and electrical thresholds of laminae IV-VI nociceptive neurons closely parallel those of ALQ-evoked pain in man. However, both lamina I and laminae IV-VI neurons usually responded to nociceptive skin temperatures (greater than 43 degrees C). This analysis indicates that pain may be signaled by the combined output of dorsal horn laminae I and IV-VI but that activation of only laminae IV-VI wide dynamic range neurons is sufficient to produce pain.