Pain
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The radicular pain of sciatica was ascribed by Mixter and Barr to compression of the spinal root by a herniated intervertebral disc. It was assumed that root compression produced prolonged firing in the injured sensory fibers and led to pain perceived in the peripheral distribution of those fibers. This concept has been challenged on the basis that acute peripheral nerve compression neuropathies are usually painless. ⋯ Chronic injury of dorsal roots or sural nerve produces a marked increase in mechanical sensitivity; several minutes of repetitive firing may follow acute compression of such chronically injured sites. Such prolonged responses could be evoked repeatedly in a population of both rapidly and slowly conducting fibers. Since mechanical compression of either the dorsal root ganglion or of chronically injured roots can induce prolonged repetitive firing in sensory axons, we conclude that radicular pain is due to activity in the fibers appropriate to the area of perceived pain.
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Comparative Study
Transcutaneous electrical stimulation and acupuncture: comparison of treatment for low-back pain.
Twelve patients suffering chronic low-back pain were treated with both acupuncture and transcutaneous electrical stimulation. The order of treatments was balanced, and changes in the intensity and quality of pain were measured with the McGill Pain Questionnaire. ⋯ Both methods, therefore, appear to be equally effective, and probably have the same underlying mechanism of action. Consideration of the advantages and disadvantages of the two methods suggests that that transcutaneous electrical stimulation is potentially the more practical, since it can be administered under supervision by paramedical personnel.
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Comparative Study Clinical Trial
Methodological problems in the measurement of pain: a comparison between the verbal rating scale and the visual analogue scale.
The effect of analgesics on pathological pain in a double-blind, complete cross-over design was assessed by means of two rating scales, a verbal rating scale (VRS) and visual analogue scale (VAS). The VRS is widely used, but has several disadvantages as compared to the VAS. The results obtained by means of the VRS showed higher F-ratios (analysis of variance and Kruskall-Wallis H-test) than those obtained by means of the VAS. ⋯ The calculated regression line (y=-29.6 + 0.55-x) was not similar to the line of identity and showed much lower values for the VAS, supporting our interpretation. The distribution of the variances of the values obtained by means of both scales was not homogenous. This indicates that the homogeneity of the distribution of variances should always be checked and a Kruskall-Wallis H-test used, if they are inhomogenously distributed.
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Controlled radiant heat stimulation for a combined psychophysical and electrophysiological research in pain was achieved by the use of an infrared Laser beam. The computer controlled stimuli, being of very brief duration (down to 5 msec) and sharply localized, are suitable for recording of averaged evoked responses as well as for determination of pain and thermal thresholds. ⋯ The threshold energy delivered by this technique is similar to that obtained by the Hardy-Wolff-Goodell method. Special precautions were taken to avoid injury to the skin and the eyes.