Pain
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Electrical potentials evoked by 5 intensities of painful dental stimulation were recorded at the scalp. During testing, volunteers indicated subjective painfulness by verbal pain ratings and visual analogue scales. Evoked potentials (EPs) to each intensity, observed between 50 and 400 msec, were characterized by 4 waveform components. ⋯ In contrast, the amplitudes of the two later components were associated with subjective painfulness but not with stimulus intensity. A strong linear relationship was observed between subjective painfulness and peak-to-peak amplitude for the EP component observed between 175 and 260 msec. The data suggest that the earlier EP components may reflect sensory transmission processes while the later components indicate brain activity when pain is perceived.
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Case Reports
Anterior spinal artery syndrome--a complication of cervical intrathecal phenol injection.
Spinal nerve block by intrathecal phenol-glycerine infusion is commonly employed for relief of severe pain in terminal carcinomatosis and, frequently, a dramatic regional anesthetic effect is achieved. However, nerve block by this procedure may in very rare instances give rise to serious complications. We have seen a case of terminal malignant melanoma in which clinical manifestations, indicative of anterior spinal artery syndrome, developed following the injection of 0.3 ml of 10% phenol-glycerine into the cervical subarachnoid space at the C4--C5 level for the control of severe right arm pain. This report describes the clinical course of the patient over a period of 4 months after the nerve block and the post-mortem findings along with a brief review of the literature.
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Twenty patients suffering from phantom limb pain were assessed for suitability for treatment by electrical stimulator implant to the peripheral nerve or the spinal cord. Twelve were so treated and seven obtained excellent and three partial relief of pain. One patient maintains excellent relief of pain by trancutaneous electrical stimulation. Factors that might influence the responsiveness of pain to electrical stimulation and the qualitative results from such treatment are discussed.