Spine
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Case Reports
Unilateral blindness as a complication of patient positioning for spinal surgery. A case report.
Extreme care must be used in positioning patients for surgery in a prone position. A padded Mayfield headrest may not be appropriate for all patients undergoing spinal surgery, as exophthalmus or a flattened nasal bridge may allow transmission of pressure to the globe. Our current approach is to use supplementary foam rubber support, with repeated, meticulous attention to keeping the eyes free from all pressure. Finally, unexplained intraoperative occurrence of a bradyarrhythmia or conduction disturbance may signal increased intraorbital pressure during general anesthesia.
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A study of 136 patients with lumbar intervertebral disc herniation was undertaken to test the hypothesis that asymmetry of the facet joints is associated with the level, type, and side of herniation. Fifty cases of central herniation and 86 cases of lateral herniation, all at the L4-5 or L5-S1 levels, were studied by computed tomographic scans. Adjacent (nonherniated) levels were used as controls. ⋯ The mean difference, however, was less than 3 degrees and not considered to be clinically relevant. There was no difference in the distribution of the more coronally or sagittally facing facet joints with respect to the side of lateral herniation. These results do not support the hypothesis that facet asymmetry is associated with lumbar intervertebral disc herniation.
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The effects of core temperature on three potentials--somatosensory spinal evoked potential, somatosensory cortical evoked potential, and spinal motor evoked potential--were studied in rats. Hyperthermia reduced the latency and increased the conduction velocity of all three potentials. Somatosensory spinal evoked potential amplitude was unchanged, whereas somatosensory cortical and spinal motor evoked potentials deteriorated above 42 C. ⋯ The amplitude of the spinal motor evoked potential decreased, and the somatosensory cortical and spinal motor evoked potentials disappeared below 28 C. Hyperthermia and hypothermia caused significant changes in the latency of all three potentials. The latency change of all three potentials became significant at 2-2.5 C above or below baseline, suggesting a range within which evoked potential studies should be performed.