Spine
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An electrophysiologic study to examine responses of dorsal horn neurons in the rat L5 spinal cord to noxious stimuli after disc herniation or application of the nucleus pulposus to the L5 nerve root. ⋯ Results suggest that somewhat pathogenic factors in the nucleus pulposus may have a crucial role in the induction of hyperalgesia. This may help to elucidate the reason why a severe pain is sometimes induced without a visually identified protrusion.