Der Schmerz
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Conventional clinical dosages of local anesthetics may not be sufficient to block conduction of all afferent impulses, which is important for an effective epidural sensory blockade. Further depression of the transmission of information can be accomplished by central modulating mechanisms, preventing sensory perception. Since there are interindividual differences in the quality of modulating mechanisms, standardized depression of impulse propagation by the local anesthetic is associated with a wide variation in the total depression of afferent impulses. ⋯ Patients with a low pain threshold require a more highly concentrated local anesthetic. The addition of opioids to the local anesthetic will permit the use of lower concentrations of the local anesthetic itself. Optimal use of diagnostic, prognostic, and therapeutic epidural blockades is possible only if the influence of modulating mechanisms is taken into account.