Neural blockade for diagnosis and prognosis. A review.

On the basis of the published material reviewed above, we conclude that there are many limitations that weaken the theoretic basis for neural blockade as a diagnostic or prognostic tool. In addition, these procedures in general lack thorough documentation of clinical usefulness. Reasonable employment of diagnostic neural blockade, therefore, requires not only care in technique and confirmation of effects, but also caution in interpretation and application of the results. This critical evaluation needs to be tempered, however, by two further observations. Experienced and observant clinicians have found these procedures may, on certain occasions, provide information that is helpful in guiding subsequent therapy, so we should not be in haste to dismiss the accumulated judgment of practitioners. Finally, the confusion and complexity that typifies diagnosis in chronic pain may justify the selective use of diagnostic blocks that make anatomic and physiologic sense, even if their validity is incompletely proved.