Forty patients with chronic pain below the waist level were evaluated in a multidisciplinary pain clinic using a refined differential spinal block (DSB) technique. The refinements consisted of verbal instructions to prevent biasing the patients, coupled with a thorough evaluation of verbal and physiologic responses to the block. When demographic and psychologic data were assessed according to pain mechanisms, a pattern of patient groups emerged along a chronic pain continuum. Stress, anxiety, depression, and hysteria, as well as the neurophysiologic and demographic factors, modified the responses to the DSB. Long-term follow-up of these patients, including repeat DSB procedures and confirmatory anatomic blocks of sympathetic and somatic nerves, validated these impressions. The findings indicate a link between pain mechanisms and psychosocial factors that may directly influence responses to DSB.