POST–SPINAL CORD INJURY PAIN STATES

Abstract

Pain, in contrast to motor deficit, is rarely the main cause of functional disability in patients with spinal cord injury (SCI). It frequently occurs, however, in conjunction with disabling motor, autonomic, and urinary tract problems. It is estimated that there are more than 200,000 patients in the United States with SCI. 38 It is probable that more than a half of all SCI patients suffer from pain. 6 These numbers reflect the overall magnitude of this problem. The severity and persistence of pain associated with SCI are, however, of greater significance than its prevalence. It is not unusual for these patients to experience pain for decades because their longevity approaches normal life expectancy owing to early interventions and rehabilitative measures. 40 The lack of effective treatment for SCI pain causes these patients great frustration because in addition to long-term motor disability, they must endure intractable pain. This article first discusses acute pains resulting from spinal injury (Table 1). The remainder of the article concentrates on chronic pains that either appear immediately or sometime after SCI and continue for more than 6 months. It is important to recognize that after 3 to 6 months, the condition of the patient's spinal cord stabilizes, and neurologic dysfunction is no longer considered chronic but rather is referred to as a permanent post-SCI neurologic condition. Pain can appear at any time after SCI (i.e., in the acute stage, during recovery, or in the stable phase). In addition, some pain syndromes are found to be related to complications of SCI. The term pain is used generically throughout the article, although it sometimes may denote more than one type of pain. Referrals to pain generally include dysesthesia because it is difficult to distinguish between these conditions before considering a detailed description of the patient's complaint, including its distribution as well as neurologic findings. 7 Nociceptive versus neurogenic pain (see the articles by Sorkin, and Yaksh and Chaplan) is presented followed by a discussion regarding central pain syndrome, which is treated separately for the purpose of this article. Cauda equina injury is a pure root/nerve injury and does not include primary spinal cord lesion. It is, however, common to include cauda equina injury in discussion of SCI pain. 15, 22, 54 This article also includes discussion about cauda equina injury for several reasons: It is caused by spinal column injury, it may occur concomitantly with conus medullaris injury, and its associated pain is similar to so-called transitional zone SCI pain.