Allodynia and hyperalgesia within dermatomes caudal to a spinal cord injury in primates and rodents

Abstract

Publisher Summary This chapter discusses allodynia and hyperalgesia within dermatomes caudal to a spinal cord injury in primates and rodents. Persistent pain of central nervous system origin is a common consequence of spinal cord injury and is highly refractory to treatment. In order to understand mechanisms and develop treatments for this condition, an effective laboratory animal model is needed. Clinical observations indicate that interruption of the spinothalamic tract is a prerequisite for development of deafferentation zone pain referred to segments well below the site of spinal cord injury. Therefore, a series of studies has evaluated nociceptive responses of monkeys and rats before and after an anterolateral spinal lesion. Attention to the variability of responses to a wide range of stimulus intensities across testing sessions has shown that contralateral sensitivity oscillates from nearly analgesic to allodynic. All animals cycled between these states of hyper- or hypo-sensitivity. Information from animal model and observations of human beings indicate that superficial lesions of lateral spinal cord white matter that do not extend into the gray matter produce an enduring contralateral hypoalgesia, with minimal allodynia and/or central pain.