BEHAVIORAL MANIFESTATIONS OF AN EXPERIMENTAL-MODEL FOR PERIPHERAL NEUROPATHY PRODUCED BY SPINAL NERVE LIGATION IN THE PRIMATE

A goal of the present study was to document the behavioral changes obs erved in a model of painful neuropathy in the primate (Macaca fascicul aris). A neuropathic state was induced by tight ligation of the L7 spi nal nerve, just distal to the L7 dorsal root ganglion. Sensory testing was done on the ventral surface of the foot, a region that includes t he L7 dermatome. Within 1 week following surgery, all monkeys (n = 3) developed a marked sensitivity to mechanical stimulation (with a camel hair brush and von Frey hairs), indicating the presence of mechanical allodynia. In 2 animals, the increased sensitivity to mechanical stim ulation was also observed on the contralateral side. The threshold for withdrawal to a heat stimulus decreased, indicating the presence of h eat hyperalgesia. Presentation of various cooling stimuli, such as ace tone and cold water baths, suggested that cold allodynia had also deve loped. These behavioral phenomena are similar to those seen in humans diagnosed with peripheral neuropathic pain. The behavioral abnormaliti es are discussed in relation to the responses of spinothalamic tract c ells recorded from primates with the same peripheral nerve injury (Pal ecek et al. 1992).