The deafferentation syndrome in monkeys: dysesthesias of spinal origin.

Chronic thoracic spinal lesions were surgically placed in 35 monkeys of 6 different species. In a very large percent of the cases, a bizarre behavioral pattern was released, which persisted for many months of observation. This syndrome was one in which the monkey severely attacked an hypoalgesic area of the body, namely, the leg. The syndrome resulted from contralateral anterolateral cordotomy or hemisection. It was very similar to the deafferentation syndrome which results from extensive dorsal rhizotomies. Bilateral spinal lesions indicated that the release of the syndrome was dependent upon the integrity of a widespread bilateral spinal pathway for peripheral nociception, but was independent of the integrity of specific sensory tracts. The deafferentation syndrome is considered to be a behavioral response to abnormal subjective sensations of central neural origin, and appears not to be relieved by morphine therapy. The incidence of this syndrome in the primate was subject to genetic variation.