Postcordotomy spontaneous dysesthesias in macaques: recurrence after spinal cord transection.

Monkeys chronically attack the hypoalgesic hindlimb after thoracic contralateral anterolateral cordotomy or hemisection. This compulsive behavior could be induced by innocuous stimulation in the hypoalgesic region, and it also appeared to occur spontaneously. The postcordotomy spontaneous compulsive self-directed behavior was studied in 4 macaques after subsequent upper lumbar crush spinal transection. Despite the paraplegia and bilateral analgesia/anesthesia, this spontaneous abnormal behavior continued to be directed to the same hindlimb as before transection, but not to the opposite hindlimb. Hence, it is concluded that the recurring syndrome originated from the initial contralateral cordotomy. The rationale for the presumption of postcordotomy spontaneous dysesthesias is presented, and the experimental results are offered in refutation of alternative interpretive hypotheses. In conjunction with previous findings, these results lead to the argument that postcordotomy dysesthesias are caused by a neuropathological compensatory response to partial deafferentation of brain somatosensory neurons.