The deafferentation syndrome in genetically blind rats: a model of the painful phantom limb.

The hypothesis was tested which states that the somatic deafferentation syndrome is a visually prompted response to sensorimotor loss. The dorsal roots, C5-T2, were bilaterally cut in a strain of rats known to be genetically blind. These complete dorsal rhizotomies left the forelimbs totally anesthetic, analgesic and paretic. Contact and visual placing reactions were absent, and responses to pinprick or pinch were absent. Self-mutilation limited to the distal digits appeared on the first or second postoperative days and then progressed proximally. The forelimbs were symmetrically affected, and no other body parts were mutilated. The spatial precision of this syndrome, in the absence of visual as well as peripheral somatosensory information from the affected limb, indicates that controlled guidance of the behavior arises from an existing central representation of the limb and its relationship with the total body; a phantom limb. Consideration of other reports regarding the deafferentation syndrome leads to the view that it is motivated by disturbing abnormal sensations (pain) of central neural origin.