Contralateral mirror-image pain following anterolateral cordotomy.

A hypothesis is put forward to explain the occurrence of mirror-image pain following pain relief by anterolateral cordotomy. This depends upon the fact that some nociceptive neurones in the deep spinal grey matter have bilaterally symmetrical receptive fields, one-half of which is normally subject to tonic descending inhibitory control. It is suggested that some cordotomy lesions may damage this descending inhibitory pathway. Experience following naloxone injection in our own cases further suggests that this inhibitory mechanism may normally involve enkephalinergic interneurones.