REFERENCE OF PAIN FOLLOWING PERCUTANEOUS CERVICAL CORDOTOMY

In order to clarify the mechanism of reference of pain following cordo tomy (ROPC), the authors investigated ROPC in 66 patients undergoing p ercutaneous cervical cordotomy (PCC) and examined the features of ROPC and the correlation between the occurrence of ROPC and the pre-operat ive pain states, as well as the results of PCC. ROPC was observed in 7 patients. It occurred immediately after PCC in 6 of 7 patients and 6 h after PCC in 1 patient. The pain was referred horizontally and crani ally from the region rendered totally or largely analgesic by PCC to t he normally innervated region. The region to which the pain was referr ed was not fixed. The referred pain disappeared by rendering the regio n where referred pain was felt analgesic with additional PCC. There wa s no correlation between the occurrence of ROPC and pre-operative pain states, or the results of PCC. From these results we postulate that: (1) ROPC occurs via a subsidiary pathway consisting of ascending chain s of short neurons connecting dorsal horn neurons longitudinally and l atitudinally; (2) the subsidiary pathway is inhibited under normal con ditions by feedback inhibition from second-order neurons and/or higher central neurons of the nociceptive pathway; and (3) ROPC results from the release of the feedback inhibition by cordotomy.