The present report provides evidence that axons in the medial part of the posterior column at T10 convey ascending nociceptive signals from pelvic visceral organs. This evidence was obtained from human surgical case studies and histological verification of the lesion in one of these cases, along with neuroanatomical and neurophysiological findings in animal experiments. A restricted lesion in this area can virtually eliminate pelvic pain due to cancer. The results remain excellent even in cases in which somatic structures of the pelvic body wall are involved. Following this procedure, neurological testing reveals no additional neurological deficit. There is no analgesia to pinprick stimuli applied to the body surface, despite the relief of the visceral pain. Since it is reasonable to attribute the favorable results of limited midline myelotomies to the interruption of axons of visceral nociceptive projection neurons in the posterior column, we have performed experiments in rats to test this hypothesis. The results in rats indicate that the dorsal column does indeed include a nociceptive component that signals pelvic visceral pain. The pathway includes neurons of the postsynaptic dorsal column pathway at the L6-S1 segmental level, axons of these neurons in the fasciculus gracilis, and neurons of the nucleus gracilis and the ventral posterolateral nucleus of the thalamus.

SUMMARY In midline myelotomy a small mechanical or radiofrequency lesion was made at the centre of the spinal cord at a single segment at the thoracolumbar junction or at C1. This procedure was used for the management of cancer pain in 20 patients, in four of whom it was combined with unilateral cordotomy. Of 14 patients with myelotomy alone at the thoracolumbar junction 10 (71.5%) had satisfactory relief of pain, with no complications or untoward sideeffects.A new procedure is described, in which midline myelotomy is limited to a single segment for the treatment of midline pelvic pain from cancer.Both lateral spinothalamic tractotomy and commissural myelotomyl-5 are accepted techniques for the treatment of intractable pain, particularly after malignancy. However, cordotomy has proved to be disappointing for pelvic or midline pain, and pain may return even after initial good relief. Classical commissural myelotomy involves a relatively extensive spinal cord section and may be followed by impairment of function of the lower extremities for several weeks.' 24 It has been reported that pain relief often exceeds the amount of analgesia produced after commissural myelotomy.' 2 45Both the recurrence of pain after cordotomy, even with excellent analgesia, and the relief of pain without analgesia in myelotomy suggest the existence of a spinal cord pathway in addition to the lateral spinothalamic tract. in patients with pelvic malignancy under general anaesthesia with the patient in the prone position. A T9 or TXo laminectomy was performed, in order to expose the spinal cord at approximately the thoracolumbar junction. The 5 mm segment of the midline of the spinal cord with the least overlying vasculature was selected through the operating microscope. A small midline incision was made in the pia, and, with a blunt microdissector, the midline of the spinal cord was gently dissected for a length of 5 to 7 mm to a depth of 6 mm (fig). Ordinarily, the pial fold of the anterior median fissure could be palpated and the dissector was moved to and fro repeatedly at that depth. Fig The dissector

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