Answer is B (Left Lateral Spinothalamic tract): `Neurosurgical Operations on the Spinal Cord' Pain sensations from the right leg are carried the contralateral Lateral Spinothalamic tract. Ventrolateral cordotomy (surgical procedure of ablating selected pain conducting tracts) of the Left Spinothalamic Tract should effectively relieve pain from the right lower extremity. Ventrolateral Cordotomy Ventrolateral cordotomy is a surgical procedures in which the spinal anterolateral ascending system, for transmission of nociception (pain) known as the spinothalamic tract is interrupted for the relief of severe, intractible pain (cancer pain) not responding to any other conventional measures of pain control. Ventrolateral cordotomy can be performed by both, percutaneous and open surgical techniques. Ventrolateral cordotomy has been shown to be most effective in the treatment of intermittent shooting pain and evoked pain such as allodynia and hyperpathia, which is essentially mediated by the Lateral Spinothalamic Tract. The optimal candidate for such a procedure is a patient with unilateral severe pain (usually with malignant cancer) not adequately treated with less invasive measures. Fibres carrying sensation of 'pain' decussate (cross obliquely) to the opposite side within the spinal cord (over one to five segments) and ascend in the contralateral white column as the Lateral spinothalamic Tract. The Left spinothalamic tract carries sensation of pain from the Right side of the body. Cordotomy (ventrolateral) therefore aims to interrupt the lateral spinothalamic tract ascending contralaterallv to the painful side. Fibres carrying sensation of pain' decussate (cross obliquely) to the opposite side within the spinal cord and ascend in the contralateral white column as the Lateral Spinothalamic Tract.