Stereotactic Spinothalamic Mesencephalic Tractotomy for the Treatment of Cancer Pain in the Neuromodulation Era: Advocacy for the Renaissance of a Forgotten Surgery.

Background: The radiofrequency unilateral interruption of the spinothalamic tract (STT) at the level of the superior colliculi in the mesencephalon is one of the more ancient functional neurosurgery operations. Based on the literature review, our aim was to consider the potential role of this old intervention in the modern neurosurgical armamentarium against cancer pain taking into account the evolution of the operative technique and the emergence of alternative approaches.

Summary: We reviewed the literature in order to analyze the anatomical targeting of the STT, the technical strategies, the efficacy on pain, the morbi-mortality, the comparison of the safety efficacy ratio with other surgical techniques depending on the indications. Among 19 published series, only 4 are reporting only cancer pain patients. Two of these 4 series are reporting an anterior approach. At the level of the superior colliculi, the STT location is quite stable. With the anterior approach, a trajectory parallel to the quadrigeminal plate and a target at 7-8 mm from the midline, the rate of permanent oculomotor palsy is very low. In patients operated under local anesthesia with electrical stimulation of the target area, painful paresthesia due to injury of the medial lemniscus is very rare (min 0, max 6%). The rate of patient with analgesia of the painful area, pain relief, and stop of pain drugs in these conditions is around 80% (min 75%-max 86%) in cancer patients. Early pain recurrences appearing within a month are due to insufficient coagulation. When a morphine pump is not an option, this intervention can transform the comfort of the last days of patients with unilateral drug-resistant pain of the upper part of the body.

Key messages: Although very ancient, the stereotactic spinothalamic mesencephalic tractotomy by radiofrequency is turning out to offer a very good safety efficacy for lateralized cancer pain at the upper part of the body in drug-resistant patients with a modest life expectancy. We recommend the young generation of neurosurgeon involved in pain surgery to learn this remarkably effective intervention.