Cordotomy—in which open or percutaneous surgery is used to disable pain pathways in the spinal cord—has long been used to help manage severe pain. However, when performed using an open surgical technique, the procedure carried a number of risks and thus had limited clinical utility. But with the implementation of intraoperative imaging, percutaneous cordotomy for cancer patients with refractory pain is now resurgent.
“Cordotomy is a well-established procedure for pain, but it historically had a fairly high complication rate due to limitations in the surgical technique,” said Ashwin Viswanathan, M.D., a clinical associate professor in the Department of Neurosurgery at The University of Texas MD Anderson Cancer Center. “Now that we have intraoperative imaging, the procedure is much safer and more effective. For certain patients, the treatment leads to dramatic reductions in pain.”
To show definitively whether image-guided percutaneous cordotomy offers a pain management benefit over best supportive care in cancer patients with refractory pain, Dr. Viswanathan and his colleagues have undertaken the first clinical trial of its kind comparing the two pain management strategies.
The most common approach to pain management for cancer patients is opioid therapy. However, not all patients respond to opioids, even when dosages are increased; and the medications can have side effects that some patients find intolerable, including pruritus, nausea, and constipation.
Patients who do not respond to opioids or cannot tolerate the side effects may benefit from surgical interventions. These interventions include intrathecal pain pump implantation (which enables the delivery of a much smaller dose of opioids directly to the spinal fluid), myelotomy (for pain caused by abdominal cancers), and cordotomy (for one-sided pain below the shoulder level), which is usually percutaneous and increasingly performed under computed tomography (CT) guidance.
In CT-guided percutaneous cordotomy, a lumbar puncture is performed first to inject a radiocontrast agent into the spinal fluid to visualize the spinal cord. A surgeon then uses real-time CT to guide the advancement of a needle into the spinal cord at the base of the skull and then the advancement of a radiofrequency electrode through the needle to the spinothalamic tract. Once properly placed, the electrode is heated to ablate the pain pathway in the spinal cord. The procedure is performed with local anesthesia to allow communication with the patient.
“We want to be in the main pain pathway in the spinal cord, so we talk to the patient and stimulate the electrode to make sure the patient gets a sensation of where it hurts, and then we can interrupt that pain pathway,” Dr. Viswanathan said.
The procedure typically takes 1–2 hours. Possible adverse effects include leg weakness, which affects about 1% of patients; in addition, some patients may be bothered by the numbness the procedure creates.
Randomized trial shows benefit
To date, only retrospective or single-arm prospective studies have investigated the efficacy of cordotomy. To get some definitive answers about the extent to which cordotomy reduces otherwise unmanageable cancer pain, Dr. Viswanathan and his colleagues have undertaken a randomized controlled study.
“This is the first time we’ve had a randomized study to compare a surgical pain intervention using modern techniques with optimal supportive care,” Dr. Viswanathan said.
In the trial (No. 2014-0833), patients with advanced cancers of any type who have one-sided, refractory pain caused by tumor involvement below the shoulder level are assigned to immediately undergo CT-guided percutaneous cordotomy or to receive best supportive care for 1 week with the option to undergo CT-guided percutaneous cordotomy afterward. Before and after the procedure, cordotomy patients complete pain and symptom questionnaires and undergo quantitative sensory testing for sharpness and heat detection. Magnetic resonance imaging is performed shortly after the procedure to determine its effect on the spinal cord.
Sixteen patients have been enrolled in the study over the past 2 years. Seven patients were assigned to immediate cordotomy; of the nine patients assigned to receive best supportive care, seven ultimately also underwent cordotomy. The trial has completed its planned enrollment, and a formal comparative analysis is underway.
Although the long-term outcomes of these patients remain to be seen, so far the results are impressive. “We had 14 patients who underwent cordotomy, and of those, 13 had fairly impressive improvements in their pain,” Dr. Viswanathan said. “Compared with the supportive care, cordotomy substantially improved patients’ pain. I generally counsel patients that there’s a 70% chance of improving pain, but our study suggests a somewhat higher response rate than that.”
The trial’s early findings underscore the increasingly prominent role that CT-guided cordotomy has in combating cancer-related pain, Dr. Viswanathan said.
“If patients have tried strong pain medications—morphine, oxycodone—and they’re still suffering from pain, I would definitely recommend this procedure,” Dr. Viswanathan said. “It’s not disruptive to their cancer care, and it can provide an immediate benefit.”
For more information, contact Dr. Ashwin Viswanathan at 713-792-2400 or firstname.lastname@example.org. For more information about the trial of CT-guided cordotomy, visit www.clinicaltrials.org and search for study No. 2014-0833.
OncoLog, August 2018, Volume 63, Issue 8