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Successful Treatment of Intractable Low Back and Pelvic Pain Caused by Advanced Prostate Cancer with Intrathecal Clonidine and Baclofen Infusion

Hai Nan Liu, Hao Chen, Jessica Hamilton and Xiulu Ruan

Background: Intrathecal opioid infusion therapy has been increasingly utilized in patients with severe malignant and nonmalignant pain syndromes in the past few decades. By infusing small amount of analgesics directly into the cerebrospinal fluid (CSF) in close proximity to the receptor site in the spinal cord, spinally mediated analgesia may be achieved while sparing some of the side effects due to systemic opioids. Traditionally, the most commonly infused analgesic for intrathecal infusion is an opioid. Morphine represents the only FDA-approved opioid for intrathecal administration, although other opioids may also be used off-label. However, in patients who have demonstrated intolerance to oral opioid(s), alternative analgesics may be tried to achieve satisfactory analgesia.
Objective: To present a case report of a 73-year old male with intractable low back and pelvic pain due to invasive prostate cancer, unable to tolerate any opioid, being successfully treated by intrathecal infusion of clonidine and baclofen. Case Report: A 73-year-old male with intractable low back pain and pelvic pain due to invasive prostate cancer was referred to our clinic for pain management. The patient had undergone hormonal therapy, radiation therapy, radical prostectomy, and rectal resection. Trial of non-opioid analgesics was unsuccessful in controlling his pain. Multiple opioids trials were complicated by persistent nausea and vomiting. Other interventional techniques were attempted, but only offered short-term efficacy. Intraspinal drug delivery (IDD) therapy was considered and attempted. Considering his intolerance to various oral opioids despite meticulous opioid dose titration, an outpatient continuous epidural infusion of clonidine was conducted, which provided satisfactory analgesia. The patient subsequently underwent permanent IDD pump placement.
Results: The intrathecal infusion of clonidine was initiated at 50 mcg/day. Over the following 4 months, the dosage was gradually titrated up to 350 mcg/day, with satisfactory pain relief. However, he did report frequent drowsiness during daytime, which was felt to be due to intrathecal clonidine. The decision to add low dose baclofen to the intrathecal infusion and simultaneously lower the clonidine dose was made. The intrathecal regimen was changed to clonidine 150 mcg/day and baclofen 50 mcg/day. His daytime sleepiness improved significantly and his pain control remained satisfactory. Over the following 3 months, his intrathecal regimen was further titrated to clonidine 200 mcg/day and baclofen 100mcg/day. He remained on this regimen for over 12 months with satisfactory pain relief and without experiencing excessive sedation. Addition of baclofen to intrathecal clonidine infusion led to improved analgesia without affecting his alertness, probably via a synergistic mechanism.
Conclusion: Under certain circumstance when intrathecal opioid infusion cannot be tolerated, intrathecal clonidine and baclofen may be used as alternatives to provide spinally mediated antinociception.