Title : Cancer pain management-with and without anesthesiologic interventions

Cancer pain patients can have their pain well managed using standard opioids and other analgesics via the oral or parenteral routes.   A review of standard opioids, adjuvant analgesics will be given. However, approximately 15% of cancer patients with pain will experience severe pain resistant to traditional analgesic therapies.  For these patients, anesthesiologic techniques often provide welcome pain relief.  With more recent acceptance and use of chronic opioid therapy for cancer pain, the current role of neuroablative techniques has chiefly been for patients with terminal disease and pain unresponsive to traditional analgesics.  The use of local anesthetics (LAs) and spinal opioids to modulate pain transmission has gained popularity in the past decade because of the low risk involved and the ability to reverse the treatment course at any time. The use of local anesthetics to provide long-term pain relief for cancer patients has involved principally infiltration around peripheral nerves and epidural or intrathecal administration.  Local anesthetics injected close to a peripheral nerve or the spinal cord will block nerve impulses and provide degrees of nociceptive, sensory, or motor nerve blockade.  

Two common sites of peripheral nerve block with local anesthetic infusion are the brachial plexus (Figure 1) and lumbar plexus.  Lung or head and neck tumors may invade the brachial plexus resulting in severe neuropathic pain, and pelvic tumors may similarly invade the lumbar plexus.  The percutaneous insertion of catheters for the infusion of local anesthetics has provided excellent and long-term pain relief among such cancer patients. 

Spinal administration of opioids for pain relief was first applied to patients in 1979 and has been advocated for the relief of intractable cancer pain.  Spinal opioids can be given by both the epidural and intrathecal routes of administration, with the epidural dose being approximately 10 times the intrathecal dose.  It is believed that spinally applied opioids modulate pain transmission by direct action on specific opioid receptors in the dorsal horn of the spinal cord.  In this way, there may be fewer and/or less intense systemic opioid side effects and a better quality of analgesia may be obtained.  Many opioids have been used to achieve successful analgesia, with morphine remaining the most common.  A single injection of spinal morphine will provide 12-24 hours of pain relief.  However, a continuous infusion of opioid is often used and can be managed safely at home.  The effective dose is titrated to analgesia or intolerable side effects.  A useful starting dose for epidural morphine is 20% of the current daily oral morphine dose, and the final daily epidural doses reported in the literature have ranged from 2 to over 1000 mg.  

Additional neurolytic blocks occasionally used to treat cancer pain include lumbar sympathetic block for urologic pain, superior hypogastric block for pelvic pain, subarachnoid block for chest wall pain, subarachnoid saddle block for perineal pain, and cranial nerve block for head & neck pain.  Noninvasive gamma knife destruction of the pituitary has also been tried for intractable bilateral cancer pain (Sloan et al. 1996).

Dr. Sloan is Professor of Anesthesiology at the University of Kentucky. He is immediate past Program Director for the Pain Medicine Fellowship, and Board certified in Anesthesiology, Pain Medicine and Palliative Medicine. He has focused on the management of cancer and chronic pain (100 papers) with an interest in opioid pharmacology. His research has focused on the treatment of chronic and cancer pain, including opioids and adjuvant analgesics. Dr. Sloan serves on the editorial board for several pain and palliative medicine journals, including JPSM. Dr. Sloan served on the Exam Committee for the American Board of Hospice and Palliative Medicine