Abstract and Introduction
Abstract
Background: Patients with pain caused by cancer frequently experience visceral pain. In addition to oral pharmacologic therapy to manage pain, neurolytic blocks of the sympathetic axis are also effective in controlling visceral cancer pain.
Methods: Four types of neurolytic blocks (interpleural phenol, celiac plexus, superior hypogastric plexus, and ganglion impar) used in the treatment of visceral cancer pain are reviewed.
Results: Several studies have documented the efficacy of neurolytic blocks in reducing pain intensity and opioid consumption. However, the narrow risk-benefit ratio associated with neurolysis techniques requires knowledge of the implications associated with the different neurolytic blocks to minimize undesirable effects.
Conclusions: Neurolysis of the sympathetic axis has been shown to be an effective and safe approach to treat visceral pain in cancer patients and should be incorporated in the armamentarium of the pain specialist as a useful adjunct to oral pharmacologic therapy.
Pain associated with cancer may be somatic, visceral, or neuropathic in origin. Approximately 50% of cancer patients experience a combination of pain types at the time of diagnosis. Stretching, compressing, invading, or distending visceral structures can result in a poorly localized noxious pain. Patients experiencing visceral pain often describe the pain as vague, deep, squeezing, crampy, or colicky. Other signs and symptoms include referred pain (eg, shoulder pain that appears when the diaphragm is invaded with tumor) and nausea/vomiting due to vagal irritation.
Visceral pain associated with cancer may be relieved with oral pharmacologic therapy that includes combinations of nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and coadjuvant therapy. In addition to pharmacologic therapy, neurolytic blocks of the sympathetic axis are also effective in controlling visceral cancer pain and should be considered as important adjuncts to pharmacologic therapy for the relief of severe pain experienced by cancer patients. These blocks rarely eliminate cancer pain because patients frequently experience coexisting somatic and neuropathic pain as well. Therefore, oral pharmacologic therapy must be continued, albeit at lower doses. The goals of performing a neurolytic block of the sympathetic axis are to maximize the analgesic effects of opioid or nonopioid analgesics and reduce the dosage of these agents to alleviate side effects.
Since neurolysis techniques have a narrow risk-benefit ratio, undesirable effects due to neurolytic blocks can be minimized with sound clinical judgment and by assessing the probable effect of the technique on each patient. A detailed description of the techniques for these blocks is beyond the scope of this review but is available elsewhere. This report describes several different approaches to achieve neurolysis, including the interpleural phenol block, celiac plexus block, superior hypogastric block, and ganglion impar block.