# 098 Intrathecal Drug Therapy for Pain, 2nd ed

FAST FACTS AND CONCEPTS #098 PDF


Author(s): Gary M Reisfield MD and George R Wilson MD

Background   Intrathecal drug delivery can be an invaluable adjunct in the management of severe pain when meticulous application of conventional drug therapy proves ineffective or produces intolerable side effects. Intrathecal analgesia is distinguished from epidural analgesia by catheter location within the neuraxis (see Fast Fact #85). In the former, the catheter lies within the subarachnoid space, where small quantities of medication have direct access to spinal drug receptor sites. In the latter, larger doses of medication (necessitated by epidural fat and vascular uptake) must diffuse across the dura to reach these receptors.

Epidural vs. Intrathecal Analgesia   Potential advantages of intrathecal – relative to epidural – techniques are:

  • Ease of catheter placement, particularly in the presence spinal pathology.
  • Superior analgesia in the following settings:
    • Presence of epidural pathology, e.g. metastatic disease, radiation fibrosis, vertebral compression.
    • Widespread pain, multiple pain locations, and pain distant from catheter site, especially upper body.
    • Pain poorly responsive to high-dose epidural therapy.
  • Fewer catheter problems such as catheter migration or tip occlusion.
  • Lower dose requirements may reduce side effects and lower drug costs.

Choice of System   There exists a spectrum of intrathecal system options – from a simple, percutaneous catheter/external pump to a totally implanted system. Choice is based on life expectancy, performance status, and available professional expertise. Pharmacoeconomic modeling suggests that the percutaneous catheter may be the most economic option for patients with prognoses of days to a few months.

Drug Choice   Arner and Arner (1985) demonstrated a relative responsiveness of pain mechanisms to intraspinal opioids as follows: continuous somatic pain > continuous visceral > intermittent somatic > intermittent visceral > neuropathic > cutaneous (ulcers or fistulas). An opioid alone is likely to be effective for nociceptive pain syndromes. The addition of coanalgesics, including local anesthetics and/or clonidine, is usually necessary for neuropathic pain syndromes. Ziconotide, a relatively new N-type calcium channel blocker, may have a role in pain syndromes refractory to traditional intrathecal opioids and coanalgesics. Frequency of adverse CNS effects (e.g. confusion, somnolence, dizziness), may be attenuated by slow titration. Experience with this drug in the palliative care setting is limited.

Complications and Side Effects   Complications may occur from a) the procedure (e.g. post-spinal headache), b) medications (e.g. opioid-related respiratory depression, sedation, urinary retention, pruritis), and c) hardware (e.g. catheter kinking/disconnection/dislodgement, infection). Major contraindications to intrathecal catheter placement include coagulopathy, infection at catheter insertion site, and sepsis.

References

  1. Bennett G, Burchiel K, Buchser E, Classen A, Deer T, et al. Clinical guidelines for intraspinal infusion: report of an expert panel. J Pain Symptom Manage. 2000; 20 (2;suppl):S37-S43.
  2. Burton AW, Rajagopol A, Shah HN, et al. Epidural and intrathecal analgesia is effective in treating refractory cancer pain. Pain Medicine. 2004; 5(3):239-247.
  3. Ferrante FM. Neuraxial infusion in the management of cancer pain. Oncology. 1999; 13(5;suppl 2):30-36.
  4. Mercadante S. Problems of long-term spinal opioid treatment in advanced cancer patients. Pain. 1999; 79:1-13.
  5. Arner S, Arner B. Differential effects of epidural morphine in the treatment of cancer related pain. Acta Anesthesiol Scand. 1985; 29:32-36.
  6. Prommer E. Ziconotide: a new option for refractory pain. Drugs Today. 2006; 42(6):369-378.

Fast Facts and Concepts are edited by Drew A Rosielle MD, Palliative Care Center, Medical College of Wisconsin. For more information write to: drosiell@mcw.edu. More information, as well as the complete set of Fast Facts, are available at EPERC: www.eperc.mcw.edu.

Version History: This Fast Fact was originally edited by David E Weissman MD. 2nd Edition was edited by Drew A Rosielle and published November 2007. Current version re-copy-edited April 2009.

Copyright/Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Reisfield GM, Wilson GR. Intrathecal Drug Therapy for Pain, 2nd Edition. Fast Facts and Concepts. November 2007; 98. Available at: http://www.eperc.mcw.edu/EPERC/FastFactsIndex/ff_098.htm.

Disclaimer: Fast Facts and Concepts provide educational information. This information is not medical advice. Health care providers should exercise their own independent clinical judgment. Some Fast Facts cite the use of a product in a dosage, for an indication, or in a manner other than that recommended in the product labeling. Accordingly, the official prescribing information should be consulted before any such product is used.

 ACGME Competencies: Medical Knowledge, Patient Care

Keyword(s): Ethics, Law, Policy Health Systems; Pain – Evaluation; Pain – Opioids