Complex Regional Pain Syndrome in Emergency Medicine Medication

Updated: Sep 07, 2023
  • Author: Marcella L Ruffo, MD; Chief Editor: Andrew K Chang, MD, MS  more...
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Medication Summary

Specialists in pain management (usually an anesthesiologist or physiatrist) commonly perform neural blockade. Use of pain modifying agents, such as cyclic antidepressants and gabapentin, usually is left to the primary care physician or pain management team.

The ED physician's primary responsibilities are to recognize the complex regional pain syndrome (CRPS) and refer patients to an appropriate specialist. However, these patients experience severe pain and should be given sufficient analgesia to provide relief. Narcotics usually are required.

Discussion of available agents has been limited to morphine and hydromorphone. ED physicians choose the agent with which they are most familiar and comfortable. Clinicians who choose to use meperidine should remember that it provides some euphoria and also has an active metabolite that may accumulate.

Agents with a short duration of action (eg, fentanyl) are not usually appropriate.

Some pain specialists prefer methadone for its long duration of action and mechanism of action benefit. This agent is an NMDA antagonist and may therefore be more effective in neuropathic pain syndromes. Conversion from other opioids to methadone should be done by a qualified pain management professional. [65] Other long-acting agents include sustained-release forms of oxycodone and morphine.

One meta-analysis from 1950 to 2017 evaluated the use of ketamine infusions for CRPS. [66]  The primary outcome was pain relief, which was found to be improved but only in short-term use (~3 months' treatment duration). Due to publication bias and study heterogenicity, there should be more trials conducted to evaluate ketamine efficacy, especially for long-term pain relief in CRPS patients.  



Class Summary

Breaking the pain cycle is high priority. Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties. Note that controversy exists among authors about the appropriateness of chronic narcotic analgesia. Some are opposed. Others note that, when more specific measures fail, patients must have pain relief in order to live their lives. The latter believe that patients with CRPS have a true chronic pain syndrome.

Morphine sulphate (Duramorph, MS Contin)

DOC for analgesia because of reliable and predictable effects, safety profile, and ease of reversibility with naloxone.

Initial dose dependent on whether patient already is taking narcotic analgesics. For patients not using long-term agents, as little as 2 mg IV/SC may be sufficient, though higher doses are often needed. Larger doses may be required in patients taking long-term narcotic analgesics.

Also available in oral form in immediate-release and timed-release preparations. Long-acting form usually is administered q12h, but many believe that it loses much of its effect after 8 h; immediate-release form may be needed for periods of pain "break-through," dose dependent on previous use. ED physician should begin at lowest available dose in newly diagnosed patients.

No intrinsic limit to the amount that can be given exists, as long as patient is observed for signs of adverse effects, especially respiratory depression. Various IV doses are used, commonly titrated until desired effect obtained.

Hydromorphone (Dilaudid)

Hydromorphone is a potent semisynthetic opiate agonist similar in structure to morphine. It is approximately 7-8 times as potent as morphine on mg-to-mg basis, with a shorter or similar duration of action. Used to manage moderate to severe pain. Available IV and PO.


General Anesthetics, Systemic

Class Summary

Agents with effects on muscle contractions appear to be effective. 

Ketamine (Ketalar)

While ketamine infusions are unlikely to be initiated by Emergency Medicine providers, there is growing evidence for its use in neuropathic syndromes, to include CRPS. Ketmaine has been evaluated for infusion therapy as well as topical.