PROCEDURE: Ketamine infusion to treat RSD
NOTE: THESE PROCEDURES OR INJECTIONS SHOULD ONLY BE ADMINISTERED BY AN MD OR DO TRAINED IN INTERVENTIONAL PAIN MEDICINE
Physicians have different protocols for the administration of ketamine, but I have learned that the quantity of ketamine is less important than the duration of the treatment regarding the ability to shut off the N-methyl-D-aspartate (NMDA) receptors in the brain over time. My experience shows that single doses of ketamine do little to improve the patient’s condition, while repeated doses of ketamine have worked very well to relieve sympathetic dysfunction. Ketamine therapy has provided significant success not only in the reduction of pain, allodynia, and other well-recognized forms of sympathetic dysfunction, but also for improving patients who suffer from the sequelae of CRPS, such as neurogenic bladder, gastropoeisis, and neurodermatitis, the most common dermatologic manifestation of CRPS. The beneficial effects of ketamine have proved far reaching.
Ketamine in the Literature There have been many articles written regarding ketamine. The 2003 review article by Hocking and Cousins3 suggests that “the efficacy for ketamine for treatment of chronic pain is moderate to weak.” Clearly our statistics and experience have shown this not to be the case. In the June 2007, Pain: Clinical Updates from the International Association for the Study of Pain (IASP)4, it was suggested that “complex regional pain syndrome may respond to intravenous ketamine, topical ketamine ointment, or epidural infusion.”
A 2005 Goldberg et al study5 suggested mixed results with outpatient ketamine, but again, ongoing treatments and sheer numbers of patients have suggested that their original data, on a small patient population, was incorrect. It is entirely possible that their patient population was too small, or the dosage of ketamine too low, as their maximum outpatient dose was 100 mg ketamine. All of this notwithstanding, it is clear that the infusions are helpful. Certainly some patients suffer side effects to include mild hallucinations (which are extremely rare), nausea, headache, and anxiety. All of these are dose related and easily controlled by adjunctive medication.
Outcomes: It is clear is that patients with CRPS who have received ketamine have made significant strides in a positive direction. Unfortunately, this is not a “cure.” Currently, patients who have been labeled “cured” all received high-level comatose doses of ketamine in either Germany or Mexico. However, the lowdose outpatient infusions are clearly beneficial and should be considered in individuals whose treatment with more “conventional” modalities has caused limited improvement. A comprehensive ketamine treatment program must include other treatment modalities. A good diet, exercise, physical and occupational therapy, and an overall attempt at a healthier lifestyle all play a positive role in improving the patient’s health. All of these modalities, and a reduction of pain medications, specifically opioids, should be incorporated into the overall treatment regimen. I advise women of childbearing age to stop ketamine therapy 30 days before conception, although there is no indication of greater residual risk than with any other medication. Finally, it should be noted that no patients have been eliminated from the treatment protocols due to unmanageable side effects. As with any therapeutic measure, more information will be necessary and will be obtained over time. I continue to make adjustments in the protocols in an effort to produce better outcomes.