Pain Research
1. Correll, Maleki, et al. “Subanesthetic ketamine infusion therapy: a retrospective analysis of a novel therapeutic approach to complex regional pain syndrome” Pain Medicine. 2004 Sep; 5(3): 263-75.
http://painmedicine.oxfordjournals.org/content/painmedicine/5/3/263.full.pdf
SUMMARY: This article reviewed 33 cases of patients with CRPS that were treated with Ketamine infusion. The patients received a prolonged low dose infusion of ketamine, on average 10-20mg/hr over 2-4 days. 76% of patients experienced complete pain relief after the first course of treatment. Pain relief lasted at least three months for most patients. Adding a second course of treatment allowed over 50% to be pain free for over a year. One patient had to discontinue additional treatments after the first infusion after developing elevated liver enzymes. These did normalize after treatment was stopped.
2. Patil S, Anitescu M. “Efficacy of outpatient ketamine infusions in refractory chronic pain syndromes: a 5-year retrospective analysis” Pain Medicine. 2012 Feb; 13(2): 263-9.
http://painmedicine.oxfordjournals.org/content/13/2/263.long
SUMMARY: This article reviewed 49 patients receiving outpatient ketamine infusions for various pain syndrome – 18 with CRPS. For patients with CRPS, the average reduction in the pain score on a ten-point scale was 7.2. For the other pain conditions, the average reduction in the pain score was 5.1. Average pain relief was at least three weeks.
3. Zhao, J, et al. “The Effect of Ketamine Infusion in the Treatment of Complex Regional Pain Syndrome: a Systemic Review and Meta-analysis” Curr Pain Headache Rep. 2018 Feb 5; 22(2): 12.
SUMMARY: A search of Embase, Pubmed, Web of Knowledge, Cochrane, Clinical Trial.gov, and FDA.gov between Jan 1, 1950 and August 1, 2017 was conducted to evaluate ketamine infusion therapy in the treatment of CRPS. Clinical trials and cohort studies were selected for analysis. The effect of ketamine treatment for complex regional pain syndrome was assessed by 0-10 scale numerical rating pain score. The secondary outcome is the pain relief event rate, which is defined as the percentage of participants who achieved 30% or higher pain relief in each of the qualified studies. The meta-analysis results showed that the ketamine treatment led to a decreased mean pain score in comparison to the self-controlled baseline (p < 0.000001). The immediate pain relief event rate was 69%. The pain relief event rate at the 1-3 months follow-ups was 58%. The findings suggested that ketamine infusion can provide clinically effective pain relief for less than 3 months.
4. Sheehy KA, et al. “Subanesthetic ketamine infusions for the treatment of children and adolescents with chronic pain: a longitudinal study” BMC Pediatr. 2015 Dec 1; 15: 198.
SUMMARY: Over a 15-month period, 63 children and adolescents with chronic pain received 277 ketamine infusions. Intravenous administration of subanesthetic doses of ketamine to children and adolescents on an outpatient basis was safe and not associated with psychotropic effects or hemodynamic perturbations. Overall, ketamine significantly reduced pain intensity (p < 0.001) and yielded greater pain reduction in patients with complex regional pain syndrome (CRPS) than in patients with other chronic pain syndromes. These data suggest that subanesthetic ketamine infusion is feasible in an outpatient setting and may benefit children and adolescents with chronic pain. Further, patients with CRPS, POTS, and a history of trauma-related chronic pain are more likely to benefit from this therapeutic modality.
5. Patil, S, et al. “Efficacy of outpatient ketamine infusions in refractory chronic pain syndromes: a 5-year retrospective analysis” Pain Med. 2012 Feb; 13(2): 263-9.
SUMMARY: A retrospective analysis identified 49 patients undergoing 369 outpatient ketamine infusions. Patients had a diagnosis of complex regional pain syndrome (CRPS), refractory headaches or severe back pain. All patients reported significant reduction in VAS score of 5.9. For patients with CRPS reduction in VAS score was 7.2; for the others the reduction was 5.1. The probability of lasting pain relief in patients with refractory pain states was 59-85% (23-51% relief over 3 weeks).