Cohen S, Khunsriraksakul c, Yoo y, Parker E, Samen-Akinsiku c, Patel n, Cohen s, Yuan x, Cheng j, Moon j

Ketamine infusions are frequently employed for refractory complex regional pain syndrome (CRPS), but there are limited data on factors associated with treatment response. Sympathetic blocks are also commonly employed in CRPS for diagnostic and therapeutic purposes and generally precede ketamine infusions.

Factors associated with a positive response to ketamine in univariable analysis were the presence of SMP (61.0% success rate vs 26.7% in those with sympathetically independent pain; P = .009) and post-block temperature increase (5.66 ± 4.20 in ketamine responders vs 3.68 ± 3.85 in non-responders; P = .043). No psychiatric factor was associated with ketamine response. In multivariable analysis, SMP (OR 6.54 [95% CI 1.83, 23.44]) and obesity (OR 8.75 [95% 1.45, 52.73]) were associated with a positive ketamine infusion outcome.

The response to sympathetic blocks may predict response to ketamine infusion in CRPS patients, with alleviation of the affective component of pain and predilection to a positive placebo effect being possible explanations.

Pain Medicine, Volume 24, Issue 3, March 2023, Pages 316–324, https://doi.org/10.1093/pm/pnac153

Cohen S, Baber Z, Buvanedran A, Mclean b, chen y, hooten wm, laker s, wasan a, kennedy d, sandbrink f

It is nearly impossible to overestimate the burden of chronic pain, which is associated with enormous personal and socioeconomic costs. Chronic pain is the leading cause of disability in the world, is associated with multiple psychiatric comorbidities, and has been causally linked to the opioid crisis. Access to pain treatment has been called a fundamental human right by numerous organizations. The current COVID-19 pandemic has strained medical resources, creating a dilemma for physicians charged with the responsibility to limit spread of the contagion and to treat the patients they are entrusted to care for.

In these guidelines, we provide a framework for pain practitioners and institutions to balance the often-conflicting goals of risk mitigation for health care providers, risk mitigation for patients, conservation of resources, and access to pain management services. Specific issues discussed include general and intervention-specific risk mitigation, patient flow issues and staffing plans, telemedicine options, triaging recommendations, strategies to reduce psychological sequelae in health care providers, and resource utilization.

Pain Medicine, Volume 21, Issue 7, July 2020, Pages 1331–1346, https://doi.org/10.1093/pm/pnaa127

Zhao Z, Larkin T, Cohen S

The shoulder is one of the most complex joints in the body, with potential pain generators such as the glenohumeral and acromioclavicular joints, multiple bursae, and numerous soft tissue structures to include multiple tendons and muscles. The lifetime prevalence of shoulder pain is estimated at 7% to 67%, with the prevalence variation stemming from differences in study populations and diagnostic criteria. According to some sources, pain arising from subacromial impingement syndrome is the most common source of chronic shoulder pain, though many patients have pain from multiple pathologies and some have pain despite minimal or no radiologic pathology. In the United States, the estimated cost of chronic shoulder pain is largely unknown, though ∼$3 billion dollars are spent each year on the evaluation and management of rotator cuff tears alone. In Australia, the average annual cost per patient with chronic shoulder pain has been estimated at AU$22,378. Yet, despite the high prevalence and economic expenditures on shoulder pain, surgical and nonsurgical treatments are characterized by high failure rates. According to one systematic review, there is no difference in pain or functional outcomes between surgical and nonsurgical management for shoulder impingement syndrome. In this issue of Pain Medicine, Eckmann et al. report their results with radiofrequency (RF) ablation of the terminal sensory articular nerves of the shoulder joint for chronic, refractory shoulder pain.

Zhao, Z., Larkin, T., & Cohen, S. (2020). Reflections on Innovative Interventional Pain-Relieving Procedures: Lessons Learned from Previous Mistakes. Pain Medicine. https://doi.org/10.1093/pm/pnz380