Search

Sander De Groote,1 Mats De Jaeger,1 Peter Van Schuerbeek,2 Stefan Sunaert,3 Ronald Peeters,3 Dirk Loeckx,4 Lisa Goudman,1,5 Patrice Forget,6 Ann De Smedt,7 Maarten Moens1,2,8 1Department of Neurosurgery, Universitair Ziekenhuis Brussel, Brussels, Belgium; 2Department of Radiology, Universitair Ziekenhuis Brussel, Brussels, Belgium; 3Department of Radiology, Universitair Ziekenhuis Leuven, Leuven, Belgium; 4COMETRIX, Leuven, Belgium; 5Pain in Motion International Research Group, Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Brussel, Belgium; 6Department Anesthesiology, Universitair Ziekenhuis Brussel, Brussels, Belgium; 7Department of Neurology, Universitair Ziekenhuis Brussel, Brussels, Belgium; 8Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium Background and purpose: Failed back surgery syndrome (FBSS) is a common and devastating chronic neuropathic pain disorder. Conventional spinal cord stimulation (SCS) applies electrical suprathreshold pulses to the spinal cord at a frequency of 40–60 Hz and relieves pain in FBSS patients. During the last decade, two major changes have emerged in the techniques of stimulating the spinal cord: paresthesia-free or subthreshold stimulation and administration of higher frequency or higher amounts of energy to the spinal cord. Despite the positive clinical results, the mechanism of action remains unclear. A functional MRI (fMRI) study was conducted to investigate the brain alterations during subthreshold and suprathreshold stimulation at different frequencies. Methods: Ten subjects with FBSS, treated with externalized SCS, received randomly four different stimulation frequencies (4 Hz, 60 Hz, 500 Hz, and 1 kHz) during four consecutive days. At every frequency, the patient underwent sub- and suprathreshold stimulation. Cerebral activity was monitored and assessed using fMRI. Results: Suprathreshold stimulation is generally accompanied with more activity than subthreshold SCS. Suprathreshold SCS resulted in increased bilateral activation of the frontal cortex, thalamus, pre- and postcentral gyri, basal ganglia, cingulate gyrus, insula, thalamus, and claustrum. We observed deactivation of the bilateral parahippocampus, amygdala, precuneus, posterior cingulate gyrus, postcentral gyrus, and unilateral superior temporal gyrus. Conclusion: Suprathreshold stimulation resulted in greater activity (both activation and deactivation) of the frontal brain regions; the sensory, limbic, and motor cortices; and the diencephalon in comparison with subthreshold stimulation. Each type of frequency at suprathreshold stimulation was characterized by an individual activation pattern. Keywords: spinal cord stimulation, fMRI, subthreshold, suprathreshold, frequency

Complex regional pain syndrome has long been recognized as a severe and high impact chronic pain disorder. However, the condition has historically been difficult to define and classify and little attention has been given to where complex regional pain syndrome sits within other apparently similar chronic pain disorders, such as fibromyalgia and regional pain syndrome. In this review challenges in regard to nomenclature, definitions, and classification of complex regional pain syndrome are reviewed and suggestions are provided about future directions.

Chronic regional pain syndrome (CRPS) can be intractable to treat and patients sometimes suffer for many years. Therefore, new treatment strategies are needed to alleviate symptoms in CRPS patients. This case report describes a patient suffering from intractable CRPS type 1 for 13 years. Due to her swollen painful feet and left knee she is wheelchair-bound. The combination of palmitoylethanolamide and ketamine 10% cream reduced her pain by more than 50% after 1 month of treatment, and a marked reduction in swelling and skin discoloration was noticed. Furthermore, she could walk independently again and she experienced no side effects. Thus, palmitoylethanolamide and topical ketamine could be a combination therapy option for treating CRPS patients.