SCS Stimulation Clamp to Assess Impact of Stimulation on Glucose Metabolism

In 1967 spinal cord stimulation (SCS) for the treatment of chronic neuropathic pain was established. Today various pain syndromes like the failed back surgery syndrome (FBSS), the complex regional pain syndrome (CRPS), ischemic pain or phantom limb pain are treated with SCS. The development of this technique based on the so called "Gate Control Theory" which states that stimulation of the mechanosensitive A fibers suppresses the transmission of pain stimuli via the pain-sensitive C fibers to the brain in the spinal cord. Conventional SCS consists of periodically emitted tonic stimuli with a frequency between 30 and 120 Hz. During implantation, the electrodes are placed in the epidural space in such a way that the paraesthesia caused by nerve stimulation covers the painful area (dermatome), thus relieving the pain. In 2010 de Ridder et al. published an article presenting the so called "Burst Stimulation" where series of high-frequency impulses are released at defined time intervals (frequency: 40 Hz with peaks of 500 Hz per volley). Compared to the tonic SCS the burst technique is more effective and in most cases no paraesthesia is reported. However, potential effects of SCS stimulation on other organ systems have only been insufficiently examined.Especially possible effects of SCS on the glucose metabolism has not been investigated so far. However, it is important to investigate a possible effect for two reasons: SCS could cause severe hypoglycemia which must be avoided. Furthermore, if SCS affects blood sugar levels, it is also of interest what mechanisms are involved and how this knowledge can be used to control elevated blood glucose levels.

The present study is a pilot. The investigators want to examine possible effects of SCS therapy on blood glucose metabolism. Therefore hyperinsulinemic euglycemic clamps with an insulin infusion of 1mU / kg body weight per minute are performed. During the clamp the investigators apply different SCS techniques in a randomly order. Insulinsensitivity is determined at different time points.