Electroencephalographic evoked pain response is suppressed by spinal cord stimulation in complex regional pain syndrome: a case report

Spinal cord stimulation (SCS) is considered as an option for the management of complex regional pain syndrome (CRPS). Hyperalgesia, an increased pain response to a mechanical or thermal stimulus at normal or increased threshold is a common feature of CRPS. Animal studies have demonstrated that SCS significantly reduces mechanical hyperalgesia. These studies suggest that SCS mechanisms may involve reduction of glial activation at spinal cord level and/or activation of μ-opioid and δ-opioid receptors. However, in humans it has been observed that SCS had no effect on experimental pain thresholds and did not produce decreased sensitivity for pressure, warmth, and cold induced pain in CRPS patients. The majority of currently available studies on the effectiveness of SCS, including those using quantitative sensory testing (QST) rely on patient reported outcomes such as visual analogue or numerical rating scales. The current case report investigates the effectiveness of SCS based on electroencephalogram (EEG) analysis of contact heat evoked potentials following experimental induction of thermal stimuli