Abstract
BACKGROUND: It is well known from cross-sectional studies that pain intensity affects brain activity as measured by electroencephalography (EEG) in people with neuropathic pain (NP). However, quantitative characterisation is scarce. METHODS: In this longitudinal study, ten people with spinal cord injury-related NP recorded their home EEG activity ten days before and after taking medications over a period of several weeks. RESULTS: The reduction in pain due to medications was accompanied by changes in the resting state EEG and its reactivity to eyes opening (EO) and closing (EC). There was a significant positive correlation between the frontal theta band and the intensity of pain (visual numerical scale) pre-medication (p = 0.007, Pearson R = 0.29) and theta, alpha, and lower beta (6-15 Hz) band power and the intensity of pain after post-medication over the frontal, central, and parietal cortices. Reactivity had a negative correlation with pain intensity at all locations and frequency bands and showed similar behaviour in wider frequency bands like 8-15 Hz at the occipital cortex and 2-12 Hz at the frontal cortex. CONCLUSIONS: EEG could be used to detect the intensity of NP to serve as a surrogate or pharmacodynamic marker.