EEG neurofeedback for the treatment of neuropathic pain in the elderly-a mechanistic review.

Neuropathic pain (NP) is a complex pain disorder that constitutes a significant problem in the aging population, impacting quality of life and everyday functioning. In the quest to develop effective treatments, much research effort has been made to understand brain activity in people with NP, revealing a number of disordered electroencephalogram (EEG) patterns. This information can then be used to inform neurofeedback therapy, a novel approach that involves volitionally training brain activity in a closed loop. In this review of the existent literature we had three main objectives: (1) to summarize the reported EEG signatures of NP, (2) to evaluate the therapeutic efficacy of neurofeedback in the treatment of NP, and (3) to present the potential mechanisms of neurofeedback action in NP. Consequently, literature searches were conducted on the PubMed/Medline, Research Gate, and Cochrane databases. We identified 18 studies that examined resting-state EEG patterns in NP, and seven studies that investigated EEG-based neurofeedback in NP. Most biomarker studies of NP showed typical EEG patterns consisting of excess theta activity and decreased alpha activity. Neurofeedback study outcomes were largely promising in terms of treatment efficacy, but their quality was low. In turn, based on these results, we proposed hypothesis-based neurofeedback protocols and discussed the potential mechanisms of neurofeedback in the treatment of NP, including why this treatment option may be beneficial in the elderly population. Neurofeedback is a promising treatment option for NP, but caution should be exercised in interpreting the results due to the low number and methodological quality of research studies. A larger body of research studies points to common patterns of EEG abnormality in NP, which could be directly targeted with neurofeedback. The main advantage of this therapeutic approach is that it has no side effects and may be considered a valuable form of treatment in more frail populations such as the elderly.