Higher pre-treatment evoked alpha-band oscillatory brain dynamics predict chronic pain reduction of non-invasive brain stimulation of non-motor targets

ABSTRACT Introduction Repetitive transcranial magnetic stimulation (rTMS) of non-motor cortical targets, including the left dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), and posterosuperior insula (PSI), has been proposed as a treatment for chronic pain with variable clinical outcomes. Previous work identified pre-treatment cortical excitability and oscillatory dynamics, assessed using the combination of transcranial magnetic stimulation and electroencephalography (TMS-EEG), that were associated with treatment response following primary motor cortex stimulation. In this secondary analysis of a large clinical trial, it was evaluated whether responders to rTMS delivered to these non-motor targets exhibited distinct pre-treatment TMS-evoked cortical responses compared with non-responders. Materials and Methods Forty-five patients with chronic pain received 12 sessions over eight weeks of 10 Hz rTMS to DLPFC, ACC or PSI. Pre-treatment cortical responses were assessed using TMS-EEG at each of the three targets. Cortical reactivity was quantified using global and local mean field power, and oscillatory dynamics were assessed using event-related spectral perturbation (ERSP) and inter-trial coherence (ITC) in the alpha-band (8–12 Hz). Results Responders (20 of 45, 44%) compared with non-responders showed higher pre-treatment alpha-band ERSP and ITC over the stimulated cortical targets (both P