Nociceptive-evoked electroencephalography can predict inter-individual differences in high frequency induced sensitisation of central nociceptive pathways: A test-retest reliability study

Evoked-EEG can capture changes in cortical responses during experimentally induced sensitised pain states. However, the test-retest reliability of such methods requires validation. The present study applied HFS across two identical sessions in the same individuals to assess the test-retest reliability of EEG dynamics evoked by a 128mN pin-prick stimulator and single-pulse electrical stimuli before and after HFS conditioning. The value of these features for reflecting individual differences in the development of hyperalgesia was also assessed. Results demonstrate poor-to-moderate test-retest reliability and relatively wide agreement at baseline for all features, with lateralised differences often present. This was further reduced when post-HFS changes were considered. α-ERD assessed from contralateral central electrodes was significantly strengthened post-HFS for both electrical and pinprick stimuli, consistent with increased sensorimotor engagement in response to hyperalgesic and non-hyperalgesic stimuli. Notably, baseline α-ERD was related to the subsequent time course of SHA development. Furthermore, whilst VP magnitude displayed a significant relationship with the general intensity of perceived pain, no specificity for SHA development was evident. Alternatively, θ-ERS captured a general habituation effect relative to variations in reported pain intensity between sessions for both stimuli modalities. These findings indicate that evoked EEG responses may be useful for investigating individual differences in the cortical processing of acute pain and the development time course of HFS-induced sensitivity yet may not possess sufficient test-retest reliability for interventional testing.