Slowed EEG rhythmicity in patients with chronic pancreatitis

Abstract

Intractable pain usually dominates the clinical presentation of chronic pancreatitis (CP). Slowing of electroencephalogram (EEG) rhythmicity has been associated with abnormal cortical pain processing in other chronic pain disorders. The aim of this study was to investigate the spectral distribution of EEG rhythmicity in patients with CP. Thirty-one patients with painful CP (mean age 52 years, 19 male) and 15 healthy volunteers (mean age 49, nine male) were included. A multichannel EEG was recorded from 62 surface electrodes. Amplitude strengths of the resting EEG were retrieved based on wavelet frequency analysis and summarized in frequency bands with corresponding topographic mapping. Patients with CP had slowed EEG rhythmicity compared with healthy volunteers. This was evident as increased activity in the lower frequency bands δ (1-3.5 Hz) (P=0.05), θ (3.5-7.5 Hz) (P<0.001) and α (7.5-13.5 Hz) (P<0.001). Due to normalization a reciprocal relationship was observed for the high frequency band β (13.5-32 Hz). In a sub-analysis, δ band activity was modified by diabetes, opioid treatment and alcohol aetiology of CP. However, no effect modification was seen for the θ or α bands. Differences in θ activity were located over centro-frontal brain regions, whereas differences in δ, α and β band activity were located in frontal regions. Slowed EEG rhythmicity was evident in patients with CP. This possibly mirrors abnormal central pain processing and may serve as a clinically useful biomarker of abnormal central pain processing.