title: Slowed EEG rhythmicity in patients with chronic pancreatitis: evidence of abnormal cerebral pain processing?
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Mech-Sense, Department of Gastroenterology, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark.
authors.forename: Søren S
authors.initials: SS
authors.lastname: Olesen
authors.forename: Tine M
authors.initials: TM
authors.lastname: Hansen
authors.forename: Carina
authors.initials: C
authors.lastname: Graversen
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Steimle
authors.forename: Oliver H G
authors.initials: OH
authors.lastname: Wilder-Smith
authors.forename: Asbjørn Mohr
authors.initials: AM
authors.lastname: Drewes
mesh_terms: D015746:Abdominal Pain / Q000188:drug therapy / Q000503:physiopathology*; D000328:Adult; D000701:Analgesics, Opioid / Q000627:therapeutic use; D001327:Autoimmune Diseases / Q000503:physiopathology; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology*; D003920:Diabetes Mellitus / Q000503:physiopathology; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D050500:Pancreatitis, Chronic / Q000188:drug therapy / Q000235:genetics / Q000276:immunology / Q000503:physiopathology*; D010507:Periodicity
chemical_list: D000701:Analgesics, Opioid