title: Cerebral excitability is abnormal in patients with painful chronic pancreatitis.
abstract: BACKGROUND
  We investigated whether patients with painful chronic pancreatitis (CP) present abnormalities in the cerebral response to experimental pain stimuli.
  
  
  METHODS
  Contact heat-evoked potentials (CHEPS) were recorded in 15 patients with CP and in 15 healthy volunteers during repetitive stimulation of the upper abdominal region (pancreatic 'viscerotome') and the right forearm (heterologous area). Three sequences of painful stimuli were applied at each site. Subjective pain scores were assessed by a visual analogue scale. Habituation was calculated as the relative change in CHEPS amplitudes between the first and the third stimulation sequence.
  
  
  RESULTS
  As expected pain scores decreased in healthy volunteers during successive stimulations at both sites (i.e., habituation), while in the CP group, they remained unchanged. The cerebral response consisted of an early-latency, low-amplitude response (N1, contralateral temporal region) followed by a late, high-amplitude, negative-positive complex (N2/P2, vertex). During successive stimulation of the pancreatic area, N2/P2 amplitude increased 25% in CP patients, while they decreased 20% in healthy volunteers (p = 0.006). After stimulation of the forearm, N2/P2 amplitudes increased 3% in CP patients compared to a decrease of 20% in healthy volunteers (p = 0.06).
  
  
  CONCLUSIONS
  Taken together, CP patients had an abnormal cerebral response to repetitive thermal stimuli. This was most prominent after stimulation of the upper abdominal area. As this area share spinal innervation with the pancreatic gland, these findings likely mirror distinctive abnormalities in cerebral pain processing.
authors.affiliation: Mech-Sense, Department of Gastroenterology and Hepatology, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark. sso@mech-sense.com
authors.forename: S S
authors.initials: SS
authors.lastname: Olesen
authors.forename: T M
authors.initials: TM
authors.lastname: Hansen
authors.forename: C
authors.initials: C
authors.lastname: Graversen
authors.forename: M
authors.initials: M
authors.lastname: Valeriani
authors.forename: A M
authors.initials: AM
authors.lastname: Drewes
mesh_terms: D000005:Abdomen; D000328:Adult; D059350:Chronic Pain / Q000503:physiopathology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D005542:Forearm; D006185:Habituation, Psychophysiologic / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D017288:Pain Threshold / Q000502:physiology*; D050500:Pancreatitis, Chronic / Q000503:physiopathology*; D013003:Somatosensory Cortex / Q000503:physiopathology*