Increased sympathetic activity in chronic pancreatitis patients is associated with hyperalgesia

Pain treatment in chronic pancreatitis patients is difficult, with pain frequently relapsing or persisting. Recent studies suggest that altered central nervous system pain processing underlies the chronic pain state in these patients. There is evidence that increased sympathetic activity may also play a role in some chronic pain syndromes. This study assessed sympathetic nervous system activity and its relation to pain processing in patients with severe painful chronic pancreatitis. The authors postulated that chronic pancreatitis patients with more sympathetic activity exhibit more generalized hyperalgesia. In 16 chronic pancreatitis patients, sympathetic activity was measured via venous plasma norepinephrine (NE) levels (supine, standing). Pain processing was quantified via pressure pain tolerance thresholds (PPTs) in dermatomes T10 (pancreatic area), C5, T4, L1. Five patients showed increased supine plasma NE levels (NE ≥ 3.0 nmol/L). PPTs were lower in patients with increased NE levels (INE) compared with patients with normal NE (NNE) (means [95% confidence interval]: INE 402 kPa [286-517] versus NNE 522 kPa [444-600]; P = .042). In severe chronic pancreatitis patients, increased sympathetic activity and hyperalgesia appear associated, suggesting that sympathetic activity may also play a role in these patients' pain.