DECREASED CEREBROSPINAL-FLUID BETA-ENDORPHIN AND INCREASED PAIN SENSITIVITY IN PATIENTS WITH FUNCTIONAL ABDOMINAL-PAIN

We investigated whether central pain mechanisms including the endogeno us antinociceptive system are involved in functional abdominal pain-th at is, abdominal pain without abnormal findings at routine examination s. Beta-Endorphin, met-enkephalin immunoreactivity, and dynorphin immu noreactivity were measured in cerebrospinal fluid (CSF) from nine pati ents with long-lasting functional abdominal pain and nine pain-free co ntrols undergoing minor surgery while under spinal analgesia. Furtherm ore, pain sensitivity was evaluated with an ischaemic pain test compar ing 21 functional abdominal pain patients with two control groups: 1) 24 patients with organic abdominal pain due to duodenal ulcer, gallsto ne, or urinary tract calculi, and 2) 13 healthy pain-free controls. Th e CSF beta-endorphin concentration was significantly decreased in the functional abdominal pain group as compared with nine matched controls (P = 0.01). Met-enkephalin and dynorphin immunoreactivities were norm al. This part of the investigation was suspended after nine patients h ad been tested, because of post-lumbar-puncture headache. With regard to pain sensitivity, no significant difference between the three group s was shown, but subdivision of the functional abdominal pain group sh owed that individuals with pain and no symptoms of irritable bowel syn drome (IBS) were significantly more sensitive to pain than functional abdominal pain patients with IBS and healthy controls (P = 0.04).