STUDY OF PRESSURE PAIN AND CELLULAR CONCENTRATION OF NEUROTRANSMITTERS RELATED TO NOCICEPTION IN EPISODIC TENSION-TYPE HEADACHE PATIENTS

The pressure pain threshold of 30 patients affected by tension-type he adache was assessed and the values compared with those of a group of 3 0 age-matched control subjects. In the patient group, pressure pain th reshold values were related to the blood cell concentration of some ne urotransmitters which are considered to be involved in the genesis and modulation of pain (beta-endorphin levels in peripheral blood mononuc lear cells [PBMCs], substance P and serotonin concentrations in platel ets). The pressure pain threshold was significantly lower in tension-t ype headache patients than in control subjects (P<0.0006). Significant ly lower levels of beta-endorphins in PBMCs and substance P in platele ts, as well as significantly higher levels of serotonin in platelets w ere found in tension-type headache patients compared to the control su bjects (P<0.0001). A significant positive correlation was found betwee n pressure pain threshold values and beta-endorphin levels in both con trol and patient groups (P<0.0001). On the contrary, a statistically s ignificant negative correlation was evident between pressure pain thre shold values and substance P levels in platelets in both patients and control subjects (P<0.01 and P<0.001, respectively). In both groups, t here was a negative correlation between beta-endorphins in PBMCs and s ubstance P in platelets (patients P<0.02. controls P<0.001). The findi ngs of altered beta-endorphin levels in blood mononuclear cells and su bstance P levels in platelets could be the peripheral biochemical refl ection of the low pressure pain threshold values in tension-type heada che patients, and support the hypothesis of an impairment of the antin ociceptive systems in this form of headache.