Objective: Our aim was to study the possible markers of pain syndrome--indicators of pain sensitivity--pain pressure tolerance thresholds (PPTT), and immuno-indicators--natural antibodies against pain processing mediators (eAb) for evaluation the possibility of its using for a objective pain assessment at chronic low back pain.
Methods: Pain sensitivity was assessed daily and nightly, by measuring the PPTT The natural antibody levels (eAb), were determined in serum by ELISA. Measurement of all parameters were performed at 1st, 10th and 21 days.
Results: 173 patients (93 women and 80 men) with chronic low back pain were included in the study. At 1st day most patients had lowered PPTT: 55% of men and 74% during the day, 72% of men and 89% of women at night. Dynamic study has shown a tendency of PPTT normalization in men. The study of diurnal PPTT variations have shown that night PPTT lower than day PPTT on 15-17%. We found gender PPTT differences: PPTT values in women 17-26% lower than in men. Analysis of individual eAb profiles has showed that elevated and high levels of eAb to β-endorphin, orphanin and histamine have 84%, 78%, 84% women and 82%, 85 and 95% men, respectively. These indicators higher than those for serotonin, dopamine and angiotensin (55%, 65%, 70% in women and 65%, 66%, 66% in men, respectively; p < 0.05). Dynamic study of eAb levels have shown a significant anti-histamine eAbs decrease (23%; p = 0.015) only.
Conclusion: The pathological changes in pain sensitivity and levels of eAbs to pain-processing mediatos are evidenced. Further investigations are necessary to clarify to role of these variations in pain processing and for use these indicators for objective pain assessment.