Modulation of central sensitisation by detoxification in MOH: Results of a 12-month detoxification study

Background: Human and animal models suggest that central sensitisation plays a role in medication-overuse headache (MOH). We aimed to study pain perception in MOH patients before and a year after withdrawal. Methods: We examined pain perception in 35 MOH patients before and two, six and 12 months after detoxification. For baseline comparison, we tested 40 healthy controls. We measured cephalic and extra-cephalic pressure-pain thresholds and supra-threshold pressure-pain scores and extra-cephalic pain thresholds, supra-threshold pain scores and temporal summation for electrical stimulation. Results: Of the 35 patients, 21 patients completed the entire study and remained cured of MOH. Statistically significant differences between patients and healthy controls were found in cephalic pressure-pain thresholds (137.3 kPa vs. 170 kPa, p<0.05), extra-cephalic pressure pain thresholds (213.3 vs. 274.3 kPa, p<0.05), in cephalic supra-threshold pressure-pain scores measured on a 100mm visual analogue scale (61 vs. 27 mm, p<0.05) and extra-cephalic supra-threshold pain scores for electrical stimulation (19.0 vs. 10.0 mm, p<0.05). Cephalic supra-threshold pain scores decreased statistically significantly from 50.3mm at baseline to 28.0mm at the 12-month follow-up. In contrast to controls, temporal summation was not found in MOH patients before withdrawal, but after detoxification temporal summation normalised. Conclusion: The central nervous system is sensitised in patients with MOH. For the first time we demonstrate that the pain perception continues to normalise up to a year after detoxification. This emphasises the importance of detoxification and follow-up to prevent relapse.