Evidence of persistent central sensitization in chronic headaches: a multi-method study

The aim of this study was to investigate central sensitization (CS) in chronic headaches and compare this phenomenon between chronic migraine (CM) and chronic tension-type headache (CTTH). We recruited 69 patients with chronic headaches and 18 control subjects. Questionnaires of headache history, allodynia and the Hospital Anxiety and Depression scale were administered. We recorded thresholds for pinprick and pressure pain, blink (BR) and nociceptive flexion reflex (NFR) R3 component coupled with wind-up ratios. Thresholds for pressure and pinprick pain, BR and NFR R3 were lower and wind-up ratios higher in patients. No differences of CS parameters between CM and CTTH were observed. CS is persistent and prevalent in patients with various types of chronic headache. CS levels are unrelated to the predominant side of pain, disease duration or depression. Neither is CS related to the headache type, suggesting similar mechanisms of headache chronification and chronicity maintaining and possibly explaining clinical similarity of various forms of chronic headache.