Hyperalgesia and Central Sensitization Signs in Patients with Cluster Headache: A Cross-Sectional Study

Abstract Objective To investigate central sensitization (CS) in cluster headache (CH) and to evaluate its relationship with disease characteristics and psychological comorbidities. Design Cross-sectional study. Settings Whether CS occurs in CH, as it does in other primary headaches, is a subject of debate. Few studies have evaluated the presence of CS and its relationship with psychological comorbidities in patients with CH. Subjects Twenty patients with episodic or chronic CH and 16 healthy controls were recruited. Methods The variables evaluated included frequency, intensity and duration of headache attacks, pressure pain thresholds (PPTs) and wind-up (WU) ratios of pain bilaterally measured over trigeminal and extratrigeminal areas, and results of questionnaires regarding anxiety and depression (Hospital Anxiety and Depression Scale [HADS], Beck Depression Inventory [BDI], State-Trait Anxiety Inventory [STAI]), quality of life (Short Form-36 [SF-36]), headache impact (Headache Impact Test [HIT-6]), and allodynia (Allodynia Symptom Checklist [ASC]). Results PPT levels were significantly lower in the CH group compared with the healthy participants (all tested points, P < 0.001). No differences were found in WU ratios between groups. However, differences in HADS (P < 0.01), BDI (P < 0.01), STAI (P < 0.01), SF-36 (P < 0.01), HIT-6 (P < 0.001), and ASC (P < 0.01) were observed between groups. The healthy group showed a moderate negative correlation between SF-36 and BDI (rho = –0.59, P = 0.03). Likewise, the CH group showed a moderate negative correlation between frequency and BDI (rho = –0.52, P = 0.03), a strong positive correlation between duration and HADS (rho = 0.86, P < 0.01), and a moderate negative correlation between intensity and PPT over symptomatic V1 (rho = –0.66, P < 0.01) and over asymptomatic V1 (rho = –0.65, P < 0.01). The CH group also showed a moderate negative correlation between SF-36 and anxiety and depression variables. Conclusions Our findings show that patients with CH have lower PPT levels at cranial and extracranial points, suggesting, as in other primary headaches, the presence of CS. We have also found a high prevalence of psychiatric comorbidities that correlate with the length and frequency of attacks. These findings highlight the importance of a multidisciplinary approach to the treatment of patients with CH.