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.