Hypertension-associated hypalgesia: a clue to the comorbidity of headache and other pain disorders

BACKGROUND: Primary headaches and chronic musculoskeletal pain are prevalent disorders with incompletely known causes. AIMS: To review the data from the HUNT studies on the comorbidity of these pain disorders, and their relation to blood pressure levels. MATERIALS & METHODS: Cross-sectional and prospective data from more than 50,000 persons participating in the HUNT studies, a large Norwegian population-based health survey RESULTS: Headache and chronic musculoskeletal complaints in all parts of the body were comorbid, and the prevalence of pain in all locations was inversely related to blood pressure levels. DISCUSSION: A likely cause for this is hypertension-associated hypalgesia, described in both animal and human experimental models, involving interactions between cardiovascular and pain modulating centres at the brainstem level, and probably also peripheral baroreceptor mechanisms. CONCLUSION: Better understanding of these mechanisms may be crucial for enabling better prevention and treatment of these very prevalent, costly and disabling disorders.