Robert L. Rogers, MD

Disclosures

March 12, 2009


Question
Does hypertension cause headaches?

Response from Robert L. Rogers, MD
Assistant Professor of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland; Director of Undergraduate Medical Education, University of Maryland School of Medicine, Baltimore, Maryland

Introduction

Approximately one fourth of the adult population in the United States has hypertension.[1,2,3] Emergency physicians are frequently faced with patients who come to the emergency department (ED) with a complaint of headache and are found to have elevated blood pressure. Additionally, some patients falsely assume that their blood pressure is elevated and will often come to the ED with a complaint of headache, thinking that the headache is secondary to hypertension.

What Does The Evidence Show?

For many years, it has been taught that hypertension causes headaches. In 1913, Janeway[4] reported the first description of the "hypertensive headache," in which his patients with hypertension would commonly attribute their frequent headaches to uncontrolled hypertension. A subsequent 1953 study by Stewart[5] found that headaches were much more common in patients who were told that they had hypertension compared with patients who had similar blood pressures but were not told that they had hypertension, thereby suggesting the involvement of psychological factors. However, the assumption that a definitive link exists between hypertension and headache still persists today. The frequency with which hypertensive headache is encountered in the ED makes the understanding of any causal relationship particularly important to the emergency physician.

Much of the evidence that hypertension causes headaches comes from hypertension medication trials that frequently report decreased headache episodes in patients taking antihypertensive medications. In a large meta-analysis of 94 randomized trials on the relationship between hypertension and headache, Law and colleagues[6] concluded that blood pressure-lowering agents significantly reduce the number of headaches. However, the authors disclosed that the causal relationship between hypertension and headache is not supported by observational studies of blood pressure and headache.

One of the more interesting observations regarding the relationship between hypertension and headache comes from a large prospective, cross-sectional study performed in Norway.[7] Results from this study indicated that both increased systolic blood pressure and pulse pressure may actually decrease headache prevalence by inducing baroreceptor-mediated hypoalgesia.[7,8] Additionally, it was found that increasing systolic blood pressure was associated with a decreased prevalence of nonmigrainous headache or migraine.[7]

Conclusion

Currently, there is no concrete evidence to establish a firm causal link between hypertension and headache. There is, however, ample evidence that hypertension does not cause headaches and in fact may be protective against the development of headache. Despite conflicting data in the medical literature, many of the large trials that have examined this relationship have found no association between hypertension and the development of headache.[7,8] This is particularly important for the practicing emergency physician who must make critical decisions for patients with hypertension. Armed with data that the causal relationship between hypertension and headache is probably a myth, emergency physicians will be in a better position to provide safe and evidence-based medical care for their patients.

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