Primary Headaches: A Convergence Hypothesis

Abstract

After reviewing the historic differentiation between migraine and tension-type headache, the authors note that the similarities between these two types of primary headaches outweigh the differences, and so hypothesize that these headaches share a common pathophysiology. The convergence hypothesis for primary headaches links the clinical features of an evolving headache to current pathophysiological models. The authors suggest that successive symptoms experienced clinically reflect an escalating pathophysiological process, beginning with the premonitory period and progressing into tension-type headache and, if uninterrupted, finally into migraine. The clinical manifestations of other headache types, such as so-called sinus headache or temporomandibular headache, may also be explained by this model. A convergence hypothesis for primary headaches has important implications for earlier recognition, diagnosis, and treatment.

Tension-type headache and migraine: Two points on a continuum?

“…Arguments against the continuum model only illustrate the obvious differences between TTH and migraine but do not address the hypothesis that migraine may refl ect a physiologic evolution from episodic TTH as severity worsens, central sensitization occurs, and additional neuronal pathways are incorporated. Migraine appears to be the result of a sensitized nervous system that can no longer adapt to the degree of sensory input leading to a loss of its ability to effectively mediate nociceptive input [1].…”

“…Whether TTH and migraine are examples of two truly distinct entities with their own pathophysiologies and natural histories or whether they represent opposite ends of a continuum has been the subject of debate for decades [1]. Much of what we have come to believe regarding the characteristics of these two disorders argues that they are undeniably different.…”

Sinus problems as a cause of headache refractoriness and migraine chronification

“…The Convergence Hypothesis was proposed in 2000 to explain the clinical observation that multiple clinical phenotypes are observed in the pathophysiological event of migraine [39]. For example, an entire spectrum of disabling primary headaches in individuals with migraine responded to migraine-specifi c treatment (sumatriptan) [40].…”

Tension-type headache in the young

“…Two theories exist relating migraines and TTH. The continuum model suggests that migraine and TTH are a single pathophysiologic disorder ranging from mild headaches (TTH) to moderate to severe headaches (migraine without aura) to the most severe headaches (migraines with aura) [8,9]. In contrast, the spectrum model suggests that these are two separate entities, with migraineurs having a full spectrum of headaches and TTH patients having headaches limited to a mild to moderate pain disorder [10].…”