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Migraine with and without aura: the same disease due to cerebral vasospasm of different intensity. A hypothesis based
1Department of Clinical Physiology/Nuclear Medicine, Bispebjerg Hospital, Copenhagen, Denmark.
Abstract:
The CBF studies performed so far during attacks of migraine, may be interpreted as favouring "the vascular theory." This applies to migraine with aura as well as to migraine without aura. Migraine without aura may be due to mild focal CBF reduction--too mild to be detected by the available CBF techniques (i.e. 20% or less) and too mild to produce ischemia and aura phenomena. Migraine with aura may be due to focal CBF reduction severe enough to produce ischemia (i.e. 50% or more) and therefore also aura phenomena. The phenomenon termed "spreading oligemia" typically seen in CBF studies during migraine with aura, may be an artifact reflecting a gradual decrease of CBF in an area of constant size. The typical "march" of the aura symptoms may reflect differences in the ischemic threshold of various neurones leading to dysfunction of more and more neurones as the blood flow gradually decreases. It is concluded that migraine with and without aura may be due to the same disease process--the only difference being the intensity of vasospasm and CBF reduction.
Insights
Cerebral blood flow (CBF) studies suggest migraine with and without aura stem from the same vascular process. Differences in migraine aura relate to the severity of reduced cerebral blood flow and potential ischemia.
Area of Science:
- Neurology
- Vascular Biology
Background:
- Cerebral blood flow (CBF) studies during migraine attacks have historically supported the vascular theory of migraine.
- Both migraine with aura and migraine without aura are considered within this vascular framework.
Purpose of the Study:
- To interpret existing CBF studies in the context of the vascular theory of migraine.
- To differentiate the potential mechanisms underlying migraine with and without aura based on CBF.
- To explore the nature of "spreading oligemia" and its relation to aura symptoms.
Main Methods:
- Review and interpretation of existing cerebral blood flow (CBF) studies conducted during migraine attacks.
- Analysis of CBF reduction thresholds associated with migraine phenomena.
- Consideration of neuronal ischemic thresholds in relation to aura progression.
Main Results:
- Migraine without aura may involve mild focal CBF reduction (≤20%), potentially below detection limits and insufficient to cause ischemia or aura.
- Migraine with aura may involve more severe focal CBF reduction (≥50%), leading to ischemia and aura phenomena.
- "Spreading oligemia" observed in CBF studies during migraine with aura might be an artifact of gradual CBF decrease, not a constant area size reduction.
Conclusions:
- Migraine with and without aura may share a common underlying disease process.
- The primary distinction between migraine with and without aura appears to be the intensity of vasospasm and the degree of cerebral blood flow reduction.