Narrative Review of Neuroimaging in Migraine With Aura

Karissa N. Arca MD; Juliana H. VanderPluym MD; Rashmi B. Halker Singh MD

Disclosures

Headache. 2021;61(9):1324-1333. 

In This Article

Abstract and Introduction

Abstract

Objective: To improve the understanding of the role and utility of various neuroimaging modalities (clinical and research) for the evaluation of migraine aura (MA) and hemiplegic migraine during the ictal and interictal phases.

Background: MA is defined by reversible neurologic symptoms and is considered a manifestation of a primary condition. As such, most patients with MA do not require imaging. However, if there are atypical features, change in symptom pattern, or it is a first-time presentation, neuroimaging may be used to evaluate for secondary conditions. Neuroimaging includes many modalities, and it is important to consider what information is being captured by these modalities (i.e., structural vs. functional). Imaging abnormalities may be noted both during (ictal) and between (interictal) MA attacks, and it is important for clinicians to be familiar with neuroimaging findings reported in migraine with aura (MWA) compared with other conditions.

Methods: With the assistance of a medical librarian, we performed a review of the literature pertaining to MWA and neuroimaging in PubMed. Search terms included were magnetic resonance imaging, positron-emission tomography, single photon-emission computed tomography, functional magnetic resonance imaging, and migraine with aura. We hand-searched these references to inform our subsequent literature review.

Results: Acute MA can be associated with several unique neuroimaging findings—reversible cortical diffusion restriction, cortical venous engorgement, and a "biphasic" transition from hypoperfusion to hyperperfusion. Imaging findings during MA tend to span more than one vascular territory. Between acute attacks, neuroimaging in people with MWA can resemble migraine without aura in terms of white matter abnormalities and "infarct-like lesions." Research imaging modalities such as volumetric analysis and functional imaging have demonstrated unique findings in migraine with aura.

Conclusion: Although migraine is a clinical diagnosis, understanding of neuroimaging findings in MWA can help clinicians interpret imaging findings and improve patient care.

Introduction

Migraine, with or without aura, is a primary headache disorder and a clinical diagnosis. Typical presentation of migraine aura (MA) is not a routine indication for imaging. However, neuroimaging may be performed in patients experiencing new, prolonged, or high-frequency aura to assess for secondary causes. If these diagnostic evaluations reveal abnormalities, one must seek to understand whether such findings can be related to MWA. Therefore, it is important to understand what imaging findings have been reported previously in MWA and how they may compare with what is reported in other conditions such as stroke or seizures. Cortical spreading depression (CSD) is one of the prominent theories for the physiologic basis of MA, although likely there are multiple mechanisms at play, including activation of subcortical structures.[1,2] In CSD, accumulation of extracellular potassium occurs in hyperexcitable cortical neurons undergoing depolarization and repolarization. Subsequently, cortical neurons become further depolarized, and the blood flow increases. This phenomenon spreads rostrally from the occipital lobe at a rate of 2–6 mm/min, although the mechanism of propagation is not fully understood. Following the initial depolarization and hyperemia is a period of reduced cell activity and oligemia.[1] With these biochemical changes occurring, one may expect a neuroimaging corollary during MA. Unique imaging findings have been demonstrated during MA attacks but mostly on a case report and case series basis. This review will explore and summarize the neuroimaging findings described during MA attacks (ictal imaging), including hemiplegic migraine (HM), as well as interictal imaging findings unique to migraine with aura (Table 1).

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