Clinical features of visual migraine aura: a systematic review

DOI: https://doi.org/10.1186/s10194- 019- 1008- x

Abstract-Summary Migraine aura (MA) is a common and disabling neurological condition, character- ized by transient visual, and less frequently sensory and dysphasic aura disturbances.

Optimal clinical classification of MA symptoms is important for more accurate diagnosis and improved understanding of the pathophysiology of MA through clini- cal studies.

A systematic review of previous prospective and retrospective systematic record- ings of visual aura symptoms (VASs) was performed to provide an overview of the different types of visual phenomena occurring during MA and their respective fre- quencies in patients.

The number of different types of VASs reported by patients in the studies ranged

from 2 to 23.

We created a comprehensive list of VAS types reported by migraine patients based on all currently available data from clinical studies, which can be used for testing and validation in future studies.

Extended: We created a list of all EVSs with their respective frequency of occur-

rence (minimum and maximum values found in the studies).

We created a comprehensive list of VASs reported by migraine patients based on

all currently available data from clinical studies.

Introduction Typical migraine aura (MA) symptoms are completely reversible visual, sensory, or language disturbances.

Visual aura symptoms (VASs) are by far the most common and occur in 98–99% of MAs, whereas disturbances of sensation and language occur in 36% and 10% of auras, respectively [109].

In clinical studies of VAS, patients have reported a plethora of different, often

complex, visual disturbances.

Several studies have investigated the clinical features of VASs but so far there is no consensus regarding which different types of EVSs occur during MA and there is no agreement on the terminology that should be used to describe EVSs.

Improved clinical characterisation of MA will likely improve the diagnostic

accuracy and identification of patient subgroups at risk of comorbidity.

The aim of this article was to review all published studies providing systematic descriptions of VASs, with information on how frequently different EVSs are reported by MA patients.

Methods We used the PubMed/MEDLINE database to identify published studies systemati- cally investigating the clinical features of visual aura.

3.2 Medical history

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The bibliographies of all included studies were also searched as well as literature

that was known to be relevant by the authors.

We excluded studies focusing exclusively on the description of visual distur-

bances relative to high-tier areas (i.e. prosopagnosia or dyschromatopsia).

Two authors independently reviewed the abstracts found in the literature search

(MV, AH).

From included articles, we extracted for the following data categories: publica- tion information (authors, years), population (number of patients), number of auras recorded, study methodology, description of visual aura disturbances, and their fre- quencies of occurrence on the total number of auras recorded.

In the list, we included only EVS, and not any visual symptoms described by a

combination of two or more EVSs (e.g. “scintillating scotoma”).

Results One study was excluded since “scintillating scotoma” (79.3%) was the only VS reported [110].

It is likely that such description (not specified in the paper) was used to indicate

any visual aura symptom, as no other type of visual disturbances were reported.

We also excluded two manuscripts due to data not being systematically presented and since it was impossible to extract the frequency of occurrence of visual distur- bances [111, 112].

Some EVSs were reported in one paper only (i.e. complex hallucinations, “slanted vision”, “like a negative film” [113]) while others were reported in the majority of studies (flickering lights, bright light, zigzag lines, scotoma/ hemianopsia).

Discussion We systematically reviewed studies of VASs in order to create a list of all visual features reported during MA.

In some cases the description of a particular VAS is not in line with the rest of literature (e.g. in one study “scintillating scotoma” is described as “a propagating “crescent” of the homonymous type” [114] without any negative visual symptom). The quality of VASs is one of the most important features and we believe that establishing a consensus in the form of an official list of all MA visual symptoms is essential.

The next step will be to apply this list to clinical studies (1) in patients with MA to better assess the frequency of the different EVSs, thereby establishing which EVSs are the most prevalent and which are clinically meaningful to include in a consensus list; (2) in patients with other visual disturbances (either due to CNS or ocular disorders) to assess the specificity and sensibility of each EVS with respect to MA.

Conclusion We created a comprehensive list of VASs reported by migraine patients based on all currently available data from clinical studies.

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3 Diagnosis

We observed a lack of prospective studies and a relatively high degree of discrep- ancy between studies, likely mostly due to differences in the terminology used to describe VASs.

We emphasize the importance of an improved classification of migraine VASs and propose that an official list of visual symptoms should be developed for this purpose, preferably within the context of the International Classification of Headache Disorders of the International Headache Society.

Acknowledgement A machine generated summary based on the work of Viana, Michele; Tronvik, Erling Andreas; Phu, Thien; Zecca, Chiara; Hougaard, Anders. 2019 in The Journal of Headache and Pain.

Cognitive dysfunction and migraine