Prevalence of typical migraine aura without headache in Japanese ophthalmology clinics

Introduction

Migraine is one of the most common neurological disorders and is observed in about 8.4% of the population in Japan (1). Migraine attacks are characterised by unilateral, throbbing and moderate-to-severe headache lasting 4–72 h, typically accompanied by nausea and photo- and phonophobia (2). In approximately 20% of patients, the migraine can also be preceded by transient neurological symptoms (aura) that usually develop gradually over >5 min and last for <60 min. Auras are most frequently visual (>90%), but may also involve other sensory symptoms (pins and needles, numbness), hemiparesis or speech deficits (2). To date, the trigger mechanisms of migraine aura/cortical spreading depression (CSD) and the question of whether or not CSD is a prerequisite for developing migraine headache remain controversial (3).

Typical aura without headache (TAWH) is diagnosed according to the operational diagnostic criteria of The International Classification of Headache Disorders (ICHD)-II (2). The reported prevalence of TAWH is 0.2–6.5% (4,5). However, the prevalence and characteristics of Japanese patients with TAWH are not known. In their study of 53 patients diagnosed as migraine with aura (MWA) followed-up for 16 years, Erikson et al. (6) reported seven (13%) patients who had TAWH. Patients with TAWH often visit an ophthalmology clinic since they only develop visual symptoms without any headache. Therefore, to determine the prevalence of TAWH in Japan, this study was performed in ophthalmology clinics and a university hospital. We investigated the prevalence and characteristics of TAWH and MWA with a special focus on the age distribution.

Subjects and methods

This study was conducted at seven general ophthalmology clinics (six ophthalmology clinics and Dokkyo Medical University Hospital) in the Kanto area (area within 150 km from the centre of Tokyo, Japan), from April 2007 to June 2008. We distributed a self-report questionnaire comprising seven items (ID migraine screener Japanese version (7,8) with six additional questions) that could be used for classification of headache according to ICHD-II (2; Table 1) to all patients, and collected their responses. The ID migraine screener Japanese version comprises four questions on the relationship of headache in the past 3 months with physical activity, occurrence of nausea or vomiting, photophobia and osmophobia, similar to the English version. Subjects who gave a positive answer to at least two of the four questions in the screener were considered migraine-positive. Six questions were then added to screen for TAWH in patients with migraine-negative and MWA; these questions were about the presence of [Q1] visual or [Q2] sensory aura, their [Q3] frequency (≥2) and [Q4] duration (≥5 min and ≤60 min), [Q5] no headache after the aura and [Q6] no past history of cerebrovascular disease based on ICHD-II. All questionnaires were distributed with the instructions for patients on how to report headaches in the past 3 months and analysed by one of the authors, a neurologist (SA). The study was approved by institutional review board appropriate for each investigator.

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Table 1.

Diagnostic criteria for typical aura without headache according to ICHD-II

A. At least two attacks fulfilling criteria B–D
B. Aura consisting of at least one of the following, with or without speech disturbance but no motor weakness
1. Fully reversible visual symptoms including positive features (eg, flickering lights, spots or lines) and/or negative features  (ie, loss of vision)
2. Fully reversible sensory symptoms including positive features (ie, pins and needles) and/or negative features (ie, numbness)
C. At least two of the following
1. Homonymous visual symptoms I and/or unilateral sensory symptoms
2. At least one aura symptom develops gradually over ≥5 min and/or different aura symptoms occur in succession over ≥5 min
3. Each symptom lasts ≥5 min and ≤60 min
D. Headache does not occur during aura nor follow aura within 60 min
E. Not attributed to another disorder

The chi-squared test with 5% level of significance and 95% confidence limit was used.

Results

Although 1914 subjects were included in the study, 851 patients were excluded due to incomplete answers in the questionnaire. The final analysis was based on data from 1063 (55.5%) subjects (Figure 1). Of the 1063 subjects, 348 were males (33%) and 715 were females (67%; Figure 2). The mean ± SD age of the subjects who completed the questionnaires was 51.3 ± 18.9 years (males, 53.4 ± 18.6 years; females, 50 ± 18.8 years; median, 54 years; range, 6–95 years). The ID migraine screener Japanese version was positive in 81 subjects. Visual or/and sensory aura as the prodromal symptom was reported by 356 of the 982 screening negative cases. We excluded 53 subjects who suffered from cerebrovascular disease, history of weakness and headache with aura. Of the 303 (28.5%) subjects, 172 (16.2%) experienced visual aura, 60 (5.6%) visual and sensory auras, and 71 (6.7%) sensory aura. Finally, of the 1063 subjects who completed the study, only 35 (3.2%) were diagnosed with TAWH according to ICHD-II criteria (Figure 1). OPEN IN VIEWER

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Figure 2.

Age distribution of 1063 patients who visited the ophthalmology out-patient clinics and answered questionnaires. Of the 1063 subjects, 348 were males (33%) and 715 were females (67%). The mean ± SD age of the subjects who completed the questionnaires was 51.3 ± 18.9 years (males, 53.4 ± 18.6 years; females, 50 ± 18.8 years).

The 35 patients comprised 12 males and 23 females (Figure 3A), with a male:female ratio of 1:1.9, and a median age of 47 years (range, 23–87 years). Among the 35 patients with attacks of TAWH, 11 had visual aura only, 9 had sensory aura only, and 15 patients had both visual and sensory aura. Sixty-seven patients (9 males and 58 females) had MWA (6.3%; Figure 3B), with a male:female ratio of 1:6.4, and median age of 42 years (range, 22–89 years). Furthermore, 14 patients (all females) had migraine without aura (MWOA; 1.3%), with a median age of 37 years (range, 25–53 years). The median age of patients of the MWA and TAWH was the fourth decade (42 years and 47 years). Although the age of patients with TAWH showed a biphasic distribution, similar to the age distribution of all patients (the second to third and sixth decades), that of MWA showed a monophasic distribution at third-fourth decade.

Visual and sensory auras were the most frequent symptoms (43%) in patients with TAWH (n = 35), followed by visual aura (31%) and sensory aura (26%). Furthermore, visual and sensory auras were the most frequent symptoms (48%) in MWA (n = 67), followed by visual aura (34%) and sensory aura (18%). The frequency of visual and sensory auras in TAWH was not different from those in MWA.

Discussion

This is the first epidemiological study of TAWH according to ICHD-II in Japan. The prevalence of TAWH in this study was 3.2%, indicating a high prevalence compared with that reported previously in neurology clinics of 0.2% (4,9). To determine the reason for the high prevalence in our study, we analysed the sex and age distribution in the two studies. The Danish studies (4,9) were conducted in 4000 patients aged 40 years, and included 3000 males and 1000 females (M:F ratio, 3:1). The results of our study indicated more females are affected with TAWH than those reported in the above two studies (4,9). Furthermore, the age distribution was different in the two studies. In our study, the 1063 patients comprised 348 males and 715 females with M:F ratio of 1:2, and a median age of 54 years (range, 6–95 years). The prevalence of MWA was 6.3%, with 0.8% males and 5.5% females, while that of TAWH was 3.2% with 1.1% males and 2.1% females. The high prevalence of TAWH in our study compared with the previous report (4) may be related to the relatively younger age of patients in that study (40 years) compared with the present investigation. Furthermore, Amos and Fleming (10) reported that TAWH is a type of migraine that seems to be reported more frequently in ophthalmology than in neurology or general medical practice. Their other report in ophthalmology (5) described that, of the 1000 primary eye care patients surveyed, 6.5% had experienced visual sensations consistent with TAWH.

In our study, the male:female ratio was in favour of females in MWA and TAWH, and the median age of MWA and TAWH was 40–49 years in both groups. Our data suggest a two-level age distribution of patients with TAWH (20–39 years and 60–69 years; Figure 3A), similar to the age distribution of all patients, compared with the narrow age distribution of MWA (30–49 years; Figure 3B). Our results are similar to those of another survey study of ophthalmology clinics (5). OPEN IN VIEWER

Hedges (11) reported 7 of 43 patients (12%) with TAWH between 5–30 years of age; 18 of 43 patients (42%) between 30–50 years; and 18 of 43 patients (42%) between 50–80 years of age. The age of patients with TAWH reported in our and Hedges’ studies seems to cover a broad span.

Eriksen et al. (6) reported the results of a 16-year follow-up study designed to assess the long-term outcome of MWA. At follow-up, attacks had ceased (no MWA for 2 years) in 19 (36%) of 53 patients. Similarly, Colongo et al. (12) conducted a 10–20 year follow-up study that assessed the long-term outcome of MWA. They identified eight patients (11%) among 81 who switched from MWA to TAWH. Mattsson et al. (13) reported that the life-time prevalence of migraine headache in 728 female was 31.5% whereas the 1-year prevalence was 18.0%. The estimated decline in the prevalence of active migraine headache in their study was 50% per decade, suggesting that the decline in the prevalence of active migraine headache with age was due to a decrease in pain intensity. Although the prevalence of visual aura was 3.8% and this rate did not change with age, the intensity of the headache decreased slightly with age (40–49 years, 4.21%; 50–59 years, 4.2%; 60–74 years, 3.1%) and the disability identified by the Visual Analogue Scale showed a clear decline with age (40–49 years, 6.5; 50–59 years, 5.0; 60–74 years, 2.0). The present study showed a decline in the prevalence of active migraine headache with age but not in the prevalence of active migraine visual aura. In addition, the headache intensity decreased after 50 years of age, whereas visual aura does not seem to decrease even in advanced age. Unfortunately, our study design did not include follow-up investigation; however, the results suggested that MWA might shift to TAWH with ageing.

Conclusions

The prevalence of TAWH is considered common in ophthalmology and our results suggest that TAWH seems to increase with ageing, emphasising the need for programmes that can deal with this issue in the future.