What happens to your brain during a migraine - Marianne Schwarz

譯者: Debby Wu 審譯者: Amanda Zhu

A throbbing, pounding headache.

不斷抽搐、陣陣劇烈的頭痛、

Bright zigzagging lines across your field of vision.

眼前鋸齒狀的亮光、

Sensitivity to light, lingering fatigue, disrupted sleep.

對光敏感、持續疲勞、中斷的睡眠。

A migraine can include any of these symptoms.

偏頭痛時，以上症狀都有可能出現。

While an incapacitating headache is one of the most common experiences of migraine,

最常見的偏頭痛經驗 就是頭痛到甚麼事都不能做，

the word “headache” doesn’t really capture the wide array of experiences

但「頭痛」這個詞無法完全表達 偏頭痛可能伴隨的各式各樣的症狀。

a migraine can entail.

No two are alike, and some don’t even involve a headache.

每個人的症狀都不同， 有人甚至不會頭痛。

So what then is a migraine? What’s happening in the brain to cause it?

那麼偏頭痛到底是什麼？

是甚麼在腦內引起偏頭痛？

To trace a migraine’s anatomy,

要追蹤偏頭痛，

we have to begin in the days and hours leading up to a migraine,

我們必須從偏頭痛發作的 前幾天或幾小時開始。

when people often identify warning signs ranging from fatigue or mood changes,

那時通常會有一些前兆， 可能是疲倦或心情轉變，

to bursts of yawning, sleep disruption, nausea,

也可能是不斷地打哈欠、 睡眠中斷、噁心、

light and sound sensitivity, or even increased thirst.

對光線與聲音敏感， 甚至一直覺得口渴。

These warning signs point to a particular part of the brain:

這些警示指向大腦的一個特定部位：

the hypothalamus.

下視丘。

The hypothalamus normally controls the systems behind these symptoms—

下視丘通常控制著 這些症狀背後的系統——

our body’s internal hormonal balances, circadian rhythms and water regulation.

我們體內的荷爾蒙平衡、 晝夜節律，以及水分調節。

It has wide connections throughout the brain,

下視丘在腦內有很廣的連結網，

and is more active than usual in the days before migraine.

在偏頭痛發生的幾天前 會比平常更活躍。

Another common warning sign is the migraine aura,

另一個常見的警示是偏頭痛的預兆，

which can take the form of transient visual changes,

它可能以短暫視覺變化、

tingling, or even trouble speaking.

刺痛，甚至說話困難的形式發生。

These sensations come from a change in charge across cell membranes

這些感覺來自細胞膜中電流的變化，

that leads to spreading changes in brain activity and blood flow across the brain.

這些變化導致腦內活動以及血流變化。

We don't know what triggers this change in charge,

我們不知道是什麼觸發這種電流變化，

but it can spread quickly over the surface of the brain,

但它能快速散布至大腦表層，

causing different aura symptoms depending on the affected area.

導致不同的預兆症狀， 端看被影響的區域。

If it inches over the visual cortex, for example,

舉例來說，如果它移動至視覺皮層，

it may cause an image or blind spot to spread over the visual field.

就可能引發影像或視覺盲點 在你的視野之中擴大。

During the headache phase, the trigeminal nerve plays a key role.

在頭痛發生時， 三叉神經扮演關鍵角色。

The trigeminal nerve normally transmits touch, temperature, and other sensations

三叉神經通常負責傳遞觸覺、 溫度及其他感官資訊——

from the skin to most of the face, part of the scalp,

從皮膚到大部分的臉部、部分頭皮

and some of the blood vessels and layers covering the cerebral cortex.

及某些包覆在大腦皮層上的 血管與皮層。

Once activated, the trigeminal nerve transmits pain signals.

三叉神經一旦啟動， 它會傳遞疼痛訊號。

During a migraine, this pain pathway becomes sensitized,

偏頭痛發生時， 這個疼痛反應變得敏感，

meaning the threshold for provoking pain is lowered.

意味著觸發疼痛的門檻降低了。

Sensations that would usually be pain-free,

平時不會引起疼痛的知覺，

such as coughing, bending over, or light and sound, can become painful.

像是咳嗽、彎腰或光線與聲音， 都會引發疼痛。

Migraines are as common as they are diverse,

偏頭痛很常見也很多元，

affecting as many as 33% of women and 13% of men in their lifetimes.

多達 33% 女性與 13% 男性 在一生中都曾受其所苦。

Still, there’s much we don’t know about them.

不過，對於它我們還有 很多不清楚的地方。

We can see that migraine is a neurological disorder

我們了解偏頭痛 是種神經系統上的失調，

affecting multiple parts of the brain—

影響大腦的多個部位——

the brainstem, cerebral hemispheres, and the nerves themselves.

腦幹、大腦半球，以及神經本身。

But we don't know for sure what exactly triggers each step,

但我們不確定是什麼觸發每一步驟、

why some people get migraines and not others,

為什麼有些人會偏頭痛而有些人不會、

why so many more women do than men,

為什麼女性比例較男性高，

or why people’s migraine patterns sometimes change over their lifetimes.

又為什麼人們的偏頭痛模式 在其ㄧ生中有時會改變。

Hormonal fluctuations are thought to have a role in some of these things:

一般認為荷爾蒙的波動跟這些東西有關：

some women experience a significant reduction in migraine frequency

有些女性在更年期停經後、 性荷爾蒙波動較小時，

after menopause, when sex hormone fluctuations are fewer.

偏頭痛的頻率會明顯下降。

Meanwhile, just before menopause, these fluctuations increase,

同時，在停經前，這些波動增加時，

and some women experience worsening or new headaches.

有些女性會發生更嚴重 或是新型態的頭痛。

People with migraines are more likely to suffer from depression,

有偏頭痛的人較容易罹患憂鬱症、

panic disorder, sleep disorders, and strokes, among other illnesses.

恐慌症、睡眠失調， 以及中風等多種疾病。

The relationship with these diseases is likely complex,

偏頭痛與這些疾病的關係可能很複雜，

possibly reflecting the effect of migraine on those diseases or vice versa,

或許反映了偏頭痛 在這些疾病上的影響，

也可能是這些疾病對偏頭痛有所影響；

or reflecting their shared genetic basis.

又或者反映出它們共通的遺傳基礎。

Genetics almost certainly play a role, although with a few exceptions,

雖然有些例外情形， 但基因必然扮演著重要的角色，

there’s no single gene that causes migraines.

但導致偏頭痛並非單一基因。

Certain genes control how easily our brains’ neurons

特定的某些基因控制著

大腦中的神經元能被 何種程度的環境刺激而激發，

are excited by environmental stimuli and how readily they transmit painful signals.

以及疼痛訊號傳遞的快慢。

It’s possible that the neurons in the brains of people who experience migraines

或許那些會偏頭痛的人腦中的神經元

are more easily triggered by environmental stimuli

較容易被環境刺激所啟動，

and less likely to block painful signals.

也較不容易阻斷疼痛訊號。

While there’s no simple way to explain what happens in our brains

雖然在這複雜的疾病發生時，

我們無法以簡單的方式解釋 腦內發生了什麼事，

with this complex disorder,

one thing is for sure: migraine is much more than a headache.

有件事是確定的：

偏頭痛絕對不僅僅是頭痛而已。