In ancient Greece, headaches were considered powerful afflictions.
在古希腊，头痛被认为是严重的疾病。
Victims prayed for relief from Asclepius, the god of medicine.
头痛者会向医神阿斯克勒庇俄斯祈祷，祈求他的救助。
And if pain continued, a medical practitioner would perform the best-known remedy
如果疼痛依然存在，医生将会实行那项著名的疗法，
drilling a small hole in the skull to drain supposedly infected blood.
在头骨上钻一个小洞，让感染的血液流出。
This dire technique, called trepanation, often replaced the headache with a more permanent condition.
这种可怕的方法称为头部穿孔（环锯术），在缓解头痛的同时，这种方法带来的是更永久的病痛。
Fortunately, doctors today don't resort to power tools to cure headaches.
幸运的是，如今的医生不会诉诸电动工具来治疗头痛了。
But we still have a lot to learn about this ancient ailment.
但对于这种古老的病痛，我们要了解的仍有很多。
Today, we've classified headaches into two camps -- primary headaches and secondary headaches.
如今，我们将头痛分为两大类：原发性头痛和继发性头痛。
The former are not symptomatic of an underlying disease, injury, or condition; they are the condition.
原发性头痛并不是某种潜在疾病或受伤的表现；它本身就是一种疾病。
But we'll come back to them in a minute because while primary headaches account for 50% of reported cases,
但我们过一会儿再聊这种疼痛，这是因为虽然原发性头痛占到了头痛病例的50%，
we actually know much more about secondary headaches.
但我们对继发性头痛的了解更多。
These are caused by other health problems,
继发性头痛的原因在于其他健康问题，
with triggers ranging from dehydration and caffeine withdrawal to head and neck injury, and heart disease.
触发疼痛的因素可能是缺水、戒掉咖啡因、头部或颈部受伤，以及心脏疾病。
Doctors have classified over 150 diagnosable types, all with different potential causes, symptoms, and treatments.
医生将其分成了150种可诊断类型，每种都有不同的潜在原因、症状以及对应治疗方法。
But we'll take just one common case -- a sinus infection -- as an example.
我们拿最普遍的鼻窦炎作为例子。
The sinuses are a system of cavities that spread behind our foreheads, noses, and upper cheeks.
鼻窦是一个腔系统，分布在我们的前额、鼻子以及面颊上半部。
When our sinuses are infected, our immune response heats up the area,
当鼻窦被感染时，免疫系统会使该区域升温，
roasting the bacteria and inflaming the cavities well past their usual size.
从而杀灭细菌，这使得腔体比平时红肿许多。
The engorged sinuses put pressure on the cranial arteries and veins, as well as muscles in the neck and head.
充血肿胀的鼻窦会给颅内动脉和血管增压，脖子和头部的肌肉也同样感受到更大压力。
Their pain receptors, called nociceptors, trigger in response,
肌肉的这种名叫伤害感受器的痛觉感受器由此触发，
cueing the brain to release a flood of neuropeptides that inflame the cranial blood vessels, swelling and heating up the head.
向大脑传递大量神经肽，它们会使颅内血管充血，使大脑肿胀发热。
This discomfort, paired with hyper-sensitive head muscles, creates the sore, throbbing pain of a headache.
这种不适感会协同高度敏感的头部肌肉共同产生酸痛和阵阵抽痛。
Not all headache pain comes from swelling.
并非所有的头痛都来自于肿胀。
Tense muscles and inflamed, sensitive nerves cause varying degrees of discomfort in each headache.
紧张的肌肉、发炎且敏感的神经都会引起不同程度的不适感。
But all cases are reactions to some cranial irritant.
但所有头痛都是对某些颅内刺激物做出的反应。
While the cause is clear in secondary headaches, the origins of primary headaches remain unknown.
虽然继发性头痛的病因现已明了，但原发性头痛的起因却仍不得而知。

Scientists are still investigating potential triggers for the three types of primary headaches:
科学家仍在研究哪些触发因素会引起以下三种原发性头痛：
recurring, long-lasting migraines; intensely painful, rapid-fire cluster headaches; and, most common of all, the tension headache.
反复出现、持久的偏头痛；痛感强烈接连不断的丛集性头痛；以及最普遍的紧张性头痛。
As the name suggests, tension headaches are known for creating the sensation of a tight band squeezed around the head.
从名字可以看出，紧张性头痛可以制造出头部被一条带子紧紧勒住的痛感。
These headaches increase the tenderness of the pericranial muscles, which then painfully pulse with blood and oxygen.
这些头痛加剧了颅骨骨膜肌肉的敏感性，它随血液和氧气疼跳动，产生疼痛。
Patients report stress, dehydration, and hormone changes as triggers, but these don't fit the symptoms quite right.
据病人反映，他们都经历了压力、缺水、荷尔蒙变化，但是这些与症状并不完全相符。
For example, in dehydration headaches, the frontal lobe actually shrinks away from the skull,
举例来说，缺水产生头痛时大脑额叶通常会缩小，
creating forehead swelling that doesn't match the location of the pain in tension headaches.
导致前额肿大，但这与紧张性头痛的疼痛位置并不相符。
Scientists have theories for what the actual cause is,
科学家推断头痛的真正原因
ranging from spasming blood vessels to overly sensitive nociceptors, but no one knows for sure.
包括血管痉挛以及过度敏感的疼痛感受器，但没人对此有十足的把握。
Meanwhile, most headache research is focused on more severe primary headaches.
与此同时，大多数头痛的研究都集中在更严重的原发性头痛上。
Migraines are recurring headaches, which create a vise-like sensation on the skull that can last from four hours to three days.
偏头痛会反复发作，使头骨产生被钳子夹痛的感觉，这种疼痛可以持续4小时到3天。
In 20% of cases, these attacks are intense enough to overload the brain with electrical energy, which hyper-excites sensory nerve endings.
在20%的偏头痛病例中，这种疼痛产生的电能量能够超过大脑的负荷，使得感受神经末梢高度兴奋。
This produces hallucinations called auras,
这会使人产生称作光晕的幻觉，
which can include seeing flashing lights and geometric patterns and experiencing tingling sensations.
包括看到闪亮的灯光、几何图形和感受到刺痛。
Cluster headaches, another primary headache type, cause burning, stabbing bursts of pain behind one eye,
丛集性头痛是另一种主要的头痛，能够在一只眼睛后产生烧灼刺痛，
leading to a red eye, constricted pupil, and drooping eyelid.
会导致眼红、瞳孔收缩、眼皮发沉。
What can be done about these conditions, which dramatically affect many people's quality of life?
这些病症严重影响了人们的生活质量，那么该如何解决它们呢？
Tension headaches and most secondary cases can be treated with over-the-counter pain medications,
对于紧张性头痛和大多数继发性头痛而言，非处方止痛药可以缓解症状，
such as anti-inflammatory drugs that reduce cranial swelling.
例如消炎药可以减少颅内肿胀。
And many secondary headache triggers, like dehydration, eye strain, and stress, can be proactively avoided.
许多导致继发性头痛的触发因素，例如失水、眼睛疲劳、压力等，可以采取主动预防的方式避免。
Migraines and cluster headaches are more complicated, and we haven't yet discovered reliable treatments that work for everyone.
偏头痛和丛集性头痛则更加复杂，我们目前还未发现对所有人都行之有效的可靠疗法。
But thankfully, pharmacologists and neurologists are hard at work cracking these pressing mysteries that weigh so heavily on our minds.
但庆幸的是，药剂师和神经学家正在努力攻克这些对大脑至关重要的难题。