What causes headaches? - Dan Kwartler

In ancient Greece, headaches were considered powerful afflictions. 00:12 Victims prayed for relief from Asclepius, the god of medicine. 00:16 And if pain continued, 00:18 a medical practitioner would perform the best-known remedy— 00:21 drilling a small hole in the skull to drain supposedly infected blood. 00:28 This dire technique, called trepanation, 00:31 often replaced the headache with a more permanent condition. 00:35 Fortunately, doctors today don't resort to power tools to cure headaches. 00:40 But we still have a lot to learn about this ancient ailment. 00:45 Today, we've classified headaches into two camps— 00:48 primary headaches 00:49 and secondary headaches. 00:50 The former are not symptomatic of an underlying disease, injury, or condition; 00:55 they are the condition. 00:57 But we'll come back to them in a minute 00:59 because while primary headaches account for 50% of reported cases, 01:03 we actually know much more about secondary headaches. 01:07 These are caused by other health problems, 01:10 with triggers ranging from dehydration and caffeine withdrawal 01:14 to head and neck injury, 01:15 and heart disease. 01:17 Doctors have classified over 150 diagnosable types, 01:22 all with different potential causes, symptoms, and treatments. 01:27 But we'll take just one common case —a sinus infection—as an example. 01:31 The sinuses are a system of cavities 01:34 that spread behind our foreheads, noses, and upper cheeks. 01:39 When our sinuses are infected, 01:40 our immune response heats up the area, 01:43 roasting the bacteria and inflaming the cavities well past their usual size. 01:49 The engorged sinuses put pressure on the cranial arteries and veins, 01:54 as well as muscles in the neck and head. 01:57 Their pain receptors, called nociceptors, trigger in response, 02:01 cueing the brain to release a flood of neuropeptides 02:05 that inflame the cranial blood vessels, swelling and heating up the head. 02:10 This discomfort, paired with hyper-sensitive head muscles, 02:13 creates the sore, throbbing pain of a headache. 02:18 Not all headache pain comes from swelling. 02:20 Tense muscles and inflamed, sensitive nerves 02:23 cause varying degrees of discomfort in each headache. 02:27 But all cases are reactions to some cranial irritant. 02:32 While the cause is clear in secondary headaches, 02:34 the origins of primary headaches remain unknown. 02:39 Scientists are still investigating potential triggers 02:41 for the three types of primary headaches: 02:44 recurring, long-lasting migraines; 02:46 intensely painful, rapid-fire cluster headaches; 02:50 and, most common of all, the tension headache. 02:53 As the name suggests, 02:55 tension headaches are known for creating the sensation 02:58 of a tight band squeezed around the head. 03:02 These headaches increase the tenderness of the pericranial muscles, 03:05 which then painfully pulse with blood and oxygen. 03:09 Patients report stress, dehydration, and hormone changes as triggers, 03:14 but these don't fit the symptoms quite right. 03:17 For example, in dehydration headaches, 03:20 the frontal lobe actually shrinks away from the skull, 03:23 creating forehead swelling 03:25 that doesn't match the location of the pain in tension headaches. 03:29 Scientists have theories for what the actual cause is, 03:32 ranging from spasming blood vessels 03:34 to overly sensitive nociceptors, 03:37 but no one knows for sure. 03:39 Meanwhile, most headache research is focused on more severe primary headaches. 03:45 Migraines are recurring headaches, which create a vise-like sensation on the skull 03:50 that can last from four hours to three days. 03:53 In 20% of cases, these attacks are intense enough 03:57 to overload the brain with electrical energy, 04:00 which hyper-excites sensory nerve endings. 04:03 This produces hallucinations called auras, 04:06 which can include seeing flashing lights 04:08 and geometric patterns and experiencing tingling sensations. 04:13 Cluster headaches, another primary headache type, 04:16 cause burning, stabbing bursts of pain behind one eye, 04:20 leading to a red eye, constricted pupil, and drooping eyelid. 04:25 What can be done about these conditions, 04:28 which dramatically affect many people's quality of life? 04:31 Tension headaches and most secondary cases 04:34 can be treated with over-the-counter pain medications, 04:37 such as anti-inflammatory drugs that reduce cranial swelling. 04:41 And many secondary headache triggers, 04:43 like dehydration, 04:44 eye strain, 04:45 and stress, 04:47 can be proactively avoided. 04:49 Migraines and cluster headaches are more complicated, 04:51 and we haven't yet discovered reliable treatments that work for everyone. 04:56 But thankfully, pharmacologists and neurologists are hard at work 05:00 cracking these pressing mysteries that weigh so heavily on our minds.