Headaches are extremely common and can take many forms, from mild to debilitating and lasting from minutes to days. When your skull hurts, it’s easy to think that your own brain tissue must be hurting. But that is not likely.
Ironically, the brain feels pain throughout the body, but doesn’t actually have its own pain receptors. So why do headaches hurt?
Headaches may stem from an underlying medical condition, for example, inflamed sinuses, low blood sugar or a head injury. But generally speaking, most headaches arise due to “referred pain,” which means that you feel the pain in a different place than where it’s actually occurring. dr. charles-clarke (opens in a new tab), a neurologist and headache specialist at Vanderbilt Health in Tennessee, told Live Science. It’s similar to how a herniated disc in the back can cause sciatica, a pain in the leg. For most headaches, a problem in another part of the body, such as the jaw, shoulders, and neck, causes pain in the muscles and nerves around the brain. , he said.
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Take tension headaches, which according to the World Health Organization (opens in a new tab), are the most common type of recurring headaches. Tension headaches often occur as pain in the muscles on the top of the head or forehead, where a sweatband or headband would fit, Clarke said. The pain is caused by tension in the muscles of the face, neck and scalp and may be related to stress, according to the National Institutes of Health (opens in a new tab) (NIH). But headache and cranial muscle tension may be secondary to another stress response, such as tense shoulders or a clenched jaw, Clarke said.
According to the NIH, pain-sensing nerves in the muscles and blood vessels around the head, neck, and face can be triggered by different processes, such as enlarged blood vessels, stress, or muscle tension. Once activated, these nerves send messages to the brain, but it can feel as if the pain is coming from deep within the brain tissue.
Migraines are another type of headacheAlthough technically, the headache is just a symptom of the neurological disorder. Migraine headaches can be felt in a variety of ways and places: deep pain, superficial pain; the back, left or right of the head; or behind the eyes. What sets migraines apart, Clarke said, is their severity.
The pain of a migraine is more intense than other headaches and can last longer. The disorder is often genetic and can cause additional symptoms, such as nausea. The underlying causes of migraines are not fully understood, but one theory is that the pain is related to the trigeminal nerve, the sensory nerve to the head and face; and the dura mater, the protective layer of the brain where blood vessels expand and contract.
One possible explanation for migraine pain is that an electrical event in the brain stimulates the trigeminal nerve pathways and triggers an inflammatory reaction (opens in a new tab). The inflammation spreads through the blood vessels of the dura mater and the fibers of the trigeminal nerve send signals back to the brainstem (opens in a new tab). The inflammation then spreads to the pain-sensitive meninges (protective tissue around the brain) and triggers a headache.
This cascade of inflamed blood vessels and irritated nerves is “a fire that’s out of control,” Clarke said. It’s like a feedback loop that gets more and more irritated, causing the experience of a migraine to build up, she said. This is the reason why many migraine treatments work better if they are implemented earlier.
While the relationships between pain around the body and headache are well established, the mechanisms that cause headaches are not yet fully understood, Clarke said. But the good news is that “we’re very good at treating them,” she said. For example, lifestyle changes, such as practicing yoga; over-the-counter medications, such as ibuprofen and aspirin; and prescription headache medications for more severe headache disorders can go a long way in reducing severity and frequency.
“If people need help [with headaches] often we can improve them a lot,” Clarke said.