How Can Our Heads Ache When Our Brain Has No Pain Receptors?

HEADACHES…. they let us know how it would feel like if we ever experienced Chinese water torture. Each one of us has suffered at least a few bouts of such wretched misery in our lives. Many people believe that headaches are a sign that the brain is experiencing spasms or hurting in some way, but the brain tissue and skull bones have no pain receptors, even though the brain receives and processes pain signals from the rest of the body.

However, some parts of your head, such as the blood vessels that supply blood to the base and surface of the brain do contain nociceptors (pain receptors). The scalp and the muscles of the head also have nerve fibers that are sensitive to pain. In short, when you are suffering from a headache, the brain isn’t in pain, but something else certainly is!

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The reasons for getting headaches may differ depending on the type of headache. Yes, those painful episodes do have categories, which is a good thing, because they aid practitioners in helping you feel better. Primary headaches are the ones that occur due to daily triggers, whereas secondary headaches are experienced if there is trauma or injury to the brain, or some illness that affects the head. Tension headache, migraines, and cluster headaches belong to the primary class of headaches and all have different causes.

Headaches 4 type on different area of patient head.Illustration about heath care and medical

Tension-Type Headache (TTH)

TTH is classified based on the duration of the headache, namely episodic or chronic. Episodic TTH is the most common type of headache that most people encounter. It occurs sporadically during times of stress (physical/emotional), fatigue, anxiety, sleep deprivation, or bad posture and subsides once those triggers are no longer present. These types of headaches occur less than 15 days per month, while the chronic type of tension headaches are more bothersome, and occur more often than 15 days per month and may continue for up to six months.

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Chronic tension-type headaches are believed to be caused by constant stretching or strain on the muscles at the base and back of the neck, muscles of the head, or a group of muscles called temporalis muscles that cover the temporal lobe. When overworked or strained, the nociceptors on these muscles generate signals that are interpreted as a throbbing pain in the head. Newer studies suggest that these are hypersensitive nociceptive neurons of the central nervous system. Increased sensitivity of the pain pathways may also be a result of the activation of nitric oxide synthase (NO Synthase) and the generation of NO.

The cessation of stressors triggering TTH leads to relief from the pain. Exercises that target neck and head muscle groups, breathing exercises, postural correction exercises, reducing screen time, and appropriate amounts of sleep are some solutions to this common problem. Over-the-counter painkillers may also help to reduce the effects of such debilitating pain.

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Migraines

If normal headaches seem like demonic curses, then migraines are the personification of the Devil himself! Migraines differ from tension headaches in the way they occur; in other words, the pain may start at a particular part of the head, but then gradually spread or shift. A migraine is usually coexistent with feelings of nausea and increased photosensitivity. In the case of migraines, certain patterns of activity in the brain trigger the constriction or dilation of blood vessels. During the dilation, certain chemicals known to cause inflammation are released. The nerves coiled around the blood vessels then shoot pain signals that pulse along with the blood flow.

To learn more about migraines, click on the link below.

Science Of Migraines: Why Do They Occur And Why Are They So Painful?

Cluster Headaches

This is the not-so-pleasant cousin of migraines. As the name suggests, cluster headaches are bouts of intense pain that are generally located around, behind, or over an eye or one side of the head that last for approximately 15 minutes, repeating roughly eight times in a 24-hour period. Thankfully, they are quite rare and only happen to 1 in 1000 individuals. Sufferers describe it as a white-hot rod being stuck in the eye and head. Along with the blinding pain, symptoms include watery eyes or reddening of the eye on the same side before the onset of intense pain. In some cases, the headache may co-occur with either a runny nose or a blocked nose on the same side of the face as the pain.

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Triggers for cluster headaches include sudden extreme changes in temperature or atmospheric pressure. Alcohol consumption makes these headaches even worse for individuals who commonly suffer from them. However, most attacks seem unprovoked by external factors. Their onset is at times periodic, meaning that the bouts always occur during the same time of the year or during the same season.

There are no known causes of cluster headaches, but due to their cyclic nature, scientists believe that they’re related to abnormalities in the hypothalamus. One of the functions of the hypothalamus is to maintain our body’s biological clock, so that part of the brain would appear to be associated with cluster headaches.

In a nutshell, your brain is never in pain. Scientists don’t yet know the exact mechanisms of every type of headache, but they do know that the surrounding muscles, blood vessels, and possibly other areas in your body that send out those pain signals, not the actual spots where people perceive the headache.

So, when you feel one of these terrible headaches coming on, don’t blame yourself…. it happens to everyone eventually!

References:

  1. Pain In The Brain – Neurosciences Institute (Stanford University)
  2. Feeling Our Pain – Indiana University SE
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About the Author:

Rujuta has a MA in Counseling Psychology and MSc in Cognitive Science. She is currently pursuing a PhD in Cognitive Science from IIT Kanpur in India. Her primary area of interest being human memory and learning, she is also interested in the neuroscience of cognitive processes. She also identifies herself as a bibliophile and a harry potter fanatic.

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