A recent study, using laboratory mice, discovered a physical link within the brain that may explain why headaches are more severe than pain we experience in other parts of the body.
- Pain perception involves both the physical sensation of pain and the emotional response to that pain.
- There are physical structures within the brain that regulate both
- Until now, a direct link between the two had only been hypothesized.
Emotion and pain physically linked
Researchers at Duke University Medical Center discovered a pathway that may explain why headaches are more severe.
- The trigeminal ganglion is physically linked to the lateral parabrachial nucleus (PB1).
- PB1 is responsible for transmitting messages about the unpleasantness and aversiveness of pain sensations.
- The trigeminal ganglion is activated during attacks of cluster headache, migraine, trigeminal neuralgia, and other painful craniofacial disorders.
- Discovering a physical link between the trigeminal ganglion and the PB1 sheds new light on our understanding of headache and facial pain disorders.
Severity is a survival instinct
- PB1 projects what could be called a “suffering index” when we experience pain.
- In addition to the trigeminal ganglion, its signal is transmitted to the hypothalamus and amygdala.
- Both structures are involved in emotional processing and our instinctive “fight or flight” responses.
- An earlier 2016 study suggested that the relative severity of head and facial pain may be related to the relative risk of injury or damage to vital function of the face and brain.
- Unlike the rest of the body, the head and face perceive all five senses.
- We can survive without an arm or leg, but disrupt our brain and we can die.
- Headaches are more severe because our bodies are hard-wired to interpret head or facial pain as life-threatening.
Blocking the signal
- Forty percent of PB1 neurons were transient receptor potential vanilloid type 1 (TRPV1)-positive.
- TRP channels (TRPV1 in particular) are responsible for pain sensation.
- Capsaicin interferes with TRPV1 signals, reducing the sensation of pain.
- This recent study demonstrated this to be true for TRPV1-positive PB1 neurons, too.
We’re not making this up
Future research may lead to the discovery of treatments that block these signals. For now, patients living with cluster headache, trigeminal neuralgia, migraine, and other headache disorders can breathe a sigh of relief. We now have strong evidence to support the validity of our pain experience.
- Headaches are more severe than other types of pain.
- We are not making it up, exaggerating its severity, or seeking attention.
- For the brain, there is no such thing as “just a headache.”
- Every headache is a serious problem that demands appropriate treatment.
- Our brains say it’s true.
Sources:
Bree, Dara. Why is Craniofacial Pain Often Worse Than Body Pain? An Explanation Emerges. Pain Research Forum, retrieved online at https://www.painresearchforum.org/news/90327-why-craniofacial-pain-often-worse-body-pain-explanation-emerges 19 Dec 2017.
Schmidt, K. et al. The differential effect of trigeminal vs. peripheral pain stimulation on visual processing and memory encoding is influenced by pain-related fear. Neuroimage 134, 386–395 (2016).
Rodriguez E, Sakurai K, Chen Y, et al. A craniofacial-specific monosynaptic circuit enables heightened affective pain. Nat Neurosci. 2017 Dec; 20(12) 1734-1743l