Flight, fright, or freeze. You may have heard that phrase to describe what happens when our nervous system perceives a threat.

That makes sense when it’s something that can do you harm: a car that doesn’t see you in the crosswalk or a rattlesnake on the trail.

But did you know that when we experience pain our nervous system responds in the same way? Our body thinks we are in harm’s way and sends the signal to fight, take flight, or freeze.

The good news is once you know the basic anatomy of the nervous system, you can use this knowledge as strategy for relieving pelvic pain.

But to understand how, let’s take a look how pain is processed in the body.

Pain and the nervous system

There is no such thing as a pain receptor. This is a common misperception and fascinating topic to study.

There are sensory receptors in the body called nociceptors that detect changes in temperature or pressure.

For example, if you put your hand on a hot stove, the nociceptors in your hand will send a signal to your brain that the stove is hot.

Your hand did not pick up a pain signal; rather it sent the message, much like Paul Revere passing along the message about danger in the form of the British invasion in Lexington and Concord.

Your brain will then interpret the signal as pain to alert you, “Danger! Remove your hand from the stove!” The brain is saying “Hey! Something’s not right!”

This is important because it illustrates how pain is one output of the nervous system. This means it has the capacity to be retrained.

This retraining of the brain is crucial to addressing persistent pelvic pain (also referred to as chronic pelvic pain).

Let’s take the example of someone who has ongoing vaginal pain after having a yeast infection. They experience pain, go to the doctor, get medical treatment, and clear the infection.

After the infection clears, the brain protects the body from potential pain by asking the pelvic floor to stand guard. That is, their pelvic floor muscle become overactive. This overactivity can cause pain when using a tampon.

As a result, this area of the body might become more primed for pain and filter information from the pelvis as potentially dangerous.

Next, they might experience sexual pain, further convincing the brain that contact with this part of their body could be dangerous.

The initial danger (the infection) was removed, but the brain is now wired to remember the initial pain experience. Subsequent activity is interpreted as dangerous so the brain sends a pain signal.

Please note: The pain is not in your head. Your brain happens to live in your head and your brain is the processing center for pain.

Some people have experienced a shaming around being told the pain is in their head and feeling like they are “making their pain up.” Absolutely not. When someone who has their foot amputated is capable of feeling intense pain in their big toe, called “phantom limb pain.” This is because the pain signal originates in the brain, not the site of pain (in this case, the toe).

Research shows us that pain is an output that can be changed. Hopefully this is the case for the majority of the readers—that you will be able to reprogram your way out of pain (with additional treatment modalities of course—not just with wishful thinking!).

Interested to learn more about pain neuroscience? Check out Tame the Beast and Lorimer Moseley’s TEDx Talk.

Branches of the nervous system

Our bodies have two main nervous systems branches called the central nervous system and the peripheral nervous system:

  • The central nervous system is made up of the brain and spinal cord.
  • The peripheral nervous system branches out into the body.

The peripheral nervous system is further divided into the somatic nervous system and the autonomic system.

The somatic nervous system sends sensory information to the brain and spinal cord (central nervous system) and motor nerve fibers to skeletal muscles.

The autonomic system is divided into the sympathetic, parasympathetic, and enteric systems:

  • The sympathetic nervous system ramps up the body (fight, flight, freeze).
  • The parasympathetic nervous system calms down the body (an oversimplification but you get the idea).
  • The enteric nervous system supplies the gastrointestinal system and other organs with nerve communication.

Parasympathetic nervous system and pain

How does this apply to people with persistent pelvic pain?

Think of the sympathetic nervous system and the parasympathetic nervous system as the gas and the brake of a car.

When you are in danger or perceived danger, your body needs to be ready to fight, run away, or freeze. This primitive evolutionary reaction remains after from years of running away from a saber-toothed tiger or other danger.

Our body physically responds:

  • Pupils dilate so we can see better.
  • Blood is shunted from our organs to our muscles so we have extra power to run.
  • Our heart rate, blood pressure, and respiratory rate increase.

The challenge with having an overactive sympathetic nervous system due to persistent pain or trauma is that your body might tend to default to this activated state. You may experience:

  • global muscle tension
  • orthopedic issues like jaw pain and headaches
  • poor digestion

The pain loop might have a harder time being broken because of this hamster wheel-like effect. Here is the scientific explanation behind the stress response:

  • The amgydala (part of the limbic system where emotion lives) trips the alarm.
  • The thalamus (a sensory relay system) instructs brain stem to release norepinephrine (increases blood flow to “large” muscles).
  • The sympathetic nervous system preps organs and muscles for “fight or flight.”

The stress hormone cortisol further stimulates amygdala via the brain stem.

The brain stem is the communication port between the body and the brain and controls our basic functions, like eating, sleeping, heart rate, and blood pressure.

This stimulation activates the sympathetic nervous system/hypothalamic pituitary adrenal (sympathetic nervous system/HPA) axis, further increasing cortisol release. This additional increase in cortisol quiets the hippocampus (part of the limbic system regulating emotions) which creates more cortisol release.

The hypothalamus tells the pituitary gland to give the green light for the adrenal glands to release epinephrine (increases heart rate & dilates pupils) and cortisol (suppresses immune function).

Long-term sympathetic nervous system/HPAA activation increases the amygdala’s response to apparent danger, thereby increasing amygdala sensitivity. The amygdala colors implicit (unconscious) memories with fear, which increases trait anxiety (generalized anxiety).

Long term sympathetic nervous system/HPAA activation diminishes function in the hippocampus which distorts the for