Understanding Pain: Peripheral vs Central Sensitization

Chronic pain patient Studio On. Physiotherapy Phnom Penh

Have you ever had an injury that seemed to hurt way more than it should? Or pain that lingers even when the injury has healed? That’s where something called sensitization comes in. There are two main types: peripheral and central. Let’s break them down in plain English.

What is Peripheral Sensitization?

This happens right where the injury is — in the tissues themselves. When you get hurt, your body releases chemicals (like inflammation markers) to help you heal. But these chemicals also make your pain sensors (called nociceptors) super sensitive.

In other words:

Your pain nerves get cranky and start reacting to things that normally wouldn’t hurt, or hurt less.

• Why it happens: Your nerves are responding to local inflammation or damage.

• Where it happens: At the site of injury (like your knee or shoulder).

• What it affects: Often changes your reaction to heat, but not so much to pressure or touch.

• Does it go away? Usually yes — once the tissue heals, the sensitivity should calm down too.

What is Central Sensitization?

Now this is when things get a little trickier. Central sensitization happens in your nervous system, particularly in your spinal cord and brain. The nervous system becomes overly reactive and starts interpreting even normal signals — like a light touch — as painful. (1)

In simple terms:

Your brain’s pain alarm system gets stuck in “high alert” mode — even if there’s no more injury.

• Why it happens: Your body has been dealing with pain for a while, and your nervous system adapts… in the wrong way.

• Where it happens: Anywhere — even in areas that aren’t injured.

• What it affects: Everything from pressure, touch, temperature — even emotions can make it worse.

• Does it go away? It can, but it usually needs treatment like exercise therapy, education, and sometimes manual therapy.

So, what’s the takeaway?

Peripheral sensitization is like your body saying “Ouch, this area is hurt, let’s protect it.”

Central sensitization is your nervous system saying “Everything feels dangerous now, even when it’s not.”

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References:

1. Volcheck MM, Graham SM, Fleming KC, Mohabbat AB, Luedtke CA. Central sensitization, chronic pain, and other symptoms: Better understanding, better management. Cleve Clin J Med. 2023 Apr 3;90(4):245-254. doi: 10.3949/ccjm.90a.22019. PMID: 37011956.