Desensitization for CRPS: Why It Backfires and What Sensory Discrimination Does Instead
Desensitization is one of the first things many people with CRPS are taught. Rub the painful area with a cotton ball. Move up to a tissue, then a washcloth, then something rougher. Keep going until the area gets used to it.
I do not use desensitization with my CRPS clients. I use sensory discrimination instead. The two are often lumped together because both involve touching the painful area, but they ask the brain to do very different things. This post is a focused look at that difference: what desensitization is designed to do, why it so often backfires with CRPS, and what sensory discrimination does instead.
What Desensitization Is Designed to Do
A typical desensitization program works like this:
- Start by touching the painful area with something soft that causes a lower level of pain, such as a cotton ball or tissue.
- Stay with it, passively, while the area hurts.
- Repeat until the pain eases, then move to a rougher texture, such as a washcloth.
- Keep progressing until you tolerate normal contact.
The theory behind it is accommodation. If you are exposed to a painful stimulus long enough, the response is supposed to fade and you get used to it.
On paper that sounds reasonable. In a CRPS limb, it runs into several problems.
Why Desensitization Backfires With CRPS
It Targets a Symptom, Not the System
Desensitization is aimed at two symptoms: allodynia (pain from things that should not hurt, like a bedsheet) and hyperalgesia (more pain than a stimulus deserves). It is not designed for the rest of what is happening in CRPS, including the brain's blurred picture of the limb and the sense that the limb no longer feels like your own.
It Is Painful by Design
The method requires you to sit in pain on purpose. In a system that is already treating ordinary input as a threat, repeatedly provoking symptoms strengthens and reinforces the pain pathways you are trying to settle. That is why so many people report that desensitization made them hurt more.
It Works Through Accommodation, Which Can Deepen the Disconnect
In CRPS, the brain loses its ability to correctly process sensory information from the affected limb. I call this a smudged map: the brain's internal picture of the area blurs, and it defaults to protection. The disconnect between brain and limb is a central part of the problem.
Accommodation teaches the brain to pay less attention to the area. We do not want the brain to tune out the limb further. Enduring input can teach distraction and dissociation from the area, which widens the gap we need to close. Desensitization can smudge the map more.
The Direction CRPS Needs: Re-Sensitization and Reintegration
If the core problem is that the brain cannot read the limb accurately, the goal is to help it read the limb accurately again. That means re-sensitizing and reintegrating sensory information from the area, so the brain and the body start speaking the same language again.
That is the job of sensory discrimination.
What Sensory Discrimination Does Instead
Sensory discrimination provides different tactile stimuli in a controlled way, and asks the brain to identify them accurately. Here is a simple example I use:
- A partner touches the skin of the painful area with one of several objects, such as a paintbrush, the back end of a pen, or a pencil eraser.
- Without looking, you identify which object it was.
- You actively focus on the sensation, comparing and distinguishing it from the others.
The point is to make the brain do the work of reading the limb. You are deliberately sharpening its ability to tell one sensation from another. Over time, that sharpens the map and reverses the smudging.
There are many variations. Drills can be made easier or harder depending on your skill level and pain severity, progressed to include movement, and adapted for almost any body region, including the pelvic floor. Sensory discrimination is my personal favorite of the brain-based drills.
Desensitization vs. Sensory Discrimination at a Glance
| Desensitization | Sensory discrimination | |
|---|---|---|
| The question it asks | Can you tolerate this? | What is this, and where is it? |
| Target | Allodynia and hyperalgesia only | How the brain reads the limb, regardless of symptom |
| Role of pain | Painful by design | Not supposed to be painful; modified if it is |
| Your role | Passive endurance | Active attention and identification |
| Effect on the map | Accommodation can smudge it further | Sharpens it and reverses smudging |
Where Sensory Discrimination Fits in the Sequence
Sensory discrimination is one of four brain-based drills I teach for CRPS, alongside left/right discrimination, explicit motor imagery, and mirror therapy. I order them from least to most likely to provoke symptoms, and start with the least provocative.
Sensory discrimination is slightly more likely to provoke symptoms than left/right discrimination or motor imagery, because it involves touching the painful area. That is why the dose matters. If a drill provokes pain, we modify it: a different texture, a nearby area, lighter contact, a shorter set. The goal of any of these drills is never to provoke pain.
Mirror therapy comes last. It can increase symptoms in highly sensitive people and has caused spreading in some. Giving a newly diagnosed person desensitization, mirror therapy, and no-pain-no-gain PT together is a pain-provoking trifecta. I walk through that combination and a client case in Desensitization, Mirror Therapy, and PT for CRPS: Why Doing All Three at Once Backfires.
If Desensitization Made Your CRPS Worse
If you followed a desensitization program faithfully and hurt more, the method was pointed in the wrong direction for your system. Your effort was not the issue. The work your limb needs is accurate, tolerable input that helps the brain read it clearly again.
Want the full picture? Watch my free three-part CRPS series: what is actually happening in the nerves and brain, which treatments help and which cost you later, and what you can do about it.
Ready for a structured plan? The Uprising: Complex Pain Academy is built to address neurologic sensitivity in CRPS step by step, in the right order.
