AREAS OF FOCUS
Complex Regional Pain Syndrome
Complex regional pain syndrome, or CRPS, is a chronic pain condition that usually affects a single limb, often after an injury that seemed minor at the time. A sprained ankle, a small fracture, or even a period in a cast can be enough to trigger it. What follows is pain far out of proportion to the original injury, along with changes family members can often see. The limb may swell, change color or temperature, and become so sensitive that even a sock or a passing breeze becomes unbearable. It is one of the more striking forms of amplified pain because the body shows outward signs of something the tests still cannot explain.
What is actually happening
CRPS is a problem of signaling, not structure. After an injury, the nervous system that carries pain information stays switched on long after the tissue has healed, and it begins to misfire. Pain messages fire without cause, and the systems that regulate blood flow, temperature, and swelling in the affected limb fall out of their normal rhythm. As a result, the limb can look different from its counterpart on the other side, warmer or cooler, redder or paler, puffy or sweaty, or changed in the way the skin, hair, and nails grow. Through all of this, the nervous system continues to behave as though the danger is still present.
What it looks like and how it feels
CRPS tends to announce itself more clearly than other amplified pain conditions. The pain is burning, deep, and constant, and it centers on one arm, leg, hand, or foot. Many children develop allodynia, in which things that should not hurt at all, such as the weight of a bedsheet, the pressure of a shoe, or a light touch, become sharply painful. The limb may swell, change color or temperature, sweat differently, or become stiff and hard to move. Because using the limb hurts, it is often held still and protected, which, in CRPS, tends to make symptoms worse.
Why movement matters more than rest
This is the part that surprises families most. For most injuries, rest and protection are the right instinct. With CRPS, the opposite is true: the longer a painful limb goes unused, the more entrenched the pain and physical changes become. The most effective treatment is steady, graded use of the limb, paired with physical and occupational therapy that gently reintroduces movement, touch, and weight, even though it is uncomfortable at first. This is combined with attention to sleep and stress and, often, support from a psychologist who understands pain, because the nervous system and the mind run on the same circuit. Early recognition and early movement yield the best results.
How Dr. Shulman approaches it
Dr. Shulman is a pediatric rheumatologist who treats CRPS and writes about the broader world of chronic pain it belongs to, including in his forthcoming book, Cramp: A Doctor’s Notes on Pain. He works from a simple conviction: the diagnosis matters, but naming CRPS and treating it are distinct tasks. A child in this much pain deserves to be believed as the harder work of recovery begins. Getting there often depends as much on trust and steady effort as on any single intervention.
Frequently Asked Questions
Is CRPS a real condition, or is my child exaggerating the pain?
CRPS is real and among the most intense pain conditions in medicine. It involves a genuine malfunction in how the nervous system processes pain and regulates the affected limb, which is why the pain is so severe and why the limb often changes visibly. A child is not exaggerating or seeking attention; the pain is exactly as they report it, and treating it as anything less tends to slow their recovery.
What causes CRPS, and why did it start after such a small injury?
CRPS often follows an injury that seemed minor, such as a sprain, a small fracture, or a period of immobilization, though it can also appear with no clear trigger at all. The size of the original injury does not predict it. What matters is that the nervous system, for reasons still being studied, fails to switch off its pain and regulatory response after the tissue heals. The result is pain and physical changes that outlast and outsize whatever started them.
How is CRPS different from other amplified pain conditions?
CRPS is often described as a localized, especially visible, form of amplified pain. What sets it apart is that it usually centers on one limb and produces outward physical signs: swelling, changes in skin color and temperature, sweating, and altered growth of skin, hair, or nails. Other forms of amplified musculoskeletal pain can be more widespread or move around the body and may not produce those visible changes. The shared thread is a nervous system caught in an overactive pain response.
Can children recover from CRPS?
Yes. Children generally do better with CRPS than adults, and many recover fully, particularly when it is caught early and treated with consistent movement rather than rest. Recovery is rarely quick or linear, and flares can occur along the way, but the outlook is genuinely hopeful with a coordinated plan. Because CRPS sits at the cutting edge of pain medicine, there is still much to learn about why some cases resolve quickly and others become long-term.
What should I do if I think my child has CRPS?
A helpful first step is to clearly name the pattern with a doctor: severe pain in one limb, disproportionate to any injury, with visible changes such as swelling or shifts in color and temperature. From there, families often work with a clinician experienced in pediatric pain and with therapists who can begin gentle, graded movement. The most important early steps are to get the right diagnosis quickly, keep the limb moving under guidance rather than immobilizing it, and start treatment aimed at the nervous system rather than repeatedly searching for structural damage that is not the cause.
Does CRPS look different in adults than in children?
The underlying mechanism is the same at any age: a nervous system that continues to send pain signals and dysregulate the affected limb long after an injury. The differences are largely in course and context. Children tend to respond better to movement-based treatment and recover more fully, whereas adults more often develop longer-lasting cases and may have other chronic conditions alongside it.
Dr. Shulman specializes in treating children and adolescents. Adults who recognize these signs can discuss them with their own physician or request a referral to a specialist in adult chronic pain, where the same principles of early movement and nervous-system-focused care apply.
For appointments or clinical questions, please contact Rady Children’s Health Orange County (formerly CHOC).