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CRPS Diagnosis

Diagnosing and understanding CRPS

If you suspect you or a loved one has Complex Regional Pain Syndrome (CRPS), one of the most overwhelming challenges is diagnosis. CRPS is not easy to pin down. There’s no single lab test or scan that gives a definitive “yes, this is CRPS.” Instead, doctors use a combination of history, physical examination, and auxiliary tests, and they must rule out other causes.

Because CRPS is a diagnosis of exclusion, having good medical records, symptom tracking, and prompt evaluation by experienced clinicians is vital. Below, we walk through how CRPS is diagnosed, what the key criteria are, and what additional tests or evaluations can help.

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Why diagnosing CRPS is a challenge

Before we get into the criteria, it helps to understand why diagnosing CRPS is more difficult than diagnosing other conditions.

  • There is no single blood test, scan, or imaging study that can reliably confirm CRPS. Diagnosis relies on clinical judgment.
  • Early on, signs may be mild, intermittent, or nonspecific. Additional symptoms may emerge over days, weeks, or months.
  • Many symptoms of CRPS, like pain, swelling, color change, and nerve irritation, can mimic other injuries, neuropathies, rheumatologic disease, vascular disease, or infections. Good doctors must exclude these alternatives.
  • No two people will display the exact same combination of symptoms, timing, or severity. Some never develop all the features of CRPS; others may show a more heightened presentation.
  • Because CRPS is rare and complex, clinicians experienced in pain medication, neurology, or rehabilitation are often needed to interpret the subtle signs and order the appropriate tests.

For these reasons, getting a timely, accurate diagnosis is critical. Early treatment tends to improve the chances of better outcomes.

What is the Budapest Criteria?

In clinical practice and research, the Budapest Criteria are the most widely accepted rules for diagnosing CRPS. These criteria were developed to improve specificity (fewer false positives) compared to older ones. To meet the Budapest Criteria for CRPS, all of the following must apply:

  • You must have continuing pain that is out of proportion to the initial event (like a fracture, surgery, or sprain).
  • You must report at least one symptom in three of these four categories:
    • Sensory, like hypersensitivity, hyperalgesia (strong pain from a painful stimulus), or allodynia (pain from normally non-painful stimuli)
    • Vasomotor, like temperature asymmetry, skin color changes, or redness/paleness
    • Sudomotor/edema, like swelling, changes in sweating (too much or too little), or sweat asymmetry
    • Motor/trophic, like decreased range of motion, weakness, tremor or spasms, or changes in skin, hair, and nails
  • At least one sign on examination in at least two of these four categories:
    • Sensory: hyperalgesia (to pinprick) or allodynia (to light touch, temperature, or joint movement)
    • Vasomotor: temperature asymmetry or skin color differences
    • Sudomotor/edema: observable swelling or sweat changes/asymmetry
    • Motor/trophic: reduced motion, weakness, tremors, or visible changes in hair, nails, or skin
  • Even if A, B, and C are met, the diagnosis can only be CRPS if no other condition better accounts for the signs and symptoms. These could include localized nerve injury, vascular disease, arthritis, or infection.

What are the advantages and limitations of the Budapest Criteria?

Pros of the Budapest Criteria include the following:

  • The Budapest Criteria require both symptoms and signs, which reduces overdiagnosis or false positives. Older criteria sometimes relied too heavily on patient reports alone.
  • They strike a balance between sensitivity (catching the true CRPS) and specificity (not mislabeling other conditions as CRPS).
  • They are internationally accepted and commonly used in both research and clinical settings.

Some of the cons of the Budapest Criteria include:

  • In some populations and early cases, not all signs may yet have appeared, so a patient might not initially fully meet all of the criteria.
  • The criteria aren’t perfect. Some studies show sensitivity ranging between 45% and 99%, and specificity between 68% and 85%.
  • They are clinical, not mechanistic, which means that they don’t tell exactly why CRPS arises in someone; they just provide a standard for diagnosing it.

Because of these limitations, clinical judgment, serial exams, and specialist interpretation remain important.

What are the steps in the diagnostic process for CRPS?

When evaluating someone for CRPS, physicians typically follow a structured approach.

First, they look for a detailed history and timeline. A careful interview with the patient is vital. Key topics include the inciting event, onset of symptoms, progression over time, symptom descriptions, what worsens or relieves symptoms, other related complaints, and past medical history. A thorough history helps map the development of CRPS and helps exclude other potential causes.

The doctor then performs a physical examination, looking for objective signs. Typical things to assess include sensory testing, temperature/color, edema/swelling, skin, hair and nail inspection, range of motion and strength, motor signs, and sympathetic testing. The examiner may use tools like von Frey filaments, thermographic cameras, infrared thermometers, goniometers, or algometers (pain pressure devices).

Although no test alone can confirm CRPS, there are auxiliary and supportive tests that can help rule out other diagnoses or provide supporting evidence:

  • X-rays may show bone demineralization (in later stages) or rule out fractures or degenerative changes.
  • MRIs can look at soft tissue changes or nerve abnormalities.
  • Bone scans may show changes in bone metabolism in the affected area.
  • Sweat and sudomotor testing to compare sweat output or detect asymmetries.
  • Nerve conduction studies are particularly useful if a nerve injury is suspected.
  • Thermography, which measures skin temperature differences.

Importantly, many of these tests are used to exclude other causes (nerve compression, vascular disease, arthritis, infection), rather than to “prove” CRPS.

Because CRPS evolves, a single exam may not capture everything. Repeated assessments over weeks to months help detect new signs or symptoms spread. Some patients may initially not meet the full Budapest Criteria but later do.

In many suspected CRPS cases, specialists are involved: pain physicians, neurologists, physiatrists, vascular specialists, and orthopedic surgeons. They may bring advanced diagnostics, interventional trials (e.g., sympathetic nerve block), and deeper experience in interpreting ambiguous findings.

Distinguishing between CRPS Type I and Type II

CRPS is historically separated into two types:

  • CRPS Type I (formerly Reflex Sympathetic Dystrophy), where there is no confirmed nerve injury.
  • CRPS Type II (formerly causalgia), where a demonstrable nerve injury is present.

Even if you start under a diagnosis of Type I, further tests (nerve conduction, imaging) may reveal nerve damage later, converting the diagnosis to Type II. From a diagnostic standpoint, both types use the same Budapest Criteria. The difference is simply whether a nerve injury is documented.

Pitfalls and challenges in CRPS diagnosis

Because CRPS is so complex, diagnoses are often challenged or misdirected. Some frequent issues include:

  • Overreliance on patient reports alone. Early criteria allowed diagnosis based solely on self-reported symptoms. That led to overdiagnosis, as many pain disorders have overlapping features. The Budapest Criteria helped correct this by demanding signs as well.
  • Misattributing symptoms to psychological causes. Because things like pain and hypersensitivity are subjective, there is a risk that other physicians or insurers may dismiss or discount symptoms as “psychosomatic” unless well-documented.
  • Delays that allow symptoms to evolve or worsen. Many cases of CRPS are diagnosed late, after more permanent changes have occurred, making the condition harder to treat and potentially more difficult to link to a triggering event.
  • Inadequate documentation. If the early signs (color shift, temperature asymmetry, or allodynia) are not recorded with photos, temperature measurements, or descriptive notes, it becomes harder to support the diagnosis later on.
  • Inappropriate exclusion of CRPS. Some clinicians may prematurely conclude another diagnosis (like nerve damage or arthritis) without fully considering CRPS as part of the picture.

Because of these challenges, legal and medical advocacy sometimes go hand in hand, and strong documentation and expert evaluation are key.

Why does an accurate CRPS diagnosis matter?

Getting the diagnosis correct matters for several reasons. First, the therapies for CRPS (nerve blocks, spinal cord stimulation, desensitization, and rehabilitation) differ from standard injury or neuropathy treatments. Also, earlier diagnosis often correlates with better outcomes. Delaying diagnosis can allow irreversible changes (bone, tissue, motor loss). It also prevents further harm, as misdiagnosis or delayed diagnosis may lead to inappropriate treatments that worsen rather than help.

In cases where CRPS is linked to an accident, injury, surgical errors, or negligence, proving diagnosis, timing, and causation is essential for compensation. A weak or undocumented diagnosis may weaken your legal standing.

Finally, for many sufferers, being believed and having a medical diagnosis provides comfort, legitimacy, and better access to support systems.

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What we recommend for clients in the CRPS diagnosis phase

From our experience handling many CRPS cases, here are some steps you or your medical team should take to strengthen your diagnosis:

  • As soon as you notice disproportionate pain or odd symptoms, consult a pain specialist or neurologist familiar with CRPS. Don’t wait.
  • Use a symptom diary that includes your pain intensity (0-10), triggers, what helps or worsens pain, and the spread of symptoms over time.
  • Take periodic photos (daily or weekly) that capture color changes, swelling, asymmetry, or skin texture. This can show the progression of CRPS over time.
  • If you have a skin thermometer or access to thermography, record temperature differences between the affected limb and the “normal” side.
  • Ask your doctors to rule out other causes using nerve conduction, vascular studies, MRI, bone scans, etc.
  • Copies of all reports, imaging, doctor’s notes, labs, consent forms, and referral memos will be very important, especially if a legal case becomes necessary.
  • Help your medical team understand the legal importance of early documentation and the specificity of findings (like “temperature asymmetry >1° C” rather than “a bit warmer”).

An example diagnostic timeline scenario

Here’s a hypothetical example of how your diagnosis might unfold:

  • Day 0. You break your wrist in a fall. A cast is placed, and the injury seems straightforward.
  • Week 2. You begin to feel burning pain, beyond what you’d expect, especially when exposed to light touch or cold.
  • Week 3. Swelling increases, skin turns blotchy, and the limb feels warmer than the uninjured arm.
  • Week 4. The pain intensifies, and you report numbness, color changes, and swelling to your physician.
  • Week 5. A neurologist or pain specialist conducts a detailed exam. You show allodynia to light touch and altered temperature on exam, as well as decreased wrist movement. These are objective signs.

Under the Budapest Criteria, you now have symptoms in sensory, vasomotor, and sudomotor categories, and signs on examination in at least two categories. Other causes (like fracture healing, infection, or nerve compression) are ruled out. You’re diagnosed with CRPS.

In this example, early reports of odd pain and sensory sensitivity, photographs of redness and swelling, and serial temperature comparisons all strengthen the case that this was CRPS tied to the fall, not just “bad pain from a fracture.”

Frequently asked questions about CRPS diagnosis

Q: If a test is negative (e.g., MRI, nerve study), can I still have CRPS?

Yes. None of the auxiliary tests is conclusive. A negative MRI or nerve study does not rule out CRPS, especially in early stages. The diagnosis rests on clinical criteria and evolution over time.

Q: Can CRPS be “missed” or misdiagnosed initially?

Yes, all the time. Because early signs are subtle, many patients are initially diagnosed with neuropathy, arthritis, tendonitis, or “just pain.” That’s why follow-up, specialist input, and re-evaluation are so important.

Q: If I don’t fully meet the Budapest Criteria at first, does that mean I don’t have CRPS?

Not necessarily. You may be in the early stages. Some signs may not yet appear. Re-examination over time may reveal more features.

Q: What role does a sympathetic nerve block play in diagnosis?

Sometimes, injecting local anesthetic around the sympathetic nerves (nerve block) temporarily relieves the pain. That response may support, but not prove, a CRPS diagnosis.

Diagnosing CRPS is less a matter of ticking one box and more a process of careful listening, repeated examination, and ruling out alternatives. Because CRPS can change and evolve, what you present with in week one may look different in week eight or week 16.

For people considering legal action where CRPS is tied to an injury, the diagnostic phase is vital. Strong, early documentation, symptom tracking, expert opinion, and medical consistency are often what make or break a case. At the CRPS Law Firm, we partner with medical providers who understand CRPS and advocate for early, thorough, and defensible diagnosis. If you or someone you know is facing uncertain pain, evolving symptoms, or unclear diagnoses after an injury, please reach out. We’re here to help you understand your options, coordinate experts, and protect your rights in your diagnosis journey. Contact CRPS Law Firm today for a free consultation by calling our offices or filling out our contact form.