Complex Regional Pain Syndrome (CRPS) is classified into two main types: CRPS Type 1 and CRPS Type 2. CRPS Type 1, previously known as Reflex Sympathetic Dystrophy (RSD), occurs without a direct nerve injury. This type often follows a minor injury, surgery, or immobilization and is characterized by pain and sensory abnormalities that cannot be explained by a single nerve's dysfunction. In contrast, CRPS Type 2, formerly called Causalgia, involves a confirmed nerve injury. Both types share similar symptoms, such as persistent pain, swelling, and changes in skin color or temperature, but the distinction lies in the presence or absence of identifiable nerve damage.

Understanding these types is essential for determining the appropriate management approach. Both forms can result in significant discomfort and disability, but their progression and response to therapies may vary. Early diagnosis and intervention are crucial to prevent complications and mitigate long-term effects. While the exact cause remains uncertain, research suggests that abnormal responses in the nervous system and inflammatory processes play pivotal roles in both types.

Diagnosing CRPS can be challenging as there is no single test for confirmation. Physicians rely on clinical evaluation and criteria, including a patient's medical history, reported symptoms, and physical examination. The Budapest Criteria is a widely accepted tool for diagnosis, focusing on four symptom categories: sensory changes, vasomotor abnormalities, sudomotor/edema issues, and motor/trophic changes. A diagnosis of CRPS is often made when symptoms persist in these categories and no other condition can explain them.

Additional tests, such as imaging or nerve studies, may be used to rule out other conditions. Bone scans, X-rays, or MRIs can identify characteristic changes in the affected area, such as osteoporosis or tissue abnormalities. These tools, while not diagnostic on their own, provide valuable information to confirm the clinical suspicion of CRPS. Since early treatment is key to better outcomes, timely evaluation by a healthcare professional is vital for individuals experiencing unexplained, persistent pain and related symptoms.