Which condition develops after a nerve injury?

• A. Complex Regional Pain Syndrome Type II
• B. Allodynia
• C. Hyperalgia
• D. Hyperpathia

Answer: (A)

Complex Regional Pain Syndrome Type II is a pain syndrome that develops after a definite nerve injury, often called causalgia. Its defining feature is persistent regional pain that follows and is disproportionate to the injury, along with autonomic and sensory changes. That clear link to a known nerve damage is why this option best fits the question. The other terms describe specific pain phenomena that can occur with nerve injury or neuropathic conditions but are not syndromes that arise specifically because of a nerve injury: allodynia is pain from normally non-painful stimuli, hyperalgesia is an amplified pain response to a painful stimulus, and hyperpathia is a delayed, exaggerated response to pain. In clinical practice, CRPS Type I refers to a similar syndrome without a confirmed nerve injury, further underscoring that the nerve-injury connection defines CRPS Type II.