If a patient reports chronic pain following a nerve injury despite normal tissue healing, which mechanism involving substance P and secondary sensitization is the most likely explanation?

💡 Explanation

Chronic pain can result from secondary sensitization in the spinal cord following nerve injury. Because 'wind-up' involves substance P release and subsequent NMDA receptor activation, it causes enhanced excitability of dorsal horn neurons, therefore the perceived pain is amplified rather than diminished by the alternative mechanisms.

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