Neuropathic pain: Chronic pain resulting from injury to the nervous system. The injury can be to the central nervous system (brain and spinal cord) or the peripheral nervous system (nerves outside the brain and spinal cord). Neuropathic pain can occur after trauma and many diseases such as multiple sclerosis and stroke. It is common and affects more than 2 million people in the US alone. This type of pain is notoriously difficult to treat.