Even more desperate are pain conditions which do not respond to morphine nor other derivatives of opium. This happens when the pain is due to injury to the pain sensing apparatus in the central nervous system itself, rather than in some body part. This distinction between normal pain and nerve injury pain was not noticed until the 1970's. With central pain, the pain signal apparently finds alternate routes to the brain. Pain coming through the alternate pathways feels garbled, unstoppable, and bizarre.
Patients use very different terms to describe central pain.
Central Pain is characterized by a melange of pain sensations, the most prominent of which is constant burning, like the afterburn of just having touched a hot stove. Intermittent shooting pains play in the background. The overall impression is that of devastating tissue damage. The steady state burning is upgraded significantly by any light touch. Signifying the nerve injury, patients are somewhat numb in the areas which burn.