Looking at the paralytic or, if the imagination is in place, listening to the Central Pain patient, it is easy to wonder if Nature and/or evolution has failed man. Why won’t the CNS heal itself.
The cold approach of traditional evolution may argue that this flaw in mankind is slowly being sorted out, as those who are vulnerable to spinal injury are taken out of the gene pool and fail to reproduce at the same rate as those who do not sustain Spinal Cord Injury. Some species have already evolved a method of regenerating spinal cord, such as the Ghost-Knife Fish, a common aquarium species, which can regenerate up to one third of the spinal cord. Birds, which often hit obstacles head on can regenerate brain tissue which has been lost. Humans cannot do this outside the hippocampus/amygdala filing system of cells. (Incidentally, the amygdala, especially the right amygdala, is smaller in cocaine addicts, leading scientists to believe its smaller size causes addicts to fail to recognize the harmful effects of addictive behavior).
Humans have a lot of brain and do a lot of brain activity compared to other species. Whether they are succeeding with what they have is arguable, but at least we appear to be headed somewhere pretty fast. The counter to the evolutionary theory is that humans are smart enough to figure out how to repair their brains medically. The evolution that counts, or the mega-trait Nature has bestowed, is intelligence. The question then becomes whether we have the intelligence to use the intelligence we are given. This question is not so uncommon and is often raised by parents of teenagers learning to drive, date, and choose music to play.
Let us assume then that Nature designed us to solve problems with our intelligence. What observations can be made about brain injury. Specifically, what can we conclude about the brain from the way pain appears in injured nerve fibers.
We first conclude that efforts at repair are a mixed blessing. Growth factors aiming at restoring function cannot reassemble things in exact order and the pain system suffers. In fact, the efforts of growth factors need regulation to make sure fetal ion channels do not suddenly appear (the Nav1.3 sodium channels of neuropathic pain). Growth factors also ramp up the pERK and CREB, preacidifiers which guarantee a miserable existence when central pain results.
How curable are these disorders. Chemical steps are amenable to blocking. The venom of deadly species is usually pathetically simple, interrupting some discrete point in the chemical cascade of brain function. It is by no means an exaggeration to suggest that simple research should overcome the problem and defeat central pain. Regeneration of spinal tissue through stem cells has already been shown to work, although the initial tests are crude and unrefined.
In short, the brain can be fixed. It is not that hard. We just have to train the people, give them money, and get out of their way.
The biggest obstacle to brain research is superstition. The amazing brain is supposedly beyond the comprehension of mortals. This is nonsense. We are behaving in a medieval, pseudo-religions mysticism to think that chemical processes are inherently unknowable. There will be surprises, but so what. It is time to spend the money and end the suffering. The amazing brain is so amazing that it can figure out ways to heal it. The trouble is that we just don’t realize how amazing the brain really is.
This author had the pleasure of discussing muscle pain in CP with the late Dr. Patrick Wall. Dr. Wall raised the cases of CP patients who feel as if their muscles are cramping, but are actually weak. Others felt as if their legs would collapse but they did not. Dr. Wall surmised that when the sensory arm of the gamma motor system (the muscle spindles which inform the brain of the state of contration of muscles) becomes hypersensitive through nerve injury, the message of muscle tone explodes into something huge, which the brain feels obligated to counter. The result is the sensation of cramp or overtightening in muscles which are then suppressed. In other words, there is an across the board misperception by the brain of what the real status of muscle tone is, and a corresponding “wish” by the muscle to relax or be put at rest.
This corresponds to the situation with pain fibers that are screaming pain at the top of their voices when no actual stimulus even exists. The brain attempts to quiet this, but the failure of the chloride switch in injured neurons makes inhibition by our friend, GABA, impossible. The only result of increased brain input is more pain. Positive feedback loops in the pain system were described by Dr. Wall in conversation and in The Textbook of Pain as “torture”.
The task then is to end hypersensitization and the meaningless signal it produces. We can help the brain do this by using our intelligence. It is time to spend the money, come up with a solution, and prove that Nature did not shortchange us when it left us with only our wits to protect us. We will not develop the hard shell of crustaceans, nor will we develop the dietary habits of enteric bacteria, but we can survive and prosper if we stay the course, and do the work. In this way we justify Nature’s trust in endowing us with intelligence.
Provided we don’t blow ourselves up before we learn to desire peace above all.