This page has moved. Click here to view.
When I talk about pain management and pain control in the cancer patient, I am going to be taking that, sort of, broad view and will be including a lot of other things with it. We can't just give patients pain medicines. We have to take into account the things that are causing the pain.
We will just start with some very basic premises of pain management. The idea of palliative care. By palliative care we mean that in its strictest sense we have switched from trying to cure someone who has cancer to accepting that that person cannot be cured but that we are going to try to keep them comfortable. The process of saying that we are going to keep them comfortable, we are going to do the very best we can and we are going to work just as hard and care just as much about them as we
Obviously there is a transition phase, too, because you are all involved with pain management of patients who are undergoing therapies at different stages. Sometimes it is still with curative intent but they are going through this same kind of process with whatever symptoms they are
The other part of this is that in a world of cost containment, people see that good palliative care is cheaper than bad palliative care or haphazard palliative care. So we just have to lay down a few very simple major principles about pain control especially. That involves the idea of knowing the natural history of that particular cancer and being able to plan ahead for the next phase.
The second thing is that what we are talking about here is trying to make patients feel better. So we want to be knowledgeable about what a therapeutic trial of some agent entails, give it a therapeutic trial, believe what the patient tells us and go on and get
The third thing is, you know, I will keep emphasizing throughout here that what we really want to do with our cancer patients is keep them ambulatory. It is so important for the patients to be self-sufficient as much as possible.
If we are going to talk at all about pain medicines, we have to do a little review of pain pathways and pain mechanisms. This is a complete non-neurologist approach to pain management, and if there are any neurologists in the room I apologize for the oversimplification. But what I want to emphasize here is the complexity and this, sort of, whole person aspect to the experience
It emphasizes several things here. We are talking at the peripheral level, afferent A-neurons coming into the dorsal root ganglion. We are talking about small pain fibers which are stimulated by different types of noxious stimuli. Those pain fibers
The processing involves several different things. For every stimulation coming in from the peripheral nerves, there is also in the small neurofibers larger pain fibers which are inhibitory. So even peripherally, there are excitation and inhibition fibers going on so that there is a modulation peripherally of the sensation or the nerve stimulation that is coming in. Now, if those nerve impulses are transmitted, they cross the spinal cord and they go up the lateral spinothalamic tract. That is the main ascending
The other part of this, though, is that there is a very sophisticated descending pathway. The descending pathway, as we will see in a minute, is something which is very powerful and it is a serotonin mediated process that comes down to each level of the spinal cord. What that does is it inhibits pain transmission so that you can have very strong pain stimulation here if it is coming in here. If it is, let's say, mediated or modulated by the descending pathway, what happens is the descending pathway stimulates the release of natural pain medicines called endorphins and enkephalins.
Enkephalins and endorphins stimulate the same receptors that morphine does exogenously. This is a little syringe giving morphine. This is stimulation from the descending pathway. If you have either one of those occur and you have enkephalins or you have endorphins released or you give morphine, you don't experience pain. So that it has been shown quite clearly in this kind of process that if you stimulate these areas in this descending pathway, if you stimulate certain areas in the brain like the periaqueductal gray matter, you can have severe pain down here and there is no transmission of pain up the spinal cord through the lateral spinothalamic tract.
The point here is that the pain that we experience is always modulated because there are excitatory and there are inhibitory factors. So, it is profoundly important what is happening to the whole person. We can't just like at, you know, the bone pain out here giving the small fiber nerve transmission. What we have to think about is the brain part of this thing, the central nervous system will modulate this and we will seeY well, this just talks about the opioids work on several different types of receptors. Most of what the opioids do is work on these nu receptors but it stimulates the descending pain pathway.
This is the serotonin projection from the human brain. The projections go all the way up into the cortex. So that this idea here that pain experience is modulated by the highest levels of our function. The moral of this story is if you have a person who, let's say, is profoundly depressed, that we know that the depression is related to serotonin deficiency, you do not