Pain Masking Devices

When dealing with chronic pain situations, we as pain medicine physicians often get to a point where nothing appears to be working to resolve their pain. The patient either has escalated upwards on their oral pain medicine or the oral pain medications haven’t worked. Obviously, devices like spinal cord stimulation would also be considered a pain masking device but that is for another day. When we get to the point that pain is poorly controlled or dosages of pain medications are escalating then a morphine pump trial can and should be considered. Although it sounds complicated or even potentially scary, the morphine or intrathecal pump is a wonderful device that can provide pain relief beyond that of oral medications. Obviously, some of the issues with oral pain medications include side effects, tolerance, and having to constantly take oral medications. The morphine pump does help to reduce some of these issues. The pump inserts either morphine or dilaudid into the spinal fluid and thus the amount of drug required to eliminate the pain can be up to 100 times less than the oral medications. A person on 100 mg of oral morphine could conceivably be on a couple of milligrams of intrathecal morphine. The pump also put the narcotic directly where it actually works since all the main opiate receptors are in the centra nervous system, I.e. the brain and spinal cord. (Of note, yes for those purists, there are other opiate receptors outside the central nervousness system, such as in the knee joint but these are minor players). Since the narcotics goes directly into the spinal fluid, it bypasses the intestinal system and the liver. This is important since not all the opiate get absorbed and usually 90% of the absorbed drugs gets destroyed by the liver, thus only a small fraction actually gets across the blood brain barrier to provide pain relief. By bypassing the intestinal system and the liver, tolerance tends to be reduced and patients often can be controlled on the same dose of medication intrathecally longer than orally. Also, in my experience, the side effects often are reduced compared to oral medications such as reduced constipation and nausea, but these are not completely eliminated. I often start to consider the pump when all other options have been exhausted and the patient is not happy with there current oral medications. The beauty of the pump, just like the spinal cord stimulator is that you first undergo a trial. The trial is simple and involves a single injection of either morphine or dilaudid into the spinal fluid through a small needle, usually a 22 or 25 gauge needle. The size of this needle rarely causes headaches post the procedure. The single shot allows the patient to determine if the intrathecal, which means within the spinal fluid, narcotic provides better relief than oral medications. In fact, I ask every patient that I want them to get better relief with the trial then they ever got with oral medications. In fact, I want the patient to want the pump and not me to talk them into it. As the trial continues, the morphine that is injected, takes a couple of hours to kick in due to it having to drift up to the brain. The effect lasts a few hours and then dissipates. Some other doctors insert a catheter for the trial but I feel that this is unnecessary and also too time consuming. Patients usually can tell if the trial is effective without and extensive trial. If the patient decides to have the pump installed, the surgery is done as an outpatient and involves two cuts, the posterior incision in the back is one to two inches and the other incision is in the abdominal wall and is around four to five inches in length. The pump is the size of a hockey puck and the battery usually lasts seven to ten years and then requires surgery to replace it. Obviously, there are risks with everything in life, even walking across the street but the risk with the pump seems to be fairly low and things that I have dealt with include hematoma, pump movement, and catheter movement. These are rare and most people do fine. I have never had an infection but that is also a possibility. Healing is over a week. After inserting numerous pumps, too many to count, I have not yet had a person want the pump out or state that they were unhappy with the pump. In fact, when there question whether the pump is working or not, I will offer to put them back on oral medications so that they could compare and they have always come back and ask to have the pump restarted. The relief is that great but sometimes people forget how much they hurt before the pump was installed. I am not going to lie, I like the intrathecal pump. Why? It offers great relief of pain, it eliminates most, if not all the oral medications and it eliminates the patient having to worry about their oral medications. It puts the control in our hands and gets the medications off the streets, which I like. It also allows patients to even give themselves a bolus as well with an external controller. We can get the concentration up to an amount that allows the patient to come in every few months. It frees the patient up and often changes their lives. We can also insert other medications as well, such as baclofen, clonidine, local anesthetics, etc to the mixture which can provide further relief. There is even a new calcium channel blocker called prialt that is a non-addictive pain medication that works on the receptors down stream from the opiate receptor and thus provides strong relief without the stigma of potential addiction. The key is to utilize the pump in the right people and not to shove it in everyone. Good patient selection leads to good outcomes. Thus, for those who are suffering, the intrathecal pump is a great option and don’t rule it out. At least consider the trial which is just a single injection. Also, there are no restrictions with the pump.

2 Comments

  • .

    tnx for info!

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