Chronic Pain – A Three-Tiered Approach

Chronic Pain – A Three-Tiered Approach

Pain serves a purpose; it exists to alert us to potential or existing damage to the body. It can arise from injury or disease. After the brain has received and processed the pain message and coordinated a suitable response, pain has served its function. Endorphins, the body’s natural pain killer, are meant to derail further pain messages from the same source. However, these natural pain killers may not dampen a continuing pain message sufficiently. Certain conditions lead to chronic pain which does not resolve. The time limit used in definitions of chronic pain ranges from three to six months but most use a flexible definition which considers pain chronic when it endures beyond a normal period of healing. Unfortunately, for those with an autoimmune condition chronic pain is something they are all too familiar with. Much has been done in the field of pain management to assist these patients. It has become clear that the best approach is often one that incorporates a multidisciplinary approach, with the greatest relief being achieved using a combination of treatment options. In this three-part article we will look at a multitude of options for pain relief and ways to improve chronic pain. These options can be classified into three broad categories: noninvasive, non-drug pain management, noninvasive pharmacologic pain management and invasive pain management.

Part 3: Invasive Pain Management.

Invasive pain management techniques involve injections, implantation of devices into the body as well as other surgical options. Surgical techniques, being the most invasive, are often considered as a last resort but can offer great relief to the patient when necessary. There are a number of considerations that need to be taken into account before undergoing in invasive pain management procedure. Firstly, the underlying cause of the pain needs to be clearly identified. Secondly, surgery should only be considered if noninvasive procedures have proven to be ineffective. Thirdly, a patient needs to be psychologically assessed and counselled. Finally, there should be a clear expectation by the patient of the potential level of success of these procedures.


Trigger Point Injections

This procedure is used to treat painful, tight areas of muscle which contain trigger points or knots that form when the muscle does not relax. A healthcare professional will, using a small needle, administer a local anesthetic, steroids or a combination of the two directly into a trigger point. As a result of the injection the trigger point is inactivated, releasing the muscular spasm and alleviating the pain. A brief course of treatment can often result in sustained relief, at least for the pain caused by that source. These injections are used to treat muscular pain the arms, legs, lower back and neck.

Botox

We all know that Botox (produced by the bacteria Clostridium botulinum) has been used extensively by the beauty industry but many chronic pain suffers are unaware that it can also be used effectively to treat certain types of chronic pain. Botox is a toxin which when administered in small amounts blocks signals from the nerves to the muscles in that area. This produces temporary skeletal muscle relaxation and acts as an analgesic by reducing muscular hyperactivity. Recent studies are now suggesting that in addition to this mechanism, Botox has direct analgesic mechanisms that act separately to its neuromuscular actions. Further studies are required to understand these mechanisms and how best to utilize them in chronic pain management. The procedure itself is minimally invasive and consists of multiple injections with extremely fine needles to the affected area. The relief experienced from it can last from three to six months and thereafter will need to be repeated if the pain returns.

Nerve Blocks

Signals from a group of nerves (called a plexus or a ganglion) can be responsible for chronic pain. It is possible to inject a nerve-numbing substance to the specific area resulting in the group of nerves being blocked and unable to fire pain signals. This method can be used in multiple ways in the treatment of chronic pain. A therapeutic nerve block is used to treat pain by injecting a local anesthetic to control acute pain. Diagnostic nerve blocks can assist in determining the source of pain, these usually contain an anesthetic with a known duration of relief. A prognostic nerve block is used to determine whether a more permanent solution (such as surgery) would be successful in treating pain. Preemptive nerve blocks are often used in conjunction with surgical procedures to prevent subsequent additional pain result from the procedure itself. Occasionally a nerve block can be used as a means to avoid surgery.

Surgical Implants

Patient-controlled analgesia (PCA) gives patients the ability to control their own relief. In this instance a computerized pump which contains a syringe of pain medication is attached directly to a patient’s intravenous line. In some cases, the pump is set to deliver a small, constant flow of pain medication. A patient can press a button to deliver additional doses if necessary. A patient may have complete control over when he or she receives pain medication and does not receive a constant flow. This is generally used for acute pain and when that has subsided a patient can be switched to oral medication. These devices do have built in fail safes so that the total amount of analgesic that can be delivered remains within safe limits.

Intrathecal drug delivery systems (spinal drug delivery systems) involves the implantation of a small pump or catheter that delivers medication directly to the spinal cord. This method, often used for cancer patients, is increasing in use for chronic pain but remains somewhat controversial. Further research for their appropriateness and effectiveness for control of chronic pain using this method is required.  The benefits of a spinal drug delivery system include increased pain relief with less medication being given. Less medication reduces the likelihood and severity of potential negative side effects experienced when higher doses are taken orally. These systems often lead to large improvements in pain allowing patients to restore a level of normality to their everyday activities. This however is an expensive option.

 

Spinal Cord Stimulation

This is generally only considered an option when other pain treatment options have failed or when surgery is not an option. This procedure involves the delivery of low-level electrical signals to the spinal cord or to specific nerves, the electrical signal disrupts the pain signal preventing it from reaching the brain. In order to be able to deliver these electrical signals a device is implanted in the body through a needle placed in the back near the spinal cord. The pulse generator is placed in the upper buttock through a small incision. The patient is able to turn the signal on and off and adjust the intensity of the signal. Depending on the device used patients can experience a tingling sensation when it is switched on. The latest devices available have pulse generators that can be recharged through the skin.  An alternative system available is one that uses an antenna, transmitter, and a receiver that relies upon radio frequency to power the device. In these systems, the antenna and transmitter are carried outside the body, while the receiver is implanted inside the body. Non-rechargeable systems will require surgery every 2-5 years to replace the device depending on how frequently the patient uses the device. Rechargeable systems can last up to 10 years if used and charged correctly.

Radiofrequency Ablation

Radiofrequency ablation (RFA) is an injection procedure done under anesthesia used to treat chronic pain resulting from a multitude of conditions. In the neck and back, pain stemming from the vertebral facet joints or the hip’s sacroiliac joints or the posterior pelvis may be treated using RFA. In this procedure radiofrequency via a needle is used to create a heat lesion in a specific part of the pain transmitting nerve. The lesion that is formed prevents the pain signal from being transmitted to the brain. RFA is used to relieve pain for longer periods of time (typically it will last between 6 to 18 months), it is used to improve range of motion allowing physical therapy to be more effective, it can be used to reduce the intake of pain medication or it can be used to avoid or delay surgery which is far more invasive.

Three different options are available for RFA.  In conventional continuous radiofrequency (CRF) ablation a needle that provides continuous high-voltage current is used to produce a heat lesion. The tip of the needle is heated between 140 to 176 degrees Fahrenheit. In pulsed radiofrequency (PRF) ablation a needle that produces short bursts of high-voltage current with silent phases in between when no current is passed is used. The needle is heated to around 107 degrees Fahrenheit in PRF. Water-cooled radiofrequency (WCRF) ablation uses a specialized needle that is heated up to 140 degrees Fahrenheit but is additionally cooled by a continuous flow of water. The water permits a regulated flow of current, preventing the needle tip from being over-heated. The option selected will depend on the size and location of the lesion required. In all cases a nerve block will be preformed first as a means to locate the target nerve and gives an indication of whether an RFA will be successful for that patient. This procedure is successful in around 60% of patients selected for it with the benefit of sustained relief.

Joint Replacement

In conditions in which joint damage contributes greatly to chronic pain, and when other pain management options have been tried and failed, your physician may refer you to an orthopedic surgeon to consider joint replacement. Joint replacement involves the removal of part or all of a damaged joint and replacing it with a prosthesis. The prosthesis can be made from plastic, metal such as surgical steel, ceramic or a combination of these materials. This procedure is performed under general anesthesia. This is considered a major surgery and the decision to move ahead with it will depend on a number of factors. How bad are the symptoms being experienced? Limited function in conjunction with chronic moderate to severe pain may be indicative of requiring a new joint. How badly damaged is the existing joint? Imaging such as x-ray will be used to establish whether bone and cartilage have deteriorated to a significant degree, if so, joint replacement will be considered. Does the resulting pain impact the patient’s daily life and quality of life? If it is thought that joint replacement will improve this it may be considered. As with any other surgical procedure there are risks associated with joint replacement including a bad reaction to anesthesia, development of a blood clot or developing a post-surgical infection. Carrying excess weight or other chronic health conditions may raise the risk associated with the procedure. A prosthesis may break, requiring a revision procedure to fix or replace it. After the procedure patients will need to work with a physio therapist to aid the muscles around the joint strengthen and properly support the area. A prosthesis can last from 15-20 years, sometimes longer, depending on the type and level of physical activity undertaken by the patient.

Deep Brain Stimulation

Although this technique has over the years been used to effectively treat movement disorders and has been used to treat chronic pain resulting from a number of conditions, new research is looking to establish whether this technique can also be used as an alternative to immunosuppressants. Pain in autoimmune patients would therefore be treated by treating the underlying cause in a new way. Deep brain stimulation (DBS) requires surgery to implant a device that sends electrical signals to the brain, the area targeted will depend on the cause and desired outcomes. Electrodes are placed deep in the brain and are connected to a stimulator device placed under the skin in the upper chest. Comparable to a heart pacemaker, a neurostimulator uses electric pulses to regulate brain activity, specifically abnormal impulses. The novel application of DBS for the treatment of autoimmune conditions such as rheumatoid arthritis and other inflammatory disorders involves stimulation of the vagus nerve. Advances in neuroscience and immunology have mapped circuits in the brain that regulate immune responses. The ‘inflammatory reflex’ is one such circuit in which signals are transmitted via the vagus nerve. This stimulation inhibits the production of cytokines, including tumor necrosis factor (TNF), an inflammatory molecule that is a major therapeutic target in inflammatory disorders. It is believed that, by stimulating the activity of this inflammatory reflex, innate immune responses can be modulated without eliminating them completely or producing significant immunosuppression. This is an exciting area of research to keep an eye on, as it may have a twofold benefit – reducing inflammation with fewer side effects than using medication as well as direct pain control.

Chronic pain can make daily activities a battle. Having a comprehensive pain management plan that incorporates a number of different techniques can greatly improve the quality of life of a patient, helping to ensure the good days out weigh the bad. With so many options available it will be necessary to discuss with your treating physician what combination they would recommend in your specific case. Do not be discouraged if pain relief is not immediate, with so many treatments now on offer, and many more being researched, it may be a case of trial and error to find out what offers the greatest relief. Be an active participant in your pain management, much of what was discussed in Part 1 of this article can be easily and inexpensively done by the patient themselves. This will help to ensure you control the pain and it doesn’t control you.

 


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ANRF
Article Author
Arthritis National Research Foundation
arthritisresearch@curearthritis.org

The Arthritis National Research Foundation's mission is to provide initial research funding to brilliant, investigative scientists with new ideas to cure arthritis and related autoimmune diseases. Writing articles about the patients affected and the science being done to find a cure shows why we need to come together to #CureArthritis!

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