CHAPTER 1: What Are Trigger Points? (Excerpt)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In this chapter you’ll learn what trigger points are, how they form, and what it feels like when they’re pressed. You’ll also learn how they refer pain to areas of the body remote from the trigger point itself, what symptoms they can cause other than pain, and what happens when they’re left untreated.

Characteristics of Trigger Points

Muscle is the largest organ in the human body, typically accounting for almost 50 percent of the body’s weight. There are approximately four hundred muscles in the human body (surprisingly, there are individual variations), and any one of them can develop trigger points, potentially causing referred pain and dysfunction. Symptoms can range from intolerable, agonizing pain to painless restriction of movement and distortion of posture.

Knots, Tight Bands, and Tenderness in the Muscle

Muscles consist of many muscle cells, or fibers, bundled together and surrounded by connective tissue. Each fiber contains numerous myofibrils. Most skeletal muscles contain approximately one thousand to two thousand myofibrils, and each myofibril consists of a chain of sarcomeres connected end-to-end. Muscular contractions take place in the sarcomere. When a trigger point is present, numerous sarcomeres are contracted into a small thickened area and the rest of the sarcomeres in the myofibril are stretched thin. Several of these contractures in the same area are probably what we feel as a “knot” or “tight band” in the muscle. These muscle fibers are not available for use because they are already contracted, which is why you cannot condition (strengthen) a muscle that contains trigger points.

When pressed, trigger points are usually very tender. The sustained contraction of the fibril probably leads to the release of sensitizing neurochemicals (body substances that affect the nervous system), producing the pain that is felt when the trigger point is pressed. Pain intensity levels can vary depending on the amount of stress placed on the muscles. The intensity of pain can also vary in response to flare-ups of any of the other perpetuating factors, such as emotional factors, illnesses, and insomnia.

Healthy muscles usually do not contain knots or tight bands, are not tender to pressure, and, when not in use, feel soft and pliable to the touch, not like the hard and dense muscles found in people with chronic pain. People often tell me their muscles feel hard and dense because they work out and do strengthening exercises, but healthy muscles feel soft and pliable when not being used, even if you work out.

Referred Pain

Trigger points may refer pain both in the local area and/or to other areas of the body, and the most common patterns have been well documented and diagramed. These are called referral patterns. Approximately half of the time, trigger points are not located in the same place where you feel symptoms. This means that if you only work on the areas where you feel pain, you probably won’t get relief. In part III, you’ll find illustrations of common pain referral patterns that you can compare with where you feel pain, and this will help you figure out where the trigger point or points causing your pain are located. Unless you know that you need to search in that location, you probably won’t resolve your pain. For example, trigger points in the upper portion of the trapezius muscle (between the neck and the shoulder) can cause headache pain in the temples, the base of the skull, in the angle of the jaw, and possibly above the ear and over the eye…

Weakness and Muscle Fatigue

Trigger points cause weakness and loss of coordination of the involved muscles, along with an inability of the muscles to tolerate use. Many people take this as a sign that they need to strengthen the weak muscles, but if the trigger points aren’t inactivated first, strengthening (conditioning) exercises will likely encourage the surrounding muscles to do the work instead of the muscle containing the trigger point, further weakening and deconditioning the muscle containing trigger points.

Muscles containing trigger points are fatigued more easily and don’t return to a relaxed state as quickly when use of the muscle ceases. In addition, trigger points may cause other muscles to tighten and become weak and fatigued in the areas where you experience the referred pain, and also cause a generalized tightening of an area as a response to pain.

Other Symptoms

Trigger points can cause symptoms not normally associated with muscular problems, such as swelling, ringing in the ears, loss of balance, dizziness, urinary frequency, buckling knees, abnormal sweating, and tearing of the eyes. You may suffer from stiff joints, fatigue, generalized weakness, twitching, trembling, and areas of numbness or other odd sensations. For example, the sternocleidomastoid muscle, in addition to causing a tension-type headache, can also cause dizziness, nausea, sinus congestion, eyelid twitching, hearing problems, eye problems, a chronic sore throat, and other symptoms. It probably wouldn’t occur to you that these symptoms could be caused by a trigger point in a muscle.

Active Phase Versus Latent Phase

A trigger point can be in either an active or a latent phase, depending on how irritated it is. If the trigger point is active, it will refer pain or other sensations and limit range of motion. If the trigger point is latent, it may cause only decreased range of motion and weakness but not pain. The more frequent and intense your headaches, the greater the number of active trigger points you’re likely to have.

Trigger points that start with some impact to the muscle, such as an injury, are usually active initially. Poor posture or poor body mechanics, repetitive use, or a nerve root irritation can also form active trigger points. Active trigger points may at some point stop referring pain and become latent. However, these latent trigger points can easily become active again, which may lead you to believe you’re experiencing a new problem when in fact an old problem—perhaps even something you’ve forgotten about—is being reaggravated. Latent trigger points can be reactivated by overuse, overstretching, or muscle chilling. Any of the perpetuating factors discussed in part II can activate previously latent trigger points and make you more prone to developing new trigger points initiated by impacts to muscles.

Latent trigger points can also develop gradually without being active first, and you don’t even know they are there. In a study of thirteen healthy people with the same eight muscles examined in each (Simons 2003), two people had latent trigger points in seven of those muscles, one person had latent trigger points in six muscles, three had latent trigger points in five muscles, two had latent trigger points in three muscles, two had latent trigger points in two muscles, two had latent trigger points in one muscle, and only one person didn’t have latent trigger points in any of the eight muscles! This means that most people have at least some latent trigger points, which can easily be converted to active trigger points. This also means that some people are more prone to develop problems with muscular pain than others (Simons 2003).

Locations of Trigger Points Within the Muscles

Trigger points tend to form where the nerve ending that causes the muscle to contract attaches to the muscle fiber, generally in the middle of the muscle fiber. These are called central myofascial trigger points. Trigger points also tend to form at the muscle’s attachments; these are called attachment trigger points. Since you may not know where the middle of the muscle fiber is or where the attachments are, I recommend that you look at the muscle drawings in part III and try to work on the entire muscle so that you won’t miss treating any trigger points within the muscle.

A primary, or key, trigger point can cause a satellite, or secondary, trigger point to develop in a different muscle. It may form because it lies within the referral zone of the primary trigger point. Alternatively, the muscle with the satellite trigger point may be overloaded because it’s substituting for the muscle with the primary trigger point, or it may be countering the tension in the muscle with the primary trigger point. When doing self-treatments, be aware that some of your trigger points may be satellite trigger points, in which case you won’t be able to treat them effectively until the primary trigger points causing them have been treated. Part III offers guidance in this regard.

What Happens When You Leave Trigger Points Untreated?

When people first develop some kind of pain problem, they usually wait to see if it will go away. Sometimes it does, and sometimes it doesn’t. The problem with “waiting to see” is that when trigger points are left untreated, muscles can be damaged, and eventually changes to the central nervous system can lead to a vicious cycle of pain. This central nervous system involvement probably explains why you are experiencing chronic headaches and pain.

Damage to the Muscle Fibers

Remember how trigger points cause portions of the myofibril to stay contracted? If this goes on too long, the myofibril may break in the middle, causing it to retract to each end and leave an empty shell in the middle. Muscle fibers damaged in this way cannot be repaired and will never be available for use again (Simons, Travell, and Simons 1999).

Facilitated Nerve Pathways

When pain travels repeatedly through the same nerve, it will cause a facilitated nerve pathway. This means that any time a new injury or other stress occurs in an area where pain was previously experienced, pain will tend to travel along the same nerve pathway again. Remember that the most common patterns have been well documented and diagramed? A facilitated nerve pathway can cause the pain referral to deviate from the most commonly found pattern. It may also cause trigger points in several muscles in the region to refer pain to the same area, making it all the harder to determine the actual source of the referred pain. This means you can’t absolutely rule out the role of a potential trigger point based only on consideration of common referral patterns, since other factors may cause you to have an uncommon referral pattern. The more intense the earlier pain and the more intense the emotions associated with it, the more likely the facilitated nerve pathway will cause deviation from the most common referral patterns (Simons, Travell, and Simons 1999).

Central Nervous System Sensitization

Recent research (Borg-Stein and Simons 2002) has shown that certain types of nerve receptors in muscles relay information to neurons located within part of the gray matter of the spinal cord. The pain is amplified there and then is relayed to areas of other muscles, thereby expanding the region of pain beyond the initially affected area.

Once this part of the central nervous system is involved, or sensitized, in this way (called central sensitization), the persistent pain leads to long-term or permanent changes in these neurons, which affect adjacent neurons through neurotransmitters (chemical substances that are produced and secreted by a neuron and then diffuse across synapses, or small gaps, between neurons, causing excitation or inhibition of another neuron). This may also cause the part of the nervous system that would normally counteract pain to malfunction and fail to do its job. The longer pain goes untreated, the greater the number of neurons that get involved, and the more muscles they affect, causing pain in new areas, and in turn causing more neurons to get involved . . . and the bigger the problem keeps getting, leading to the likelihood that the pain is going to turn into a chronic problem. The sooner pain is treated, the less likely it will become a permanent problem with widespread muscle involvement and central nervous system changes…

How Trigger Points Form

Trigger points may form after a sudden trauma or injury, or they may develop gradually. Common initiating and perpetuating factors are mechanical stresses, injuries, nutritional problems, emotional factors, sleep problems, acute or chronic infections, organ dysfunction and disease, and other medical conditions. Part II goes into detail about these causes and perpetuators of trigger points.

Part of the current hypothesis about the mechanism responsible for the formation of trigger points is the energy crisis component theory. The sarcoplasmic reticulum, a part of each cell, is responsible for storing and releasing ionized calcium. The type of nerve ending that causes the muscle fiber to contract is called a motor endplate. This nerve ending releases acetylcholine, a neurotransmitter that tells the sarcoplasmic reticulum to release calcium, and then the muscle fiber contracts. If it is operating normally, when contraction of the muscle fiber is no longer needed, the nerve ending stops releasing acetylcholine and the calcium pump in the sarcoplasmic reticulum returns calcium into the sarcoplasmic reticulum. If a trauma occurs or there is a large increase in the motor endplate’s release of acetylcholine, an excessive amount of calcium can be released by the sarcoplasmic reticulum, causing a maximal contracture of a segment of muscle, leading to a maximal demand for energy and impairment of local circulation. If circulation is impeded, the calcium pump doesn’t get the fuel and oxygen it needs to pump calcium back into the sarcoplasmic reticulum, so the muscle fiber continues to contract.

The areas at the ends of the muscle fibers (either at the bone or where the muscle attaches to a tendon) also become tender as the attachments are stressed by the contraction in the center of the fiber (Simons, Travell, and Simons 1999). Once the central nervous system has been sensitized, various substances are released: histamine (a compound that causes dilation and permeability of blood vessels), serotonin (a neurotransmitter that constricts blood vessels), bradykinin (a hormone that dilates peripheral blood vessels and increases small blood vessel permeability), and substance P (a compound involved in the regulation of the pain threshold). These substances stimulate the nervous system to release even more acetylcholine locally, adding to the perpetuation of the dysfunctional cycle (Borg-Stein and Simons 2002). This vicious cycle continues until some sort of outside intervention stretches the contracted portion of the muscle fiber. Anxiety and nervous tension also increase autonomic nervous system activity (the part of the nervous system that controls the release of acetylcholine, along with involuntary functions of blood vessels and glands), which commonly aggravates trigger points and their associated symptoms (Simons 2004).

Conclusion

Trigger points are tender when pressed, and the multiple contractures forming the trigger point may feel like a small lump in the muscle. Healthy muscles don’t contain trigger points, and they don’t feel tender with pressure. If trigger points are left untreated, the damage to the muscle cells can be irreparable and can even cause long-term changes in the central nervous system, leading to a self-perpetuating cycle of trigger points, pain, and muscular damage. Trigger points can cause symptoms other than pain, which should be taken into consideration and may help you determine the location of your trigger points. This is particularly important when the referral pattern deviates from the common pattern, making the location of the trigger points harder to determine.

In the next chapter* you’ll learn more about treating trigger points and when you should see a doctor.

*Chapter 2 is not available for preview online. Purchase "Trigger Point Therapy for Headaches & Migraines" to access the full text.

These Sample Chapters are reprinted with permission from New Harbinger Publications, Inc. "Trigger Point Therapy for Headaches & Migraines: Your Self-Treatment Workbook for Pain Relief," by Valerie DeLaune.

 

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