Here are some key points to know about trigger points:
1. Causes: Trigger points can be caused by a variety of factors, including muscle overuse, poor posture, muscle imbalances, direct trauma, stress, and even chronic medical conditions. Repetitive motions, such as typing or lifting heavy objects, can contribute to the development of trigger points.
2. Symptoms: Trigger points often cause local pain or discomfort in the affected muscle. They can also lead to referred pain, where pain is felt in other areas of the body. For example, a trigger point in the neck or shoulder could cause pain that radiates down the arm. Other symptoms might include muscle stiffness, limited range of motion, and muscle weakness.
3. Palpation: Healthcare professionals, such as physical therapists or massage therapists, can often locate trigger points by palpating the muscle tissue. Trigger points can feel like small nodules or knots within the muscle. When pressure is applied to a trigger point, it can often reproduce the pain or discomfort that a person is experiencing.
4. Treatment: There are several approaches to treating trigger points, depending on their severity and underlying causes. Some common treatments include:
o Manual Therapy: Massage therapy, myofascial release, and other hands-on techniques can help release tension in the muscle and alleviate trigger point-related pain.
o Stretching and Exercise: Gentle stretching and specific exercises can help relax the muscle and prevent the formation of new trigger points. Strengthening weak muscles can also help improve muscle imbalances that might contribute to trigger points.
o Heat and Cold Therapy: Applying heat or cold to the affected area can help relax the muscle and reduce pain. Heat can help increase blood flow, while cold can help reduce inflammation.
o Trigger Point Injections: In some cases, a healthcare provider might inject a local anesthetic or other medication directly into the trigger point to alleviate pain and reduce muscle tension.
o Medications: Over-the-counter pain relievers, such as nonsteroidal anti-inflammatory drugs (NSAIDs), can help manage pain and inflammation associated with trigger points.
5. Prevention: To prevent trigger points from forming or recurring, it's important to maintain good posture, practice regular stretching and exercise, stay hydrated, manage stress and avoid prolonged periods of overuse.
Trigger points are thought to be areas of hyperirritable muscle tissue that are characterized by tight bands or knots. They can develop in both skeletal and smooth muscles. The exact mechanisms behind trigger point formation and their effects are not fully understood, but there are a few theories that help explain what might be happening within the muscle:
1. Microtrauma and Muscle Fiber Dysfunction: One theory suggests that trigger points can form due to microtrauma or small injuries to muscle fibers. These injuries can be caused by overuse, strain, or direct trauma. When muscle fibers become damaged, they can contract and tighten, forming taut bands within the muscle. This contraction can restrict blood flow to the affected area, leading to a decrease in oxygen and nutrients, and an accumulation of waste products.
2. Neuromuscular Junction Dysfunction: Another theory proposes that trigger points may result from dysfunction at the neuromuscular junction—the point where nerves communicate with muscle fibers. It's believed that excessive nerve impulses can cause muscle fibers to contract and remain in a shortened state, leading to the formation of trigger points. Typically the nerve is in an irritated state due to compression in or around the spine or along its course through the myofascial chain.
3. Energy Crisis Hypothesis: This theory suggests that trigger points develop due to an energy crisis within muscle cells. When muscle fibers are overused or stressed, they can become depleted of energy-rich molecules like ATP. This energy deficit can lead to a sustained state of contraction in localized muscle fibers, contributing to the development of trigger points.
4. Motor Endplate Hypothesis: According to this theory, trigger points form due to dysfunctional motor endplates, which are specialized areas where nerve terminals connect with muscle fibers. The communication between nerves and muscle fibers can become disrupted, leading to muscle fiber contraction, reduced blood flow, and the formation of trigger points.
5. In addition to the underlying mechanisms, trigger points can cause a cycle of pain and dysfunction. When a trigger point forms, it can cause the muscle to become shortened and tense, which can lead to decreased blood circulation, oxygen deprivation, and a buildup of metabolic waste products like lactic acid, substance P, CGRP, prostaglandins and bradykinins. This can further irritate nerve endings and contribute to pain. The pain itself can lead to protective muscle guarding, which can perpetuate the cycle by causing additional muscle tension and trigger point formation.
6. It's important to note that the science behind trigger points is still evolving, and there is ongoing research to better understand their causes and mechanisms. Treatment approaches are often based on relieving muscle tension, promoting blood flow, and addressing any underlying factors that contribute to their development.
Let’s take a look at the anatomy of the muscle fiber itself to see what is happening to cause a trigger point: Notice in the diagram that the myofibrils within the sarcomere are in a semicontracted state due to a local dysfunction. The cause of this dysfunction can vary.
There are a few theories to explain why the trigger point is not always located in the painful area. Referred pain is a phenomenon in which pain is perceived in an area of the body that is remote from the actual source of the pain. This can often be confusing and challenging to diagnose because the pain appears to be coming from a location that is not directly related to the underlying issue. Referred pain occurs due to the complex network of sensory nerves and the way the brain interprets these signals. Here are a few of the proposed theories.
1. Nerve Convergence: Nerves from different parts of the body often converge or come together and share pathways as they travel to the spinal cord and brain. This convergence can lead to a phenomenon known as "cross-talk" between nerve pathways. When a trigger point is active and sending pain signals to the spinal cord, the brain might interpret those signals as originating from a different area of the body that shares nerve pathways with the affected muscle.
2. Central Sensitization: Trigger points can sensitize the central nervous system, which includes the brain and spinal cord. This means that the nervous system becomes more sensitive to pain signals. When a trigger point is active, it can heighten the sensitivity of nerves in the spinal cord, amplifying pain signals. As a result, the brain might perceive pain as coming from a larger area than just the trigger point itself.
3. Dermatomes and Innervation Patterns: Dermatomes are specific regions of the skin that are innervated by a single spinal nerve. Each spinal nerve carries sensory information from a particular area of the body. When there is convergence of nerve pathways in the spinal cord, pain signals from a specific organ or muscle might be perceived in the dermatome associated with the same spinal nerve.
4. Referred Pain Patterns: Some trigger points have consistent patterns of referred pain that are well-documented. These patterns are thought to be related to the specific muscle's innervation and nerve connections. For example, a trigger point in the trapezius muscle in the upper back might refer pain down the arm and into the hand, into the side of the scalp or the lower jaw, even though the trigger point is located in the upper back.
5. Neural Sensitization: Trigger points can cause abnormal sensory signals to be sent to the brain. These abnormal signals can lead to the brain interpreting the sensations as pain in different areas of the body. Additionally, the nervous system's response to the presence of a trigger point can cause surrounding muscles to tense up and contribute to the spread of pain.
Referred pain can sometimes make diagnosing the source of pain challenging, as the actual cause of the pain may be located quite far from where the pain is felt. Healthcare professionals, such as physical therapists and doctors, often rely on their knowledge of anatomy, pain patterns, and patient history to help determine the true source of the pain. Usually, a thorough evaluation to identify the source of the pain and develop an appropriate treatment plan.
Trigger points can be present along the course of a dermatome or myotome.
Dermatomes and myotomes are an important concept in understanding how referred pain from trigger points occurs. Let's explore in more detail:
1. Dermatomes:
A dermatome is a specific region of the skin that is innervated by sensory nerve fibers from a single spinal nerve. These nerve fibers transmit sensory information such as touch, temperature, and pain from the skin to the spinal cord and then to the brain. Each spinal nerve is responsible for supplying sensory input to a specific dermatome.
2. Dermatomes are arranged in a segmented pattern along the body, with overlapping regions. Because of this overlap, adjacent dermatomes share some degree of sensory innervation. This overlap plays a crucial role in the phenomenon of referred pain.
3. A myotome refers to a group of muscles that are innervated by the same segment of the spinal cord. In other words, a myotome is a region of the body that is primarily controlled by a single spinal nerve or a specific segment of the spinal cord. Myotomes play a critical role in muscle movement and coordination throughout the body. Trigger points may be located in muscles innervated by a specific spinal segment.
4. Each spinal nerve in the human body is associated with a specific myotome, and these myotomes are responsible for providing motor control to various muscle groups. When a motor nerve signal is sent from the spinal cord to a particular myotome, it triggers the contraction of the muscles within that myotome, leading to coordinated movement. Muscles fibers that contain trigger points have been shown to be twice under twice as much resting tension, and twice as weak as a regular muscle fiber. This affects all coordinated movement along the myotome.
5. The concept of myotomes is often used in medical and clinical contexts, such as in the assessment of muscle strength and the diagnosis of neurological conditions. Healthcare professionals may evaluate specific myotomes to determine the extent of muscle weakness or dysfunction associated with trigger points.
6. Referred pain occurs when the brain misinterprets sensory signals and perceives pain in an area of the body different from the actual source of the pain. This often happens because the pain signals from an internal organ or deep tissue converge onto the same spinal nerve pathways that supply the skin in a certain dermatome or myotome.
7. For example, let's consider the classic example of a heart attack. The heart is supplied by sensory nerves that converge onto spinal nerves in the upper thoracic region of the spinal cord. These spinal nerves also supply the skin over the chest and upper left arm. As a result, during a heart attack, the brain might interpret the intense pain from the heart as originating from the chest and left arm—the same dermatome that shares nerve pathways with the heart.
8. In cases like this, the pain is referred to the skin because the sensory nerve pathways from the affected organ and the skin overlap in the spinal cord. This creates a connection between the internal source of pain and the skin in a specific dermatome
9. Understanding dermatomes/myotomes and referred pain is important in medical diagnosis. When a patient reports pain in a certain area, healthcare professionals can use their knowledge of dermatomes and myotomes to locate the active, latent, and satellite trigger points.
10. However, it's important to note that while referral patterns are generally consistent, individual variation can occur. Some people might experience slightly different referred pain patterns due to their unique nerve connections.
Typical pain referral pattern for a trigger point in the Serratus Posterior Superior muscle.
If you feel your pain could be trigger point related, schedule now for a free consult with a physical therapist at Lanier Therapy in Motion to look at possible treatment options.
