Extensor Carpi Radialis Brevis Myofascial Pain Syndrome

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Extensor Carpi Radialis Brevis Myofascial Pain Syndrome

The extensor carpi radialis brevis muscle is the primary dorsiflexor of the wrist and it works in conjunction with the extensor carpi radialis longus muscle to extend the wrist and abduct the hand. The extensor carpi radialis brevis muscle originates from the lateral epicondyle of the humerus as part of the common extensor tendon which it shares with other muscles in the posterior superficial compartment of the forearm. It inserts at the posterior aspect of the base of the third metacarpal bone and is innervated by the deep branch of the radial nerve (C7, C8).

The extensor carpi radialis brevis muscle is susceptible to repeated overload and microtrauma (e.g., hammering, using a screwdriver, typing on a keyboard, or using a mouse), leading to the development of myofascial pain syndrome and a trigger point within the muscle.

Myofascial pain syndrome of the extensor carpi radialis brevis initially presents with pain in the region of the lateral epicondyle, often leading to a misdiagnosis of lateral elbow tendinopathy (Tennis Elbow). Over time, the pain becomes more dominant in the posterior wrist and hand. Often, patients forget that they initially had lateral elbow pain, which may cause the extensor carpi radialis brevis trigger point to be overlooked given that its most common location is near the elbow.

Please note: Trigger points may be located anywhere within a muscle and its fascia. Therefore, the entire muscle should be examined thoroughly, particularly because trigger points are often located well away from the site of pain. However, based on clinical experience, the typical location for the trigger point in the extensor carpi radials brevis muscle is within the muscle belly, a short distance from the lateral epicondyle (as shown by the black cross in the image below).

Myofascial pain is prevalent and is a frequent cause of visits to primary care physicians and pain clinics. Different studies have demonstrated that myofascial trigger points are associated with several pain conditions including headache and pain in the neck, low back, and upper and lower extremities.

Myofascial Trigger Points –  A myofascial trigger point is a contraction knot found within a band of a muscle or in the muscle’s fascia. This contraction knot is considered to be responsible for nodularity which can be detected by palpation. Previous publications have suggested that trigger points are found in specific locations within a muscle. However, more recent publications suggest that they can be found anywhere within a muscle. Therefore, the entire muscle should be thoroughly examined in order to locate them.

Diagnostic Criteria for Myofascial Trigger Points – A 2019 international consensus concluded that moderate to excellent reliability for the presence of myofascial trigger points is based on the combination of a taut band, tender spot, local twitch response, and referred pain. The consensus was that at least two of the above criteria are required for a myofascial trigger point diagnosis.

Taut Band and Tender Spot – Myofascial trigger points typically involve an exquisitely tender spot found within a taut band of the muscle or in the muscle’s fascia.

Local Twitch Response – A local twitch response is defined as a quick visible or palpable contraction of the muscle fibers when pressure is applied within a taut band of a trigger point.

Active and Latent Trigger Points – Myofascial trigger points can be classified as active or latent. An active trigger point is one that reproduces or intensifies the patient’s familiar (referred) pain when it is compressed. A latent trigger point is one that does not reproduce the patient’s familiar pain when it is compressed.

Referred Pain – A key feature of an active trigger point is the presence of referred pain which is a manifestation of central sensitization. This central sensitization results in a spread of perceived pain to distant and larger areas of the body than just the local tenderness found at the taut band.

Research suggests that the combination of acidic pH and pro-inflammatory mediators at the active trigger point contributes to the segmental spread of nociceptive input into the dorsal horn of the spinal cord. The dorsal horn neuron, in turn, sensitizes the central nervous system by transmitting nociceptive impulses superiorly to activate the somatosensory cortex, where pain information is perceived and interpreted. This is believed to cause hyperalgesia and referred pain.

Risk Factors – Many different activities and medical conditions may place individuals at greater risk for developing myofascial pain syndrome. These include:

• Joint hypermobility or ligamentous laxity (i.e., when the ligaments are unable to provide joint stability, muscles remain in constant contraction to stabilize the joint. This is believed to cause the formation of trigger points within muscles)
• Musculoskeletal injuries
• Unaccustomed or intense exercise
• Muscle overload or repetitive physical activity
• Prolonged incorrect posture (e.g., poor ergonomics or habitual postures)
• Cold drafts or an intense cooling of muscles (e.g., sleeping in front of an air conditioner or under a ceiling fan)
• Lack of sleep or poor sleep
• Leg length inequality or other biomechanical disturbances
• Psychological stress, anxiety, and depression
• Fatigue

• Pain that is initially felt in the region of the lateral epicondyle and then becomes more dominant in the posterior wrist and hand
• Pain is typically provoked by activities (e.g., gripping, typing, hammering, and using a screwdriver)
• Grip weakness may be reported (e.g., picking up and lifting a coffee cup)
• Pain is often reported as an insidious onset without the patient remembering a causative factor
• Pain may be relieved by stretching the wrist extensor muscles

• The patient’s pain may be provoked by Cozen test (resisted wrist extension).
• The patient’s pain may be provoked by Maudsley’s test (resisted middle finger extension).
• The patient’s pain may be provoked when they firmly grip an object.
• Palpation typically reveals a trigger point within the belly of the extensor carpi radialis brevis muscle.
• The patient’s pain may be reproduced when pressure is applied to the trigger point in the extensor carpi radialis brevis muscle.

Imaging is not usually required in cases of myofascial pain syndrome, except to help rule out other conditions.

The following are examples of “red flags” for patients presenting with wrist pain:

• History of a significant injury
• Severe pain
• Unrelenting pain
• Nocturnal pain
• Unexplained weight loss
• Fever
• Deformity
• Large joint swelling
• Significant loss of range of motion
• Significant neurological impairment
• Severe tenderness on palpation or severe pain during an examination procedure

If any “red flags” are identified during history taking and clinical examination, referral for urgent medical evaluation and further investigation is warranted.

How to Locate the Extensor Carpi Radials Brevis Muscle

Begin by palpating the posterior aspect of the base of the 3rd metacarpal joint. While the patient extends and abducts their wrist, locate the tendon that attaches to the 3rd metacarpal joint. While the patient repeatedly extends and abducts their wrist, follow the tightening tendon proximally to the contracting muscle belly.

Trigger Point Pressure Release Technique

When performing the Trigger Point Pressure Release Technique:

Step 1: Begin by applying a gentle pressure on the trigger point and gradually increase this pressure until the patient reports some initial local pain (you will feel an increase in tissue resistance). Maintain this pressure without increasing it until the patient reports that the pain has eased (you will feel a concurrent easing of tissue resistance).

Step 2: Once the pain has eased, gradually apply deeper pressure on the trigger point until the patient once again reports the return of local pain (you will once again feel an increase in tissue resistance). Maintain this pressure until the patient reports that the pain has eased.

Step 3: Once the pain has eased again, gradually apply an even deeper pressure on the trigger point until the patient reports the return of local pain (you will feel an increase in tissue resistance). Maintain this pressure until the patient reports that the pain has eased.

Posterior Wrist Pain Caused by Myofascial Pain Syndromes

• Extensor Carpi Radialis Brevis Muscle: Primarily refers pain to the posterior wrist, but may also refer pain to the lateral elbow.
• Extensor Carpi Ulnaris Muscle: Primarily refers pain to the ulnar aspect of the posterior wrist, but may also refer pain to the lateral elbow.
• Extensor Carpi Radialis Longus Muscle: Primarily refers pain to the lateral elbow, but may also refer pain to the radial side of the posterior wrist.

Differential Diagnosis of Wrist Pain

In addition to myofascial pain syndrome, differential diagnosis of wrist pain should include:

• Cervical radiculopathy
• Cervical joint dysfunction
• Wrist joint dysfunction
• Wrist fracture and dislocation
• Radioulnar and carpal joint sprain
• Osteoarthritis of the wrist
• Ganglion cyst