THE CLINICAL SYNDROME

• The brachioradialis muscle is responsible for flexing the forearm at the elbow, as well as pronating and supinating the forearm depending on whether it is supinated or pronated.

• The upper lateral supracondylar ridge of the humerus and the lateral intermuscular septum of the humerus are its points of origin.

• The insertion points for this muscle are the superior aspect of the styloid process of the radius, the lateral side of the distal radius, and the antebrachial fascia.

• The radial nerve provides the muscle with its innervation.

• Myofascial pain syndrome can potentially manifest in the brachioradialis muscle if the proper precautions are not taken.

• This pain is most commonly caused by repetitive microtrauma to the muscle, which can occur as a result of activities such as turning a screwdriver, ironing for an extended period of time, repeatedly flexing the forearm at the elbow (for example, when using exercise equipment), shaking hands, or digging with a trowel.

• Myofascial pain syndrome has also been linked to tennis injuries that were caused by an improper one-handed backhand technique.

• Blunt trauma to the muscle has also been linked to myofascial pain syndrome as an initiating factor.

SIGNS AND SYMPTOMS

• The pathologic lesion of brachioradialis syndrome is referred to as the trigger point, and it is characterized by a local point of exquisite tenderness in the brachioradialis muscle.

• The most effective way to demonstrate this trigger point is to have the patient simultaneously flex and pronate the forearm while they are working against active resistance.

• There is also a possibility that there will be point tenderness over the lateral supracondylar ridge of the humerus, which may be treatable with injection therapy.

• When a trigger point is mechanically stimulated, either by palpation or stretching, it produces intense local pain as well as referred pain in the surrounding area.

• A pain over the brachioradialis muscle that radiates from the lateral epicondyle and superior portion of the muscle into the forearm is another symptom that is typical of brachioradialis syndrome.

• The jump sign is also a characteristic of this condition.

TESTING

• The results of biopsies performed on clinically identified trigger points have not revealed abnormal histologic features in a consistent manner.

• The muscle that is home to the trigger points has been variously referred to as "moth-eaten" and as having "waxy degeneration" in its structure.

• In some patients with brachioradialis syndrome, an increased plasma myoglobin has been reported; however, this finding has not been supported by the findings of any additional researchers.

• When patients with brachioradialis syndrome underwent electrodiagnostic testing, the results showed that some patients had an increase in muscle tension.

• However, this finding has not been able to be replicated in other patients.

• Because there are no objective diagnostic tests available, the clinician needs to rule out any other diseases that may be present concurrently and could be presenting as brachioradialis syndrome.

DIFFERENTIAL DIAGNOSIS

• Instead of specific laboratory, electrodiagnostic, or radiographic testing, a diagnosis of brachioradialis syndrome is made based on the clinical findings of the patient.

• Because of this, a specific history and physical examination, including a methodical search for trigger points and the identification of a positive jump sign, are required to be performed on every patient who may be suffering from brachioradialis syndrome.

• The clinician needs to rule out any other diseases that may be present at the same time as brachioradialis syndrome, such as primary inflammatory muscle disease and collagen vascular disease.

• Both of these conditions have the potential to mimic brachioradialis syndrome.

• Radiographic testing, including magnetic resonance imaging, can be helpful in identifying coexisting pathologic processes such as internal derangement of the elbow, tumor, bursitis, tendinitis, crystal deposition diseases, and tennis elbow.

• Radiographic testing can also help diagnose crystal deposition diseases.

• Electromyography is able to rule out carpal tunnel syndrome as well as radial tunnel syndrome.

• The clinician is responsible for determining whether or not the patient has any coexisting psychological or behavioral abnormalities, as these can either obscure or exacerbate the symptoms of brachioradialis syndrome.

TREATMENT

• The primary goals of treatment are to inhibit the myofascial trigger and bring about sustained relaxation in the muscle that is being affected.

• When developing a treatment strategy, it is common practice to incorporate an element of trial and error due to the limited understanding of the underlying mechanism of action.

• The first step in treatment is typically conservative therapy, which may include trigger-point injections with either a local anesthetic or saline solution.

• The administration of antidepressants is a crucial component of the majority of treatment strategies for brachioradialis syndrome of the cervical spine.

• This is due to the fact that many patients suffering from this condition also experience underlying depression and anxiety.

• It has also been demonstrated that pregabalin and gabapentin can provide some relief from the symptoms associated with fibromyalgia.

• Milnacipran, which is an inhibitor of the reuptake of both serotonin and norepinephrine, has also been shown to be effective in the treatment of fibromyalgia.

• Nabilone, a synthetic cannabinoid, has also been used to manage fibromyalgia in certain patients who have not responded favorably to other treatment modalities.

• These patients have been carefully selected.

COMPLICATIONS AND PITFALLS

• If one pays close attention to the clinically relevant anatomy, trigger-point injections can be performed in a completely risk-free manner.

• In order to prevent infection, sterile technique must be utilized, and universal precautions must be taken in order to lessen the likelihood that the operator will be put in harm's way.

• The majority of the complications that can arise from trigger-point injection are due to needle-induced trauma at the injection site as well as in the tissues beneath the skin.

• If pressure is applied to the injection site immediately after the injection, this can help reduce the risk of complications such as ecchymosis and hematoma formation.

• It is possible to reduce the risk of trauma to the structures beneath the skin by avoiding needles that are excessively long.

• When injecting trigger points in the area surrounding the elbow and the forearm, one must exercise extreme caution to prevent causing damage to the underlying neural structures.