THE CLINICAL SYNDROME

• The supinator muscle is responsible for supinating the forearm, as its name suggests.

• The supinator muscle is made up of two layers: the superficial layer, which wraps around the upper third of the radius, and the deep layer, which runs along the length of the radius.

• A tendinous insertion from the lateral epicondyle of the humerus, the radial collateral ligament of the elbow, and the annular ligament of the supinator crest of the ulna are the origins of the superficial layer.

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

• This pain is most commonly brought on by repetitive microtrauma to the muscle, which can be brought on by activities such as turning a screwdriver, ironing for an extended period of time, 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.

• Myofascial pain syndrome is a type of chronic pain syndrome that can affect a specific area of the body or multiple areas of the body simultaneously.

• The identification of myofascial trigger points during a physical examination is a prerequisite for the diagnosis of myofascial pain syndrome.

• Although these trigger points are typically localized to the part of the body that is affected, pain is frequently referred to other regions of the body.

• This referred pain may be misdiagnosed or attributed to other organ systems, which may then lead to extensive evaluation and treatment that is not successful.

• Patients suffering from myofascial pain syndrome that affects the supinator muscle frequently report experiencing referred pain in the ipsilateral forearm.

SIGNS AND SYMPTOMS

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

• The most effective way to demonstrate this trigger point is to have the patient supinate the forearm while they are faced with active resistance.

• There is also a possibility of experiencing point tenderness over the lateral epicondyle, which might respond well to 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.

• Pain over the supinator muscle that radiates from the lateral epicondyle and superior portion of the muscle into the forearm is another sign that is indicative of supinator 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.

• Increased plasma myoglobin has been reported in some patients diagnosed with supinator syndrome; however, this finding has not been supported by the findings of any additional researchers.

• An increase in muscle tension has been found in some patients undergoing electrodiagnostic testing for supinator syndrome; however, this finding has not been able to be replicated, which is another reason why the finding is not conclusive.

• Because there are no objective diagnostic tests available, the clinician must first eliminate the possibility that the patient has another disease process that is coexisting with supinator syndrome.

DIFFERENTIAL DIAGNOSIS

• Clinical findings, as opposed to more specific laboratory, electrodiagnostic, or radiographic testing, are used to arrive at a diagnosis of supinator syndrome.

• Because of this, a focused 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 supinator syndrome.

• Other coexisting disease processes, such as primary inflammatory muscle disease, collagen vascular disease, inflammatory arthritis, tennis elbow, radial tunnel syndrome, tumor, bursitis, tendinitis, and crystal deposition diseases, must be ruled out by the clinician before a diagnosis of supinator syndrome can be made.

• These other diseases include: Radiographic testing, including magnetic resonance imaging of the elbow, can be helpful in identifying coexisting pathologic processes, such as internal derangement of the elbow, tendinitis, and bursitis.

• Radiographic testing can also help determine the severity of these conditions.

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

• Supinator syndrome is characterized by a collection of symptoms, some of which may be masked or made worse by coexisting psychological and behavioral abnormalities.

• The clinician is responsible for identifying these coexisting abnormalities.

TREATMENT

• The treatment focuses on preventing the myofascial trigger point from activating and achieving a state of prolonged 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 triggerpoint injections with either a local anesthetic or saline solution.

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

• This is due to the fact that many patients suffering from supinator syndrome of the cervical spine 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 demonstrated to be effective in the treatment of fibromyalgia.

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

• These patients have been specifically targeted.

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.