Although trauma is the common denominator in patients with omohyoid syndrome, there is usually no history of trauma in patients suffering from sternohyoid syndrome.
The clinical presentation of sternohyoid syndrome mirrors that of omohyoid syndrome. Both painful conditions present as anterior supraclavicular neck pain with associated dysphagia and a foreign body sensation in the throat.
The pain of sternohyoid syndrome appears to be the result of damage to the fibers of the belly of the sternohyoid muscle or as the result of abnormal attachment of the muscle to the mid-clavicle rather than to the more medial clavicle.
This pain manifests as myofascial. It is constant and exacerbated with movement of the affected muscle.
A trigger point in the affected sternohyoid muscle is often present and provides a basis for treatment. The pain of omohyoid syndrome starts just above the clavicle at the mid to medial aspect of the clavicular attachment of the sternocleidomastoid muscle.
The pain may radiate into the anterolateral neck and an abnormal mass adjacent to the anterior border of the sternocleidomastoid muscle may be palpable and in some cases visible.
This abnormal muscle mass may be seen to move superiorly along with the larynx when the patient swallows. Injection of the trigger point in the belly of the sternohyoid muscle with local anesthetic and steroid serves as a diagnostic and therapeutic maneuver.
What are the Symptoms of Sternohyoid Syndrome
Patients suffering from sternohyoid syndrome present with pain in the supraclavicular region at a point just medial and superior to the attachment of the sternocleidomastoid muscle to the clavicle.
A baseline level of pain is present even without movement of the muscle. The pain intensity ranges from minor to moderate. The pain often radiates into the anterolateral neck and increases with swallowing and movement of the sternohyoid muscle. An abnormal mass adjacent to the anterior border of the sternocleidomastoid muscle may be palpable and, in some cases, visible.
This abnormal muscle mass may be seen to move superiorly along with the larynx when the patient swallows. A trigger point in the belly of the sternohyoid muscle is often present. The pain of sternohyoid syndrome is often exacerbated by swallowing. The neurological examination of a patient with sternohyoid syndrome is normal.
How is Sternohyoid Syndrome diagnosed?
Magnetic resonance imaging (MRI), computerized tomography, and/or ultrasound imaging of the soft tissues of the neck may reveal hematoma formation of the sternohyoid muscle acutely if trauma has occurred and calcification, fibrosis, or both as the syndrome becomes more chronic.
These imaging modalities may also aid in the identification of abnormalities of the muscle and its insertion. Injection of the belly of the sternohyoid muscle with local anesthetic can serve as a diagnostic maneuver to help strengthen the diagnosis. Occasionally, surgical section of the sternohyoid muscle may be required to provide long-lasting relief.
Soft tissue injuries to the region may mimic sternohyoid syndrome. Because trauma is invariably involved in the evolution of the painful condition, strain and sprain of other soft tissues often exist concurrently with omohyoid syndrome.
Omohyoid syndrome as well as primary or metastatic tumors of the neck and hypopharynx also may mimic the clinical presentation of omohyoid syndrome and should be high on the list of diagnostic possibilities if the history of trauma is weak or absent.
Nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors represent a reasonable first step in the treatment of omohyoid syndrome.
The use of tricyclic antidepressants, such as nortriptyline, at a single bedtime dose of 25 mg, titrating upward as side effects allow also is helpful, especially if sleep disturbance is present. The injection of trigger points in the belly of the sternohyoid muscle often produces dramatic improvement in pain symptoms.
The key landmark for injecting when treating omohyoid syndrome is the medial aspect of the clavicular extent of the sternocleidomastoid muscle. The sternohyoid muscle is located just lateral to the trachea and the trigger point and/or abnormal mass can usually be identified approximately ¾ to 1 inch above the superior margin of the clavicle, medial to the sternocleidomastoid.
The muscle finds its origin on the medial portion of the clavicle and the sternum and its tendon inserts onto the hyoid bone, slightly lateral and deep to the clavicular head of the sternocleidomastoid muscle. Given the relationship of the great vessels of the neck to the sternohyoid muscle, care must be taken when placing needles in this anatomical area.
The patient is placed in the supine position, with the head turned away from the side to be blocked. Using a 5-mL sterile syringe, 3 mL of local anesthetic is drawn up. When treating sternohyoid syndrome, 80 mg of depot steroid is added to the local anesthetic with the first block, and 40 mg of depot steroid is added with subsequent blocks.
The patient is asked to raise the head against the resistance of the pain specialist’s hand to aid in identification of the anteromedial border of the sternocleidomastoid muscle.
The point at which the medial border of the sternocleidomastoid attaches to the clavicle is identified. At this point, slightly medial and approximately 1 inch above the clavicle, after preparation of the skin with antiseptic solution, a 1½-inch needle is inserted directly perpendicular to the table top. The needle should be advanced slowly because of proximity of the great vessels and brachial plexus. A “pop” often is felt as the fascia of the sternohyoid muscle is pierced; this should occur at a depth of ½ to ¾ of an inch.
If strict attention to technique is observed, and the needle is not placed or directed too laterally, the brachial plexus should not be encountered. Because of the proximity of the brachial plexus, the patient should be warned that a paresthesia could occur; the patient should be instructed to say “There!” if a paresthesia is felt. The needle should never be directed in a more inferior medial trajectory because pneumothorax is likely to occur.
After the muscle is identified, gentle aspiration is done to identify blood or cerebrospinal fluid. If the aspiration test is negative, and no paresthesia into the distribution of the brachial plexus is encountered, 3 mL of solution is slowly injected, with the patient being monitored closely for signs of local anesthetic toxicity or inadvertent neuraxial injection.
This technique can also be utilized for injection of botulinum toxin into the sternohyoid muscle. Ultrasound guidance may improve the accuracy of needle placement and decrease the incidence of needle-related complications.
The major complication in the treatment of patients thought to have sternohyoid syndrome is wrong diagnosis. Occult cervical spine fractures or instability after trauma remain an ever-present possibility. Failure to diagnose such injuries can put the patient at significant risk for permanent neurological sequelae. As mentioned earlier, if the history of trauma is suspect, the diagnosis of sternohyoid syndrome should become one of exclusion.
A careful search for tumors of the neck, apex of the lung, anterior triangle of the neck, and hypopharynx is indicated. If a significant history of vomiting is ascertained, esophageal tear also should be considered.
Although the injection technique for sternohyoid syndrome is safe, complications can occur. In addition to the potential for complications involving the vasculature, if the needle is placed too laterally, the proximity of the brachial plexus, the central neuroaxial structures, and the phrenic nerve can result in side effects and complications.
Although these complications should be rare if proper technique is observed, the potential for inadvertent epidural, subdural, or subarachnoid injection remains a possibility. Inadvertent phrenic nerve block also can occur when using this injection technique to treat sternohyoid syndrome if the needle placement is too far posterolaterally.
In the absence of significant pulmonary disease, unilateral phrenic nerve block should rarely create respiratory embarrassment. Inadvertent blockade of the recurrent laryngeal nerve with its attendant vocal cord paralysis combined with paralysis of the diaphragm from phrenic nerve block may make the clearing of pulmonary and upper airway secretions difficult, however.
Because of the proximity of the apex of the lung, pneumothorax is a distinct possibility and the patient should be informed of this.
Although an uncommon cause of pain, sternohyoid syndrome is a clinically distinct and easily recognizable pain syndrome. Because of the similarities in presentation of the more common omohyoid syndrome and the rarer sternohyoid syndrome, careful physical examination and imaging may be required to distinguish the two uncommon causes of anterior neck pain.
The key to performing this injection technique safely is a clear understanding of the anatomy and careful identification of the anatomical landmarks necessary to perform the block. The brachial plexus is quite superficial at the level at which this block is performed.
The needle should rarely be inserted deeper than ¾ of an inch in all but the most obese patients. If strict adherence to technique is observed, and the needle is never advanced medially from the lateral border of the insertion of the sternocleidomastoid muscle on the clavicle, the incidence of pneumothorax should be less than 0.5%.
Sternohyoid syndrome is a diagnosis of exclusion. The clinician should always evaluate a patient with pain in this anatomical region for occult malignancy.
Tumors of the larynx, hypopharynx, and anterior triangle of the neck may manifest with clinical symptoms identical to sternohyoid syndrome.
In the setting of flexion/extension injuries or other forceful trauma to the soft tissues of the neck, cervical spine, or both, the clinician also should evaluate the patient for trauma to the cervical spine and brachial plexus by careful physical examination and electromyography.