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Sternalis Syndrome – Interesting Facts
- Sternalis syndrome is a myofascial pain syndrome and is characterized by trigger points in the midsternal area. In contrast to costosternal syndrome, which also manifests as midsternal pain, the pain of sternalis syndrome is not exacerbated by movement of the chest wall and shoulder.
- The intensity of the pain associated with sternalis syndrome is mild to moderate and described as having a deep, aching character. The pain of sternalis syndrome is intermittent.
- Chest wall pain syndromes are commonly encountered in clinical practice. Some occur with relatively greater frequency and are more readily identified by the clinician, such as costochondritis and Tietze syndrome.
- Others occur so infrequently that they are often misdiagnosed, resulting in a suboptimal outcome. Sternalis syndrome is one such infrequent cause of anterior chest wall pain. Sternalis is a constellation of symptoms affecting the midline anterior chest wall that can radiate to the retrosternal area and the medial aspect of the arm.
- Sternalis syndrome can mimic the pain of myocardial infarction and is frequently misdiagnosed as such.
What are the Symptoms of Sternalis Syndrome
Symptoms of sternalis syndrome may include:
- Pain or discomfort in the chest area, which may be localized to the site of the sternalis muscle.
- Palpable or tender mass in the upper chest.
- Muscle spasms or twitching in the area of the sternalis muscle.
- Associated breast pain or nipple sensitivity, especially in females.
- On physical examination, a patient with sternalis syndrome exhibits myofascial trigger points at the midline over the sternum.
- Occasionally, a coexistent trigger point is located in the pectoralis muscle or sternal head of the sternocleidomastoid muscle.
- Pain is reproduced with palpation of these trigger points, rather than movement of the chest wall and shoulders.
- A positive jump sign is present when these trigger points are stimulated.
- Trigger points at the lateral border of the scapula also may be present and amenable to injection therapy.
- Movement of the shoulders and chest wall does not exacerbate the pain.
What causes sternalis syndrome?
- The cause of sternalis syndrome is unknown but it is thought to be a self-limiting condition and unlikely to cause persistent pain
How is Sternalis Syndrome diagnosed?
- Plain radiographs are indicated in all patients thought to have sternalis syndrome to rule out occult bony pathological processes, including metastatic lesions. Based on the patient’s clinical presentation, additional tests, including complete blood cell count, prostate-specific antigen level, erythrocyte sedimentation rate, and antinuclear antibody testing, may be indicated.
- Computed tomography (CT) and magnetic resonance imaging (MRI) of the chest are indicated if a retrosternal mass, such as thymoma, is suspected, as well as to help confirm the presence of a sternalis muscle or other anterior chest wall mass.
- Ultrasound imaging may help further characterize the nature of masses involving the anterior chest wall. Electromyography is indicated in patients with sternalis syndrome to help rule out cervical radiculopathy or plexopathy that may be considered because of the referred arm pain.
- Injection of the sternalis muscle with a local anesthetic and steroid serves as a diagnostic and therapeutic maneuver.
Differential Diagnosis
- Tietze syndrome
- Neuropathic pain
As mentioned earlier, the pain of sternalis syndrome is often mistaken for pain of cardiac origin and can lead to visits to the emergency department and unnecessary cardiac workups. If trauma has occurred, sternalis syndrome may coexist with fractured ribs or fractures of the sternum itself, which can be missed on plain radiographs and may require radionucleotide bone scanning for proper identification.
Tietze syndrome, which is painful enlargement of the upper costochondral cartilage associated with viral infections, can be confused with sternalis syndrome, as can costosternal syndrome and congenital abnormalities of the sternum.
Neuropathic pain involving the chest wall also may be confused or coexist with costosternal syndrome. Examples of such neuropathic pain include diabetic polyneuropathies and acute herpes zoster involving the thoracic nerves.
The possibility of diseases of the structures of the anterior chest wall and mediastinum is ever present, and these diseases sometimes can be difficult to diagnose. Pathological processes that inflame the pleura, such as pulmonary embolus, infection, and tumor, also should be considered.
Treatment
- Initial treatment of sternalis syndrome should include a combination of simple analgesics and nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors. Local application of heat and cold also may be beneficial to provide symptomatic relief of the pain of sternalis syndrome.
- The use of an elastic rib belt may help provide symptomatic relief in some patients. For patients who do not respond to these treatment modalities, injection of the trigger areas located in the sternalis muscle using a local anesthetic and steroid may be a reasonable next step. Ultrasound guidance may improve the accuracy of needle placement and decrease the incidence of needle-related complications.
Complications
- The major problem in the care of patients thought to have sternalis syndrome is the failure to identify potentially serious pathological conditions of the thorax, mediastinum, or both.
- Given the proximity of the pleural space, pneumothorax after injection of the sternalis muscle is a possibility, as is injury to the mediastinal and intrathoracic structures.
- Approximately 25% of patients report a transient increase in pain after this injection technique and should be warned about this.
Summary
Sternalis syndrome, also known as sternalis muscle syndrome, is a relatively rare condition characterized by the presence of an additional muscle called the sternalis muscle in the chest. The sternalis muscle is an anatomical variation that occurs in some individuals, where it is an accessory muscle located alongside or in place of the sternum (breastbone).
The sternalis muscle can present as a thin, flat, or cord-like muscle, usually on one side of the chest. It may be bilateral in some cases, occurring on both sides. The muscle can vary in size and shape and is typically located in the upper part of the chest, originating from the sternum or nearby connective tissue and inserting into the upper arm or axilla (armpit).
While the sternalis muscle itself is usually asymptomatic and does not cause any issues, sternalis syndrome refers to the presence of symptoms or discomfort associated with this muscle. The exact cause of sternalis syndrome is not well understood, and the condition is often discovered incidentally during imaging or surgery.
Symptoms of sternalis syndrome may include:
- Pain or discomfort in the chest area, which may be localized to the site of the sternalis muscle.
- Palpable or tender mass in the upper chest.
- Muscle spasms or twitching in the area of the sternalis muscle.
- Associated breast pain or nipple sensitivity, especially in females.
Treatment for sternalis syndrome is generally conservative and focused on managing symptoms. This may involve pain management techniques such as nonsteroidal anti-inflammatory drugs (NSAIDs), heat or cold therapy, physical therapy exercises, and stretching to relieve muscle tension.
In rare cases where the symptoms are severe or significantly impact daily life, surgical excision of the sternalis muscle may be considered. However, surgical intervention is generally not recommended unless the symptoms are particularly problematic or other conservative measures have been ineffective.
If you suspect you may have sternalis syndrome or are experiencing chest discomfort, it is advisable to consult with a healthcare professional for a proper evaluation and diagnosis. They can provide guidance on appropriate management options based on your specific situation.
