Scalenus syndrome is a nerve compression syndrome that is one of the thoracic outlet syndromes. In the syndrome, the brachial plexus becomes entrapped in the scelenus gap between the scalenus anterior and medius muscles. Surgical release of the compressed nerve is performed if neurologic deficits are present.
What is scalenus syndrome?
The so-called bottleneck syndromes are a group of compression syndromes. Compression syndromes are medical terms for conditions that result from the jamming of an anatomical structure in a specific narrow passage of the body. Scalenus syndrome is a nerve compression syndrome in which the brachial plexus becomes jammed in what is called the scalenus gap. The scalenus anterior muscle is a muscle between the cervical vertebrae and the ribs that can constrict the brachial plexus under certain circumstances. Scalenus syndrome is also called cervical rib syndrome or Naffziger syndrome. It is now grouped under the broader term thoracic-outlet syndrome. These syndromes are neurovascular compression syndromes of the upper thorax. Other nerve compression syndromes in this disease group include hyperabduction syndrome, pectoralis-minor syndrome, Paget-von-Schroetter syndrome, and costoclavicular syndrome. An exact prevalence for scalenus syndrome is not known. However, thoracic-outlet syndromes are considered relatively common overall.
Causes
The cause of scalenus syndrome is compression of the brachial plexus. This brachial plexus runs along the arms, shoulders, and chest. The scalenus anterior muscle runs between the cervical vertebrae and the ribs. The area between the scalenus anterior muscle and the scalneus medius muscle is also called the scalenus gap. This site is a bottleneck for the brachial plexus especially if the patient has an additional cervical rib. Additional cervical ribs are thus considered one of the most common causes of scalenus syndrome. However, the cause of the syndrome does not necessarily have to be due to a supernumerary bony element, but can also be related to the muscle itself. For example, the muscle may be affected by muscle hypertrophy. The resulting oversize of the muscle tissue can also constrict the brachial plexus. Another cause is a steep stance or exostosis of the upper ribs, which can result in a severely narrowed scalenus gap. In the latter case, in addition to the brachial plexus cords, cords of the subclavian artery are also affected by compression. In certain circumstances, compression may also be associated with an overly prominent ligamentous apparatus.
Symptoms, complaints, and signs
The brachial plexus innervates the shoulder and chest muscles motorically and is also involved in motor and sensory innervation of the arm and hand. For this reason, patients with scalene syndrome typically suffer from load-dependent neuralgiform pain in the shoulder and arm, manifesting predominantly in the ulnar forearm. Because sensory innervation of the hand is disrupted due to nerve compression, hypesthesias or paresthesias occur in the hand area. In some cases, these sensory disturbances are associated with intermittent circulatory disturbances, especially in the case of simultaneous compression of the subclavian artery. The affected arm increasingly falls asleep due to these circulatory disturbances. In some cases, numbness and a feeling of heaviness also occur. In the later stages of scalenus syndrome, the patient may complain of paralysis of the arm and chest muscles, since the muscles in this area are innervated by the compressed brachial plexus. From a certain stage onwards, increasing atrophy of the musculature due to paralysis is also conceivable, especially of the small hand muscles. In addition, due to a narrowing of the subclavian artery, very small blood clots occur in the advanced stage of the syndrome, which may occlude the finger vessels and thus lead to discoloration of the fingers.
Diagnosis and course of the disease
The diagnosis of scalenus syndrome is usually made by the physician using provocation testing. Imaging of the thorax may also be required as a diagnostic tool. Differentially, the physician must differentiate the syndrome from other thoracic outlet syndromes.The prognosis for patients with scalenus syndrome is generally favorable.
Complications
Patients with scalenus syndrome typically suffer from load-dependent pain in the shoulder and arm. These are usually associated with sensory disturbances and circulatory disturbances, which can lead, for example, to restricted movement and, rarely, to the development of blood clots. In the later stages of the disease, atrophies of the musculature can occur. The small muscles of the hand are particularly affected, which are less efficient due to the tissue atrophy and considerably restrict the affected person in daily tasks. As the disease progresses, neurological deficits such as paralysis and movement disorders occasionally develop. If these symptoms remain untreated, permanent damage can be left behind in the compressed nerve plexus. In addition, thrombosis occurs, occluding the finger vessels and leading to discoloration of the fingers. In pain therapy, the individual drugs can cause side effects and, under certain circumstances, major complications. If local anesthetics are injected, poisoning of the surrounding tissue can theoretically occur. Associated with this are nervousness, dizziness and seizures. In rare cases, a drop in blood pressure and cardiac arrhythmia may also be experienced. A surgical procedure carries the usual risks: Infection, bleeding, nerve injury and wound healing problems.
When should you see a doctor?
Medical treatment is always necessary for scalenus syndrome. In most cases, it can cause significant limitations and discomfort in everyday life. Scalenus syndrome does not heal on its own. For this reason, a medical professional should be consulted at the first signs to alleviate these complaints. A doctor should be consulted if the affected person suffers from severe pain in the arms or shoulders. This pain usually occurs without any particular reason and has a very negative effect on movement and also on the quality of life of the affected person. In many cases, disorders of blood circulation or sensory disturbances also indicate the scalenus syndrome and should also be examined by a doctor. Numbness can also be an indication of the scalenus syndrome. Furthermore, a doctor should be consulted if blood clots form. Scalenus syndrome can be recognized and treated by a general practitioner or by an orthopedic surgeon.
Treatment and therapy
Mild scalenus syndromes often do not require further therapy. In this case, treatment focuses primarily on mitigating the pain symptoms. Such alleviation can be achieved by conservative medical treatment of the patient. In most cases, however, the primary goal is to avoid the stresses and strains that trigger the pain. In this way, the patient does not have to be treated unnecessarily with painkillers. In the case of pronounced pain symptoms, the reduction of pain is usually achieved by means of pain therapy. One such method is local infiltration of the affected muscle with a local anesthetic. Under certain circumstances, this therapeutic local anesthesia can also take place with the aid of an implant that regularly releases local anesthetics into the muscle. If symptoms are present in addition to pain, pain therapy is not sufficient to treat scalenus syndrome. This is especially true if neurological deficits such as paralysis develop. Surgical intervention may be indicated to restore the patient’s ability to move. It is imperative that the intervention be performed before permanent damage occurs to the compressed nerve plexus. Surgical intervention involves correcting the primary cause of the compression. Often, this therapeutic step corresponds to the surgical removal of an additional cervical rib, for example.
Prevention
Scalenus syndrome cannot be prevented in the strict sense of the word, as the syndrome sometimes develops most frequently because of supernumerary cervical ribs. Such supernumerary neck ribs are congenital and cannot be prevented by active steps. However, the pain symptomatology of the syndrome can be prevented to the extent that pain-generating strains are avoided.
Follow-up
In most cases, the options and measures of follow-up care for scalenus syndrome are significantly limited.In this case, the patient is in any case dependent on a quick and, above all, on an early diagnosis and treatment of this disease, so that it does not come to complications or to other complaints in the further course. The earlier a doctor is consulted in the case of scalenus syndrome, the better the further course of this disease usually is. Most of those affected by the scalenus syndrome are dependent on the measures of physiotherapy and physiotherapy. Some of the exercises from these therapies can also be repeated in the patient’s own home, which accelerates the healing process. Likewise, in many cases, it is also necessary to take various medications to alleviate the discomfort. In this case, the affected person should always pay attention to the prescribed dosage and to regular intake. If there is a desire to have children, genetic testing and counseling can also be performed. This can prevent the recurrence of the disease. Further measures of aftercare are usually not available to the affected person.
What you can do yourself
In everyday life, care should be taken to avoid situations of physical overexertion. The body should be protected from overstraining. To support the muscular system, it is recommended to use massages or regular warm baths. If there are restrictions in the range of movement, physiotherapeutic treatments are carried out. The affected person can also carry out exercises and training units learned on his own responsibility outside the fixed therapy times to improve his own health. Since thrombosis can develop, disorders of the blood circulation must be prevented at an early stage. Rigid postures should therefore not be adopted under any circumstances. If sensory disturbances of the skin or a tingling sensation on the skin occur, compensatory movements should be performed immediately. Overall, sufficient movement helps to strengthen the immune system and stimulate blood circulation. Characteristic for the scalenus syndrome is an intense pain development. Although these symptoms are treated with medication, it has been proven in many patients that strengthening the mental area can lead to an alleviation of the pain perception. It is therefore advisable to try methods such as mental training, yoga or autogenic training. The techniques of the relaxation methods described can also be integrated independently and on one’s own responsibility at any time in everyday life by the person affected. In addition, cognitive patterns are optimized and dealing with the disease is thus facilitated.
