Thoracic outlet syndrome is an umbrella term for a number of diseases, all of which cause vascular and nerve compression in the area of the upper thorax. The Thoracic outlet syndrome is often also called constriction syndrome of the upper thoracic aperture or shoulder girdle compression syndrome. Thoracic outlet syndrome leads to an acute, temporary or chronic, prolonged squeezing of the vascular nerve bundle that runs in this area. The affected anatomical structures are the brachial plexus nerve bundle, the subclavian vein and artery.
Causes
Thoracic outlet syndrome has a wide variety of different causes. These differ depending on where the vascular nerve bundle is pinched. The subgroups of the Thoracic outlet syndrome then have the appropriate names for the constriction.
The vascular nerve bundle runs as one unit from the neck towards the arms to supply them. This bundle has to overcome three constrictions that pose a risk of entrapment. The first constriction is the so-called scalenus gap.
This gap is located at the side of the neck and is formed by two muscles. A constriction at this point can be caused by a significant increase in the muscles and by an additional rib in this area, which is then called the cervical rib. The associated constriction syndrome is called scalenus syndrome.
The second constriction, through which the vascular-nerve bundle runs, is located behind the collarbone. Here, the bundle runs between the back of the collarbone and the front of the ribs located there. If there is excessive new bone formation at this point due to a broken collarbone or rib fracture, also known as callus, the constriction becomes even tighter.
The associated disease is called costoclavicular syndrome. The third major subgroup of the thoracic outlet syndrome is the hyperabduction syndrome. It develops at the third constriction and is caused by a too strongly trained and therefore too large chest muscle (M. pectoralis minor).
Symptoms
Thoracic outlet syndrome causes numerous symptoms, since not only nerves are compressed, as in classic carpal tunnel syndrome, but arteries and veins are also constricted. Which symptom of thoracic outlet syndrome is the most prominent depends primarily on which of the three structures is compressed the most. One of the main symptoms of thoracic outlet syndrome is pain under stress.
This can affect the shoulder as well as the entire arm, especially on the side of the ulna. The squeezing of the nerves can cause not only pain but also sensation in the hand. As a maximum form, such a bruise can lead to an absence of sensation.
Furthermore, especially at night, sensations of discomfort in the hands can occur, which are perceived as “formication” or “falling asleep”. In addition to sensory discomfort, the fingers can become cold and increased sweat production can occur in the affected area. In pronounced cases, weakness and degeneration of the thumb muscles may eventually result.
Due to the constant pressure damage to the nerves, a disturbance of the fine motor skills can occur in the course of the thoracic outlet syndrome, so that the affected patient finds it difficult to write on a computer keyboard or play the piano. All these symptoms are accompanied by damage to the nerves. If the thoracic outlet syndrome mainly compresses the subclavian artery and thus hinders the blood flow in the arm, other symptoms are the main focus.
This compression is mainly accompanied by a feeling of cold, a possible weakening of the pulse and even pulselessness. However, rapid fatigue when working with the hands or even when working overhead, such as when painting the ceiling or combing, can also be an indication of Thoracic outlet Syndrome. If the thoracic outlet syndrome mainly compresses the arterial vessel, the affected arm may have a lower blood pressure than the healthy side. However, if the thoracic outlet syndrome only compresses the nerves or veins, the blood pressure in the affected arm does not change.