connect.
enrich.
support.
What causes TOS?
Neurogenic TOS
Typically, NTOS is caused by a combination of the following:
(1) Being born with anatomical variations and anomalies within the thoracic outlet such as:
-
Cervical rib
-
Elongated C7 transverse process
-
Fibrous bands
-
Enlarged scalene muscles
-
Fused scalene muscles
-
Extra scalene muscle (scalene minimus)
-
Anomalous first rib
and
(2) Acquired anatomical changes within the thoracic outlet such as either:
-
An injury/trauma to the head, neck, shoulder or arm. Most commonly this is a hyperextension neck injury (such as whiplash) or a fall on an outstretched arm.
and/or
-
An occupation/sport/hobby that requires repetitive, heavy or overhead use of the arms such as swimming, baseball pitching, weightlifting, mechanic, violinist, hairdresser, dental assistant, factory work or any job requiring a lot of typing.
Venous TOS
Typically, VTOS is caused by a combination of the following:
(1) Being born with anatomical variations and anomalies within the thoracic outlet such as:
-
Abnormal vein positioning
-
Anomalous first rib
-
Costoclavicular ligament insertion point being further away from the sternum than usual
-
Thickened or enlarged subclavius muscle
-
Enlarged or hypertrophied anterior scalene muscle
-
Fibrous bands
and
(2) Acquired anatomical changes within the thoracic outlet such as either:
-
An injury/trauma to the chest or shoulder resulting in first rib or collarbone (clavicle) fracture or sometimes even a fracture of the first rib without a known cause and that doesn’t show up on x-rays.
and/or
-
An occupation/sport/hobby that requires repetitive, heavy or overhead use of the arms such as swimming, baseball pitching, weightlifting, mechanic, violinist, hairdresser, dental assistant, factory work or any job requiring a lot of typing.
Sometimes, another contributing factor to VTOS is the patient having a blood clotting disorder.
Arterial TOS
Typically, ATOS is caused by the following:
Being born with anatomical variations and anomalies within the thoracic outlet such as:
-
Cervical rib
-
Elongated C7 transverse process
-
Anomalous first rib
Occasionally, the following can also cause and/or contribute to ATOS:
-
Fibrous bands
-
Enlarged scalene muscles
-
Fused scalene muscles
-
Bony abnormalities related to fractures of the collarbone or first rib
Pec Minor Syndrome
Since this is commonly present along with NTOS, the causative factors listed above for NTOS can also apply to Neurogenic PMS. Typically, PMS is caused by acquired anatomical changes within the thoracic outlet such as either:
(1) An injury/trauma such as a fall or car accident.
and/or
(2) An occupation/sport/hobby that requires repetitive, heavy or overhead use of the arm or
shoulder such as swimming, baseball pitching, weightlifting, volleyball, or factory work.
