TOS-Test (Thoracic Outlet Syndrome)

Description

Thoracic outlet syndrome (TOS) is a condition in which there is compression of the nerves, arteries, or veins in the passageway from the lower neck to the armpit.

Usually, extrinsic factors are responsible for the symptoms of TOS, but an aneurysm of the subclavian artery can also trigger TOS. Intrinsic factors, such as activities that have been carried out for many years with heavy strain on the muscles, especially in competitive athletes or musicians for example, are some common triggers for TOS. This action of the extrinsic as well as intrinsic factors can cause compression of the vessels.

Measurement Principle

Do determine whether the cause of the symptoms is from a vascular or neurogenic origin, the patient is usually advised to perform a series of provocation tests in different postures while the arterial blood flow in his arms is measured. These test protocols vary depending on country or institution and might include:

Turning the head to the affected side with lifting the chin and deep inspiration, as well as an additional pull of the arm downwards. May lead to a disappearance of the radial pulse and symptoms.
Disappearance of the radial pulse when the arm is raised, when withdrawing the shoulder or turning the head may be observed.

The aim is to determine whether the patient’s blood flow decreases when a specific posture is maintained. To do so, modern systems apply optical PPG sensors on left and right index fingers to record the pulse oscillations during provocation.

Main Parameters

Parameter	Unit	Description
AMPLITUDE	%	The height from the beginning of the steepest rise to the highest point of the pulse curve is the amplitude.
RISE TIME	ms	The rise time marks the time interval of the steepest rise to the highest point of the pulse curve. It should be < 200 milliseconds for normal values.
RISE TO FALL	%	The quotient, stated in percentage, of rise time and fall time. It should be < 33% for normal values.
SKIN TEMPERATURE	°C	Skin temperature on toes recorded by the probes on the optical sensors. Side differences of more the 3 °C should be observed.

Medical Applications

Suspicion of TOS (Thoracic Outlet Syndrome)

Test Examples

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Table of Contents

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