Upper Limb Ultrasounds
Diagnostic Ultrasound for Arterial Evaluation of the Upper Limb
Performed to look at arteries and veins of the arm, the Upper Limb Ultrasound is taken with the arm in a number of positions to evaluate thoracic outlet syndrome. Diagnostic ultrasound can identify a number of other specific conditions to the arms and shoulder region including bursitis or wear and tear to joints and tendons.
Thoracic outlet syndrome poses quite a diagnostic dilemma. Symptoms are usually due to compression of the brachial plexus rather than the subclavian artery and may be difficult to differentiate from cervical spondylosis, carpal tunnel syndrome or the vasospastic disorders. Rarely the compression from a cervical rib is severe enough to result in aneurysmal dilatation of the artery and subsequent embolic episodes to the fingers or total occlusion of the artery.
The key to diagnosis is demonstration of obliteration of peripheral pulses on abduction and external rotation of the arm however up to 50% of normal men show evidence of positional reduction in flow. This finding is therefore only significant in association with symptoms of nerve compression.
Photoplethysmography probes are attached to fingers and recordings taken with the arm first at rest, then in a series of 5 different positions. This is followed up by an arterial duplex scan from the subclavian to the radial and ulnar arteries.
Vasospastic disorders include primary and secondary cold sensitivity of the Raynauds type, livedo reticularis and acrocyanosis. There is reduced arterial pressure to the extermities as a result of intense vasoconstriction and this can be documented by measuring a digital/brachial pressure index using Doppler ultrasound in a similar manner to the ankle/brachial pressure index in the leg. The test can be complimented by a cold water immersion test to precipitate symptoms