Female 33 years old complains pain in right arm when she
has her arm in abduction and elevated position.
Ultrasound findings:
Fig 1: Right side of the image indicates normal dimension on
transversal section of the R subclavian artery (arrow) before the test by which
the patient elevates her arm in external rotation; left side of the image
indicates small dimension on transversal section of the R subclavian artery
during the test due to compression between the anterior scalene muscle anteriorly (white arrow
head) and exostosis of the first rib posteriorly (black arrow).
Figure 2:The spectrum waveform of
the radial artery before and during the test.
Fig 3: Longitudinal section of the R subclavian artery
indicates the stenosed segment with high flow velocity displayed by aliasing
phenomenon and post-stenotic dilatation
segment as well. Note that focal thickening of the wall of the R subclavian
artery at stenotic region (white arrow).
Fig 4: CT Angio images of the R subclavian artery demonstrate
the stenosed segment due to exostosis of the first rib (red arrow) and
poststenotic dilatation segment.
Diagnosis:
Thoracic outlet
syndrome in the first
space.
Discussion: Thoracic outlet syndrome (TOS)
is the name of a variety of conditions attributed to compression of the
neurovascular structures as they traverse the thoracic outlet. (TOS) can occur
at 3 spaces: 1/ The first space is the interscalene triangle. It is bordered by
the anterior scalene muscle, the middle scalene muscle, and the upper border of
the first rib. The interscalene triangle is the most common site for neural
compression, vascular compression. 2/ The second space is the costoclavicular
triangle, which is bordered by the clavicle, first rib, and scapula and
contains the subclavian artery and vein
and the brachial nerves; 3/ The third and final space is beneath the coracoid
process just deep to the pectoralis minor tendon; it is referred to as the
subcoracoid space.
Reference:
1.Daryl A Rosenbaum,
MD; Chief Editor: Sherwin SW Ho, MD. Thoracic Outlet Syndrome . http://emedicine.medscape.com.
2/ Paul B.
Kreienberg, Dhiraj M.Shah et al. Thoracic outlet syndrome. Vascular diagnosis.
Elsevier Saunders. 2005. P.512-522
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