PMC9660269_01
(A) Computed tomography (CT)-scan of the neck in neutral position, axial
image at level C5. No obstruction is visible. Aberrant course of the
right vertebral artery (VA) is evident, along with a hypoplastic left
VA. (B) Computed tomography (CT)-scan of the neck with rotation of the
neck to the right, axial image at level C6. The superior cornu (c) of
the thyroid cartilage is seen, with the anterior tubercle (t) of C6
transverse process almost touching the thyroid cartilage. The right
carotid artery (RCA) is seen, and the jugular vein is compressed. The
right vertebral artery is completely occluded and is not visible on this
scan at this level.
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The right VA traversed anterior to an enlarged C6 tubercle of the transverse process, between longus colli and longus capitis muscles at levels C4-5, and entered the foramen transversarium at C4 (Figure 1A). This was felt to be secondary to compression between the longus colli and the longus capitis muscles against an enlarged anterior C6 tubercle of the transverse process (Figure 1B).
Computed tomography (CT)-scan of the neck during maximal ipsilateral
rotation of the neck causing dizziness. (A-D) Axial images from caudal
(level vertebra C6) to cranial (level vertebra C5). Long arrow: right
vertebral artery (VA) compressed by the lateral border and superior
cornu of the thyroid cartilage. Triangular arrow: left hypoplastic VA.
Note lacking anterior tubercle of the transverse process C6 due to
previous compressive surgery.
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A new CT-scan during provocation of symptoms by right sided neck rotation revealed significant focal narrowing of the right VA at C6 level from extrinsic compression from the adjacent posterior border and superior cornu of the thyroid cartilage (Figure 2).
Perioperative image of the thyroid cartilage with resection marked
out on the right side of the thyroid cartilage. Strap muscles are
retracted anteriorly.. Abbreviations: L, left; R, right; *, thyroid notch.
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After freeing the thyroid cartilage from the overlying straps, the resection was marked out to include the lateral thyroid cartilage and superior cornu (Figure 3).