Case 30
History:
81 year old male with syncope
Findings:
Contrast enhanced MRA of the neck shows focal stenosis involving the left subclavian artery proximal to the take off of the vertebral artery. The corresponding axia l2 D time of flight shows no flow signal from the left vertebral artery. Doppler examination of the vertebral arteries show normal antegrade flow on the right and reversed flow on the left consistent with Steal phenomenon.
Diagnosis:
Subclavian steal syndrome (SSS)
Discussion:
Subclavian steal phenomenon (SSP) refers to subclavian artery steno-occlusive disease proximal to the origin of the vertebral artery and is associated with flow reversal in the vertebral artery. The term subclavian steal syndrome (SSS) should be reserved for retrograde vertebral artery flow associated with transient neurologic symptoms related to cerebral schema.
Patients are symptomatic when compensatory flow to the subclavian artery from the vertebral artery diverts too much flow toward the arm and away from intracranial structures. In SSS patients, risk of stroke is poorly documented but seems low, around 9 percent, however symptoms can be debilitating.
Doppler examination of the vertebral arteries typically shows reversed flow on the affected vessel. Contrast enhanced MRA of the neck shows focal stenosis involving the left subclavian artery proximal to the take off of the vertebral artery. The corresponding axial 2 D time of flight shows no flow signal from the left vertebral artery.
References:
- Bornstein NM, Norris JW. Subclavian steal: a harmless haemodynamic phenomenon? Lancet. Aug 9 1986;2(8502):303-5
- Ackermann H, Diener HC, Seboldt H, Huth C. Ultrasonographic follow-up of subclavian stenosis and occlusion: natural history and surgical treatment. Stroke. Apr 1988;19(4):431-5.
- http://emedicine.medscape.com/article/418203-overview
