23 Takayasu’s Arteritis with Right-sided Subclavian Steal

Takayasu’s Arteritis with Right-sided Subclavian Steal

Clinical Presentation

A 32-year-old man of Turkish origin was admitted with an episode of unconsciousness that lasted for ~2 minutes, and was then followed by nausea and vomiting. He complained about worsening of his visual acuity in the preceding 3 days. Several years earlier he had sustained a similar episode of unconsciousness that at the time was considered to be due to orthostatic dysregulation. At that time, no neurologic examination or cerebral imaging had been performed. The patient had no vascular risk factors and no relevant past medical history. On neurologic examination, he had left complete and right partial homonymous hemianopia (National Institute of Health Stroke Scale [NIHSS] score: 3). In addition, asymmetric radial pulses were noted.

Initial Neuroradiologic Findings

MRI showed bilateral subacute occipital ischemic brain lesions in the posterior cerebral artery (PCA) territory (Fig. B23.1). MR angiography (MRA) was not performed.

Suspected Diagnosis

Transient “top of the basilar” syndrome with incomplete cortical blindness caused by bilateral infarction in the PCA territory.

Questions to Answer by Ultrasound Techniques

Was there evidence of pathologic change in the vertebrobasilar system?
If so, was it of atherosclerotic or vasculitic origin?

Initial Neurosonologic Findings

Extracranial Duplex Sonography

There was no evidence of atherosclerotic or vasculitic changes in the carotid arteries. The caliber of both vertebral arteries (VAs) was normal (left 4.5 mm; right 3.9 mm). The left VA presented a poststenotic flow pattern with delayed systolic flow increase and reduced flow velocity in its V2 segment. At its origin an increased flow reaching 246 cm/s peak systolic flow velocity was detected. The left subclavian artery (SA) was not visualized. Doppler spectrum analysis of the right V2-VA segment revealed alternating, mostly retrograde flow. Muscular activity of the right arm led to an increase of the retrograde flow component. The right SA was not detectable (Fig. B23.2, Fig. B23.3, Fig. B23.4, Fig. B23.5; see also Video B23.1). A normal triphasic flow signal was seen in the left brachial artery. The right brachial artery revealed a poststenotic flow pattern with a monophasic flow signal and reduced pulsatility (not shown).

Transcranial Duplex Sonography

Normal findings were seen in both anterior and middle cerebral arteries. Both PCAs were visible but presented a marked poststenotic flow pattern in all segments with a band-like nonpulsatile flow and reduced flow velocities. Transforaminal insonation revealed a mildly poststenotic flow pattern in the left V4-VA segment and alternating flow in the right V4-VA segment. The basilar artery (BA) was not visualized (Fig. B23.6, Fig. B23.7, Fig. B23.8, Fig. B23.9; see also Video B23.2).

Conclusion

Proximal high-grade stenosis of the left VA and right-sided incomplete subclavian steal syndrome (grade 2) indicating high-grade stenosis or occlusion of the proximal right SA. In addition, marked hemodynamically compromised flow in both PCAs indicating no relevant collateralization from the anterior circulation via the posterior communicating artery (PCoA).

Conventional Angiography

Emergency digital subtraction angiography (DSA) was performed shortly after ultrasound examination and demonstrated a proximal short high-grade stenosis of the right SA proximal to the origin of the VA. The right VA was not visualized, but a high-grade stenosis was observed at the origin of the left VA, with collateral vessels in its vicinity. No further obstacle was seen in the left intracranial VA and in the BA. The flow in both PCAs appeared diminished, without signs of obstruction. Both carotid arteries were regular but no collateral flow was detectable via one or both PCoAs. Both renal arteries and the aorta were normal (Fig. B23.10, Fig. B23.11, Fig. B23.12).

Fig. B23.1 MR FLAIR image, axial plane. Bilateral occipital hyperintense areas (arrowheads) with right-sided accentuation considered to be subacute territorial PCA infarctions. Additional small left cerebellar lesion evaluated as small left superior cerebellar infarction.

Fig. B23.2 Extracranial duplex, longitudinal plane. Reduced flow velocity and pulsatility, suggesting a poststenotic flow pattern in the left V2-VA, which shows a normal diameter of 4.5 mm (flow velocity 36/16 cm/s).

Fig. B23.3 Extracranial duplex, longitudinal plane. Increased flow in the proximal left V1-VA segment (angle-corrected flow velocity 246/106 cm/s).

Fig. B23.4 Extracranial duplex, longitudinal plane. Alternating, but almost retrograde flow in the right V2-VA with a normal diameter of 3.9 mm (flow velocity 40/0 cm/s).

Clinical Course (1)

An artery-to-artery embolic event from the proximal left VA stenosis was thought to be the cause of the cerebral ischemia. An atherosclerotic etiology was considered unlikely because of the angiographic and ultrasound findings, the young age of the patient, and the lack of vascular risk factors. Infectious diseases were ruled out by laboratory tests and analysis of the cerebrospinal fluid (CSF). However, mild anemia, an increased erythrocyte sedimentation rate (ESR) of 47 mm/h, a C-reactive protein (CRP) level of 10 mg/L (normal <5 mg/L), and the involvement of the proximal vessel segments were suggestive of Takayasu’s arteritis. Long-term therapy with oral steroids (75 mg/day prednisolone) and antiplatelet therapy with aspirin was commenced. Six months later the patient was admitted for follow-up examination and ultrasound imaging.

Question to Answer by Ultrasound Techniques (6 Months)

Was there evidence of stenosis regression after the steroid treatment?