41 Right Internal Carotid Artery as the Remaining Patent Brain-supplying Artery

Case 41

Right Internal Carotid Artery as the Remaining Patent Brain-supplying Artery

Clinical Presentation

A 51-year-old man was admitted to the hospital with recurrent worsening of a pre-existing dysarthria which he had acquired 4 years earlier due to a left-sided rostral paramedian medullary infarction. The infarct, diagnosed in a different hospital, was assumed to be caused by a proximal basilar artery (BA) occlusion which showed collateralization from the anterior circulation. Furthermore, an asymptomatic left-sided internal carotid artery (ICA) occlusion was reported. Since then he had been treated with aspirin, a statin, and β-blockers. His neurologic examination showed a mild right-sided sensorimotor hemiparesis and dysarthria, the degree of which seemed unchanged. Arterial hypertension was his only known vascular risk factor. On admission, however, his systolic blood pressure was low, at ~100 mm Hg.

Initial Neuroradiologic Findings

Acute cerebral MRI was performed because of the posterior circulation pathology mentioned above. Diffusion-weighted images disclosed acute vascular lesions. FLAIR sequences showed a slim left paramedian rostral medullary infarct. On contrast-enhanced MR angiography (ce-MRA) the reported left ICA occlusion was confirmed. The vertebrobasilar arteries showed a left vertebral artery (VA) occlusion distal of the posterior cerebellar artery (PICA) origin, and a right-sided complete PICA-ending VA. The BA was visualized over its entire length with a small vessel lumen. Intracranial time-off-light (TOF) MRA showed reduced brightness of the left middle cerebral artery (MCA), indicative of hemodynamic restrictions and no BA and left V4-VA signal. Furthermore, a left fetal-type (FT) posterior cerebral artery (PCA) and a right posterior communicating artery (PCoA) could be identified (Fig. B41.1, Fig. B41.2, Fig. B41.3, Fig. B41.4).

Suspected Diagnosis

Recurrent brainstem ischemia of possible hemodynamic origin in severely impaired vertebrobasilar circulation and left-sided ICA occlusion.

Questions to Answer by Ultrasound Techniques

  • Was there atherosclerosis causing the vasculopathy of the anterior and posterior circulation?
  • Could the left ICA occlusion, the left distal VA occlusion, and the right PICA-ending VA be confirmed?
  • If yes, what were the hemodynamic consequences on intracranial flow?

Neurosonologic Findings (Day 2)

Extracranial Duplex Sonography

B-mode imaging showed moderate mixed echogenic plaques in both carotid bifurcations. A stenosis was seen in the right external carotid artery (ECA). The right common carotid artery (CCA) was wider than the contralateral CCA. No flow was detected in the left ICA. A markedly increased flow velocity and blood volume flow (BVF) of 630 mL/min was seen in the right ICA. The left V2-VA displayed normal diameter of 3.2 mm and the right VA a smaller diameter of 2.6 mm. Both vessels had a mildly increased pulsatility with a preserved diastolic flow (Figs. B41.5B41.12).

Transcranial Duplex Sonography

Transtemporal insonation on the right side revealed normal flow parameters in the M1-MCA and markedly increased flow velocities in the A1-ACA. The flow in the left-sided A1-ACA was retrograde and a moderately post-stenotic flow pattern was seen in the left M1-MCA. The anterior communicating artery (ACoA) revealed a functional stenosis. On both sides, a prominent PCoA was detectable with a flow toward the posterior circulation. On the right side, a prominent retrograde P1-PCA flow was detectable, which could be followed up to the reversed perfused distal BA. The right P2-PCA showed a normal flow signal. The left P2-PCA had a poststenotic flow pattern similar to the ipsilateral M1-MCA, so an FT-PCA was considered. Transforaminal insonation confirmed a retrograde BA flow with low flow velocities. Both V4-VA yielded flow signals different from the V2-VA flow signals, which was considered to be an angle-related phenomenon. The right ophthalmic artery (OA) revealed a normal antegrade flow. The left OA was internalized and had a retrograde flow (Figs. B41.13B41.29; see also Video images B41.1).

Jun 20, 2018 | Posted by in NEUROSURGERY | Comments Off on 41 Right Internal Carotid Artery as the Remaining Patent Brain-supplying Artery
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