40 Left Internal Carotid Artery Occlusion and Ipsilateral Arteriovenous Malformation in Inflammatory Bowel Disease

Case 40


Left Internal Carotid Artery Occlusion and Ipsilateral Arteriovenous Malformation in Inflammatory Bowel Disease


Clinical Presentation


A 52-year-old otherwise healthy woman was admitted to the department of internal medicine with weight loss (5 kg) and frequent diarrhea that had been recurring over the past few weeks. Physical examination revealed signs of dehydration. Her initial laboratory work-up showed an increased C-reactive protein (CRP) of 140 mg/L (normal <5 mg/L), leukocytosis of 21,000 μg/L (normal < 11,000 μg/L), and moderate thrombocytosis of 650/nL (normal <400/nL). Colposcopy examination on the next day was suggestive of Crohn’s disease. That day, she developed recurrent episodes of right-sided hemiparesis and aphasia, each ranging from seconds to a few minutes. Subsequently, she was transferred to neurology with suspected brain ischemia. Other than smoking, no vascular risk factors were known. No headaches, facial, or neck pains were reported. Her neurologic examination was normal and, of note, no Horner’s syndrome was present.


Initial Neuroradiologic Findings


Cranial CT showed dilated cortical veins and spots of calcifications in the left frontoparietal hemisphere (Fig. B40.1).


Suspected Diagnosis


Transient ischemic attacks (TIA) considered as a steal phenomenon in a left-sided arteriovenous malformation (AVM).


Questions to Answer by Ultrasound Techniques



  • Were there signs of feeding arteries extracranially or intracranially?
  • Were there signs of draining venous vessels extracranially or intracranially?
  • Were there other vascular findings explaining the symptoms?

Initial Neurosonologic Findings


Extracranial Duplex Sonography


Duplex sonography revealed an unexpected proximal occlusion of the left extracranial internal carotid artery (ICA) without evidence of dissection or atherosclerosis. We observed a large, hyperechoic, partial floating structure in the left ICA (see also Video images B40.1). The right ICA and both vertebral arteries (VAs) showed high velocities and low pulsatility, which was most pronounced in the right ICA. For indirect assessment of the AVM shunt volume, blood volume flow (BVF) measurements were performed in all three remaining brain-supplying arteries. The calculated global BVF was 1,270 mL/min (right ICA 530 mL/min; left VA 290 mL/min; right VA 450 mL/ min), which was significantly increased in comparison to normal values from the literature (733 ± 54 mL/min). The left internal jugular vein (IJV) revealed a spiculated flow pattern indicative of an increased flow, whereas a normal flow signal was seen in the right IJV. The global circulation time measured between the right ICA and left IJV was shortened to 3 seconds compared with the normal value of 7 ± 1.3 seconds (Figs. B40.2B40.7; see also Video images B40.2).


Transcranial Duplex Sonography


Color-mode imaging through the left temporal window revealed a vascular nidus slightly above the cella media plane with atypical vessel signals in the midline and parasagittal region with an extension of 26 × 24 mm. Ipsilateral to the ICA occlusion, the M1 and M2 segments of the middle cerebral artery (MCA) had moderate poststenotic flow patterns, but normal flow velocities. Additional prominent insular MCA branches were seen distally and considered to partly feed the AVM. The A1 segment of the left anterior cerebral artery (ACA) had a very low-pulsatile, band-like antegrade flow pattern. Only one A2-ACA segment was detectable, showing a severely poststenotic flow pattern but normal flow velocities. Examination of the more distal A2-ACA segment revealed a severely turbulent and poststenotic flow pattern in projection of the pericallosal artery. The left P1 and P2 segments of the posterior cerebral artery (PCA) and its cortical branches presented markedly increased velocities. As pulsatility in the latter was normal, the observed high flow velocities were interpreted as collateral flow to compensate for the ICA occlusion and not as AVM feeding vessels. The left posterior communicating artery (PCoA) showed a functional stenosis. On the contralateral side, the right M1-MCA and PCA segments presented normal flow signals. An increased flow velocity was seen in the right A1-ACA and a functional stenosis in the anterior communicating artery (ACoA), both indicating collateral leptomeningeal flow to the left ACA territory and/or toward the AVM. Finally, a marked retrograde flow signal was seen in the left ophthalmic artery (OA). The right OA showed a normal antegrade flow (Figs. B40.8B40.21; see also Video images B40.3). Venous analysis showed a normal flow in the right basal vein of Rosenthal (BVR); the left BVR could not be detected. Mildly increased flow velocities were seen in the straight sinus (StS) and right transverse sinus (TS). The left TS revealed the highest flow velocities (Fig. B40.22 and Fig. B40.23).









Conclusion


The neurosonologic findings were, at least in part, difficult to interpret. Undoubtedly, a left nonathero-sclerotic ICA occlusion was present, probably caused by a fresh thrombus. Also, an AVM was clearly present, assured by the visualization of a left centroparietal parasagittal nidus. Difficulties arose during interpretation due to high flow velocities and low resistance flow patterns, which could have been interpreted as either (1) ICA occlusion-induced collateral flow, (2) AVM-induced hyperperfusion, or (3) a mixture of both conditions. The antegrade left A1-ACA flow indicated that the left MCA territory was mainly perfused via ipsilateral vessels, which were the PCA via the PCoA and the PCA via leptomeningeal collaterals, as well via the left OA. The major AVM feeder was assumed to be the left MCA, but also the contralateral ACA. Venous return seemed mainly to drain into ascending cortical veins via the superior sagittal sinus and to a lesser extent into the deep venous system with the left IJV as the final outflow vessel.


MRI, MR Angiography, and Dynamic MR Angiography


MRI ruled out both ischemia and hemorrhage, and showed the AVM nidus in the left parasagittal centroparietal region comprising enlarged veins and arteries. Cross-sectional examination of the neck vessels including T2 fat-suppressed images excluded ICA dissection as (1) the vessel lumen was not widened and (2) no vessel wall hematoma was visible. However, the vessel was filled by a moderate homogeneous mass, compatible with a thrombus. Time-of-flight MR angiography (TOF-MRA) confirmed left ICA occlusion and left AVM. Only one A2-ACA segment was visible, which was interpreted as an azygous anatomic variant. The latter, the pericallosal artery, and the left MCA were markedly dilated indicating their role as AVM feeders. The PCA appeared narrower. Contrast enhanced (ce) MRA again confirmed left proximal ICA occlusion near to its origin. Dynamic MRA showed AVM flow kinetics in more detail (Fig. B40.24, Fig. B40.25, Fig. B40.26, Fig. B40.27, Fig. B40.28; see also Video images B40.4).


Clinical Course


Repeated hemodynamic TIAs due to left ICA occlusion facilitated by diarrhea-induced exsiccosis were considered the most probable cause of the clinical symptoms. As no cardioembolic source could be identified, the ICA occlusion was interpreted as an in-situ thrombosis related to inflammatory bowel disease and thrombocytosis. The AVM had to be interpreted as an incidental finding and interventional treatment was rejected given the Spetzler–Martin grade (3 points; one point each for size, location, and deep venous drainage) and that no previous bleeding had occurred. The gastroenterologic complaints spontaneously remitted without specific treatment. The patient declined further endoscopic and laboratory examinations and was therefore discharged. Ultrasound and neurologic follow-up was arranged in 9 months.


Follow-up Neurosonologic Findings (10 Months)


Extracranial Duplex Sonography


The patient had done well. The left ICA remained occluded but no floating thrombotic material was present anymore (Fig. B40.29). No further changes were detected.


Jun 20, 2018 | Posted by in NEUROSURGERY | Comments Off on 40 Left Internal Carotid Artery Occlusion and Ipsilateral Arteriovenous Malformation in Inflammatory Bowel Disease
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