13 Right Internal Carotid Artery Stenosis in Fibromuscular Dysplasia and Granulomatosis with Polyangiitis (formerly Wegener’s Granulomatosis)

Case 13


Right Internal Carotid Artery Stenosis in Fibromuscular Dysplasia and Granulomatosis with Polyangiitis (formerly Wegener’s Granulomatosis)


Clinical Presentation


A 51-year-old woman presented with stepwise deterioration of a left hemiparesis that had started 3 days before admission. The medical history revealed chronic rhinitis, sinusitis, and bronchitis but no vascular risk factors. On neurologic examination, the patient had a severe left-sided brachiofacial hemiparesis (National Institutes of Health Stroke Scale [NIHSS] score: 8). In addition, she had nasal congestion.


Initial Neuroradiologic Findings


Cerebral CT (CCT) scan on the day of admission revealed ischemic infarction in the anterior and posterior territories of the right middle cerebral artery (MCA). MRI was not performed (Fig. B13.1).


Suspected Diagnosis


Ischemic brain infarction in the right MCA territory of unknown origin.


Question to Answer by Ultrasound Techniques



  • Was there evidence of a stenotic process, particularly in the right internal carotid artery (ICA) or MCA?

Initial Neurosonologic Findings (Day 1)


Extracranial Duplex Sonography


B-mode sonography revealed only mild atherosclerosis of the carotid arteries. Color imaging showed elongation and caliber variations of both distal ICAs, but predominantly affecting the right side. Blood flow velocity in the proximal right ICA was mildly reduced (flow velocity: 47/24 cm/s) and the pulsatility slightly increased. Within the distal segment of the right ICA, a non-angle-corrected peak systolic flow velocity of 250 cm/s was observed. Normal flow velocities were seen in the remaining extracranial vessels (Fig. B13.2 and Fig. B13.3).


Transcranial Duplex Sonography


The temporal window was inadequate for a complete insonation of the anterior circulation. Punctual signals of the proximal M1-MCA could be obtained, revealing an obvious flow velocity difference between the two sides (flow velocity: right M1-MCA, 57/25 cm/s; left M1-MCA, 111/55 cm/s) (not shown). The calculated Zanette asymmetry index for the systolic velocities was 64 and the right-to-left ratio (= velocity of the affected M1/normal M1 velocity) was 0.51. Assessment of the other intracranial vessels showed normal and symmetric flow signals.


Conclusion


Distal extracranial right ICA stenosis, ~70%. Suspected right distal M1-MCA occlusion, probably embolic in nature.


Clinical Course (1)


Thrombolysis was not indicated because of the time delay and the signs of infarction on CT. The above vascular changes in a relatively young patient without classic vascular risk factors did not favor an atherosclerotic etiology. In particular, no arterial hypertension was present. Normal 24-hour ECG and echocardiography made a cardioembolic source unlikely. There was no coagulopathy involving proteins C and S, anticardiolipin antibodies, activated protein C resistance, and lupus inhibitor. The cerebrospinal fluid (CSF) was normal. In view of the history of chronic rhinitis, sinusitis, and bronchitis, specific laboratory tests were performed which revealed an increased erythrocyte sedimentation rate (ESR) (70 mm/hour, Westergren), mild anemia, and thrombocytosis of 1,200/nL (normal range 130–340/nL), but normal white blood cell counts. In addition, the level of cytoplasmic antineutrophilic cytoplasmic antibody (cANCA) was increased to 98 E/mL (normal value <15 E/mL), and urine proteins and erythrocytes were elevated. Finally, a nasal mucosa biopsy confirmed granulomatosis with polyangiitis (GPA; formerly known as Wegener’s granulomatosis).


Conventional Angiography (Day 5)


Digital subtraction angiography (DSA) was performed to examine the presumed ICA stenosis and to rule out vasculitis. Multiple irregular concentric constrictions with normal and dilated intervening segments were found in both distal extracranial ICAs, though predominantly affecting the right side. This “string of beads” pattern led to the diagnosis of fibromuscular dysplasia (FMD) (Fig. B13.4 and Fig. B13.5). Mild caliber variations were also seen in the left distal vertebral artery (VA) and the right renal artery. The intracranial vessels, in particular the MCA branches, were not affected. Dissection and vasculitis were excluded.


Clinical Course (2)


A recurrent artery-to-artery embolism from the greater affected right ICA was assumed to be the most likely cause of the stroke. Antiplatelet therapy was therefore commenced for secondary stroke prevention. Interventional treatment by stenting or surgery was not recommended because of the complex vessel pathology and GPA. The GPA was treated with cyclophosphamide and corticosteroids. A clinical follow-up 6 months after the initial presentation showed only a minor improvement of the hemiparesis. ESR and cANCA had normalized during the immunosuppressive therapy. Cranial CT scan showed the residual large ischemic MCA territory infarction (Fig. B13.6). On this occasion MRI was also performed which demonstrated Wallerian degeneration of the pyramidal tract up to the pyramidal decussation (Fig. B13.7). The patient remained asymptomatic over the subsequent 5 years.



Follow-up Neurosonologic Findings (5 Years)


Extracranial Duplex Sonography


B-mode sonography revealed unchanged mild atherosclerosis of the carotid arteries. In the right common carotid artery (CCA), a high-resistance flow signal was seen. The right external carotid artery (ECA) showed an “internalized” low-resistance flow signal, indicating orbital collateral flow. Doppler spectrum analysis of the proximal right ICA demonstrated a “stump signal” (Fig. B13.8 and Fig. B13.9).


Transcranial Duplex Sonography


The transcranial bone window had further worsened. Doppler spectrum analysis of the right MCA revealed a positive oscillation effect on slight digital tapping of the left ICA at the submandibular level but not of the dominant VA at the atlas loop. The anterior communicating artery (ACoA) demonstrated turbulent flow. The remaining intracranial vessels could not be visualized. The ophthalmic arteries (OAs) were not examined.



Conclusion


Right ICA occlusion secondary to FMD. Suspected collateralization via the contralateral A1-ACA (cross-flow) and ipsilateral OA.


Final Diagnosis


Large territorial MCA infarction caused by artery-to-artery embolism originating from the right ICA that was severely affected by FMD. Thrombocytosis due to GPA may have been a predisposing cofactor. Secondarily, clinically asymptomatic right extracranial ICA occlusion.




Jun 20, 2018 | Posted by in NEUROSURGERY | Comments Off on 13 Right Internal Carotid Artery Stenosis in Fibromuscular Dysplasia and Granulomatosis with Polyangiitis (formerly Wegener’s Granulomatosis)
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