Angiographic findings suggesting Moyamoya syndrome with a proximal pseudo-stenosis appearance due to terminal internal carotid artery occlusion: A case report

Introduction: Moyamoya is a cerebrovascular disease characterized by progressive steno-occlusive changes in the terminal internal carotid artery and its main branches, with an accompanying abnormal collateral vessel network. When similar angiographic findings occur together with an underlying disease, it is defined as Moyamoya syndrome. This report presents a patient in whom angiography showed findings suggestive of Moyamoya syndrome.Case: A 66-year-old man who had had transient numbness in the fingers one month earlier and in the left face, arm, and leg one week earlier had been evaluated at another center with a preliminary diagnosis of transient ischemic attack, and acetylsalicylic acid and clopidogrel had been started. He was referred to our center because of suspected near-occlusion of the right internal carotid artery (ICA). His history included hypertension and rheumatoid arthritis diagnosed at another center. Elective digital subtraction angiography (DSA) was planned. His neurological examination was unremarkable. Carotid Doppler ultrasonography showed flow changes in the right ICA suggesting advanced stenosis or occlusion at the cranial level. Computed tomography angiography showed that the right ICA was thin in caliber from its origin and markedly thinned in the intracranial segment. On DSA, the right ICA narrowed from the distal bulb and filled very poorly up to the terminal segment, and no flow was seen in the middle cerebral artery (MCA) or anterior cerebral artery (ACA) beyond the terminal ICA. This appearance of a proximally tapering ICA was interpreted as pseudo-stenosis due to terminal ICA occlusion, with a dissection-like appearance. (Figure 1 A and B) In the left ICA terminal segment there was 90% focal stenosis, with areas of neovascularization around it that created a smoke-like appearance in the capillary phase. Flow was present in the left MCA and ACA. (Figure 2 A and B) Selective injection of the left vertebral artery showed collateral filling of the anterior circulation through the posterior communicating arteries. (Figure 2 C) Because of the history of rheumatoid arthritis and chronically elevated acute-phase reactants, vasculitis investigations for secondary causes were planned.Discussion/Conclusion: In this case, DSA showed bilateral intracranial steno-occlusive changes and neovascularization consistent with Moyamoya. Because of the history of rheumatological disease, Moyamoya syndrome was considered more likely than primary Moyamoya disease. Detailed evaluation of the angiographic pattern and investigation of secondary causes are important for differential diagnosis, particularly in atypical carotid stenoses.Keywords: