9  Moyamoya Disease

Case 9


Moyamoya Disease


Clinical Presentation


A 32-year-old white man was admitted after suffering a mild brachiofacial weakness, aphasia, and a homonymous hemianopia to the right side. He was a smoker. No further vascular risk factors were present. On admission, no sensorimotor deficit was detected but he had a right homonymous hemianopia and mild fluent aphasia (National Institute of Health Stroke Scale [NIHSS] score: 3).


Initial Neuroradiologic Findings


Immediately performed MRI demonstrated on diffusion-weighted images a large acute territorial left occipital ischemia in the posterior cerebral artery (PCA) territory as well as a small territorial left parietal precentral infarction in the left middle cerebral artery (MCA) territory. FLAIR-weighted images unmasked a right frontal territorial infarction in the anterior cerebral artery (ACA) territory. Furthermore bilateral small internal border zone infarctions (BZI) and dilated leptomeningeal vessels pronounced on the left hemisphere were detected. Also, a moderate parietal accentuated hemiatrophy was seen on the right side. Contrast-enhanced MR angiography (ce-MRA) showed signs of bilateral distal carotid artery occlusion in otherwise normal extracranial brain-supplying arteries. The MCA and ACA were undetectable on both sides. Instead, multiple small vessels were seen. Otherwise, the insular and cortical branches appeared normal. Intracranial time-of-flight (TOF) MRA was also suspicious for bilateral proximal MCA and ACA occlusion. However, on T2-weighted images both M1-MCAs could be depicted by their signal voids, indicating real flow in these vessels (Fig. B9.1, Fig. B9.2, Fig. B9.3, Fig. B9.4). Because of the large infarcted areas no thrombolysis was performed.


Suspected Diagnosis


Bilateral territorial and hemodynamic infarctions in bilateral severe steno-occlusive distal internal carotid artery (ICA) pathology compatible with moyamoya disease (MMD).


Conventional Angiography (Day 3)


Selective ICA contrast filling demonstrated bilateral terminal ICA occlusion. Furthermore, a network of small capillary collateral vessels was visible in the region of the distal ICA and proximal MCA. The distal branches of both MCAs and ACAs, seen in the late arterial phase, showed regular contrast. In addition, a collateral leptomeningeal flow was seen via the posterior communicating artery (PCoA) and dural anastomoses on the right side. Selective left vertebral artery (VA) filling yielded a prominent right PCA and the suspicion of a left distal PCA occlusion. Similar to the anterior circulation, a network of small vessels indicating collateral pathways was seen in the area of the proximal PCA (Fig. B9.5, Fig. B9.6, Fig. B9.7, Fig. B9.8).


Conclusion


Moyamoya disease stage IV with acute left MCA and PCA territorial strokes in severe carotid-T pathology and left-sided PCA occlusion.


Clinical Course (1)


The neurologic deficits partially regressed and the patient was started on aspirin for secondary stroke prevention. For further occupational and physiotherapeutic treatment he was transferred to a rehabilitation center and an extracranial–intracranial (EC–IC) bypass was recommended to be performed after rehabilitation. A first detailed ultrasound examination was performed in the rehabilitation center.


Questions to Answer by Ultrasound Techniques



  • Was there any evidence of pathologic vascular changes in the cervical vessels?
  • Was there antegrade flow detectable in the MCA and ACA on both sides?
  • Were the proximal PCAs also involved in the stenoocclusive process?
  • Could the collateral blood flow be assessed?

Initial Neurosonologic Findings (Week 6)


Extracranial Duplex Sonography


B-mode and color-mode imaging revealed no atherosclerotic vascular changes. The lumen of both ICAs appeared reduced compared with the diameter especially of the right VA. Doppler spectrum analysis showed normal and symmetric flow signals, but volume flow measurements showed mildly reduced flow in the ICAs and compensatory increased flow in the VAs (Fig. B9.9 and Fig. B9.10).










Transcranial Duplex Sonography


Despite good insonation conditions, the distal ICA could not be detected on both sides. Using color-mode imaging, a network of small arteries was visible in both perimesencephalic cisterns. Both M1-MCAs revealed a poststenotic flow pattern, severely affected on the right side and moderate affected on the left side. Bilateral flow velocities were markedly reduced. A similar flow profile was observed in the right A1-ACA and no signal could be depicted in the left A1-ACA. The left PCA was patent. Turbulent flow and markedly raised flow velocities were observed in both P1/P2-PCA segments and also in cortical PCA branches, i.e., in the anterior temporal artery (ATA) and in the occipitotemporal artery (OTA). The ubiquity phenomenon in all accessible PCA segments was suggestive for increased collateral flow but did not rule out the presence of additional stenoses (Figs. B9.11B9.18; see also Video images B9.1).






Jun 20, 2018 | Posted by in NEUROSURGERY | Comments Off on 9  Moyamoya Disease
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