Moyamoya: superficial temporal artery to middle cerebral artery bypass
Presentation
Previous history of left brain vascular surgery due to a vasculo-occlusive disease.
Patient Data
Classical Moya-Moya findings include bilateral terminal ICA occlusions, bypassed by extensive lenticulostriate ("puff of smoke") and some ophthalmic collaterals, along with large caliber PCOM's.
Left STA-MCA bypass appears well patent.
Posterior circulation appears preserved.
Brain parenchyma and CSF spaces appear normal.
Cerebral Angiogram
Well-established features of MoyaMoya are demonstrated in both carotid circulations.
The extracranial carotid arteries are free of fibromuscular disease, focal stenosis or dissection, but of relatively small caliber.
Both vertebral arteries are large caliber vessels also free of significant disease.
On the left, there is a markedly enlarged posterior communicating artery supplying the posterior cerebral artery, with high-grade stenosis of the internal carotid artery above this adjacent to the anterior choroidal artery, and then with occlusion of the carotid "T".
Well-established Moya Moya collateral lenticulostriate vessels are shown, with some faint antegrade opacification of the A1 and A2 segments, but with most filling of the anterior cerebral circulation being retrograde from posterior cerebral artery pial collaterals.No definite macroscopic aneurysms are identified.
The left middle cerebral artery is predominantly filled through the craniotomy defect by branches of both the middle meningeal artery, and superficial temporal artery, with evidence of high flow retrograde filling of the middle cerebral artery branch to which it is attached, with then reflux and retrograde filling of the remainder of the middle cerebral artery territory.
Despite oblique views, a single focal anastomosis was difficult to define, and there was an area of diffuse hypervascularity, the latter especially supplied by the middle meningeal artery, and more in keeping with parasitized vessels from a vascularized graft.
On the right carotid the appearances of the posterior communicating, posterior cerebral and Para ophthalmic internal carotid artery similar, with occlusion of the supraclinoid internal carotid artery, with prominent collateral vessels.
Prominent pial retrograde filling of anterior cerebral artery territory is again demonstrated.
There was no appreciable filling of the cerebral circulation from selective external carotid artery injection.
Vertebral artery injections demonstrated the prominent posterior cerebral circulation with pial collaterals reconstituting much of the middle cerebral artery territory on the right, and a small amount on the left, together with anterior cerebral artery filling.
Conclusion:
MoyaMoya disease with bilateral terminal internal carotid artery occlusion, MoyaMoya lenticulostriate collaterals, and a high flow left external carotid-middle cerebral artery anastomosis, with supply from both middle meningeal and superficial temporal arteries
The patient was submitted to the first surgery, on the left side, when he was a child. Now he was submitted to a similar posterior on the right side.
Bilateral terminal ICA tapering occlusions, above the level of the relatively large caliber PCOM's, is again noted, along with mild-to-moderate residual lenticulostriate moyamoya phenomenon.
Bilateral STA to MCA bypasses appear patent, with MCA branches maintaining good flow signal beyond the Sylvian fissures. Accordingly, contrast-enhanced PWI shows relatively preserved cerebral blood flow and volume on both sides, with no major perfusion defect shown.
In addition, no overt infarct/ischemic change, diffusion restriction or magnetic susceptibility is shown, apart from a solitary 4 mm chronic ischemic focus in the posterior right frontal centrum semiovale.
In addition, no overt residual/recurrent intra/extra-axial hematoma is shown.
A small inferior basilar artery fenestration is evident, with no posterior circulation stenosis demonstrated.
The remainder of the study is unremarkable.
Case Discussion
Moyamoya disease is an idiopathic and non-inflammatory progressive vasculo-occlusive disease involving the circle of Willis, typically the supraclinoid internal carotid arteries.
Bypassing the occlusive segments is the aim of most surgical therapy and, as in this case, anastomoses can be performed between the superficial temporal artery to middle cerebral artery (STA-MCA).