Case 6 - Moyamoya Syndrome

Dr. Yousem has provided the following report as a sample report for your reference. It does not match the case reviewed in the video.

Indication: Left M in the lower extremity weakness. CTA concerning for bilateral carotid clots versus spasm. NIH stroke scale 3. Concern for moyamoya.

TECHNIQUE: Axial CT scan images were performed through the brain without contrast. These are followed by CT angiographic images with CT perfusion protocol.

FINDINGS: There is effacement of the sulci of the right inferior frontal lobe in part secondary to patient's motion artifact. There is no evidence of intracranial hemorrhage. There appears to be focal lacunar infarction in the globus pallidus on the right side.

CT angiographic images show diminution in the caliber of the left M1 segment of the middle cerebral artery and both cavernous internal carotid arteries. The supraclinoid left internal carotid artery is nearly occluded with high-grade stenosis. The petrous internal carotid arteries are small in caliber, left worse than right. There is rapid tapering of the internal carotid artery caliber shortly after the carotid bifurcations. The common carotid arteries show no areas of stenosis. The patient has a balanced vertebral artery system without stenoses with large V4 segments supplying the basilar artery. The left A1 segment is narrowed. The termination of both supraclinoid internal carotid arteries shows narrowing with moyamoya effect on the right side more so than the left side.

The distal anterior cerebral and middle cerebral artery branches show no focal stenoses. The posterior cerebral arteries are unremarkable bilaterally.

On the perfusion sequences the cerebral blood flow maps are symmetric from side to side. The cerebral blood volume maps show slight asymmetry in the white matter blood volume. The mean transit time shows mild central delay bilaterally and symmetrically. 

The same is true with the time to drain with mild watershed anterior delay. Overall the time to drain and Tmax studies show slower drainage of the anterior circulation compared to the posterior circulation.

Impression:

Vascular stenoses of bilateral supraclinoid internal carotid arteries and left M1 segment with moyamoya effect on the left side. No thrombi are detected.

CT perfusion shows no evidence of current infarction but with bilateral diffuse hypoperfusion on time to drain and Tmax and the anterior circulation compared to the posterior circulation especially affecting the watershed zone on the left side between the anterior cerebral and posterior cerebral arteries.

MRI BRAIN WO CONTRAST

INDICATION: c/f moya moya disease and secondary strokes rate headaches, dizziness, acute onset left-sided weakness.

TECHNIQUE: Multiplanar multisequence magnetic resonance images of the brain without intravenous contrast.

COMPARISON: CTA performed same day

FINDINGS:

Innumerable punctate areas of cortical and subcortical restricted diffusion are noted throughout the paramedian frontal lobes bilaterally with extension into the centrum semiovale and corona radiata (right more than left). Additional foci restricted diffusion within the right parietal lobe and right posterior temporal lobe, right periatrial periventricular white matter, right head of caudate and right globus pallidus. Lesions in both cerebral hemispheres show variable signal intensities, suggesting variability in age, acute to subacute. 2 the more subacute appearing lesions within the left centrum semiovale/corona radiata show signal loss on SWI (series 12, image 61). This appears to correspond to the areas of increased time to drain and Tmax on the CT perfusion exam.

There is no significant mass effect. The ventricles are normal in size configuration without hydrocephalus. Loss of the left M1 flow void again noted. Slow flow within the right distal MCA branches suspected on FLAIR. Midline structures are normal. 

Posterior fossa is unremarkable.

Paranasal sinuses are clear. No mastoid effusions. Calvarial marrow signal is within normal limits.

IMPRESSION:

Innumerable foci of subcortical and cortical restricted diffusion within the paramedian frontal lobes, right parietal lobe, right posterior temporal lobe and right deep gray nuclei patible with acute/subacute infarcts, a minority of which are associated with microhemorrhage. Findings are most suggestive of embolic phenomenon, possibly cerebral fat emboli in this clinical context.
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MRI BRAIN STROKE WO CONTRAST AND MRA

INDICATION: hx moya moya syndrome, recent stroke admission, now with stuttering sx's eval for hypoperfusion vs new stroke

TECHNIQUE: Multiplanar multisequence magnetic resonance images of the brain without intravenous contrast. 3D time-of-flight MRA of the head with MIPs.

COMPARISON: Catheter angiogram 1/29/20, MRI 1/27/20, CTA 1/27/20.

FINDINGS:

MRI BRAIN:

Several new areas of cortical and subcortical reduced diffusivity throughout the right middle and superior frontal gyri compared to 1/27/20 indicative of new infarcts in the right ACA and MCA territory. The dominant infarct measures 2.2 x 1.5 cm in the right anterior frontal lobe. New punctate infarcts are also noted in both the right precentral and post-central gyri. Punctate infarcts also noted in the right temporal lobe, right putamen and head of caudate and left paramedian frontal lobe from prior.

Several late subacute/chronic infarcts are also seen in the paramedian frontal lobes, right more than left, as well as the right periventricular white matter from infarcts on prior. Slow flow in right hemispheric perisylvian MCA branches flow voids is less apparent on this exam, although minimal FLAIR hyperintense signal is noted in the inferior left frontal vascular structures similar to the previous exam.

There is cerebellar volume loss present, similar to the prior study. No evidence of hydrocephalus.

No evidence of hemorrhage on susceptibility weighted imaging. Marked tapering of the anterior circulation flow voids in keeping with moya moya disease, similar to prior. 

The included paranasal sinuses are clear. The mastoid air cells are clear.

The marrow signal is within normal limits.

MRA HEAD: 

Moderately small caliber of the petrocavernous ICAs bilaterally, left more than right. Again seen is occlusion of the opthalmic segment of the left cavernous ICA with reconstitution of the moderately narrowed supraclinoid segment. Moderate to severe narrowing the right supraclinoid segment. 

Significantly diminished caliber of the M1 segments bilaterally, more so on the left side. Posterior left M2 branches are not seen, as on prior.

Apparent 9 mm short segment occlusion of the mid A2 segments bilaterally (image #1) with partially imaged reconstitution. An artifact is not excluded. The A1 segments are not clearly seen on this exam, likely related to diminished flow and technical limitations.. A patent anterior communicating artery is visualized.

Posterior cerebral arteries are patent and prominent with visualization into the distal portions posteriorly. Bilateral posterior communicating arteries are patent. Prominent PCA-MCA collaterals are noted in the posterior temporal regions. 

No significant stenosis of the vertebral arteries. The basilar artery is patent.

No evidence of aneurysm or arteriovenous malformation.

IMPRESSION:

1. Several new acute infarcts in the right paramedian frontal lobe, right pre and post-central gyri, and right lentiform nuclei in addition to new punctate infarcts in the right temporal lobe and left paramedian frontal lobe. These involve the right ACA and MCA distributions with some infarcts in the right ACA-MCA watershed distribution.

2. Subacute/chronic appearing infarcts again noted in both cerebral hemispheres as seen on the prior exam.

3. Moderate to marked bilateral supraclinoid ICA steno-occlusive disease (left more than right) with marked tapering/occlusion of the left M1 vessels compatible with moya-moya phenomenon as depicted on prior angiograms. 

4. Apparent occlusion of the A2 segments bilaterally which was better depicted on the prior angiogram. Non-visualized and possibly near occluded A1 segments, with poor visualization compared to prior CTA.