Case Challenge

Brain

Vascular

Daniel Cornfeld

Gain confidence interpreting Subtle Strokes Cases on CT and MRI with MRI Online. Quiz yourself using real-world, interactive scrollable cases &amp; earn CME. Try it free!

Case Review

Neuroradiology

Vascular Imaging

Case 1 - 60-year-old with double vision and dizziness.

Case 2 - 65-year-old with altered mental status.

Case 3 - 65-year-old. Altered mental status.

Case 4 - 68-year-old. Dysphagia and aphasia.

Case 5 - 82-year-old with right hemiparesis.

Case 6 - 70-year-old with confusion.

Case 7 - 60-year-old with right sided weakness.

Case 8 - 70-year-old with right-sided weakness.

Case 9 - 68-year old with aphasia.

Case 10 - 50-year-old with right-sided weakness.

Case 11 - 65-year-old with right visual field defects.

Case 12 - 65-year-old with right-sided weakness.

Case 13 - 60-year-old with left-sided weakness.

Case 14 - 60-year-old with left-sided stroke symptoms.

Case 15 - 60-year-old with bilateral weakness.

Case 16 - 50-year-old with right-sided weakness.

Case 17 - 65-year-old with right-sided weakness.

Case 18 - 60-year-old with altered mental status.

Case 19 - 55-year-old with aphasia.

Case 20 - 60-year-old with left-sided weakness.

Case 21 - 60-year-old with left hemiparesis.

Case 22 - 60-year-old with left visual field defects.

Case 23 - 68-year-old with weakness.

Case 24 - 60-year-old with bilateral weakness.

Case 25 - 90-year-old with acute left hemiplegia.

Subtle Stroke Case Challenge

Course Evaluation

Post-Course Activities

Learn to master subtle stroke cases on CT and MRI! Gain experience detecting strokes on CT by reviewing the 25 cases of subtle strokes presented in this module. The purpose is not to comprehensively explain the role of imaging in the evaluation of acute stroke or to teach a junior physician how to approach a CT scan of the brain. Instead, by reviewing these difficult cases, the reader will become better at detecting the subtle CT findings of acute stroke. Some of these cases were initially interpreted correctly. Many were not.

Subtle Strokes Case Challenge

Case Findings (Scan 1)
Hemorrhage: No
Hydrocephalus: No
Herniation: No
Gray-white differentiation/wedge-shaped hypodensity/cortical involvement: Yes.
Subtle hypodensities in the left frontal corona radiata subcortical white matter, age-indeterminate though suspicious for acute infarct.
Deep gray nuclei: Preserved
Hyperdense vessels: None


Case Discussion:
1. Careful scrutiny of this motion degraded head CT axial images on stroke window may reveal 2 focal hypodensities seen in the periventricular white matter, specifically the left frontal 'corona radiata'. As an anatomical review, the subcortical white matter superior to the ventricles is referred to as the 'centrum semiovale', with the appearance of two half-moons. The corona radiata refers to the white matter tracts at the level of the ventricles. Written another way, if you see ventricles on axial imaging, the periventricular white matter is likely the corona radiata. If you do not see ventricles on axial imaging, the periventricular white matter is likely the centrum semiovale.

Periventricular white matter hypoattenuation is most commonly due to chronic small vessel angiopathy. Symmetry and stability when compared to prior exams are findings useful for excluding recent infarct. However in the absence of these features there is always the possibility the findings are due to recent stroke.


Imaging follow up MRI (Scan 2)
Subsequent brain MRI demonstrates an acute infarct centered in the left frontal corona radiata (high DWI, low ADC signal). Additionally, a much larger acute/subacute superior temporal infarct is evident (high DWI, low/isointense ADC) with regions of hemorrhage. These infarcts correspond to the left middle cerebral artery vascular territory, and the suggestion of differing ages potentially reflects embolic etiology.

This is another case where an extensive cortical infarct was occult on CT imaging despite retrospective review. The temporal lobes and occipital lobes tend to be difficult to assess for subtle cortical infarcts given beam hardening artifact related to the skull base, though scrutiny of the opercular regions with sagittal reformations is suggested, particularly in the setting of aphasia.
To further expand upon the temporal vascular territories, both the middle cerebral artery and posterior cerebral artery supply the temporal lobe. The middle cerebral artery supplies the superior portion of the temporal lobe, and the posterior cerebral artery supplies the inferior portion of the temporal lobe.
Given that the middle cerebral artery supplies the majority the frontoparietal parenchyma, and the posterior cerebral artery supplies the occipital lobe, make note that the parietal lobe is superior to the occipital lobe. With this mindset, it is logical that the middle cerebral artery with supply the superior portion of the temporal lobe, while the posterior cerebral artery will supply the inferior portion of the temporal lobe. In clinical practice, at the level of the temporal horns of the lateral ventricles and inferiorly on axial imaging, this is likely the posterior cerebral artery vascular territory.

A critical differential consideration for temporal lobe diffusion restriction should be herpes encephalitis, particularly when hemorrhage is present. In this case, the presence of an additional infarct within the same vascular territory favors infarct over herpes encephalitis, though the consideration for herpes encephalitis should be communicated with the treating clinician given the importance of prompt retroviral therapy for improved patient outcomes.
Should temporal lobe diffusion signal abnormalities involve both the superior and inferior temporal lobe parenchyma, herpes encephalitis is of even greater concern as infarcts simultaneously involving the MCA/PCA distributions would be less likely.

For this MRI, a reasonable impression would be:
Acute left frontal corona radiata infarct and probable acute/subacute hemorrhagic left temporal lobe infarct without a mass occupying hematoma, both corresponding to the left middle cerebral artery vascular territory. Although infarct is favored, correlation for superimposed left temporal herpes encephalitis is recommended given the imaging appearance.


Primary teaching points:
1. Anatomic review of the periventricular white matter, specifically the centrum semiovale and corona radiata.
2. Additional example of additional infarcts occult on CT and evident on MRI.
3. Delineation of the middle cerebral artery and posterior cerebral artery vascular territories in the temporal lobe.
4. Herpes encephalitis as a differential consideration for temporal signal abnormalities, particularly with hemorrhagic diffusion restriction.


Non-Contrast CT

Besides infarct, what would also be in the differential diagnosis in this case based on the MRI findings?