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 blurring of the gray-white matter junction in the left frontoparietal region.
Deep gray nuclei: Preserved
Hyperdense vessels: None

Case Discussion:
These cases are the most challenging head CT examinations, and ‘no definite acute abnormality’ would be a reasonable conclusion for this case. For this case, there is very subtle asymmetric blurring of the gray-white matter junction in the left frontoparietal region. However, reliably detecting these subtle findings with reasonable sensitivity and specificity would be extraordinarily difficult for every unenhanced head CT exam. This is a known limitation of the technique. In the presence of clinical symptoms concerning for an acute infarct without definite CT correlate, adding to the impression that "MRI would be more sensitive for detection of acute ischemia" would be reasonable.


Imaging follow up MRI 24 hours later (Scan 2)
MRI was performed 24 hours later. Diffusion weighted and FLAIR sequences readily demonstrate an acute infarct (increased DWI and FLAIR signal) involving the left frontoparietal and posterior insular cortices.
When there is no definite abnormality to suggest acute infarct, focusing on the strengths of head CT examinations for detecting acute hemorrhage, hydrocephalus, and herniation becomes even more critical. Specifically, the presence of hemorrhage may change treatment options when infarcts are clinically suspected.
Detection of brain herniations on axial imaging depends upon scrutiny of the suprasellar and perimesencephalic cisterns. Again, simply knowing the names of the cisterns may result in increased detection of abnormalities in these regions. 

As a brief review:
a) Suprasellar cistern and sylvian fissure:
I remember these cisterns as being above the bony sella/pituitary gland. Note the midline pituitary stalk. Make sure it looks like a 6-pointed star, including contributions from the crural and interpeduncular cisterns. Double check the medial temporal lobes to exclude an uncal herniation.
b) Perimesencephalic cistern components:
Interpeduncular cistern, crural cistern, ambient cistern, quadrigeminal cistern. (Tip: I remember these perimesencephalic cisterns as one may be 'inter'ested in obtaining a 'CAQ' [certificate of added qualification] in neuroradiology from the American Board of Radiology.)
c) Focused clinical review of the interpeduncular cistern:
For some cases, trace subarachnoid hemorrhage may be noted layering within the interpeduncular cistern and visible no where else. Additionally, which cranial nerve arises from the interpeduncular cistern? If you said oculomotor cranial nerve III, you would be correct. Recall that the basilar artery gives off the superior cerebellar artery (supplying the superior cerebellum) and often terminates as the posterior cerebral arteries (supplying the occipital and posterior temporal brain). Cranial nerves III courses between the PCA and SCA. If there is a cranial nerve III palsy, consider aneurysmal etiology. If you see the interpeduncular cistern, you are in the region of the basilar/PCA/SCA arteries. Hopefully this high yield review will assist with recall of the anatomy, developing a practical search pattern, and honing clinical skills.


Primary teaching points:
1. Limitations of unenhanced head CT for detecting acute infarcts. When infarct is clinically suspected, MRI would be more sensitive for detection of acute ischemia, BUT MAY NOT BE NECESSARY CLINICALLY IF THE PATIENT HAS SYMPTOMS OF STROKE.
2. Naming major suprasellar and perimesencephalic cistern components for detecting herniations on axial imaging.
3. Focused clinical review of the interpeduncular cistern with relevant anatomy and pathology.


Non-Contrast CT

Which cranial nerve arises in the interpeduncular cistern?