Fogging phenomenon - stroke

Case contributed by Assoc Prof Frank Gaillard


New neurological symptoms on the right, 2 days ago. Patient presents to peripheral hospital.

Patient Data

Age: 40 years
Gender: Female

CT brain on presentation

Single image from a digitized non contrast CT of the brain demonstrates a low density region within the left frontal lobe involving both white matter and overlying grey matter which is indistinct. The basal ganglia are spared. There is only minor positive mass effect. 

The patient was eventually transferred, and had a repeat CT scan. She has had no specific therapy. 


CT brain 7 days later

Single slice at the same level, obtained 7 days later, demonstrates essentially normal appearing brain. 


MRI brain 12 days after presentation

Features are characteristic of an evolving left superior division MCA territory infarct, and confirm the CT appearance.  The cortex of the affected region is T2 hyperintense with some intrinsic high T1 signal consistent with petechial hemorrhage, demonstrates gyriform enhancement, and is now beginning to have negative mass effect as swelling subsides.  

There are no features suggestive of an underlying tumor, nor of an infective process.

Case Discussion

This case illustrates the typical appearance and time course of CT fogging phenomenon. It is essential to be familiar with this process if confusion and possible unnecessary intervention are to be avoided. 

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Case information

rID: 21683
Published: 10th Feb 2013
Last edited: 28th Sep 2020
Inclusion in quiz mode: Included

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