DWI in TGA

/static-content/images/646/art%253A10.1007%252Fs00234-011-0889-4/MediaObjects/234_2011_889_Fig1_HTML.gif

Transient global amnesia is an interesting condition, often presenting to the ED as a stroke mimic. C. Miller Fisher wrote the first description along with Raymond Adams. Here’s a link to this initial article, which the publisher’s website has split up into sections for some reason. If that link to the article itself doesn’t work, here’s the PubMed link.

One point to note is that there is now a substantial literature that patients with TGA often have small foci of restricted diffusion in the hippocampus and that this doesn’t mean that the diagnosis is actually stroke. Here’s one article on that point; it references many others. Ironically, recent authors have been emphasizing that finding DWI lesions depends on timing, slice thickness, and field strength, implying that in TGA, it is the lack of DWI abnormality, rather than the presence of such, that is the unexpected finding.

Having said that, it is possible to get fooled. I once saw someone with severe cardiomyopathy and a TGA presentation whose MRI showed multiple scattered foci of restricted diffusion consistent with a proximal source of embolism. I also saw a patient with a TGA presentation who noted at the same time that he was lacking a radial pulse. Imaging showed subclavian artery thrombosis and a relatively large, wedge-shaped, area of DWI abnormality in the ipsilateral medial temporal lobe, rather than the punctate focus usually described. As always, it’s important to render a diagnosis based on complete consideration of the patient’s medical history and exam findings.

About Justin A. Sattin

I'm a vascular neurologist and residency program director. I created this blog in order to share some thoughts with my resident and other colleagues, and to foster my own learning as well.
This entry was posted in Medical Knowledge. Bookmark the permalink.