What happens when memory suddenly disappears?
Neuroscience has made amazing discoveries in the last few years, highlighted by the popularity of literature on the neuroscience of love, of parenting, of aging, of good sleep and good diets.
Yet, surprisingly, nearly a third of conditions that bring people to neurologists, such as me, are of unknown cause. Despite our technological advances such as advanced MRI imaging, that percentage—one-third—has remained steady for decades. We call them “fascinomas,” or “unknowns.”
One such puzzling neurological condition was recently experienced and openly discussed by journalist Katie Couric: Transient Global Amnesia (TGA).
TGA causes brief, but profound, loss of memory. People totally lose memory for a period of hours, despite appearing on the outside to be acting normally. Katie Couric conducted a panel discussion in the throes of the event! But afterward, she had no memory of what she said or did.
Medical journal articles discussing TGA have described surgeons completing entire operations successfully, then afterward having absolutely no memory of what they did in the operating room!
Sometimes the person will ask the same questions over and over…usually related to orientation…
For example:
- “Where am I?”
- “What time is it?”
- “What just happened?”
You can give them the answer, they nod, then a several seconds later ask the same question again, and again.
Fortunately, TGA is benign; although it rarely may recur, and it is not generally a harbinger of future stroke or seizure.
Neuroimaging is often normal, although in some patients MRI brain scans show tiny lesions in the hippocampus (our memory center) which interestingly don’t appear right away, but after 12 to 72 hours, and then disappear in a week or two.
Our brain, the most complex structure known, is still mysterious in many ways, and leaves us much yet to explore.
