Can sudden-onset unawareness be caused
by a transient ischemic attack?

I posed this question to Rob Lapporte, MD, board certified in emergency medicine and chief medical officer of Physician 360, a telemedicine service.

Dr. Lapporte replies, “Yes, a TIA can cause disorientation, amnesia or even loss of consciousness.”

This means that a person can drop to the floor as a result of a TIA, sustaining injury from the fall.

Transient ischemic attacks are associated with the following symptoms, all sudden-onset: weakness or a heavy feeling on one side of the body or in a limb; numbness or paralysis in a limb; facial drooping; slurred or nonsensical speech; dizziness; blurry vision and mental confusion.

Dr. Lapporte explains, “Think of it this way…The brain has many functions and every part of the brain requires blood flow to stay functional.  If any portion of the brain is deprived of blood (therefore, oxygen), it will cease to function properly.

“While this [loss of consciousness, disorientation or unawareness] may not be the most common presentation of a patient with a TIA, it’s certainly possible.”

How possible is unawareness or loss of consciousness from a TIA?

“Loss of consciousness is extremely rare in TIAs (but not impossible),” states a report in Practical Neurology (2014 Feb; 14(1): 23–31).

Much more likely than not, a seemingly sudden loss of consciousness is caused by something other than a TIA, such as a rapid and big drop in blood pressure, or an abnormal heart rhythm.

When a TIA actually does cause a loss of consciousness (and this is very rare), it’s when the blood clot is located in the brainstem or thalamus.

Dr. Lapportedr. lapporte has been practicing evidence-based clinical medicine in emergency rooms and urgent care centers for almost 20 years.