What could be causing these post-stroke blackouts?

Shimi asked...

My father is 66 years old and suffered a stroke on his left side in June 2002. He was able to recover with a limp, slight speech disorder and the shaking of his right hand. However he started to get blackouts in March 2010 and would fall to the ground. These blackouts happened quickly and frequently and he would recover just as fast. We took him to do a number of tests but the doctors are not seeing anything that is causing it. Anyway, these blackouts went on for at least a month and then they stopped. He was good again for awhile but 5 months later it happened again. Can you tell me what can be causing this ailment? Is he getting another stroke? With the first stroke, they did an operation where they cleaned the veins that were blocked in his neck.

Expert Answer

James Castle, M.D. is a neurologist at NorthShore University HealthSystem (affiliated with The University of Chicago) and an expert on strokes.

Recurrent black-outs after a stroke are almost undoubtedly not due to recurrent stroke events. They are almost always caused by either seizure activity, or, more commonly, a sudden drop in blood pressure. A typical evaluation for these episodes would include an electroencephalogram (looking for evidence of a seizure focus), a Holter or Cardiac Event Monitor (looking for evidence of a cardiac arrythmia which could cause a sudden drop in blood pressure), an Echocardiogram (an ultrasound of the heart looking for an area of blockage of blood flow), and a blood pressure log. Of all these, monitoring the blood pressure for sudden drops is the most likely to give you the answer as to the cause. It may be that your father is now on too much blood pressure medication and is fainting as a result.

With all the above in mind, it is important to remember that not uncommonly, a detailed search looking for the cause of the blackouts does not reveal anything very specific. If that occurs, it might be worth talking to your father's doctor about doing a trial of cutting back on his blood pressure medications, to see if that helps limit the number of blackout spells.