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If they saw a "fluid pocket" in the spine surgery, I assume that there was some sort of spinal fluid leak during the surgery.
This could explain the blood and the air in the brain on the head CT scan -- because the blood from the surgical site in the lower back can enter into wherever the spinal fluid leak was occurring and travel to the brain. So I would agree that this is not a stroke.
However, it is possible that the air and the blood was irritating to the brain, and can cause headaches and confusion in people. However - if this was one month ago, and he is still not doing well, this is beyond the timeframe in which I would expect him to have improved just based on that fluid pocket / leak in surgery.
Certainly, if he had a stroke during surgery, this could cause some of the symptoms, but that air in the brain is not the stroke. A MRI of the brain at this point can see if there was a stroke, and may help to explain his persistent neurologic symptoms. He also would benefit from seeing a neurologist.
They have done CTs and MRI and it showed no strokes, but they are saying now it was a CVA. thats is a form of a stroke correct? What would be the next step? He seems very depressed also