A brief guide on how to use non-enhanced CT scans in acute stroke management.
One of the first steps of acute stroke management is to obtain a non-enhanced head CT. A previously healthy patient is now having symptoms of an ischemic stroke. What is the earliest typically time after symptom onset that would you generally expect to see evidence of an ischemic stroke on non-enhanced head CT?
- A) Within 5-15 minutes
- B) 60 minutes
- C) 6 hours
- D) 24 hours
Scroll down for the answer.
The answer is C) 6 hours – as a rule of thumb, this is usually the earliest time frame in which you might see evidence of an ischemic stroke on CT. For most patients, presenting with the 4.5 hour tPA time window, we expect to see a normal head CT.
Injured and dying brain tissue no longer has ATP to run the cell membrane Na+/K+ pump, causing the cells to swell with water – it is this increase in water in the dying cell that causes early hypodensity on CT.
The key point here is that most hyper-acute ischemic strokes do NOT show up on head CT! It takes time to develop. The key role of a head CT in acute stroke is to rule out intracranial hemorrhage and identify other conditions that would contraindicate tPA.
Read more in the stroke and imaging sections of the medical student review book.