A 65-year-old man awakened from an afternoon nap and noted a
complete hemiparesis involving his arm, face, and leg. His wife
called EMS and he was brought to the ED within half an hour.
A noncontrast head CT was obtained immediately after the patient’s
arrival (Figure 1). The CT was initially interpreted as normal.
- On which side was the patient’s
- What are the early CT signs of an ischemic
- Should thrombolytic agents be administered?
The principal role of CT in patients with a stroke is to exclude
intracranial hemorrhage (10–15% of strokes) or
other lesions such as a tumor, abscess, or SDH, which could be the
cause of the patient’s neurological deficit. CT has a limited
ability to detect acute ischemic changes within 12–24 hours
of onset, although subtle signs of early ischemia can be detected
in a substantial proportion of patients, even within 3 hours of
stroke onset. After 24 hours, CT is better able to detect an ischemic
stroke because there is more pronounced cerebral edema.
With the advent of thrombolytic therapy for patients that present
within 3 hours of stroke onset, CT plays two additional roles in
emergency patient care. First, and foremost, CT detects hemorrhage,
which is an absolute contraindication to thrombolytic therapy. Second,
a large area of early ischemic change is
considered by some clinicians to be a contraindication to the use
of thrombolytic therapy because it is associated with an increased
risk of hemorrhage. A third potential role of imaging would be to
confirm the diagnosis of an acute ischemic stroke, although CT has
a limited ability to do this.
CT Signs of
There are three stages in the evolution
of an ischemic stroke as depicted on CT.
Acute ischemic changes occur within
24 hours and may be visible within three hours of the onset of stroke.
These early ischemic changes are due to cytotoxic
edema that accumulates intracellularly. Subacute changes
occur after 24 hours, peak in 3 to 5 days, and gradually subside
over 1 to 4 weeks. They are ...