erebral perfusion is defined as the
steady-state delivery of blood to cerebral
tissue through capillaries. Perfusion is
measured in niL/100 g tissue/minute and
under normal conditions cerebral perfu-
sion is 50 to 60 mL/IOO g/minute. An
acute stroke is caused by an abrupt local-
ized reduction in cerebral blood flow that
causes a reduction in cerebral pertusion.
This results in cerebral ischemia and,
ultimately, infarction of the compro-
mised cerebral tissue. However, there is
often viable tissue surrounding the
ischemic core or penumbra. Although
the penumbra has a limited blood supply,
metabolism is preserved and this tissue
can recover if the insult is reversed
within a narrow lime frame.-^ Currently,
thrombolysis remains the treatment of
choice for acute ischemic stroke within