ISNVD Abstract Book

MONDAY – FEBRUARY 20, 2012 8:30am-8:50am
Stroke and Brain Perfusion (Vida Demarin, CROATIA)
Stroke is the second most common cause of death and major cause of disability, thus representing enormous
burden on global health. Cerebral ischemia, or restricted blood flow, is the main cause of stroke, typically due
to occlusion of a cerebral artery as a result of progressive atherosclerosis or an embolus from the heart or neck
vessels. Anatomical features and functional responses-cerebral autoregulation-allow high cerebral blood flow
and provide protection against ischemia. Cerebral autoregulation is impaired in ischaemic stroke and this may
result in an already damaged brain being excessively sensitive to fluctuations in perfusion pressure. Irrespective
of cause or mechanism of ischemia, collateral flow might compensate potential injury to the brain.
Physiologically effective collateral perfusion is evident when cerebral blood flow and cerebral blood volume are
maintained within the territory of the occluded artery. In acute stroke, ischemia is more often incomplete, with
the injured area of the brain receiving a collateral blood supply from uninjured arterial and leptomeningeal
territories. Acute cerebral ischemia may result in a central irreversibly infarcted tissue core surrounded by a
peripheral region of stunned cells that is called a penumbra. The penumbra is a dynamic entity that exists
within a narrow range of perfusion pressures, and the duration of the delay in recanalization is inversely related
to the size of the penumbra. Penumbra has important implications for selection of the appropriate therapy and
prediction of the clinical outcome. Results of recent studies have demonstrated that intravenous thrombolytic
therapy may benefit patients who are carefully selected according to findings of a penumbra at neuroimaging.
Important advances in the imaging of collateral blood vessels and collateral blood flow will need to be
followed by a rigorous assessment of the therapeutic value of techniques aimed at improving or maintaining
collateral flow in patients with acute ischemic stroke.
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