Relationship of neurovascular elements to neuron injury during ischemia.

Occlusion of flow to the brain regions identifies regions of vulnerability within the vascular territory at risk, which coalesce to become the mature ischemic lesion. A large number of unsuccessful clinical trials have focused on neuron and extravascular targets in humans that have shown apparent salvage in preclinical models. However, the observation that microvessel and neuron responses to ischemia occur simultaneously in these regions suggest that the responses could be coordinated. This presentation examines evidence in support of the conceptual 'neurovascular unit' and its application to the setting of acute intervention trials in ischemic stroke. There are no uniform reasons for which nonvascular interventions, as a class, have not been successful in clinical trials, but both the clinical observations and the hypothesis imply the need to understand interactions with the neurovascular unit as a prelude to further neuron protectant trials.