Reversible brain ischemia: lessons from transient ischemic attack

Factors Associated with Cognitive Decline in Transient Ischemic Attack Patients

Chronic cerebrovascular disease and large ischemic stroke are both associated with cognitive impairment. Much less is known about the acute cognitive sequelae of transient ischemic attack (TIA). Although often overlooked, there is increasing evidence that cognitive impairment does occur following TIA. In some patients, cognitive changes persist after resolution of focal neurological deficits, but the temporal profile of these symptoms is unknown. In addition, clinical and imaging correlates of cognitive impairment after TIA have not been systematically studied. This under-studied and recognized problem has significant implications for TIA patient management. In this review, we summarize the evidence currently available and identify future research priorities.

Neuronal plasticity after ischemic preconditioning and TIA-like preconditioning ischemic periods

Transient ischemic attacks (TIAs) have recently become the center of attention since they are thought to share some characteristics with experimental ischemic preconditioning (IPC). This phenomenon describes the situation that a brief, per se harmless, cerebral ischemic period renders the brain resistant to a subsequent severe and normally damaging ischemia. Preconditioning (PC) is not restricted to the brain but also occurs in other organs. Furthermore, apart from a short ischemia, the PC event may comprise nearly any noxious stimulus which, however, must not exceed the threshold to tissue damage. In the last two decades, our knowledge concerning the underlying molecular basis of PC has substantially grown and there is hope to potentially imitate the induction of an endogenous neuroprotective state in patients with a high risk of cerebral ischemia. While, at present, there is virtually no neuropathological data on changes after TIAs or TIA-like PC ischemic periods in human brains, the following review will briefly summarize the current knowledge of plastic neuronal changes after PC in animal models, still awaiting their detection in the human brain.