Causes of TIA and ischemic

The causes of spontaneous intracerebral hemorrhage are sometimes, but not always, different from those of TIA and ischemic stroke. Spontaneous intracranial hemorrhage may be classified as ... 

Transient ischemic attack (TIA) is a clinical syndrome characterized by focal neurological symptoms presumed to be of vascular origin that last less than 24 h. Despite the transient nature of symptoms, the cerebrovascular thread is not over yet following a TIA. The mechanism that has given rise to the transient spell may also cause more severe ischemic syndromes if not properly treated. About 10% of patients with TIA suffer from stroke within the ensuing 3 months, 50% of which occur within the first 2 days (Johnston et al. 2003). Accurate and prompt recognition of ischemia as the cause of neurological symptoms is imperative to prevent subsequent strokes. This is, however, a complicated task... 

Unlike TIA patients with infarction on DWI, it is not obvious that patients with normal DWI have suffered from ischemia as the cause of their transient symptoms. In these patients, TIA mimics should also be considered (see Chap. 19). However, an ischemic etiology for transient symptoms cannot be excluded by the lack of an associated hyperintense lesion on DWI. A short-lasting episode of ischemia without DWI changes, or with reversible DWI changes as demonstrated in animals (Minematsu et al. 1992 Mintorovitch et al. 1991), might have occurred at the time of symptoms. In addition, DWI may occasionally miss very small infarctions, especially in the brainstem location (Ay et al. 1999 Kuker et al. 2002 Lovblad et al. 1998). This is most likely due to susceptibility artifacts induced by surrounding bones at the skull base. New multi-array head coil systems and parallel imaging techniques promise to overcome this limitation and improve the detection rate of small infarctions in the brainstem. 

Arterial dissection is a common cause of ischemic stroke and TIA in young adults and may also occur in older people. Sometimes there is a predisposing cause (Schievink 2001 Rubinstein et al. 2005) (Table 6.4) but often there is no explanation. The artery may become occluded by the wall hematoma itself thrombosis and emboUsm may complicate occlusive or non-occlusive dissections, and aneurysmal bulging of the weakened wall may occur (O Connell et al. 1985). Arterial rupture is unusual. 

Transient ischemic attacks are but one cause of transient focal neurological attacks (Box 8.1) and transient monocular blindness (Box 8.2). There is no test to confirm a TIA, and the gold standard method of diagnosis remains a thorough clinical assessment as soon as possible after the event by an experienced stroke physician, although the advent of... 

Vascular risk factors (Ch. 2) and diseases should be sought. It is unusual for an ischemic stroke or TIA to occur in someone with no vascular risk factors, unless they are very old, or are young with some unusual cause of stroke (Ch. 6). A history of heart disease may be relevant and cardiac symptoms should be specifically inquired about. 

Cardioembolism Cardioembolism accounts for approximately 30% of all stroke and 25-30% of strokes in the young (age <45 years)." AF accounts for a large proportion of these strokes (15-25%). Symptoms may be suggestive, but they are not diagnostic. Repetitive, stereotyped, transient ischemic attacks (TIAs) are unusual in embolic stroke. The classic presentation for cardioembolism is the sudden onset of maximal symptoms. The size of the embolic material determines, in part, the course of the embolic material. Small emboli can cause retinal ischemic or lacunar symptoms. Posterior cerebral artery territory infarcts, in particular, are often due to cardiac embolism. This predilection is not completely consistent across the various cardiac structural abnormalities that predispose to stroke, and may be due to patterns of blood flow associated with specific cardiac pathologies. 

A number of hematological disorders may occasionally cause ischemic stroke and TIA (Tatlisumak and Fisher 1996 Arbors and Besses 1997 Markus and Hambley 1998 Matijevic and Wu 2006) (Box 6.2). 

The risks of stroke, other acute vascular events and death after stroke have been studied in six population-based cohorts over a follow-up period of five or more years (Scmidt et aL 1988 Burn et al. 1994 Hankey et al. 2000 Petty et al. 2000 Brpnnum-Hansen et al. 2001 Hartmann et al. 2001). Two of these studies included ischemic stroke only (Petty et al. 2000 Hartmann et al. 2001) and the remaining four included both ischemic and hemorrhagic stroke. One study included incident and recurrent events (Br0nnum-Hansen et al. 2001) and the remaining five included incident stroke only. The risks of death at five years varied between 41% and 72%, while the proportion of deaths caused by acute coronary disease and stroke (either inception event or recurrent stroke) were similar. As in the TIA outcome... 

Cerebrovascular thrombosis (CVT) occurs in over 1.5 million individuals yearly in the USA of these 66% suffer death or severe permanent paralysis. In those suffering CVT, including transient cerebral ischemic attacks (TIA s), small stroke syndrome (SSS) and Sank thrombotic stroke, at least 30% harbor a blood coagulation protein or platelet defect causing thrombosis. Like the disorders discussed above, the need for defining the presence or absence and type of defect is of obvious importance. 

Smith WS, Lev MH, English JD et al (2009) Significance of large vessel intracranial occlusion causing acute ischemic stroke and TIA. Stroke 40(12) 3834-3840... 

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