Stroke mimics

Thus, PI is a particularly important tool in DWI negative vascular events and non-ischemic strokelike episodes and may, indeed, clarify the underlying pathology. The majority of patients with DWI negative scans can be classified correctly based on PI as suffering from a cerebrovascular event or from a stroke mimic. Negative DWI and PI studies should intensify the search for non-ischemic conditions. However, in the majority of stroke patients DWI will reveal the clinically relevant lesion and has now become the centerpiece of integrated stroke MRI examinations. 

Ay et al. (1999a) found normal DWI in brain regions clinically implicated in 3.5% (27 of 782) of consecutive patients scanned when stroke-like neurologic deficits were still present. DWI negative stroke mimics were believed to have ischemic stroke because of enduring neurological deficits as observed in approximately 7% (ten of 782 consecutive patients scanned by DWI). 

Anything that causes a TIA may, if more severe or prolonged, cause a stroke (Sempere et al. 1998). There are many non-vascular conditions that may cause symptoms suggestive of TIA or stroke, and these are referred to in this book as TIA mimics or stroke mimics. The separation of TIA from stroke on the basis of a 24-hour time limit is useful since the differential diagnosis of the two syndromes is different to some extent (i.e. the spectrum of TIA mimics differs from that of stroke mimics). 

Finally, attention must be paid to avoiding interpretation pitfalls such as streak artifact (Fig. 3.9), patient tilt (Fig. 3.2b), and stroke mimics - such as multiple sclerosis - that can present with similar signs and symptoms (Fig. 3.10). 

Due to the narrow time window available for the initiation of thrombolytic treatment, speed is of the essence. The rationale in the work up for acute stroke is, therefore, to identify as quickly as possible those patients who may benefit from lA or IV thrombolysis or other available acute stroke therapies. Importantly, CTA excludes from treatment patients with occlusive stroke mimics (e.g., transient ischemic attack [TIA], complex migraine, seizure) who will not benefit from, and may be harmed by, such therapies. 

Rapid evaluation of patient to rule out acute MI, aortic dissection, other comorbid condition or nonstroke etiology (i.e., stroke mimic), and medical contraindications to t-PA. Identify severity of neurologic deficit and potential contraindications to IV t-PA... 

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