Segmental narrowing of the supraclinoid carotid artery in young patients with ischemic stroke.

have been hypothesized, and these large multimers of von Willebrand molecules have been shown to clump platelets in vitro. The neurological manifestations of TTP are diverse, but in most instances an acute confusional state, seizures, transient hemiparesis, and stupor predominate.' The clinicoanatomic correlation in patients with decreased levels of consciousness alone is problematic but may be related to widespread vascular involvement in the cortex. CT or MRI findings in TTP have been mostly linked to transient focal neurological deficits, but coma and fluctuating level of consciousness have been correlated with multiple areas of decreased attenuation in white matter. Recently, a few reports of patients with TTP who undergo MRI have suggested that although recovery may be complete, small to minute cerebral infarcts can be demonstrated. Our patient is of particular interest because his clinical course, documented by serial MRI scans, provides presumptive evidence that ischemic infarcts may go unnoticed. The diagnostic value of MRI in TTP has not been systematically evaluated, and in two recently investigated patients with decreased level of consciousness alone and relapsing TTP at our institution, MRI investigation was normal (E.F.M.W., unpublished data, 1994). The observation of unrelenting cerebral infarction may influence the decision of whether to use antiplatelet drugs or high doses of corticosteroids as adjuncts to plasma exchange.