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DIAGNOSIS AND PREVENTION

Laboratory tests should include a complete blood count, a metabolic panel and, especially in patients taking oral anticoagulants, clotting status (i.e. prothrombin time or international normalized INR ratio and activated thromboplastin part time).

Programs should be offered to reduce the risk factors associated with stroke including screening and monitoring for hypertension, diabetes, and hypercholesterolemia. Cigarette smoking causes a twofold increase in the risk of ischemic stroke so smoking cessation can reduce this risk. Weight reduction can also be promoted through exercise and nutrition programs. Occupational health nurses play a valuable role in returning employees to work after a stroke. They can assist with appropriate job placement or reasonable accommodations.

Categorization of subtypes of ischemic stroke has had considerable study, but definitions are hard to formulate and their application for diagnosis in an

Individual patient outcomes can often be a problem in the classification of ischemic stroke. In the past, classifications have been primarily based on risk factor profiles, clinical features, and brain imaging studies (CT or MRI). However, these features can overlap and are not specific to any particular subtype of stroke. Bamford et al. recently reported that outcomes and likelihood of recurrent stroke differed significantly by stroke subtype. Large hemispheric infarcts, typically resulting from occlusion of the internal carotid artery or proximal middle cerebral artery, had the worst prognosis. These investigators classified strokes based on clinical features that predicted the size and site of the ischemic lesion, but did not consider the potential etiology of the stroke. Determining the cause of stroke does influence choices for management. Carotid endarterectomy has proven usefulness in preventing recurrent stroke in patients with large-artery stenosis, as

Aspirin and clopidine are commonly used in patients with small-artery occlusive disease or lesser degrees of large-artery stenosis. Clinical trials of these modalities have specifically excluded patients with cardioembolic stroke, but no separate analyses were performed on patients with large-vessel or small-vessel disease. Anticoagulants or even cardiac surgery may be prescribed to prevent recurrent cardioembolic stroke.

There are a lot of systems for the diagnosis of the subtype of ischemic stroke that use components of existing diagnostic schemes. We then tested the ease of use of this algorithm and attached definitions. Two neurologists who had not participated in the preparation of the TOAST diagnostic system independently used it in diagnosing the subtype of ischemic stroke. Interrater agreement was then measured. This report describes the methodology for diagnosing stroke subtype using the TOAST.

fi ti titi ti tisystem and presents the results of bedside tes ng. The physician can apply the clinical and imagingndings when rst assessing the pa ent and then consider the results of other diagnos c testslater. An important part of the classi ca on is the ability of the physician to categorize a speci csubtype diagnosis as probable or possible based on the degree of certainty. A "probable" diagnosisis made if the clinical ndings, neuroimaging data, and results of diagnos c studies are consistentwith one subtype and other e ologies have been excluded. A "possible" diagnosis is made whenthe clinical ndings and neuroimaging data suggest a speci c subtype but other studies are notdone. Because many pa ents will have a limited number of diagnos c tests, the probable andpossible subcategoriza ons allow the physician to make as precise a subgroup diagnosis as can beachieved.

Large-artery atherosclerosis. These pa ents will have clinical and brain imaging ndings of

eithersigni cant (>50%) stenosis or occlusion of a major brain artery or branch cor cal artery, presumablydue to atherosclerosis (Table 2). Clinical ndings include those of cerebral cor cal impairment(aphasia, neglect, restricted motor involvement, etc.) or brain stem or cerebellar dysfunc on. Ahistory of intermi ent claudica on, transient ischemic a acks (TIAs) in the same vascular territory,a caro d bruit, or diminished pulses helps support the clinical diagnosis. Cor cal or cerebellarlesions and brain stem or subcor cal hemispheric infarcts greater than 1.5 cm in diameter on CT orMRI are considered to be of poten al large-artery atherosclero c origin. Suppor ve evidence byduplex imaging or arteriography of a stenosis of greater than 50% of an appropriate intracranial orextracranial artery is needed. Diagnos c studies should exclude poten al sources of cardiogenicembolism. The diagnosis of stroke secondary to largeartery atherosclerosis cannot be made ifduplex or arteriographic

studies are normal or show only minimal changes. Cardioembolism. This category includes patients with arterial occlusions presumably due to an embolus arising in the heart (Table 2). Cardiac sources are divided into high-risk and medium-risk groups based on the evidence of their relative propensities for embolism16 (Table 3). At least one cardiac source for an embolus must be identified for a possible or probable diagnosis of cardioembolic stroke. Clinical and brain imaging findings are similar to those described for large-artery atherosclerosis. Evidence of a previous TIA or stroke in more than one vascular territory or systemic embolism supports a clinical diagnosis of cardiogenic stroke. Potential large-artery atherosclerotic sources of thrombosis or embolism should be eliminated. A stroke in a patient with a medium-risk cardiac source of embolism and no other cause of stroke is classified as a possible cardioembolic stroke. Small-artery occlusion (lacune). This category includes patients whose strokes

are o en labeled as lacunar infarcts in other classifications (Table 2). The patient should have one of the traditional clinical lacunar syndromes and should not have evidence of cerebral cortical dysfunction. A history of diabetes mellitus or hypertension supports the clinical diagnosis. The patient should also have a normal CT/MRI examination or a relevant brain stem or subcortical hemispheric lesion with a diameter of less than 1.5 cm demonstrated.

Potential cardiac sources for embolism should be absent, and evaluation of the large extracranial arteries should not demonstrate a stenosis of greater than 50% in an ipsilateral artery. Acute stroke of other determined etiology. This category includes patients with rare causes of stroke, such as nonatherosclerotic vasculopathies, hypercoagulable states, or hematologic disorders. Patients in this group.

Stroke of undetermined etiology. In several instances, the cause of a stroke cannot be determined with any degree of confidence. Some patients will have no likely explanation for their stroke despite a thorough evaluation.

ology determined despite an extensive evaluation. In others, no cause is found but the evaluation was cursory. This category also includes patients with two or more potential causes of stroke so that the physician is unable to make a final diagnosis. For example, a patient with a medium-risk cardiac source of embolism who has not undergone a thorough evaluation.