Keyword: the limitations of cerebral infarction
(A) CT in cerebral infarction onset within 4 to 6 hours, and some cases can be seen slightly ill-low-density lesions. But early CT examination to exclude cerebral hemorrhage, subdural hematoma, intracranial tumors, cerebral infarction-like disease. Most cases occur in the 24 hours after the border was clear low density lesions (Figure 24-3). About one week, there may be a strengthening of the infarct uneven. CT advantages for convenient, quick, applicable to critically ill patients, uncooperative patients. Can be found in the the infarct peripheral edema, brain mass effect and whether converted to hemorrhagic infarction. But less than 5mm infarction and posterior fossa infarct appeared difficult for CT. Cortical surface of the infarct is often not perceived by CT.
(B) magnetic resonance imaging (MRI) MRI of the high magnetic field (1.5Tesla), in one hour of the onset may show cortical surface and infarction of the posterior fossa. Six hours after the onset of infarction can almost MRI showed performance for the T1-weighted low signal and T2-weighted high signal. The disadvantage of MRI is the high price of imaging a long time, does not apply to patients with critical illness, substandard authors and equipped metal dentures and ECG, pacemaker patients.
(C) The non-invasive vascular screening duplex ultrasound (duplexsonography) can be used for assessment of extracranial carotid artery disease and the degree of stenosis. Transcranial Doppler (transcranial Doppler, TCD) can detect the base of the brain artery flow velocity, found the middle cerebral artery, the distal segment of the vertebral artery and the basilar artery stenosis or blocked, the assessment of collateral circulation. The TCD instrument of the recent development of bifocal probe, dual-channel or four-channel TCD instrument can be used for the detection cardiogenic of of asymptomatic emboli and vertebral measured emboli or arterial origin. Magnetic resonance angiography (MRI angiography) can be used to check for extracranial and intracranial the brain large artery lesions.
(D) arteriography selective cerebral arteriography and several less angiography (DSA) applicable to ultrasound found severe stenosis of the internal carotid artery considered for carotid endarterectomy patients or clinical manifestations unusual suspect artery layered or arteritis those. This is an invasive examination, 2% to 12% of the subjects may be complicated the artery layered or embolic stroke.
(E) blood tests should be routinely measured blood count, Classification, platelets, prothrombin time, partial thromboplastin time, blood glucose, electrolytes, creatinine. On the part of the patient based on the clinical situation, the selective determination of protein C, protein S, antithrombin III (AT III), fibrinogen, anticardiolipin antibodies, plasminogen activator inhibitor factor (PAI), syphilis serology test and so on. It should be measured after the acute phase of stroke onset to affect lipid levels.
(VI) in cerebrospinal fluid in clinical suspicion of infectious diseases or by imaging and other tests can not determine the diagnosis before considering lumbar puncture.
(Vii) Other ECG is essential. Also should be as routine chest X-ray to rule out tumor thrombus, can serve as a comparison of aspiration pneumonia occurred later.