Neurosonology in Cerebral Ischemia: Future Application of Transcranial Doppler in Acute Stroke

Abstract

Transcranial Doppler (TCD) has become a general practice in recent years in the diagnostic study of patients with cerebral ischemia. This is due to the fact that it is a rapid, noninvasive, reproducible and dynamic examination of intracranial circulation. In the acute phase of cerebral infarction, it can detect MCA occlusion with a good correlation with angiographic findings and, what is even more important, the patients who will later suffer lacunar infarctions almost always show a normal Doppler examination. Acute abnormalities can also demonstrate the mechanism of the clinical signs; the examination informs us of the existence of collaterals and severe occlusions or stenoses of the extracranial arteries, and can change the priority in the search for the etiological diagnosis. The diagnosis of intracranial stenoses as a cause of clinical signs is another immediate application of TCD, right from the acute phase. If in the future anticoagulation is shown to be an optimum treatment for secondary prophylaxis in intracranial stenoses, TCD will probably become the diagnostic technique of choice. The ability to predict the prognosis based on parameters obtained by TCD opens up the possibility of using it as an auxiliary technique for the selection of patients for reperfusion treatment, having in its favor that it is quick and easy to perform, and therefore suitable for treatment monitoring. It seems clear that the data obtained by Doppler in the first 6 h are a good predictor of both spontaneous improvement and early impairment, which could help to avoid treatment in patients in whom a rapid improvement can be expected. Finally, the hemodynamic data of the TCD could be of inestimable value in the assessment and monitoring of intracranial hypertension treatments and for hemodynamic management of the patient, allowing the treatment margins of the acute phase of arterial hypertension to be reliably established without compromising the perfusion pressure. In conclusion, TCD will possibly be more widely used in the future in the acute phase of cerebral infarction as a guide to diagnostic procedures, for treatment selection and for monitoring of cerebral hemodynamics.