Acute Neurologic Injury in the ICU: Role of Transcranial Doppler in Disorders of the Vertebrobasilar Circulation

Abstract

Points 1. TCD of the vertebrobasilar system helps guide clinical management in aneurysmal subarachnoid hemorrhage. Sensitivity and specificity are better for the basilar artery than for the vertebral arteries; they are both enhanced when using thresholds >85 cm/s or a BA/VA ratio greater than 3.0. 2. A novel approach combining mean flow velocity (MFV) and stenotic to prestenotic ratio (SPR) improves the sensitivity of transcranial Doppler (TCD) in the detection of intracranial stenosis. 3. Microembolus signal detection (MES) in the vertebrobasilar circulation is correlated with both the presence of intracranial vertebrobasilar atherosclerosis and the degree of stenosis making it a useful tool in determining stroke etiology. 4. Intracardiac right to left shunt (RLS) has been implicated in cryptogenic stroke and closure has emerged as a viable therapeutic option. Detection of a RLS using gaseous contrast TCD of the vertebrobasilar circulation through a suboccipital window is both highly sensitive and specific when transtemporal windows are insufficient.