Transcranial Doppler ultrasonography in the assessment of cerebral circulation arrest: improving sensitivity by trancervical and transorbital carotid insonation and serial examinations.

INTRODUCTION: Transcranial Doppler (TCD) can detect the cerebral circulation arrest (CCA) in brain death. TCD is highly specific, but less sensitive because of false-negatives accounting for up to 10\%. The aim of the study was to explore the diagnostic accuracy of TCD and to determine whether it can be augmented by strategies such as the insonation of the extracranial internal carotid artery (ICA) and sequential examinations. METHODS: Data of 184 patients, who met clinical criteria of brain death, observed from 1998 through 2006, were retrospectively reviewed. The study of cerebral arteries was performed through the transtemporal approach, suboccipital insonation of the vertebro-basilar system, transorbital insonation of the ICA and ophthalmic artery, and transcervical insonation of the extracranial ICA. Repeated exams were performed in cases of persistent diastolic flow. RESULTS: The specificity of the testing was 100\%, no false-positive cases were recorded. The sensitivity of conventional TCD examination was 82.1\%. The insonation of the extracranial ICA increased sensitivity to 88\% allowing the detection of CCA in those patients lacking temporal windows; serial examinations further increased sensitivity to 95.6\%. CONCLUSIONS: The addition of insonation of the cervical ICA and of the siphon increased sensitivity of TCD. Nevertheless, a CCA flow patterns may appear later on those segments. Serial examinations, may be needed in those cases.