The role of cervical color Doppler ultrasound in the diagnosis of brain death

Brain death (BD) is defined as the irreversible destruction of all brain functions. It is usually diagnosed through a clinical examination, but in certain circumstances, ancillary examinations (such as digital subtraction angiography (DSA), transcranial color Doppler (TCD), computed tomography angiography (CTA), magnetic resonance angiography (MRA), or radionuclide scanning) are required as confirmatory tests. In many countries, cervical color Doppler sonography (CCD) is not recognized as a valid test. The aim of our study is to assess its accuracy as a non-invasive, inexpensive, and easily available examination to determine cerebral circulatory arrest (CCA). We performed a retrospective study in which 123 patients with clinical diagnosis of BD underwent bedside cervical color Doppler as an additional examination for CCA assessment. We compared these cervical color Doppler findings with the results of validated ancillary tests such as CTA, TCD, and DSA. Cervical color Doppler exams showed a sensitivity of 78% (96/123 patients) in detecting CCA compared to standard ancillary tests. Twenty-seven patients showed a persistent diastolic flow in one or two of the four arterial vessels examined and thus considered as false negatives. Our results show that cervical color Doppler may become a reliable and safe technique in detecting CCA, which can shorten the time for declaring brain death. In particular, in patients lacking good bone windows at transcranial color Doppler, cervical color Doppler of the cervical internal carotids and vertebral arteries could be recommended to increase the sensitivity of transcranial color Doppler, or as an alternative bedside examination