Purpose or Case Report: There are 2 types of transcranial Doppler ultrasound. In the non-imaging technique, vessels are identified and interrogated based on sound, waveform, and sample depth, often using a transorbital window. The imaging technique involves the use of color Doppler to visualize the vessels themselves, commonly via a transtemporal window. Non-imaging transcranial doppler has long been used as diagnostic tool to assess for intracranial vasospasm in critically ill adults. Imaging transcranial Doppler is a common tool used in the surveillance of children with sickle cell anemia to evaluate for risk of stroke. This presentation describes the use of the imaging transcranial Doppler technique to monitor the intracranial circulation in critically ill children in neurocritical care setting.
Methods & Materials: A review of the limited available literature is performed. Indications for the exam are detailed. The technique used to acquire images and the protocol used are described. Velocities, direction of flow, and waveforms are discussed. The template used to report the results is reviewed. The relationship of the major vessels to the probe is depicted graphically. Recommendations in the use of this technique to determine brain death are noted.
Results: A 3V sector probe is used with transtemporal and transforaminal approach to interrogate the Circle of Willis including the middle cerebral artery, anterior cerebral artery, posterior cerebral artery, distal internal carotid artery, basilar artery and vertebral arteries. Mean velocities and pulsatility indices are recorded. Detection and evaluation of the hemodynamic effects of severe stenosis or occlusion of the extracranial (greater than or equal to 60% diameter reduction) and major basal intracranial arteries (greater than or equal to 50% diameter reduction) are possible. Transcranial Doppler has the advantage of providing real-time evaluation of cerebral vasculature without the use of contrast agents, ionizing radiation, or sedation.
Conclusions: Imaging transcranial Doppler can be a useful diagnostic aid in the approach to managing treatment in the pediatric neurocritical care unit.