Transcranial Doppler ultrasound in neurovascular diseases: diagnostic and therapeutic aspects

Abstract

Albeit no direct anatomical information can be obtained, neurosonological methods provide real-time determination of velocity, and spectral waveform of blood flow in basal intracranial arteries adds significant benefit to the care of the patients with neurovascular diseases. Several features, such as relative simplicity in terms of interpretation and performance, significantly low cost, totally non-invasiveness, portability, and excellent temporal resolution, make neurosonology increasingly popular tool for evaluation, planning, and monitoring of treatment, and for determining prognosis in various neurovascular diseases. Usefulness of transcranial Doppler in diagnosing/monitoring subarachnoid hemorrhage related vasospasm and sickle cell vasculopathy is already well known. Utility in diagnosis of intracranial arterial stenosis, acute occlusion and recanalization, intracranial hemodynamic effect of the cervical arterial pathologies, intracranial pressure increase, and cerebral circulatory arrest are also well established. Neurosonological determination of vasomotor reactivity, cerebral autoregulation, neurovascular coupling, and micro-embolic signals detection are useful in the assessment of stroke risk, diagnosis of right-to-left shunting, and monitoring during surgery and interventional procedures. Transcranial Doppler is also an evolving ultrasound method with a therapeutic potential such as augmentation of clot lysis and cerebral delivery of thrombolytic or neuroprotective agent loaded nanobubbles in neurovascular diseases. The aim of this study is to give an overview of current usage of the different ultrasound modalities in different neurovascular diseases.

Transcranial Doppler Ultrasound: A Review of the Physical Principles and Major Applications in Critical Care

“…Filtering for English language review articles retrieved 72 articles. Eleven articles focusing on critical care applications of TCD in adults published in the last 10 years were retrieved [2, 4, 5, 9, 18–24]. Abstracts were screened to deem final appropriateness before the article and its references were consulted in depth to gather information for this current review.…”

“…In the context of a high MFV, an LR <3 indicates hyperdynamic flow and >3 indicates vasospasm [31]. A modified LR (BA MFV/average of left and right extracranial VA MFV) and Sloan's hemispheric ratio (ACA MFV/ECICA MFV) can be similarly applied to the BA and ACA, respectively (see [5] for a summary of threshold values). MFV and LR measurements used to grade vasospasm severity are presented in Table 3 [31, 32].…”

Intracranial Aneurysms: Wall Motion Analysis for Prediction of Rupture

“…16 Moreover, some of the observed pulsation may be related to very slow intra-aneurysmal blood flow during part of the cardiac cycle, leading to the absence of a Doppler signal and hence exaggerating apparent wall motion. Other limitations of transcranial power Doppler ultrasonography are limited acoustic windows due to bone structures; additionally, 20% of patients have poor or absent acoustic windows 65 and limited spatial resolution, especially with low-frequency transducers that are required to image deep arteries. Temporal and spatial resolutions are indeed dependent on the frequency of the transducer and the depth of the structure of interest.…”

Lung Ultrasound in the Critically Ill

“…TCCD can be used for monitoring of cerebral blood flow alterations which follow traumatic brain injury and in patients with sickle cell anemia. It also can be used in the detection of patent foramen ovale and in the diagnosis of cerebral circulatory arrest which is a component of brain death [79].…”