Transcranial sonography in the critical patient

Transcranial ultrasonography is a non-invasive, bedside technique that has become a widely implemented tool in the evaluation and management of neurocritically ill patients. It constitutes a technique in continuous growth whose fundamentals (and limitations) must be known by the intensivist. This review provides a practical approach for the intensivist, including the different sonographic windows and planes of insonation and its role in different conditions of the neurocritical patients and in critical care patients of other etiologies.

Dentate-nucleus gadolinium deposition on magnetic resonance imaging: ultrasonographic and clinical correlates in multiple sclerosis patients

Objective

The objective of this study is to find out whether gadolinium accumulation in the dentate nucleus (DN) after repeated gadolinium-based contrast agent (GBCA) administration in multiple sclerosis (MS) patients is related to tissue alteration detectable on transcranial ultrasound.

Methods

In this case–control study, 34 patients (17 with, and 17 age-, sex-, MS severity-, and duration-matched participants without visually rated DN T1-hyperintensity) who had received 2–28 (mean, 11 ± 7) consecutive 1.5-Tesla MRI examinations with application of linear GBCA were included. Real-time MRI-ultrasound fusion imaging was applied, exactly superimposing the DN identified on MRI to calculate its corresponding echo-intensity on digitized ultrasound image analysis. In addition, cerebellar ataxia and cognitive performance were assessed. Correlation analyses were adjusted for age, MS duration, MS severity, and time between MRI scans.

Results

DN-to-pons T1-signal intensity-ratios (DPSIR) were larger in patients with visually rated DN T1-hyperintensity compared to those without (1.16 ± 0.10 vs 1.09 ± 0.06; p = 0.01). In the combined group, DPSIR correlated with the cumulative linear-GBCA dose (r = 0.49, p = 0.003), as did the DPSIR change on last versus first MRI (r = 0.59, p = 0.003). Neither DPSIR nor globus pallidus internus-to-thalamus T1-signal intensity-ratios were related to echo-intensity of corresponding ROI’s. DPSIR correlated with the dysarthria (r = 0.57, p = 0.001), but no other, subscore of the International Cooperative Ataxia Rating Scale, and no other clinical score.

Conclusions

DN gadolinium accumulation is not associated with trace metal accumulation, calcification, or other tissue alteration detectable on ultrasound. A possible mild effect of DN gadolinium accumulation on cerebellar speech function in MS patients, suggested by present data, needs to be validated in larger study samples.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-021-05702-4.

Transcranial ultrasonography as a reliable instrument for the measurement of the cerebral ventricles in rats with experimental hydrocephalus: a pilot study

PURPOSES

Demonstrate that transcranial ultrasonography (TUS) scanning is viable and useful as a diagnostic method in experimental hydrocephalus, as well as to compare measurements of cerebral and ventricular width obtained from TUS scans of hydrocephalic rats with post-mortem anatomical specimens, aiming for the development of accurate criteria to establish ventricular enlargement and progression of hydrocephalus subsequently.

METHODS

Thirty-five male Wistar rats were used. Following hydrocephalus induction, they underwent a transcranial ultrasound scan to measure cerebral and ventricular dimensions, in the fourth and 21 post-induction days. By the end of the experiments, measurements obtained from TUS scans were compared with actual values as seen in the post-mortem specimens of each animal.

RESULTS

Ventricular dilation could be clearly visualized in hydrocephalic animals. We performed intraclass correlation coefficient and linear regression analyses that have demonstrated a precise correlation between measurements of TUS scans and post-mortem specimens; we have found a similarity of 0,95 for the cerebral diameter and 0,97 for ventricular width.

CONCLUSIONS

Transcranial ultrasonography is a useful and reliable diagnostic tool for experimental hydrocephalus; also, it can be used to assess the progression of ventriculomegaly in animal models of hydrocephalus.

Diagnostic value of transcranial ultrasonography for selecting subjects with large vessel occlusion: a systematic review

Introduction

A number of pre-hospital clinical assessment tools have been developed to triage subjects with acute stroke due to large vessel occlusion (LVO) to a specialised endovascular centre, but their false negative rates remain high leading to inappropriate and costly emergency transfers. Transcranial ultrasonography may represent a valuable pre-hospital tool for selecting patients with LVO who could benefit from rapid transfer to a dedicated centre.

Methods

Diagnostic accuracy of transcranial ultrasonography in acute stroke was subjected to systematic review. Medline, Embase, PubMed, Scopus, and The Cochrane Library were searched. Published articles reporting diagnostic accuracy of transcranial ultrasonography in comparison to a reference imaging method were selected. Studies reporting estimates of diagnostic accuracy were included in the meta-analysis.

Results

Twenty-seven published articles were selected for the systematic review. Transcranial Doppler findings, such as absent or diminished blood flow signal in a major cerebral artery and asymmetry index ≥ 21% were shown to be suggestive of LVO. It demonstrated sensitivity ranging from 68 to 100% and specificity of 78–99% for detecting acute steno-occlusive lesions. Area under the receiver operating characteristics curve was 0.91. Transcranial ultrasonography can also detect haemorrhagic foci, however, its application is largely restricted by lesion location.

Conclusions

Transcranial ultrasonography might potentially be used for the selection of subjects with acute LVO, to help streamline patient care and allow direct transfer to specialised endovascular centres. It can also assist in detecting haemorrhagic lesions in some cases, however, its applicability here is largely restricted. Additional research should optimize the scanning technique. Further work is required to demonstrate whether this diagnostic approach, possibly combined with clinical assessment, could be used at the pre-hospital stage to justify direct transfer to a regional thrombectomy centre in suitable cases.

The relationship between right-to-left shunt and brain white matter lesions in Japanese patients with migraine: a single center study

BACKGROUND

There may be a link between right-to-left shunt (RLs) and brain white matter lesions (WMLs) in patients with migraine. In this study, we assessed the relationship between WMLs and RLs in Japanese migraine patients.

METHODS

A total of 107 consecutive patients with migraine with (MA) and without aura (MWOA) were included in this study. Contrast transcranial Doppler ultrasound was used to detect RLs. WMLs were graded using brain magnetic resonance imaging based on well-established criteria.

FINDINGS

The prevalence of RLs was significantly increased in the WMLs positive group (n = 24) compared with the WMLs negative group (n = 83) (75.0% vs. 47.0%, p = 0.015). In prevalence of WMLs between MA and MWOA patients, there were no statistical differences (p = 0.410). Logistic regression analysis adjusted by age and disease duration of migraine identified an RLs-positive status as the sole determinant for the presence of WMLs (OR = 6.15; 95% CI 1.82-20.8; p = 0.003) CONCLUSION: Our study suggests a possible link between RLs and WMLs in Japanese patients with migraine.