Identification of ventricular enlargement and estimation of intracranial pressure by transcranial color-coded real-time sonography

Reliability of Third Ventricle Assessment by Transcranial Ultrasound: A Computational Model of the Effect of Insonation Angle

INTRODUCTION

Transcranial sonography (TCS) is a bedside examination which is currently used in multiple neurocritical care settings. Third ventricle ultrasound is usually a simple technique, though a large insonation angle could lead to an overestimation of third ventricular diameter. The aim of this study was to use a mathematical model to evaluate the impact of probe inclination on the false positive rate when using TCS to evaluate third ventricle enlargement.

METHODS

Using R software, we simulated a pool of 100,000 fictitious patients with a normal third ventricle size (diameter from 0 to 9 mm) in daily follow-up for ventricle enlargement for 30 consecutive days using TCS. Each day, a different, random insonation angle (α) was generated and a corresponding measured diameter calculated as: measured diameter=real diameter/cos α. If the measured diameter was >9.0 mm, the simulation registered a "misdiagnosis" episode and the simulation loop was interrupted; otherwise, the simulation continued to its thirtieth iteration.

RESULTS

Of the 100,000 "patient" simulations, 30,905 (30.9%) had an erroneous TCS diagnosis of ventricular enlargement. Angles of insonation >35 degrees contributed to 79.3% of the total misdiagnoses of ventricular enlargement (false positive rate, 3.71%), whereas misdiagnosis was rare when the insonation angle was ≤15 degrees (1.30% of the total misdiagnoses; false positive rate, 0.06%).

CONCLUSION

Using probe inclinations <15 degrees, erroneous diagnosis of third ventricular enlargement was rare. Our results suggest that TCS has a low rate of false positives when the angle of insonation is minimized.

Fewer neurocognitive deficits and less brain atrophy by third ventricle measurement in PLWH treated with modern ART: A prospective analysis

Background

Despite antiretroviral therapy, cognitive dysfunction seems to remain a major issue for people living with human immunodeficiency virus (PLWH). Previous studies showed a correlation between the width of the third ventricle (WTV) and neurocognitive disorders in PLWH.

Patients and methods

We investigated prevalence and correlation of neuropsychological disorders using WTV as a brain atrophy marker examined by transcranial sonography and MRI in PLWH and healthy age- and gender-matched controls. We used Becks Depression Inventory (BDI) for depression screening, the questionnaires Fatigue Severity Scale (FSS) for fatigue and Short-Form-36 (SF36) for quality of life (QoL) evaluation and Consortium to establish a registry for Alzheimer's disease (CERAD-PLUS) as neuropsychological test battery.

Results

52 PLWH (47 males) and 28 non-infected controls (23 males) with a median age of 52 years (24–78 years) and 51 years (22–79) were analyzed. WTV correlated significantly with age (p < 0.01) but showed no significantly difference in PLWH (median = 3.4 mm) compared to healthy controls (median = 2.8 mm) (p = 0.085). PLWH had both significantly higher BDI-Scores (p = 0.005) and FSS-Scores (p = 0.012). Controls reported higher QoL (SF-36) with significant differences in most items. However, the overall cognitive performance (CERAD total score) showed no significant difference. The WTV of all subjects correlated with neurocognitive performance measured as CERAD total score (p = 0.009) and trail making tests A (p < 0.001) and B (p = 0.018). There was no correlation between the scores of BDI, FSS, SF-36, and CERAD-PLUS items and WTV.

Conclusion

WTV is considered as a predictor of cognitive deficits in neurodegenerative diseases. Nevertheless, we found no significant difference in WTV or overall cognitive performance between PLWH and controls. PLWH suffer more often from depression and fatigue and report reduced QoL when compared to healthy controls.

Sonografisches Neuromonitoring auf der Stroke Unit und in der neurologischen Intensivmedizin

Hintergrund Der Artikel gibt einen Überblick über die aktuellen diagnostischen Einsatzmöglichkeiten sonographischer Anwendung in der neurologischen Intensivmedizin.

Methoden Selektive Literaturrecherche mit kritischer Beurteilung ab dem Jahr 1984 sowie nationaler und internationaler Leitlinien sowie Expertenmeinung.

Ergebnisse Neben der raschen validen Abklärung akuter Schlaganfälle bieten verschiedene neurosonografische Monitoring-verfahren gerade in der Intensivmedizin spezifische Vorteile wie die beliebig häufige Wiederholbarkeit am Patientenbett selbst und die Darstellung in Echtzeit. Innovative Entwicklungen machen die Neurosonografie auch wissenschaftlich zu einem interessanten Gebiet.

Schlussfolgerung Die neurosonografische Diagnostik nimmt seit Jahren einen wichtigen Stellenwert in der neurologischen Intensivmedizin ein. Weitere Anstrengungen sind notwendig, um die Verbreitung der Methode zu fördern und durch wissenschaftliche Evidenz zu stärken.

Brain Ultrasonography Consensus on Skill Recommendations and Competence Levels Within the Critical Care Setting

BACKGROUND

To report a consensus on the different competency levels for the elaboration of skill recommendations in performing brain ultrasonography within the neurocritical care setting.

METHODS

Four brain ultrasound experts, supported by a methodologist, performed a preselection of indicators and skills based on the current literature and clinical expertise. An international panel of experts was recruited and subjected to web-based questionnaires according to a Delphi method presented in three separate rounds. A pre-defined threshold of agreement was established on expert subjective opinions, > 84% of votes was set to support a strong recommendation and > 68% for a weak recommendation. Below these thresholds, no recommendation reached.

RESULTS

We defined four different skill levels (basic, basic-plus, pre-advanced, advanced). Twenty-five experts participated to the full process. After four rounds of questions, two items received a strong recommendation in the basic skill category, three in the advanced, twelve in the basic-plus, and seven in the pre-advanced. Two items in the pre-advanced category received a weak recommendation and three could not be collocated and were excluded from the list.

CONCLUSIONS

Results from this consensus permitted stratification of the different ultrasound examination skills in four levels with progressively increasing competences. This consensus can be useful as a guide for beginners in brain ultrasonography and for the development of specific training programs within this field.

Changes of third ventricle diameter (TVD) mirror changes of the entire ventricular system at acute shunt failure and after shunt revision in pediatric hydrocephalus

PURPOSE

In hydrocephalic children, regular investigations of the ventricles are important for initial diagnosis and after initial treatment. Our recent study showed that changes of the third ventricle diameter (TVD) reliably reflect changes of the entire ventricular system at diagnosis and following initial therapy. This study compares changes of TVD with changes of ventricle indices at acute shunt failure and after shunt revision in hydrocephalic children.

METHODS

A total of 117 children with hydrocephalus were included in this study. MRI/CT images of 30 children were evaluated at the time of acute shunt dysfunction and after subsequent shunt revision. Measurements included axial TVD and three standard measures of lateral ventricles (Evans index, frontal occipital horn ratio (FOHR), and cella media index (CMI)). In 97 children, correlation between axial and coronal/diagonal TVD was evaluated at the time of initial diagnosis of hydrocephalus.

RESULTS

At acute shunt dysfunction, the best linear correlation was found between TVD and CMI (r = 0.702, p < 0.01). Changes of TVD correlated very well to changes of FOHR (r = 0.74, p < 0.01) after shunt revision. The correlation between axial and coronal/diagonal TVD was outstanding (r = 0.995, p < 0.01).

CONCLUSION

TVD showed a significant correlation with all lateral ventricle indices at acute shunt dysfunction and after shunt revision. It is therefore not only an excellent mirror of ventricular changes at initial hydrocephalus diagnosis and therapy, but it can also reliably reflect changes of the ventricular system in relevant clinical situations associated with the lifelong treatment of pediatric hydrocephalus.

Changes of third ventricle diameter (TVD) mirror changes of the entire ventricular system after initial therapy and during follow-up in pediatric hydrocephalus

PURPOSE

Regular measurement of ventricular size is important in children with hydrocephalus. After closure of the fontanelle this is currently addressed by repetitive cranial MRI or CT imaging, coming along with risks of anaesthesia or radiation. As the third ventricle is accessible via the temporal bone window using ultrasound, determination of its diameter might be an easy and radiation-free alternative to assess the ventricular system. An essential precondition is that changes of the third ventricle diameter (TVD) mirror changes of the whole ventricular system. This study compares changes of TVD with changes of ventricular indices before and after initial treatment of hydrocephalus and during the following evolution.

METHODS

MRT/CT images from 117 children with hydrocephalus were evaluated at time of diagnosis, after initial therapy and during follow-up with functional shunts. Measurements included axial TVD and three standard linear measures of the lateral ventricles (Evans Index - EI, fronto-occipital horn ratio - FOHR Index, and Cella Media Index - CMI). Furthermore, a correlation within subjects was calculated in 8 patients over the entire available follow-up.

RESULTS

Relative changes of TVD were significantly correlated to relative changes of all ventricular indices (r = 0.48, r = 0.68 and r = 0.701 for EI, FOHR and CMI, respectively, p < 0.01). The correlation within subjects was outstanding for EI (r = 0.988), FOHR (r = 0.99) and CMI (r = 0.99).

CONCLUSION

TVD showed a significant correlation with all three linear indices at the time of diagnosis and during follow-up changes independently of age, aetiology and ventricular width. TVD and its changes are therefore a reliable surrogate of changes in ventricular size in pediatric hydrocephalus undergoing treatment.

Brain ultrasonography: methodology, basic and advanced principles and clinical applications. A narrative review

Brain ultrasonography can be used to evaluate cerebral anatomy and pathology, as well as cerebral circulation through analysis of blood flow velocities. Transcranial colour-coded duplex sonography is a generally safe, repeatable, non-invasive, bedside technique that has a strong potential in neurocritical care patients in many clinical scenarios, including traumatic brain injury, aneurysmal subarachnoid haemorrhage, hydrocephalus, and the diagnosis of cerebral circulatory arrest. Furthermore, the clinical applications of this technique may extend to different settings, including the general intensive care unit and the emergency department. Its increasing use reflects a growing interest in non-invasive cerebral and systemic assessment. The aim of this manuscript is to provide an overview of the basic and advanced principles underlying brain ultrasonography, and to review the different techniques and different clinical applications of this approach in the monitoring and treatment of critically ill patients.

Polyether Ether Ketone Cranioplasties Are Permeable to Diagnostic Ultrasound

It is a common assumption that the human skull and solid skull implants are impermeable to diagnostic ultrasound. We demonstrated in 2 patients that frontoparietal polyetheretherketone cranioplasties allowed useful imaging of intracranial parenchymal and vascular structures with higher ultrasound frequencies than the 2 MHz used for the temporal bone window. This knowledge about additional imaging properties may be helpful in emergency situations and for vascular monitoring. The decision for a polyether ether ketone cranioplasty may contribute to patient safety.

Transcranial Duplex Sonography Predicts Outcome following an Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

Several radiologic features such as hematoma volume are related to poor outcome following an intracerebral hemorrhage and can be measured with transcranial duplex sonography. We sought to determine the prognostic value of transcranial duplex sonography in patients with intracerebral hemorrhage.

MATERIALS AND METHODS

We conducted a prospective study of patients diagnosed with spontaneous intracerebral hemorrhage. Transcranial duplex sonography examinations were performed within 2 hours of baseline CT, and we recorded the following variables: hematoma volume, midline shift, third ventricle and lateral ventricle diameters, and the pulsatility index in both MCAs. We correlated these data with the CT scans and assessed the prognostic value of the transcranial duplex sonography measurements. We assessed early neurologic deterioration during hospitalization and mortality at 1-month follow-up.

RESULTS

We included 35 patients with a mean age of 72.2 ± 12.8 years. Median baseline hematoma volume was 9.85 mL (interquartile range, 2.74-68.29 mL). We found good agreement and excellent correlation between transcranial duplex sonography and CT when measuring hematoma volume (r = 0.791; P < .001) and midline shift (r = 0.827; P < .001). The logistic regression analysis with transcranial duplex sonography measurements showed that hematoma volume was an independent predictor of early neurologic deterioration (OR, 1.078; 95% CI, 1.023-1.135) and mortality (OR, 1.089; 95% CI, 1.020-1.160). A second regression analysis with CT variables also demonstrated that hematoma volume was associated with early neurologic deterioration and mortality. When we compared the rating operation curves of both models, their predictive power was similar.

CONCLUSIONS

Transcranial duplex sonography showed an excellent correlation with CT in assessing hematoma volume and midline shift in patients with intracerebral hemorrhage. Hematoma volume measured with transcranial duplex sonography was an independent predictor of poor outcome.

Transcranial ultrasound to detect elevated intracranial pressure: comparison of septum pellucidum undulations and optic nerve sheath diameter

Two ultrasound tests that can be used to assess increased intracranial pressure (ICP) at the bedside are described. In outpatients receiving lumbar puncture and in intensive care patients with invasive ICP monitoring, we measured the optic nerve sheath diameter (ONSD) with transbulbar B-mode sonography and septum pellucidum undulation (SPU) induced by repeated passive head rotation with transtemporal M-mode sonography. We assessed the sensitivity and specificity of ONSD and SPU in the prediction of ICP >20 cm H2O. For ONSD, sensitivity was 53% and specificity 100% (n = 35, p < 0.001). The sensitivity of the SPU test was 75% and the specificity 100% (n = 32, p < 0.001). Although the SPU test may not feasible in some patients, it has high sensitivity and specificity comparable to those of ONSD measurement. The SPU test and ONSD may be useful alternatives to fundoscopy in clinical routine, preferably in combination.

The study of deep brain structures by transcranial duplex sonography and imaging resonance correlation

Transcranial duplex sonography (TCS) currently provides us with images of deep brain structures with sufficient resolution. We chose 2 sonographic quantitative parameters: the diameter of the third ventricle and a measurement not used by TCS to date, the midbrain area. Their reliability and reproducibility were assessed using magnetic resonance imaging (MRI) as the reference. A total of 99 patients free from neurodegenerative disorders were examined using TCS, and both parameters were measured by 2 independent explorers. Measurements of third-ventricle diameter by TCS showed very good correlation (r = 0.80) and agreement (ICC = 0.89) with measurements obtained by MRI. Measurements of the midbrain area by TCS also provided acceptable values with moderate correlation (r = 0.36) and agreement (ICC = 0.53). Interexplorer correlation values were good (ICC = 0.98 and 0.79 for the third ventricle and midbrain areas, respectively). Further studies will be required to determine the potential diagnostic usefulness of these parameters.

Transcranial Doppler ultrasound in neurovascular diseases: diagnostic and therapeutic aspects

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.

Sonographic monitoring of midline shift predicts outcome after intracerebral hemorrhage

BACKGROUND

Spontaneous intracerebral hemorrhage (ICH) and the evolution of subsequent perihemorrhagic edema lead to midline shift (MLS), which can be assessed by transcranial duplex sonography (TDS). In this observational study, we monitored MLS with TDS in patients with supratentorial ICH up to day 14 after the ictus, and then correlated MLS with the outcome 6 months after hospital discharge.

METHODS

Sixty-eight patients with spontaneous ICH (volume >20 cm(3)) were admitted during a 1-year period between April 2009 and April 2010. Sixty-one patients fulfilled the inclusion criteria and were eligible for analysis. TDS to measure MLS was performed upon admission and then subsequently, using serial examinations in 24-hour intervals up to day 14. Statistical tests were used to determine cut-off values for functional outcome and mortality after 6 months.

RESULTS

The median National Institutes of Health Stroke Scale (NIHSS) score upon admission was 21 and the mean hematoma volume was 52 cm(3). NIHSS score, functional outcome, hematoma volume and MLS were correlated in the examined patient cohort. ICH score upon admission, hematoma volume and the extent of MLS on days 1-14 were predictive of functional outcome and death. Values of MLS showed two peaks, the first between day 2 and day 5 and the second between day 12 and day 14, indicating that edema progresses not only during the acute but also during the subacute phase. Depending on the time point, an MLS of 4.5-7.5 mm or greater indicated an impending failure of conservative therapy. An MLS of 12 mm or greater at any time indicated mortality with a sensitivity of 69%, a specificity of 100% and positive and negative predictive values of 100 and 74%, respectively.

CONCLUSIONS

MLS seems to be a crucial factor for outcome after ICH. Apart from the hematoma volume itself, edema adds to the intracranial pressure. To monitor MLS in early patient management after ICH, TDS is a useful noninvasive bedside alternative, avoiding increased radiation exposure and repeated transportation of critically ill patients. Cut-off values may help to reliably predict functional outcome and treatment failure in patients undergoing maximal neurointensive therapy.

[Sonographic diagnostics in neurological emergency and intensive care medicine]

BACKGROUND

This article gives an up-to-date overview of neurosonographic emergency and intensive care diagnostics.

METHODS

Selective literature research from 1984 with critical appraisal and including national and international guidelines.

RESULTS

Fast and valid diagnostics in acute stroke is the main field of application of neurosonography. Specific monitoring methods bear great advantages for intensive care patients, especially "as-often-as-wanted" repetitive imaging under real-time conditions. A number of new developments make neurosonography an interesting area of research.

CONCLUSIONS

Neurosonography has played a key role in neurological emergency and intensive care medicine for many years. It remains important to continuously support dissemination of the method.

Usefulness of transcranial echography in patients with decompressive craniectomy: a comparison with computed tomography scan

OBJECTIVE

To assess the agreement between computed tomography and transcranial sonography in patients after decompressive craniectomy.

DESIGN

Prospective study.

SETTING

The medical intensive care unit of a university-affiliated teaching hospital.

PATIENTS

Thirty head-injured patients consecutively admitted to the intensive care unit of "A. Gemelli" Hospital who underwent decompressive craniectomy were studied. Immediately before brain cranial tomography, transcranial ultrasonography was performed.

MEASUREMENTS AND MAIN RESULTS

The mean difference between computed tomography and echography in measuring the dislocation of midline structures was 0.3 ± 1.6 mm (95% confidence interval 0.2-0.9 mm; intraclass correlation coefficient, 0.979; p < .01). An excellent correlation was found between computed tomography and transcranial sonography in assessing volumes of hyperdense lesions (intraclass correlation coefficient, 0.993; p < .01). Lesions that appear hypodense on computed tomography scan were divided in ischemic and late hemorrhagic. No ischemic lesion was localized on echography; a poor correlation was found between computed tomography and echography in assessing the volume of late hemorrhagic lesions (intraclass correlation coefficient, 0.151; p = .53). A quite good correlation between transcranial ultrasonography and computed tomography was found in measuring lateral ventricles width (intraclass correlation coefficient, 0.967; p < .01). Sensitivity and specificity of transcranial ultrasonography in comparison with computed tomography to detect the position of intracranial pressure catheter was 100% and 78%.

CONCLUSIONS

Echography may be a valid option to computed tomography in patients with decompressive craniectomy to assess the size of acute hemorrhagic lesions, to measure midline structures and the width of lateral ventricles, and to visualize the tip of the ventricular catheter.

Width of the third ventricle assessed by transcranial sonography can monitor brain atrophy in a time- and cost-effective manner--results from a longitudinal study on 500 subjects

Ventricular width and its enlargement over time are discussed as promising markers for preclinical brain atrophy. The aim of our study was to define whether brain atrophy can reliably be monitored by transcranial ultrasound (TCS). In a prospective longitudinal trial over 5years, 500 healthy persons were examined by a standardized protocol with TCS in addition to an extensive cognitive testing using the Consortium to Establish a Registry of Alzheimer's Disease - Neuropsychological Testing (CERAD-NP). TCS displayed the third ventricle in 96% of all cases at the follow-up with a high intra-individual reproducibility and excellent inter-rater coefficient (0.992). The mean diameter of the third ventricle in subjects with a cognitive decline was significantly wider (6mm±2) than in subjects with normal cognitive testing results (4.6mm±1.8). We demonstrated that the width of the third ventricle, as a marker of brain atrophy can reliably be monitored by using TCS as a non-invasive, time- and cost-effective method. We provide evidence that the assessed width of the third ventricle can differentiate between subjects with a normal cognitive performance and subjects with a cognitive decline. TCS may be a useful screening tool in the early diagnosis of cognitive decline.

Diameter assessment of the third ventricle with transcranial sonography in patients with multiple sclerosis

BACKGROUND AND PURPOSE

Diameter measurement of the third ventricle with magnetic resonance imaging (MRI) and recently also with transcranial sonography (TCS) has emerged as a surrogate marker for brain atrophy and disease progression in multiple sclerosis (MS). This study aims to evaluate TCS measurements of the third ventricle diameter in a clinical routine setting against MRI.

METHODS

Transverse diameters of the third ventricle were determined in 27 MS patients using both, TCS and MRI. In TCS, the distance between the leading edges of the brain-ventricle interfaces was assessed in axial image planes. In MRI, the transverse diameter of the mid-portion of the third ventricle was measured on axial T1-weighted images.

RESULTS

The mean diameter of the third ventricle was 4.0 mm (SD 1.7 mm), when measured with MRI, and 4.4 mm (SD 1.7 mm), when measured with TCS. The 95% limits of agreement of the Bland-Altman Plot were 2.93 mm (95% CI 2.08 to 3.78 mm) and -2.23 mm (95%CI -3.08 to -1.38 mm). Pearson correlation coefficient was .71 (P < .0001).

CONCLUSIONS

TCS may appear suitable as screening examination for the extent of brain atrophy at a single-point study, but at least in the early stages of the disease, TCS is not useful to monitor disease progression.

Third ventricle midline shift due to spontaneous supratentorial intracerebral hemorrhage evaluated by transcranial color-coded sonography

OBJECTIVE

We aimed to assess the clinical usefulness of the third ventricle midline shift (MLS) evaluated by transcranial color-coded sonography (TCCS) in acute spontaneous supratentorial intracerebral hemorrhage (ICH).

METHODS

Consecutive patients with acute (<24 hours after symptom onset) ICH were recruited for this TCCS study. Sonographic measurement of MLS and the pulsatility index (PI) of the middle cerebral arteries were compared with head computed tomographic (CT) data, including MLS, and hematoma volume. Poor functional outcome at 30 days after stroke onset was defined as modified Rankin scale greater than 2.

RESULTS

There were 51 patients with spontaneous supratentorial ICH who received CT and TCCS studies within a 12-hour window. Correlation between MLS by TCCS (mean +/- SD, 3.2 +/- 2.6 mm) and CT (3.0 +/- 2.4 mm) was high (gamma = 0.91; P < .01). There was also a good linear correlation between hematoma volume and MLS by TCCS (gamma = 0.81; P < .01). Compared with ICH volume less than 25 mL, those with greater volume had more severe MLS and a higher PI of the ipsilateral middle cerebral artery (P < .001). Midline shift by TCCS was more sensitive and specific than the PI in detecting large ICH (accuracy = 0.82 if MLS > or = 2.5 mm), and it was also a significant predictor of poor outcome (odds ratio, 2.09 by 1-mm increase; 95% confidence interval, 1.06-4.13).

CONCLUSIONS

Midline shift may be measured reliably by TCCS in spontaneous supratentorial ICH. Our study also showed that MLS on TCCS is a useful and convenient method to identify patients with large ICH and hematoma expansion and to predict short-term functional outcome.

Evaluation of the ventricular system in children using transcranial ultrasound: reference values for routine diagnostics

In children, evaluation of the size of the ventricular system is important. Transcranial Doppler sonography (TCD), a broadly available and easily applicable method that is not hampered by side effects, such as radiation, is a valuable tool for routine examinations. However, standard TCD values of the ventricular system are lacking. In this study, we performed TCD through the temporal acoustic bone window in a large cohort of 1693 healthy children. Of these, 157 had to be excluded because of insufficient bone windows. In the remaining children, a mean width of 1.4 +/- 0.8 mm for the third ventricle, 14.4 +/- 0.8 mm for the right and 14.6 +/- 0.7 mm for the left cella media, and 1.6 +/- 0.7 mm for the right and 1.9 +/- 0.8 mm for the left temporal horn were measured. Side differences are indicated and values are given in relation to age and gender. Inter-rater reproducibility obtained in 25 children was adequate, with no significant difference between the two measurements in any of the parts of the ventricular system measured, rendering these values suitable for reference.

Sonographic imaging of the brain parenchyma

Using B-mode transcranial sonography (TCS), it is possible to image the brain parenchyma through the intact skull with conventional low-frequency probes. Several brain disorders can be depicted by TCS such as bleedings, brain tumors, or enlargement of the ventricular system. More recently there is evidence that TCS findings can complement information from other neuroimaging techniques in neurodegenerative disorders leading to new insights and pathophysiological concepts.

Perspectives of B-mode transcranial ultrasound

Transcranial color coded sonography has proved valuable in the diagnostic work-up of cerebrovascular disorders in adults. More recently, evidences have converged that transcranial sonography is also useful in the diagnosis of brain parenchymal disorders. Here, a new field of application is the visualization of signal intensity shift in specific brain areas in some neurodegenerative disorders (Parkinson's disease, idiopathic dystonia, and depression). Findings obtained by transcranial ultrasound complement information from other neuroimaging data in these disorders and have led to the generation of new pathophysiological concepts. In this review we summarize the application fields of transcranial sonography with special emphasis on recent findings in neurodegenerative disorders and their implications for future research. As new application and processing techniques are being developed transcranial color coded sonography will gain increasing impact on both diagnosis and research of neurological disorders.

Clinical application of transcranial colour-coded duplex sonography--a review

Transcranial colour-coded duplex sonography (TCCS) is a new and non-invasive ultrasound application that combines both imaging of intracranial vessels and parenchymal structures at a high spatial resolution. This manuscript reviews the clinical applications of TCCS with focus on its diagnostic abilities in acute stroke patients. Furthermore, new experimental imaging techniques are discussed.

Dynamic and three-dimensional transcranial ultrasonography of an arachnoid cyst in the cerebral convexity. Technical note

Structural imaging of the brain, such as cerebral computerized tomography (CT) and magnetic resonance (MR) imaging, is state-of-the-art. Dynamic transcranial (dTC) ultrasonography and three-dimensional (3D) transcranial color-coded duplex (TCC) ultrasonography are complementary, noninvasive procedures with the capacity for real-time imaging, which may aid in the temporary management of space-occupying lesions. A 16-year-old woman presented with recurrent tension-type headaches. A space-occupying arachnoid cyst in the cerebral convexity was demonstrated on MR images. The patient underwent an examination for raised intracranial pressure. which was performed using a standard color-coded duplex ultrasonography system attached to a personal computer-based system for 3D data acquisition. Transcranial ultrasonography was used to identify the outer arachnoid membrane of the cyst, which undulated freely in response to rotation of the patient's head (headshake maneuver). Three-dimensional data sets were acquired and, using a multiplanar reformatting reconstruction algorithm, the authors obtained high-resolution images that corresponded to the initial MR image and a follow-up cranial CT scan. No detectable differences were observed on dTC or 3D TC ultrasonograms obtained at follow-up examinations performed 9 and 28 months later. Three-dimensional TCC and dTC ultrasonography may complement conventional diagnostic procedures such as MR and CT imaging. This report represents evidence of the high resolution and good reproducibility of 3D TC methods. Ultrasonography is a mobile and inexpensive tool and may be used to improve management and therapeutic strategies for patients with space-occupying brain lesions in selected cases.

Sonographic monitoring of midline shift in space-occupying stroke: an early outcome predictor

BACKGROUND AND PURPOSE

Transcranial color-coded duplex sonography (TCCS) allows bedside imaging of intracranial hemodynamics and parenchymal structures. It provides reliable information regarding midline shift (MLS) in space-occupying hemispheric stroke. We studied the value of MLS measurement to predict fatal outcome at different time points after stroke onset.

METHODS

Forty-two patients with acute, severe hemispheric stroke were enrolled. Cranial computed tomography (CCT) and extracranial duplex sonography were performed on admission. TCCS was carried out 8+/-3, 16+/-3, 24+/-3, 32+/-3, and 40+/-3 hours after stroke onset. Lesion size was determined from follow-up CCT.

RESULTS

Twelve patients died as the result of cerebral herniation (group 1); 28 survived (group 2). Two patients received decompressive hemicraniectomy and were therefore excluded from further evaluation. MLS was significantly higher in group 1 as early as 16 hours after onset of stroke. Specificity and positive predictive values for death caused by cerebral herniation of MLS >/=2.5, 3.5, 4.0, and 5.0 mm after 16, 24, 32, and 40 hours were 1.0.

CONCLUSIONS

TCCS helps to estimate outcome as early as 16 hours after stroke onset and thus facilitates identification of patients who are unlikely to survive without decompressive craniectomy. Because of its noninvasive character and bedside suitability, sonographic monitoring of MLS might be a useful tool in management of critically ill patients who cannot undergo repeated CCT scans.

Transcranial colour-coded sonography for the bedside evaluation of mass effect after stroke

Repeated cranial computerized tomography scan examination in patients with elevated intracranial pressure is time consuming and requires patient transportation. We prospectively evaluated the diagnostic value of transcranial duplex sonography as a bedside tool for detection of the mass effect after space-occupying ischemic stroke and brain haemorrhage and for evaluating the width and dislocation of the ventricular system and the dislocation of brain mid-line structures. We used transcranial duplex sonography in 21 consecutive patients with space-occupying ischemic middle cerebral artery infarction and brain haemorrhage. The transcranial duplex sonography examinations were performed within 2 h before or after corresponding follow-up cranial computerized tomography scans. We measured the third ventricular width as a parameter for infratentorial and the mid-line shift for supratentorial space-occupying effect. In all patients, mid-line structures could be identified by transcranial duplex sonography. Significant third ventricular dilation was found subsequently in most patients with infratentorial mass effect, and mid-line shift occurred in all patients with supratentorial space-occupying lesions, respectively. The mean difference (absolute values) between transcranial duplex sonography and cranial computerized tomography measurements was 0.8 mm for the ventricular width (standard deviation 1 mm) and 1.1 mm for the mid-line shift (standard deviation: 1.46 mm), with a tendency for these parameters to be underestimated at higher values using transcranial duplex sonography. The linear correlation coefficients were R = 0.97 and R = 0.94, respectively. Transcranial duplex sonography appears to be a sufficiently reliable bedside method for evaluating the width and the lateral displacement of the third ventricle, as validated by cranial computerized tomography scan. Thus, it may be suitable for monitoring the space-occupying effect of both supra- and infratentorial strokes during treatment on critical care and stroke units.

Transcranial sonography of the brain parenchyma: comparison of B-mode imaging and tissue harmonic imaging

Transcranial color-coded Duplex sonography (TCCS) has been used for the identification of cerebrovascular disorders. Recently, its value in the diagnosis of disorders of the brain parenchyma has been proposed. The object of this study was to determine systematically the echo pattern of the brain parenchyma and to compare conventional B-mode imaging with tissue harmonic imaging (THI). Transcranial sonography (TCS) was performed in 54 healthy individuals through the temporal bone window using conventional B-mode imaging and THI by two experienced investigators. Identification rates for several brain structures were assessed, and the quality of depiction of each method was graded semiquantitatively. In addition, several parts of the ventricular system and the basal cerebral cisterns were measured. Four subjects did not have an adequate bone window for transcranial examination. In the remaining people, the bone window was assessed to be adequate (59%) or excellent (33%). In the majority (> 80%), TCS allowed an unequivocal identification of various brain structures. Inter-rater variability of the assessments of tissue echogenicity and measurements of the ventricular width were found to be low for several structures (e.g., brainstem, thalamus, or 3rd ventricle). The echo pattern of brain tissue in THI is identical to that described for B-mode imaging. Using THI, contours of brain structures were typically visualized more clearly and the reproducibility of measurements was more consistent. In our experience, insonation of the contralateral lobes was limited when depths were higher than 12 cm using THI. In conclusion, TCS allowed the sonographic examination of the brain parenchyma in the majority of our subjects. THI substantially improves the identification of parenchymal structures when the depth is below 12 cm.

Dynamic and three-dimensional transcranial sonography studies of an asymptomatic, cerebral convexity arachnoid cyst

Dynamic and three-dimensional transcranial sonography (dTCS and 3D-TCCS) examinations are complementary, noninvasive methods used in the assessment and follow up of patients with cerebrospinal fluid (CSF) circulation disorders.

A 16-year-old female patient who presented with a space-occupying, cerebral convexity arachnoid cyst and recurrent tension-type headache underwent examination for raised intracranial pressure (ICP) by using a standard color-coded duplex sonography system attached to a personal computer–based system for 3D data acquisition. Conventional TCS identified the outer arachnoid membrane of the cyst, which undulated freely after short rotation of the head (“headshake maneuver”). The undulation was documented as a QuickTime movie that is included with this article. A 3D dataset was acquired and, by using a multiplanar reformatting reconstruction algorithm, the authors obtained images with excellent resolution that corresponded to an initial magnetic resonance (MR) imaging study. No differences on dTCS and 3D-TCS were detectable at follow up 9 months later, indicating normal ICP and a stable, benign condition.

The use of 3D-TCCS and dTCS ultrasonography may complement other diagnostic procedures such as MR imaging and, thus, can improve management and therapeutic strategies for patients with CSF circulation disorders. In this report the authors present evidence of the excellent fine resolution and exact reproducibility of reconstructed ultrasound image planes derived from 3D datasets and the additional biomedical information from dynamic imaging.

Basal ganglia alterations and brain atrophy in Huntington's disease depicted by transcranial real time sonography

OBJECTIVES AND METHODS

Transcranial real time sonography (TCS) was applied to 49 patients with Huntington's disease and 39 control subjects to visualise alterations in the echotexture of the basal ganglia. For comparison T1 weighted, T2 weighted, and fast spin echo MRI was performed in 12 patients with Huntington's disease with and in nine patients without alterations of the basal ganglia echotexture as detected by TCS and T1 weighted, T2 weighted, and fast spin echo MRI. Furthermore, the widths of the frontal horns, third ventricle, and the lateral ventricles were depicted in TCS examinations and correlations examined with corresponding CT slices.

RESULTS

Eighteen out of 45 (40%) of the patients with Huntington's disease with adequate insonation conditions showed hyperechogenic lesions of at least one basal ganglia region. In 12 patients TCS depicted hyperechogenic lesions of the substantia nigra; in six patients the head of the caudate nucleus was affected. The lentiform nucleus (n=3) and the thalamus (n=0) were less often affected or spared. Hyperechogenic lesions were significantly more frequent in patients with Huntington's disease than in 39 control subjects, who had alterations of the echotexture in 12.8% (4/39) of the examinations. The number of CAG repeats and the clinical status correlated with the identification of hyperechogenic lesions of the substantia nigra (p<0.01). Hyperechogenic lesions of the caudate nucleus were associated with an increased signal intensity in T2 weighted MR images (p<0.05). All TCS parameters indicating brain atrophy correlated with CT findings (p<0.0001).

CONCLUSIONS

TCS detects primarily abnormalities of the caudate nucleus and substantia nigra in Huntington's disease. These changes in the echotexture may represent degenerative changes in the basal ganglia matrix and are partially associated with CAG repeat expansion and the severity of clinical findings.

Differentiation between intracerebral hemorrhage and ischemic stroke by transcranial color-coded duplex-sonography

BACKGROUND AND PURPOSE

The differential diagnosis of intracerebral hemorrhage versus ischemic stroke has critical implications for stroke management. Transcranial color-coded duplex sonography (TCCS) has been shown to identify intracerebral hemorrhages and intracerebral vessel occlusions. We conducted this study to evaluate the sensitivity and specificity of TCCS in this differential diagnosis and in the detection of stroke complications.

METHODS

One hundred fifty-one patients (58 women, 93 men; mean age, 65.6 years [range, 32 to 89 years] ) with acute hemiparesis were enrolled in this prospective study. On admission all patients had a complete neurological examination. A cranial CT scan and a sonographic examination of the brain parenchyma and all extracranial and intracranial cerebral arteries were conducted. The sonographer was blinded for the radiological findings.

RESULTS

According to CT criteria, 60 patients had an intracerebral hemorrhage and 67 patients had an ischemic stroke, and in 24 patients CT findings were inconclusive, showing neither bleeding nor an ischemic stroke. On sonographic examination, 18 patients (12%) had no sufficient acoustic bone window. Of the remaining 133 patients, 126 (95%) were diagnosed correctly by sonography in agreement with CT. Sonography missed 3 atypical bleedings (2 with upper parietal location). In 4 patients without bleeding, an intracerebral hemorrhage was suspected by TCCS because of increased white matter echo density due to microangiopathy. Stroke complications depicted by CT (disturbance of cerebrospinal fluid circulation, hemorrhagic transformation, midline shift, ventricular bleeding) (n=54) were correctly shown by TCCS in 45 patients (83%). No complication was missed that would have required further treatment.

CONCLUSIONS

In comparison to the "gold standard" of CT, TCCS identified stroke complications and differentiated between intracerebral hemorrhage and ischemic stroke with reasonable sensitivity. Thus, if CT is not readily available, TCCS may complement clinical examination in patients with acute stroke. In addition, it may also be useful in detecting stroke complications in the follow-up of stroke patients.

Comparison of transcranial sonography, magnetic resonance imaging, and single photon emission computed tomography findings in idiopathic spasmodic torticollis

Various lines of evidence suggest that the basal ganglia and thalamus are involved in the pathogenesis of idiopathic dystonia, but unfortunately neuroradiological and pathological data are sparse and controversial. In this study, we have examined 10 patients with spasmodic torticollis by neuroimaging techniques, including transcranial sonography (TS; n = 10), conventional (n = 10) and diffusion-weighted (n = 5) magnetic resonance imaging (MRI), and single photon emission computed tomography (SPECT; n = 10), employing [123I]iodobenzamide (IBZM) as a ligand with a high affinity to the D2 receptor. In seven patients, TS showed small hyperechogenic lesions in the medial segments of the lentiform nucleus contralateral to the side of head deviation. In accordance with the site of TS abnormalities, diffusion-weighted MRI displayed a hyperintense lesion in only one patient, while standard MRI of this area was normal in all patients. SPECT revealed a slight but statistically nonsignificant reduction of IBZM tracer uptake in an area corresponding to the dorsal portions of the striatum in 9 of the 10 patients. TS findings support the hypothesis that structural alternations of the pallidothalamic circuit contralateral to the side of head deviation are involved in the pathogenesis of idiopathic spasmodic torticollis. TS may be more sensitive in detecting basal ganglia alterations than MRI.

Evaluation of the ventricular system in adults by transcranial duplex sonography

Transcranial duplex color-flow sonography provides visualization of intracranial structures, and measures angle-corrected blood flow velocity in the basal cerebral arteries of adults. In 44 patients with central nervous system disease, the oblique diameters of the third and the middle part of the lateral ventricle were measured by transcranial duplex color-flow sonography using a system with a 2.5-MHz transducer, and compared to computed tomography measurements. The correlation coefficients for the third and lateral ventricle measurements were r = 0.83 (p < 0.0001, N = 38) and 0.73 (p < 0.0001, N = 78), respectively. A second investigation was performed by transcranial duplex to evaluate intraobserver and interobserver reproducibility. The correlation coefficient representing interobserver reproducibility in 27 patients was r = 0.87 (p < 0.0001, N = 47) for the lateral ventricle and r = 0.9 (p < 0.0001, N = 49) for the third ventricle. The intraobserver reproducibility correlation coefficient was r = 0.93 (p < 0.0001, N = 22) for the lateral ventricle in 12 patients. In 49 healthy volunteers the oblique diameters of the lateral and third ventricles were age dependent, measuring 16.7 +/- 2.3 mm and 4.8 +/- 1.9 mm, respectively, in those younger than 59 years, compared to 19.0 +/- 2.9 mm and 7.6 +/- 2.1 mm in those 60 years or older. Therefore, transcranial duplex color-flow sonography measures noninvasively the third and the lateral ventricle in adults.