Transcranial Doppler assessment of cerebral vasospasm

Chasing the Mystery of the Etiology of Acute Kidney Injury in Pediatric Severe Malaria

Acute kidney injury (AKI) is increasingly recognized in pediatric severe malaria, but an understanding of contributory mechanisms is lacking. We evaluated potential hemodynamic contributors to AKI in children with cerebral malaria. Structural AKI was defined using urine neutrophil gelatinase-associated lipocalin (uNGAL) values >125 ng/mL. We included 62 patients (median age 53.5 [31, 71] months), and 38 (61%) had AKI at hospital admission. Blantyre Coma Score <2 (aOR 9.1, 95%CI 1.8-43, P = .003), a low-flow phenotype on transcranial doppler ultrasound (TCD) (aOR 2.3, 95%CI 1.1-7.7, P = .05), and thrombocytopenia <75,000 × 106/L (aOR 4.2, 95%CI 1.3-12.8, P = .03) were associated with AKI. Cardiac index (CI) was lower (P = .01) and systemic vascular resistive index (SVRI) higher (P = .03) in children with AKI compared to those without. AKI was associated with poor outcome (sequelae or death: OR 5.7, 95%CI 1.5-19, P = .01). AKI is common in children with cerebral malaria. Hemodynamic measurements suggest increased vascular tone contributes to AKI.

Diagnostic value of transcranial doppler to predict delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage : To predict delayed cerebral ischemia

BACKGROUND

Transcranial Doppler (TCD) is a technique to assess blood flow velocity in the cerebral arteries. TCD is frequently used to monitor aneurysmal subarachnoid hemorrhage (aSAH) patients. This study compares TCD-criteria for vasospasm and its association with Delayed Cerebral Ischemia (DCI). An overall score based on flow velocities of various intracranial arteries was developed and evaluated.

METHODS

A retrospective diagnostic accuracy study was conducted between 1998 and 2017 with 621 patients included. Mean flow velocity (MFV) of the cerebral artery was measured between 2-5 days and between 6-9 days after ictus. Cutoff values from the literature, new cutoff values, and a new composite score (Combined Severity Score) were used to predict DCI. Sensitivity, specificity, and area under the curve (AUC) were determined, and logistic regression analysis was performed.

RESULTS

The Combined Severity Score showed an AUC 0.64 (95%CI 0.56-.71) at days 2-5, with sensitivity 0.53 and specificity 0.74. The Combined Severity Score had an adjusted Odds Ratio of 3.41 (95CI 1.86-6.32) for DCI. MCA-measurements yielded the highest AUC to detect DCI at day 2-5: AUC 0.65 (95%CI 0.58-0.73). Optimal cutoff MFV of 83 cm/s for MCA resulted in sensitivity 0.73 and specificity 0.50 at days 2-5.

CONCLUSION

TCD-monitoring of aSAH patients may be a valuable strategy for DCI risk stratification. Lower cutoff values can be used in the early phase after the ictus (day 2-5) than are commonly used now. The Combined Severity Score incorporating all major cerebral arteries may provide a meaningful contribution to interpreting TCD measurements.

Transcranial Doppler analysis based on computer and artificial intelligence for acute cerebrovascular disease

Cerebrovascular disease refers to damage to brain tissue caused by impaired intracranial blood circulation. It usually presents clinically as an acute nonfatal event and is characterized by high morbidity, disability, and mortality. Transcranial Doppler (TCD) ultrasonography is a non-invasive method for the diagnosis of cerebrovascular disease that uses the Doppler effect to detect the hemodynamic and physiological parameters of the major intracranial basilar arteries. It can provide important hemodynamic information that cannot be measured by other diagnostic imaging techniques for cerebrovascular disease. And the result parameters of TCD ultrasonography such as blood flow velocity and beat index can reflect the type of cerebrovascular disease and serve as a basis to assist physicians in the treatment of cerebrovascular diseases. Artificial intelligence (AI) is a branch of computer science which is used in a wide range of applications in agriculture, communications, medicine, finance, and other fields. In recent years, there are much research devoted to the application of AI to TCD. The review and summary of related technologies is an important work to promote the development of this field, which can provide an intuitive technical summary for future researchers. In this paper, we first review the development, principles, and applications of TCD ultrasonography and other related knowledge, and briefly introduce the development of AI in the field of medicine and emergency medicine. Finally, we summarize in detail the applications and advantages of AI technology in TCD ultrasonography including the establishment of an examination system combining brain computer interface (BCI) and TCD ultrasonography, the classification and noise cancellation of TCD ultrasonography signals using AI algorithms, and the use of intelligent robots to assist physicians in TCD ultrasonography and discuss the prospects for the development of AI in TCD ultrasonography.

Role of Nimodipine and Milrinone in Delayed Cerebral Ischemia

OBJECTIVE

The role of nimodipine and milrinone in the management of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) was studied using clinical and TCD (transcranial Doppler) parameters.

METHODS

In this prospective observational study, patients with DCI after aneurysmal SAH presenting between November 2020 and June 2021 who were treated by either intra-arterial nimodipine (IAN) or intravenous milrinone (IVM) were included after excluding patients in whom both IAN and IVM had been given or mechanical angioplasty was performed. Twelve-hourly TCD was performed during the course of the therapy. Clinical improvement and the development of new brain infarcts were also assessed. A P value <0.05 was considered statistically significant.

RESULTS

Thirty-four patients fulfilled the inclusion criteria (IVM, 13/34 [38%]; IAN, 21/34 [62%]); patients in the IVM group (vs. IAN group) had poorer median Glasgow Coma Scale score (12 vs. 13), poorer motor response (<M6 response, 5/13 [38%] vs. 5/21 [24%]; P = 0.36) and higher grades (modified Fisher grade ≥3) of SAH (12/13 [92%] vs. 8/21 [86%]; P = 0.56). More patients in the IAN group (vs. IVM group) showed clinical improvement (17/21 [81%] vs. 10/13 [77%]; P = 0.77), development of new infarcts (15/21 [71%] vs. 7/13 [54%]; P = 0.29] and discharged to home (13/21 [62%] vs. 6/13 [46%]; P = 0.36) with less mortality (1/21 [9%] vs. 4/13 [23%]; P = 0.037). On TCD analysis, both IAN and IVM protocols showed similar effects in middle cerebral artery vasospasm; however, IAN proved better over time. In group-effect analysis, the IAN protocol was significantly better in anterior cerebral artery and posterior cerebral artery vasospasm compared with IVM protocol.

CONCLUSIONS

In this single-center small study, patients in the IAN group had significantly less mortality compared with the IVM group in the management of DCI after aneurysmal SAH.

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.

Transcranial Dopplers Revisited: Development of Novel Markers for Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage

Background

Cerebral vasospasm has been monitored by conventional angiography or transcranial Doppler (TCD). While angiography is the most accurate and reliable method for detection, TCDs are a noninvasive alternative to monitor onset and resolution of vasospasm. We aim to determine whether alternative TCD parameters rather than Lindegaard ratio lead to an improved method to diagnose and potentially prevent cerebral vasospasm.

Methods

A total of 103 consecutive patients with subarachnoid hemorrhage (SAH) were retrospectively reviewed and TCD studies were performed during the first 14 days post-bleed or longer if indicated. Multivariate logistic regression models were developed using significant univariate characteristics. Receiver operating characteristic (ROC) curves evaluated the mean middle cerebral artery (MCA), peak systolic MCA (PSV MCA), and end diastolic MCA (EDV MCA) velocities as well as ratios when compared to the ipsilateral extracranial internal carotid artery (ICA). The area under the curve was calculated to compare accuracy for symptomatic vasospasm.

Results

Thirteen patients (12.6%) were observed to develop cerebral vasospasm. Aneurysm location (p = 0.51), Hunt and Hess grade (p = 0.44), Fischer grade (p = 0.87), comorbidities, age (p = 0.67), or gender (p = 0.41) did not appear to have any effect in predicting the presence of vasospasm. ROC curves demonstrated that MCA EDV appeared to be slightly better compared to MCA velocity in predicting symptomatic vasospasm. PSV MCA/extracranial ICA and the EDV MCA/extracranial ICA ratios appeared to be an improvement to the Lindegaard ratio in the prediction of symptomatic vasospasm.

Conclusion

The utility of peak systolic and end diastolic velocities, instead of the classically referenced mean velocities and Lindegaard ratio, may improve diagnostic sensitivity of cerebral vasospasm after subarachnoid hemorrhage.

Adaptive Maximal Blood Flow Velocity Estimation From Transcranial Doppler Echos

OBJECTIVE

Novel applications of transcranial Doppler (TCD) ultrasonography, such as the assessment of cerebral vessel narrowing/occlusion or the non-invasive estimation of intracranial pressure (ICP), require high-quality maximal flow velocity waveforms. However, due to the low signal-to-noise ratio of TCD spectrograms, measuring the maximal flow velocity is challenging. In this work, we propose a calibration-free algorithm for estimating maximal flow velocities from TCD spectrograms and present a pertaining beat-by-beat signal quality index.

METHODS

Our algorithm performs multiple binary segmentations of the TCD spectrogram and then extracts the pertaining envelopes (maximal flow velocity waveforms) via an edge-following step that incorporates physiological constraints. The candidate maximal flow velocity waveform with the highest signal quality index is finally selected.

RESULTS

We evaluated the algorithm on 32 TCD recordings from the middle cerebral and internal carotid arteries in 6 healthy and 12 neurocritical care patients. Compared to manual spectrogram tracings, we obtained a relative error of -1.5%, when considering the whole waveform, and a relative error of -3.3% for the peak systolic velocity.

CONCLUSION

The feedback loop between the signal quality assessment and the binary segmentation yields a robust algorithm for maximal flow velocity estimation. Clinical Impact: The algorithm has already been used in our ICP estimation pipeline. By making the code and the data publicly available, we hope that the algorithm will be a useful building block for the development of novel TCD applications that require high-quality flow velocity waveforms.

Variability Predictors of Vasospasm in Subarachnoid Hemorrhage: A Feasibility Study

BACKGROUND

Mean cerebral blood flow velocity (mean-CBFV) obtained from Transcranial Doppler (TCD) poorly predicts cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage (aSAH). Variability descriptors of mean-CBFV obtained during extended TCD recordings may improve this prediction. We assessed the feasibility of generating reliable linear and non-linear descriptors of mean-CBFV variability using extended recordings in aSAH patients and in healthy controls. We also explored which of those metrics might have the ability to discriminate between aSAH patients and healthy controls, and among patients who would go on to develop vasospasm and those who would not.

METHODS

Bilateral mean-CBFV, blood pressure, and heart rate were continuously recorded for 40 minutes in aSAH patients (n = 8) within the first 5 days after ictus, in age-matched healthy controls (n = 8) and in additional young controls (n = 8). We obtained linear [standard deviation, coefficient of variations, and the very-low (0.003-0.040 Hz), low (0.040-0.150 Hz), and high-frequency (0.15-0.4 Hz) power spectra] and non-linear (Fractality, deterministic Chaos analyses) variability metrics.

RESULTS

We successfully obtained TCD recordings from patients and healthy controls and calculated the desired metrics of mean-CBFV variability. Differences were appreciable between aSAH patients and healthy controls, as well as between aSAH patients who later developed vasospasm and those who did not.

CONCLUSIONS

A 40-minute TCD recording provides reliable variability metrics in aSAH patients and healthy controls. Future studies are required to determine if mean-CBFV variability metrics remain stable over time, and whether they may serve to identify patients who are at greatest risk of developing cerebral vasospasm after aSAH.

Monitoring cerebral vasospasm: How much can we rely on transcranial Doppler

Cerebral vasospasm leading to delayed cerebral ischaemia is one of the major concerns following subarachnoid haemorrhage (SAH). Various modalities are present for evaluation and detection of cerebral vasospasm that occurs following SAH. They include transcranial Doppler (TCD), computed tomographic angiography (CTA), computed tomographic (CT) perfusion and digital subtraction angiography (DSA). The recent guidelines have advocated the use of TCD and have described it as a reasonable technique for monitoring the development of vasospasm. This review describes the functioning of TCD, the cerebral haemodynamic changes during vasospasm and TCD-based detection of vasospasm. The review shall highlight as to how the TCD derived values are relevant in the settings of neurocritical care. The data in the review have been consolidated based on our search of literature from year 1981 till 2016 using various data base.

The Need for a Rational Approach to Vasoconstrictive Syndromes: Transcranial Doppler and Calcium Channel Blockade in Reversible Cerebral Vasoconstriction Syndrome

INTRODUCTION

Reversible cerebral vasoconstriction syndrome (RCVS) typically affects young patients and left untreated can result in hemorrhage or ischemic stroke. Though the disorder has been well characterized in the literature, the most appropriate way to diagnose, treat, and evaluate therapeutic response remains unclear. In previous studies, transcranial Doppler ultrasound (TCD) has shown elevated velocities indicative of vasospasm. This imaging modality is noninvasive and inexpensive; an attractive option for diagnosis and therapeutic monitoring if it is sensitive enough to detect changes in the acute setting given that RCVS often affects the distal vessels early in the course of disease. There is also limited data that calcium channel blockade may be effective in treating vasospasm secondary to RCVS, though the agent of choice, formulation, and dose are unclear.

METHODS

We report a small cohort of seven patients presenting with thunderclap headache whose vascular imaging was consistent with RCVS. All were treated with calcium channel blockade and monitored with TCD performed every 1-2 days.

RESULTS

On presentation, TCD correlated with standard neuroimaging findings of vasospasm (on MR, CT, and conventional angiography). TCD was also able to detect improvement in velocities in the acute setting that correlated well with initiation of calcium channel blockade. Long-acting verapamil appeared to have the greatest effect on velocities compared to nimodipine and shorter-acting calcium channel blockers.

CONCLUSION

Though small, our cohort demonstrates potential utility of TCD to monitor RCVS, and relative superiority of extended-release verapamil over other calcium channel blockers, illustrating the need for larger randomized trials.

The Horizontal Angle of the Middle Cerebral Artery from the Middle TCD Temporal Window

Transcranial Doppler (TCD)is a common test used for cerebrovascular diseases. Typically, TCDs are done blindly, with no angle correction for any of the intracranial arteries. The authors measured the angle of the middle cerebral artery (MCA), as seen from the middle temporal sono-graphic window, on computed tomography (CT) scans of the brain. The head CT scans of 100 random adult patients were studied. The angles were measured once on each side by two blinded readers, with 200 measurements per reader, for a total of 400 measured angles. The mean angle of the MCA, as seen from the middle temporal window, is 33.9 degrees. There was no statistical difference between readers. When interrogating the MCA with TCD via the middle temporal sonographic window, it seems appropriate to use a 30-degree angle correction. More research needs to be done to determine the clinical utility of this finding.

Cerebral vasomotor reactivity in reversible cerebral vasoconstriction syndrome

Background

Altered cerebrovascular tone is implicated in reversible cerebral vasoconstriction syndrome (RCVS). We evaluated vasomotor reactivity using bedside transcranial Doppler in RCVS patients.

Methods

In this retrospective case-control study, middle cerebral artery (MCA) blood flow velocities were compared at rest and in response to breath-hold in RCVS ( n = 8), Migraineurs ( n = 10), and non-headache Controls ( n = 10). Hyperventilation response was measured in RCVS.

Results

In RCVS, Breath Holding Index (BHI) was severely reduced in seven of eight patients and 14/16 MCAs; seven of 16 MCAs showed exhausted (BHI < 0.1) or inverted (BHI < 0) vasomotor reactivity. Mean BHI in RCVS (0.23 ± 0.5) was significantly lower than Migraine (1.52 ± 0.57) and Controls (1.51 ± 0.32), p < 0.001. Triphasic velocity responses were seen in all groups. The maximum Vmean decline during the middle negative phase was −15.5 ± 9.2% in RCVS, −15.4 ± 7% in Migraine, and −10.3 ± 5% in Controls ( p = 0.04). In the late positive phase, average Vmean increase was 6.2 ± 14% in RCVS, which was significantly lower ( p < 0.001) than Migraine (30.5 ± 11%) and Controls (30.2 ± 6%). With hyperventilation, RCVS patients showed 23% decrease in Vmean.

Conclusion

Cerebral arterial tone is abnormal in RCVS, with proximal vasoconstriction and abnormally reduced capacity for vasodilation. Further studies are needed to determine the utility of BHI to diagnose RCVS before angiographic reversibility is established, and to estimate prognosis.

Reversible cerebral vasoconstriction syndrome - A narrative revision of the literature

Reversible Cerebral Vasoconstriction Syndrome (RCVS) is a not very well known clinical-imaging entity; it is characterized by thunderclap headache, which mimics an aneurysmal subarachnoid haemorrhage, and a diffuse and segmental constriction of cerebral arteries, that resolves spontaneously within 3 months. The pathophysiology remains unknown. The female gender is the more affected and more than half of cases occur in the puerperium or after exposure to vasoactive substances. Typically, RCVS is self-limited and has a benign course, although it may have more serious complications with permanent neurologic sequelae and death. Treatment is predominantly supportive and directed to the symptoms.

Mixture Models for Estimating Maximum Blood Flow Velocity

OBJECTIVES

A gaussian mixture model (GMM) was recently developed for estimating the probability density function of blood flow velocity measured with transcranial Doppler ultrasound data. In turn, the quantiles of the probability density function allow one to construct estimators of the "maximum" blood flow velocity. However, GMMs assume gaussianity, a feature that is not omnipresent in observed data. The objective of this work was to develop mixture models that do not invoke the gaussian assumption.

METHODS

Here, GMMs were extended to a skewed GMM and a nongaussian kernel mixture model. All models were developed on data from 59 patients with closed head injuries from multiple hospitals in the United States, with ages ranging from 13 to 81 years and Glasgow Coma Scale scores ranging from 3 to 11. The models were assessed in terms of the log likelihood (a goodness-of-fit measure) and via visual comparison with the underlying spectrograms.

RESULTS

Among the models examined, the skewed GMM showed a significantly (P< .05) higher log likelihood for 56 of the 59 patients and produced maximum flow velocity estimates consistent with the observed spectrograms for all patients. Kernel mixture models are generally less "robust" in that their quality is inconsistent across patients.

CONCLUSIONS

Among the models examined, it was found that the skewed GMM provided a better model of the data both in terms of the quality of the fit and in terms of visual comparison of the underlying spectrogram and the estimated maximum blood flow velocity. Nongaussian mixture models have potential for even higher-quality assessment of blood flow, but further development is called for.

Posttraumatic cerebral infarction in severe traumatic brain injury: characteristics, risk factors and potential mechanisms

BACKGROUND

Posttraumatic cerebral infarction (PTCI) is a severe secondary insult of traumatic brain injury (TBI). This study aimed to evaluate the characteristics and risk factors of PTCI after severe TBI (sTBI) and explore possible mechanism.

METHODS

This retrospective study included a cohort of 339 patients with sTBI; they were divided into the PTCI and non-PTCI groups. Clinical data and follow-up charts were reviewed for comparison. The logistic regression model was used for multivariate analysis to detect the risk factors of PTCI. The Glasgow Outcome Scale (GOS) and Barthel index (BI) for activities of daily living (ADL) were applied to evaluate their outcome.

RESULTS

PTCI led to an increased mortality (43.5 % vs. 10.7 %, P < 0.001) and days of intensive care unit stay (14.3 days vs. 7.1 days, P < 0.001), decreased GOS (3.1 vs. 4.1, P < 0.001) and BI (25.0 vs. 77.9, P < 0.001). Increased infarction volume led to poor outcome assessed by GOS (r = -0.46, P < 0.0001) and BI for ADL (r = -0.36, P = 0.026) for surviving patients. Compared with non-PTCI patients, PTCI patients had a high incidence of midline shift (36.2 % vs. 20.7 %, P = 0.011) and posttraumatic vasospasm (PTV) (42.0 % vs. 27.4 %, P = 0.027). Daily prevalence of PTCI occurred in two peaks: one (73.9 %) was in the first 24 h after injury, while the other (18.8 %) was in the span of 43 to 60 h postinjury. In multivariate analysis, hyperthermia [adjusted odds ratio (OR), 3.11; P = 0.001] in the first 24 h, thrombocytopenia (OR, 27.08; P < 0.001), abnormal prothrombin time (OR, 7.66; P < 0.001) and traumatic subarachnoid hemorrhage (OR, 2.33; P = 0.022) were independent predictors for PTCI.

CONCLUSIONS

PTCI deteriorates the outcome of sTBI patients. Mechanical compression and hemocoagulative disturbance serve as potential mechanisms mediating this pathophysiological process. PTV may also contribute to PTCI, but its association with PTCI is weak and needs further exploration. Early recognition and intervention of these factors might be beneficial for preventing PTCI.

A double-gaussian, percentile-based method for estimating maximum blood flow velocity

OBJECTIVES

Transcranial Doppler sonography allows for the estimation of blood flow velocity, whose maximum value, especially at systole, is often of clinical interest. Given that observed values of flow velocity are subject to noise, a useful notion of "maximum" requires a criterion for separating the signal from the noise. All commonly used criteria produce a point estimate (ie, a single value) of maximum flow velocity at any time and therefore convey no information on the distribution or uncertainty of flow velocity. This limitation has clinical consequences especially for patients in vasospasm, whose largest flow velocities can be difficult to measure. Therefore, a method for estimating flow velocity and its uncertainty is desirable.

METHODS

A gaussian mixture model is used to separate the noise from the signal distribution. The time series of a given percentile of the latter, then, provides a flow velocity envelope. This means of estimating the flow velocity envelope naturally allows for displaying several percentiles (e.g., 95th and 99th), thereby conveying uncertainty in the highest flow velocity.

RESULTS

Such envelopes were computed for 59 patients and were shown to provide reasonable and useful estimates of the largest flow velocities compared to a standard algorithm. Moreover, we found that the commonly used envelope was generally consistent with the 90th percentile of the signal distribution derived via the gaussian mixture model.

CONCLUSIONS

Separating the observed distribution of flow velocity into a noise component and a signal component, using a double-gaussian mixture model, allows for the percentiles of the latter to provide meaningful measures of the largest flow velocities and their uncertainty.

Is asymptomatic vasospasm associated with poor outcome in subarachnoid hemorrhage?

BACKGROUND

Vasospasm occurs in up to 70% of aneurysmal subarachnoid hemorrhage (aSAH), but only half becomes symptomatic. It is unclear whether asymptomatic vasospasm (AV) detected by noninvasive testing affects outcome. Prophylactic hemodilutional, hypertensive, and hypervolemic (HHH) therapy is widely used but the benefit remains unproven. We aim to determine whether AV increases the risk of poor outcome and whether HHH is safe.

METHODS

A total of 175 consecutive patients with aSAH without clinical vasospasm were included. Patients with sonographic (transcranial doppler) or radiologic (computed tomography [CT] Angiography) vasospasm were assigned to AV group, while those without were assigned to no vasospasm (NV) group. Logistic regression was used to determine the association between AV and HHH on poor outcome, defined as modified Rankin scale (mRS) >3 at discharge or 3 to 6 months' follow-up.

RESULTS

In all, 106 patients had NV and 25 received HHH. A total of 69 patients had AV and 54 received HHH. Asymptomatic vasospasm compared to NV was not associated with poor outcome (odds ratio [OR] 2.6, 95% confidence interval [CI]: 0.75-8.9; P = .1). Hemodilutional, hypertensive, and hypervolemic use in patients with AV did not improve the outcome (OR 0.16, 95%CI: 0.009-2.84; P = .2). In patients with NV, HHH use showed trend toward poor outcome after multivariable adjustment (OR 12.6, 95%CI: 1.08-146.5 P = .04).

CONCLUSION

Asymptomatic vasospasm does not appear to be associated with poor outcome in aSAH. Hemodilutional, hypertensive, and hypervolemic therapy in AV was not associated with improved outcome and may be harmful to patients who do not have vasospasm. Further research is needed to validate this finding.

Image-guided transcranial Doppler sonography for monitoring of defined segments of intracranial arteries

BACKGROUND

Transcranial Doppler sonography (TCD) is widely used in neurointensive care. Image guidance (IG) could simplify secure vessel identification and reduce interinvestigator and intrainvestigator variability. The present study was purposed to investigate the precision and reproducibility of image-guided TCD.

METHODS

The Kolibri IG system (Brainlab AG, Feldkirchen, Germany) was used to track a hand-held Doppler probe of a DWL Multi-Dop® T digital device (Compumedics Germany GmbH, Singen, Germany). The patient's head was registered noninvasively to the IG system. Distance between predefined vascular target and optimal Doppler signal was evaluated to assess spatial accuracy of image-guided TCD. To investigate reproducibility, spatial accuracy of trajectories acquired during an initial examination using the IG system was analyzed in serial examinations. Furthermore, stability of noninvasive registration of the patient's head to the IG system was analyzed. Data are presented as mean±SD for descriptive statistics. Twelve patients were included.

RESULTS

Using IG, a Doppler signal was recorded immediately in all cases for middle cerebral artery (MCA) (29 examinations), in 81% for carotid-T (27 examinations), and in 90% for basilar tip (29 examinations). The optimal Doppler signal was found within 2.64±1.15 mm (94 preplanned targets). At serial examinations, a spatial deviation of 2.75±1.20 mm was found (56 trajectories acquired in 19 serial examinations). Examination time did not influence accuracy of noninvasive patient registration.

CONCLUSIONS

Data suggest that image-guided TCD allows for accurate examinations with high intraprocedural and high interprocedural reproducibility. It facilitates identification of specific vessel segments and generation of standardized examination protocols for serial examinations.

Use of Transcranial Doppler (TCD) ultrasound in the Neurocritical Care Unit

Transcranial Doppler (TCD) is a portable device that uses a handheld 2-MHz transducer. It is most commonly used in subarachnoid hemorrhage where cerebral blood flow velocities in major intracranial blood vessels are measured to detect vasospasm in the first 2 to 3 weeks. TCD is used to detect vasospasm in traumatic brain injury and post-tumor resection, measurement of cerebral autoregulation and cerebrovascular reactivity, diagnosis of acute arterial occlusions in stroke, screening for patent foramen ovale and monitoring of emboli. It can be used to detect abnormally high intracranial pressure and for confirmation of total cerebral circulatory arrest in brain death.

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.

Derivation of transcranial Doppler criteria for angiographically proven middle cerebral artery vasospasm after aneurysmal subarachnoid hemorrhage

BACKGROUND

Transcranial Doppler (TCD) has been subjected to criticism for detecting vasospasm (VSP). Our study's aim is to derive criteria for middle cerebral artery (MCA) vasospasm (MCA-VSP) based on cerebral angiography (CA).

METHODS

A prospective data of patients with aneurysmal subarachnoid hemorrhage (aSAH) from January 2004 to August 2009. TCD was performed daily from day 2 to 14 from symptom's onset. Follow-up CA was done at day 7-9. TCD mean flow velocities (MFV) of all vessels at baseline (b), middle (m) and before CA (preangio) were recorded. Several MCA MFV ratios were computed. Moderate to severe VSP on CA was defined as >1/3 luminal narrowing. Univariate and stepwise logistic regression analysis were performed.

RESULTS

One hundred sixty-nine patients (338 MCA) with aSAH were included, mean age: 54.8 ± 13, women: 103 (62%). Twenty-nine patients (8.6%) had angiographic MCA-VSP. TCD scoring system of 3 points for MCA-VSP was computed based on (a) bMCA MFV ≥ 120 cm/s (sensitivity: 59.3%, specificity: 85%, PPV: 36.4%, NPV: 93.5%, P < .001) (1 point), Preangio MCA MFV ≥ 150 cm/s (79.3%, 89.9%, 39%, 97.3%, <.001) (1 point), and affected preangio MCA/bMCA MFV ratio ≥ 1.5 (84%, 63%, 25.6%, 96.3%, .001) (1 point). The score of 3 has 96% sensitivity and 96% specificity (OR: 300) whereas the score of 1 has 12% sensitivity and 58% specificity (OR: 4.3) for identifying MCA-VSP.

CONCLUSION

TCD stringent criteria for moderate to severe MCA-VSP are feasible and applicable in aSAH population.

[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.

Vasospasm shortens cerebral arterial time constant

BACKGROUND

Cerebrovascular time constant (τ) estimates how fast cerebral blood arrives in cerebral arterial bed after each heart stroke. We investigate the pattern of changes in τ following subarachnoid hemorrhage (SAH), with specific emphasis on the temporal profile of changes in relation to the development of cerebral vasospasm.

METHODS

Simultaneous recordings of arterial blood pressure (ABP) and transcranial Doppler (TCD) blood flow velocity (CBFV) in MCA were performed daily in patients after SAH. In 22 patients (10 males and 12 females; median age: 48 years, range: 34-84 years) recordings done before spasm were compared to those done during spasm. Vasospasm was confirmed with TCD (mean CBFV in MCA > 120 cm/s and Lindegaard ratio > 3). τ was estimated as a product of compliance of cerebral arteries (C (a)) and cerebrovascular resistance (CVR). C (a) and CVR were estimated using mathematical transformations of ABP and CBFV waveforms.

RESULTS

Vasospasm caused shortening of τ on both the spastic (before: 0.20 ± 0.05 s vs. spasm: 0.14 ± 0.04 s, P < 0.0008) and contralateral side (before: 0.22 ± 0.05 s vs. spasm: 0.16 ± 0.04 s, P < 0.0008). Before TCD signs of vasospasm were detected, τ demonstrated asymmetry with lower values on ipsilateral side to aneurysm, in comparison to contralateral side (P < 0.009),

CONCLUSIONS

Cerebral vasospasm causes shortening of τ. Shorter τ at the side of aneurysm can be observed before formal TCD signs of vasospasm are observed, therefore, potentially reducing time to escalation of treatment.

The role of transcranial Doppler ultrasound monitoring in patients with aneurysmal subarachnoid haemorrhage

The effect of transcranial Doppler (TCD) ultrasound monitoring of vasospasm on patient management following aneurysmal subarachnoid haemorrhage (aSAH) remains unclear. We reviewed our departmental use of TCD by retrospectively analysing 152 medical records. Results of investigations and management changes, including frequency of neurological monitoring and changes in triple H therapy, were examined. TCD monitoring occurred in 87 patients (57%) by untrained neurosurgical registrars. There was high variability in the number of operators for each patient (over 50% of patients had more than two different operators), insonation protocol and monitoring duration (at least 50% of patients were monitored for fewer than seven days). TCD results influenced management in only 18 (12%) patients, while clinical deterioration or improvement dictated more than 80% of changes in triple H therapy and neurological monitoring. Prospective validation in similar neurosurgical settings is needed to justify continued usage of TCD monitoring. Formal training for operators and a standard monitoring protocol should also be considered to increase TCD utility. Prospective evaluation of TCD at our centre has recently been completed.

The effect of intraventricular thrombolysis in combination with low-frequency head motion after severe subarachnoid hemorrhage: interim analysis of safety, clot clearance rate and delayed cerebral ischemia

OBJECTIVE

The current clinical prospective randomized phase II study was initiated in order to analyze the effect of enhanced washout by discontinuous intraventricular thrombolysis in combination with low-frequency head-motion therapy on side effects, clot clearance rate, cerebral vasospasm and clinical outcome after severe subarachnoid hemorrhage (SAH).

METHODS

Data from 40 adult patients with aneurysmal SAH were included in this interim analysis. Patients randomized to the study group achieved additional intraventricular application of rt-PA (Actilyse(®)) bolus 5 mg every 12 h and lateral rotational therapy (RotoRest(®)). Clot clearance rate was evaluated based on computed tomography (CT). Delayed cerebral ischemia (DCI) and early clinical outcome of patients were determined.

RESULTS

No severe side effects due to the combined therapy were documented. The clot clearance rate was significantly higher in the study group than in the control group regarding the cranial and basal CT slices (p = 0.003 cranial slices and p = 0.037 basal slices). Delayed ischemic neurological deficits (DIND) were increased in the control group (p = 0.016).

CONCLUSION

The present study demonstrates that a combination of intraventricular thrombolysis and lateral rotational therapy is not associated with a higher complication rate. Furthermore, the therapy leads to a significant acceleration of the clot clearance rate.

The correlation between COMT gene polymorphism and early cerebral vasospasm after subarachnoid hemorrhage

BACKGROUND

The individual difference of cerebral vasospasm (CVS) degree after subarachnoid hemorrhage (SAH) is common in clinic observation. Numerous studies have found that early CVS after SAH is associated with derangements in catecholamine (CA) metabolism. Catechol-O-methyltransferase (COMT) is a key rate-limiting enzyme in the degradation of CA. In this study, we investigate the correlation between COMT gene polymorphism of patients and early CVS after SAH.

METHODS

One hundred and sixty-seven patients with spontaneous SAH in early stage were selected in this study. COMT genotyping was performed by means of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The degree of CVS was identified by TCD. Hunt-Hess classification was used to evaluate the severity of the patients' condition. The bleeding amount was evaluated by means of Fisher classification of head CT. χ2 test (SPSS13.0 software) and logistic regression were adopted to analyze the correlation of COMT gene polymorphism and other clinical data of patients with early CVS after SAH.

RESULTS

The distribution of each allele matched Hardy-Weinberg law and research samples were heredity equilibrium population. Early CVS incidence of patients with COMT-A allele was much higher than those with COMT-G allele (P<0.01). Early CVS incidence of patients with COMT A/A genotype was obviously higher than those with COMT G/G genotype (P<0.05). Univariate logistic regression demonstrated that COMT-A allele, A/A genotype and Grade 3-5 of Hunt-Hess classification were all associated with early CVS. After adjustment of general information, further multivariate logistic regression demonstrated that COMT-A allele, A/A genotype were risk factors of early CVS after SAH.

CONCLUSION

COMT-A allele, A/A genotype were risk factors of early CVS after SAH.

The role of transcranial Doppler ultrasonography in the diagnosis and management of vasospasm after aneurysmal subarachnoid hemorrhage

Transcranial Doppler ultrasonography (TCD) is a tool employed by the neurosurgeon and neurointensivist in the management of vasospasm in the intensive care unit after aneurysmal subarachnoid hemorrhage. A review of the current indications, monitoring parameters, indices, and relevance of modern TCD technology is provided, as well as algorithms for the use of TCD ultrasonography in the management of patients with subarachnoid hemorrhage. Other current uses of TCD ultrasonography are also discussed in the setting of neurocritical care.

Interaction of neurovascular protection of erythropoietin with age, sepsis, and statin therapy following aneurysmal subarachnoid hemorrhage

Object

In a previous randomized controlled trial, the authors demonstrated that acute erythropoietin (EPO) therapy reduced severe vasospasm and delayed ischemic deficits (DIDs) following aneurysmal subarachnoid hemorrhage. In this study, the authors aimed to investigate the potential interaction of neurovascular protection by EPO with age, sepsis, and concurrent statin therapy.

Methods

The clinical events of 80 adults older than 18 years and with < 72 hours of aneurysmal subarachnoid hemorrhage, who were randomized to receive 30,000 U of intravenous EPO-β or placebo every 48 hours for a total of 3 doses, were analyzed by stratification according to age (< or ≥ 60 years), sepsis, or concomitant statin therapy. End points in the trial included cerebral vasospasm and impaired autoregulation on transcranial Doppler ultrasonography, DIDs, and unfavorable outcome at discharge and at 6 months measured with the modified Rankin Scale and Glasgow Outcome Scale. Analyses were performed using the t-test and/or ANOVA for repeated measurements.

Results

Younger patients (< 60 years old) or those without sepsis obtained benefits from EPO by a reduction in vasospasm, impaired autoregulation, and unfavorable outcome at discharge. Compared with nonseptic patients taking EPO, those with sepsis taking EPO had a lower absolute reticulocyte count (nonsepsis vs sepsis, 143.5 vs. 105.8 × 109/L on Day 6; p = 0.01), suggesting sepsis impaired both hematopoiesis and neurovascular protection by EPO. In the EPO group, none of the statin users suffered DIDs (p = 0.078), implying statins may potentiate neuroprotection by EPO.

Conclusions

Erythropoietin-related neurovascular protection appears to be attenuated by old age and sepsis and enhanced by statins, an important finding for designing Phase III trials.

Reversible cerebral vasoconstriction syndrome: an under-recognized clinical emergency

Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by recurrent thunderclap headaches and reversible cerebral vasoconstrictions. RCVS is more common than previously thought and should be differentiated from aneurismal subarachnoid hemorrhage. RCVS can be spontaneous or evoked by pregnancy or exposure to vasoactive substances. Patients tend to be middle-aged women but pediatric patients have been seen. Up to 80% of sufferers have identifiable triggers. Thunderclap headaches tend to recur daily and last for a period of around 2 weeks, while the vasoconstrictions may last for months. About one-third of patients have blood pressure surges accompanying headache attacks. The potential complications of RCVS include posterior reversible encephalopathy syndrome, ischemic strokes over watershed zones, cortical subarachnoid hemorrhage and intracerebral hemorrhage. Magnetic resonance images including angiography and venography and lumbar punctures are the studies of choice, whereas catheter angiography should not be implemented routinely. Patients with a mean flow velocity of the middle cerebral artery greater than 120 cm/s shown by transcranial color-coded sonography have a greater risk of ischemic complications than those without. The pathophysiology of RCVS remains unknown; sympathetic hyperactivity may play a role. Open-label trials showed calcium channel blockers, such as nimodipine may be an effective treatment in prevention of thunderclap headache attacks. In severe cases, intra-arterial therapy may be considered. Most patients with RCVS recover without sequelae; however, relapse has been reported in a small proportion of patients.

Acute systemic erythropoietin therapy to reduce delayed ischemic deficits following aneurysmal subarachnoid hemorrhage: a Phase II randomized, double-blind, placebo-controlled trial

Object

Delayed ischemic deficits (DIDs), a major source of disability following aneurysmal subarachnoid hemorrhage (aSAH), are usually associated with severe cerebral vasospasm and impaired autoregulation. Systemic erythropoietin (EPO) therapy has been demonstrated to have neuroprotective properties acting via EPO receptors on cerebrovascular endothelia and ischemic neurons. In this trial, the authors explored the potential neuroprotective effects of acute EPO therapy following aSAH.

Methods

Within 72 hours of aSAH, 80 patients (age range 24–82 years) were randomized to receive intravenous EPO (30,000 U) or placebo every 48 hours for a total of 90,000 U. Primary end points were the incidence, duration, and severity of vasospasm and impaired autoregulation on transcranial Doppler ultrasonography. Secondary end points were incidence of DIDs and outcome at discharge and at 6 months.

Results

Randomization characteristics were balanced except for age, with the EPO group being older (mean age 59.6 vs 53.3 years, p = 0.034). No differences were demonstrated in the incidence of vasospasm and adverse events; however, patients receiving EPO had a decreased incidence of severe vasospasm from 27.5 to 7.5% (p = 0.037), reduced DIDs with new cerebral infarcts from 40.0 to 7.5% (p = 0.001), a shortened duration of impaired autoregulation (ipsilateral side, p < 0.001), and more favorable outcome at discharge (favorable Glasgow Outcome Scale score, p = 0.039). Among the 71 survivors, the EPO group had fewer deficits measured with National Institutes of Health Stroke Scale (median Score 2 vs 6, p = 0.008).

Conclusions

This preliminary study showed that EPO seemed to reduce delayed cerebral ischemia following aSAH via decreasing severity of vasospasm and shortening impaired autoregulation.

Transcranial Doppler assessment of cerebral autoregulation

Cerebral autoregulation describes the process by which cerebral blood flow is maintained despite fluctuations in cerebral perfusion pressure. The assessment of cerebral autoregulation is a key to the optimisation of cerebral perfusion pressure in patients with brain injury. This review evaluates the current evidence for transcranial Doppler in the assessment of cerebral autoregulation. The study of cerebral autoregulation classically assesses changes in cerebral perfusion pressure secondary to changes in systemic blood pressure. It is defined static autoregulation if blood pressure changes are progressive, thereby allowing a steady-state autoregulatory response to be completed. For sudden changes in blood pressure, the autoregulatory response is defined as dynamic. The static and dynamic components of cerebral autoregulation have been approached using linear mathematical models (models based in direct correlations). Over the past decade, demonstration of the nonstationary (the property of changing over time or space) behaviour of cerebral autoregulation has emphasised the benefit obtained in using nonlinear statistical models (models based on changeable functions), suggesting that these methods may improve the mathematical representation of cerebral autoregulation. Despite the multiple determinants involved in cerebral autoregulation, it appears feasible to reliably assess cerebral autoregulation through the combination of linear and nonlinear methods. Nonlinear methods appear attractive in the research setting, but the challenge is how to adopt these methods to the clinical setting.

Performance of bedside transpulmonary thermodilution monitoring for goal-directed hemodynamic management after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Early goal-directed hemodynamic therapy is of particular importance for adequate cerebral circulation of patients with vasospasm after subarachnoid hemorrhage but is often precluded by the invasiveness of established cardiac output determination using a pulmonary artery catheter. This study was undertaken to validate the usefulness of less invasive goal-directed hemodynamic monitoring by transpulmonary thermodilution technique in patients after subarachnoid hemorrhage.

METHODS

One hundred sixteen patients with subarachnoid hemorrhage who underwent surgical clipping within 24 hours of ictus were investigated. Validation of transpulmonary thermodilution-derived intermittent/continuous cardiac output and cardiac preload (global end diastolic volume) were compared with pulmonary artery catheter-derived reference cardiac output and pulmonary capillary wedge pressure or central venous pressure in 16 patients diagnosed with vasospasm. In a subsequent trial of 100 consecutive cases, clinical results between the new and standard management paradigms were compared.

RESULTS

Transpulmonary thermodilution-derived intermittent cardiac output and transpulmonary thermodilution-derived continuous cardiac output showed close agreement to catheter-derived reference cardiac output with high correlation (r=0.85 and 0.77) and low percentage error (13.5% and 18.0%). Fluid responsiveness to defined volume loading was predicted better with global end diastolic volume than with pulmonary capillary wedge pressure and central venous pressure for larger receiver operating characteristic curve area. Patients receiving early goal-directed management by transpulmonary thermodilution experienced reduced frequencies of vasospasm and cardiopulmonary complications compared with those managed with standard therapy (P<0.05), whereas their functional outcomes at 3 months were not different (P=0.06).

CONCLUSIONS

Goal-directed hemodynamic management guided by transpulmonary thermodilution appears to have a therapeutic advantage for optimizing the prognosis of patients with subarachnoid hemorrhage with vasospasm over conventional methods.

Inferring cerebrovascular changes from latencies of systemic and intracranial pulses: a model-based latency subtraction algorithm

Changes in cerebral blood flow velocity (CBFV) pulse latency reflect pathophysiological changes of the cerebral vasculature based on the theory of pulse wave propagation. Timing CBFV pulse onset relative to electrocardiogram QRS is practical. However, it introduces confounding factors of extracranial origins for characterizing the cerebral vasculature. This study introduces an approach to reducing confounding influences on CBFV latency. This correction approach is based on modeling the relationship between CBFV latency and systemic arterial blood pressure (ABP) pulse latency. It is tested using an existing data set of CBFV and ABP from 14 normal subjects undergoing pressure cuff tests under both normoxic and acute hypoxic states. The results show that the proposed CBFV latency correction approach produces a more accurate measure of cerebral vascular changes, with an improved positive correlation between beat-to-beat CBFV and the CBFV latency time series, for example, correlation coefficient increased from 0.643 to 0.836 for group-averaged cuff deflation traces at normoxia. In conclusion, this study suggests that subtraction of systemic ABP latency improves CBFV latency measurements, which in turn improve the characterization of cerebral vascular changes.

Is Transcranial Doppler Ultrasonography Old-fashioned?: One Institutional Validity Study

OBJECTIVE

The purpose of this study is to investigate the correlation between various transcranial Doppler (TCD) ultrasonography parameters and clinical vasospasm after aneurysmal subarachnoid hemorrhage (SAH).

METHODS

This study enrolled 40 patients presented with aneurysmal SAH between September 2006 and August 2007. We measured differences of mean blood flow velocity (BFVm), highest systolic blood flow velocity (BFVh), and Lindegaard ratio (LR) in the middle cerebral artery on TCD examination. These parameters were evaluated for correlation with clinical vasospasm by univariate analysis and the receiver operating characteristic analysis.

RESULTS

Twelve patients (30%) developed clinical vasospasm. The best TCD parameters for the detection of clinical vasospasm were revealed to be differences of BFVm, BFVh, and LR values between 1(st) TCD test and 3(rd) TCD (7 cm/s, 11.5 cm/s, 0.45 respectively). The positive predictive value of any one of three parameters was 60% and the negative predictive value was 100%.

CONCLUSION

TCD is still considered a useful tool for screening clinical vasospasm. To confirm the predictive value of the above parameters, further prospective study will be needed.