[Emergency transcranial doppler ultrasound: predictive value for the development of symptomatic vasospasm in spontaneous subarachnoid hemorrhage in patients in good neurological condition]

Transcranial sonography in the critical patient

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

Predictive value of the transcranial Doppler and mean arterial flow velocity for early detection of cerebral vasospasm in aneurysmal subarachnoid hemorrhage

Objectives

We aimed to predict cerebral vasospasm in acute aneurysmal subarachnoid hemorrhage and to determine the cut-off values of the mean flow velocity by the use of transcranial Doppler.

Methods

A total of 40 patients with acute aneurysmal subarachnoid hemorrhage were included in this study and classified into two groups. The first group was 26 patients (65%) with cerebral vasospasm and the second group was 14 patients (35%) without vasospasm. Initial evaluation using the Glasgow Coma Scale and the severity of aneurysmal subarachnoid hemorrhage was detected by using both the clinical Hunt and Hess and radiological Fisher grading scales. All patients underwent transcranial Doppler evaluations five times in 10 days measuring the mean flow velocities (MFV) of cerebral arteries.

Results

Patients with cerebral vasospasm were associated with significantly higher mean Glasgow Coma Scale score (p = 0.03), significantly higher mean Hunt and Hess scale grades (p = 0.04), with significantly higher mean diabetes mellitus (p = 0.03), significantly higher mean systolic blood pressure and diastolic blood pressure (p = 0.02 and p = 0.005 respectively) and significantly higher MFVs measured within the first 10 days. Logistic regression analysis demonstrated that MFV ≥81 cm/s in the middle cerebral artery is accompanied by an almost five-fold increased risk of vasospasm (OR 4.92, p < 0.01), while MFV ≥63 cm/s in the anterior cerebral artery is accompanied by a three-fold increased risk of vasospasm (OR 3.12, p < 0.01), and MFV ≥42 cm/s in the posterior cerebral artery is accompanied by a two-fold increased risk of vasospasm (OR 2.11, p < 0.05).

Conclusion

Transcranial Doppler is a useful tool for early detection, monitoring, and prediction of post subarachnoid vasospasm and valuable for early therapeutic intervention before irreversible ischemic neurological deficits take place.

A Comparison of Pathophysiology in Humans and Rodent Models of Subarachnoid Hemorrhage

Non-traumatic subarachnoid hemorrhage (SAH) affects an estimated 30,000 people each year in the United States, with an overall mortality of ~30%. Most cases of SAH result from a ruptured intracranial aneurysm, require long hospital stays, and result in significant disability and high fatality. Early brain injury (EBI) and delayed cerebral vasospasm (CV) have been implicated as leading causes of morbidity and mortality in these patients, necessitating intense focus on developing preclinical animal models that replicate clinical SAH complete with delayed CV. Despite the variety of animal models currently available, translation of findings from rodent models to clinical trials has proven especially difficult. While the explanation for this lack of translation is unclear, possibilities include the lack of standardized practices and poor replication of human pathophysiology, such as delayed cerebral vasospasm and ischemia, in rodent models of SAH. In this review, we summarize the different approaches to simulating SAH in rodents, in particular elucidating the key pathophysiology of the various methods and models. Ultimately, we suggest the development of standardized model of rodent SAH that better replicates human pathophysiology for moving forward with translational research.

Point-of-care transcranial Doppler by intensivists

In the unconscious patient, there is a diagnostic void between the neurologic physical exam, and more invasive, costly and potentially harmful investigations. Transcranial color-coded sonography and two-dimensional transcranial Doppler imaging of the brain have the potential to be a middle ground to bridge this gap for certain diagnoses. With the increasing availability of point-of-care ultrasound devices, coupled with the need for rapid diagnosis of deteriorating neurologic patients, intensivists may be trained to perform point-of-care transcranial Doppler at the bedside. The feasibility and value of this technique in the intensive care unit to help rule-in specific intra-cranial pathologies will form the focus of this article. The proposed scope for point-of-care transcranial Doppler for the intensivist will be put forth and illustrated using four representative cases: presence of midline shift, vasospasm, raised intra-cranial pressure, and progression of cerebral circulatory arrest. We will review the technical details, including methods of image acquisition and interpretation. Common pitfalls and limitations of point-of-care transcranial Doppler will also be reviewed, as they must be understood for accurate diagnoses during interpretation, as well as the drawbacks and inadequacies of the modality in general.

Role of L-type Ca(2+) channels, sarcoplasmic reticulum and Rho kinase in rat basilar artery contractile properties in a new model of subarachnoid hemorrhage

We have previously described that L-type Ca(2+) channels' (LTCCs) activation and metabotropic Ca(2+) release from the sarcoplasmic reticulum (SR) regulate RhoA/Rho kinase (ROCK) activity and sustained arterial contraction. We have investigated whether this signaling pathway can be altered in a new experimental model of subarachnoid hemorrhage (SAH). For this purpose, arterial reactivity was evaluated on days 1 to 5 after surgery. A significant increase of basal tone, measured 4 and 60min after normalization, was observed on day 5 after SAH and at 60min on days 2 and 3 after SAH. This phenomenon was suppressed with LTCCs and ROCK inhibitors. We have also studied arterial rings vasoreactivity in response to high K(+) solutions. Interestingly, there were no significant differences in the phasic component of the high K(+)-induced contraction between sham and SAH groups, whereas a significant increase in the sustained contraction was observed on day 5 after SAH. This latter component was sensitive to fasudil, and selectively reduced by low nifedipine concentration, and phospholipase C and SR-ATPase inhibitors. Therefore, our data suggest that the metabotropic function of LTCCs is potentiated in SAH. Our results could provide a new strategy to optimize the pharmacological treatment of this pathological process.

External lumbar cerebrospinal fluid drainage in patients with aneurysmal subarachnoid hemorrhage: A systematic review and meta-analysis of controlled trials

INTRODUCTION

External lumbar drainage is a promising measure for the prevention of delayed aneurysmal subarachnoid hemorrhage-related ischemic complications.

METHODS

Controlled studies evaluating the effects of external lumbar drainage in patients with aneurysmal subarachnoid hemorrhage were included. Primary outcomes were: new cerebral infarctions and severe disability. Secondary outcomes were: clinical deterioration due to delayed cerebral ischemia, mortality, and the need of definitive ventricular shunting. Results were presented as pooled relative risks, with their 95% confidence intervals (95% CI).

RESULTS

A total of 6 controlled studies were included. Pooled relative risks were: new cerebral infarctions, 0.48 (95% CI: 0.32-0.72); severe disability, 0.5 (95% CI: 0.29-0.85); delayed cerebral ischemia-related clinical deterioration, 0.46 (95% CI: 0.34-0.63); mortality, 0.71 (95% CI: 0.24-2.06), and need of definitive ventricular shunting, 0.80 (95% CI: 0.51-1.24). Assessment of heterogeneity only revealed statistically significant indexes for the analysis of severe disability (I(2)=70% and P=.01).

CONCLUSION

External lumbar drainage was associated with a statistically significant decrease in the risk of delayed cerebral ischemia-related complications (cerebral infarctions and clinical deterioration), as well as the risk of severe disability; however, it was not translated in a lower mortality. Nevertheless, it is not prudent to provide definitive recommendations at this time because of the qualitative and quantitative heterogeneity among included studies. More randomized controlled trials with more homogeneous outcomes and definitions are needed to clarify its impact in patients with aneurysmal subarachnoid hemorrhage.