Acute intracranial hemorrhage during the installation of the LICOX microdialysis system: A case report

Neuro-monitoring is widely employed for the evaluation of intubated patients in the intensive care unit with stroke, severe head trauma, subarachnoid hemorrhage and/or hepatic encephalopathy. The present study reports the case of a patient with acute intracranial hemorrhage following the insertion of neuromonitoring catheters, which required surgical management. The patient was a 14-year-old male who sustained a severe traumatic brain injury and underwent a right-sided hemicraniectomy. During the installation of the neuromonitoring catheters, an acute hemorrhage was noted with a rapidly elevating intracranial pressure. A craniotomy was performed to identify and coagulate the injured cortical vessel. As demonstrated herein, the thorough evaluation of the clotting profile of the patient, a meticulous surgical technique and obtaining a post-insertion computed tomography scan may minimize the risk of any neuromonitoring-associated hemorrhagic complications.

Prognostic role of optic nerve sheath diameter in stroke in emergency department, A case control study

Background

Sonographic measurement of optic nerve sheath diameter (ONSD) can reflect intracranial pressure (ICP) indirectly and determine the neurology intensive care unit (NICU) requirement and mortality in acute ischemic stroke (AIS).

Aim

To demonstrate the effectiveness of ONSD to determine mortality, morbidity, and NICU requirement on patients with the AIS.

Methods

The sonographic ONSD measurements were performed on each patient with AIS, over 18 years old. All patients were categorized according to the Oxfordshire Community Stroke Project (OCSP) classification system. MRI images were examined for increased ICP, and the patients were categorized into two groups as increased ICP (i-ICP) and normal ICP. The ONSD results were evaluated in terms of classifications, outcomes, and prognosis of the patients.

Results

One hundred and five patients were included and 31 (35.2%) were in the i-ICP group. The median ONSDs were 5.26 mm in the i-ICP group and 4.62 mm in the normal ICP group (P < 0.001). The median ONSDs were 5.13 mm in the NICU group and 4.69 mm in the neurology ward (NW) group (P = 0.001). The total anterior circulation infarction (TACI) subgroup had higher ONSDs than the others (TACI: 5.27 mm; PACI: 4.73 mm; POCI: 4.77 mm; and LACI: 4.64 mm, P < 0.001). The NICU requirements were higher in the TACI subgroup. The median ONSD was 5.42 mm in the deceased group (survived: 4.77 mm, P < 0.001).

Conclusion

ONSD may be favorable for predicting the increased ICP and the NICU requirement in OCSP subgroups. Moreover, ONSD can be used to foresee the mortality of AIS.

Validating Existing Scales for Identification of Acute Stroke in an Inpatient Setting

Background and Purpose

A significant proportion of strokes occur while patients are hospitalized for other reasons. Numerous stroke scales have been developed and validated for use in pre-hospital and emergency department settings, and there is growing interest to adapt these scales for use in the inpatient setting. We aimed to validate existing stroke scales for inpatient stroke codes.

Methods

We retrospectively reviewed charts from inpatient stroke code activations at an urban academic medical center from January 2016 through December 2018. Receiver operating characteristic analysis was performed for each specified stroke scale including NIHSS, FAST, BE-FAST, 2CAN, FABS, TeleStroke Mimic, and LAMS. We also used logistic regression to identify independent predictors of stroke and to derive a novel scale.

Results

Of the 958 stroke code activations reviewed, 151 (15.8%) had a final diagnosis of ischemic or hemorrhagic stroke. The area under the curve (AUC) of existing scales varied from .465 (FABS score) to .563 (2CAN score). Four risk factors independently predicted stroke: (1) recent cardiovascular procedure, (2) platelet count less than 50 × 109 per liter, (3) gaze deviation, and (4) presence of unilateral leg weakness. Combining these 4 factors into a new score yielded an AUC of .653 (95% confidence interval [CI] .604-.702).

Conclusion

This study suggests that currently available stroke scales may not be sufficient to differentiate strokes from mimics in the inpatient setting. Our data suggest that novel approaches may be required to help with diagnosis in this unique population.

Effects of reading contextualized physics problems among men and women: A psychophysiological approach

To counteract declining interest in science, contextualizing course material has been suggested, despite little evidence supporting this strategy. We assessed how reading physics problems in different contexts-none, technical, or humanistic-impacted performance and implicit cognitive and affective situational interest (SI) among undergraduate men and women (n = 60). We hypothesized that contextualized problems would increase cognitive SI, boosting performance. We also investigated existing hypotheses that this influence would be stronger when contexts matched stereotypical gender interests. Pupillometric and electroencephalographic data served to indicate cognitive SI, while electrodermal activity (EDA) and valence were measures of affective SI. Significantly higher valence was observed in decontextualized than humanistic problems (p = 0.003) specifically among men (p < 0.001). Greater EDA (p = 0.019) and decontextualized problems (p < 0.001) yielded greater performance than contextualized problems for all participants. Results emphasize the importance of affective SI and of avoiding gender biases in curricular development. This study encourages caution if implementing contextualization.

Preliminary evaluation of a non-invasive device for monitoring intracranial pressure waveforms in dogs

OBJECTIVES

The objective of this study was to compare waveforms obtained with a new device for the non-invasive monitoring of intracranial pressure (ICP) in dogs with and without neurological disease.

MATERIALS AND METHODS

This prospective study was conducted on both neurologically normal dogs and dogs with neurological diseases. First, non-invasive ICP waveforms were recorded in normal dogs using the Braincare® BcMM 2000 monitor while the dogs were under general anaesthesia induced for procedures unrelated to this study. The dogs were positioned in lateral recumbency, and the sensor was placed over the skin of the parietal region. Secondly, non-invasive ICP waveforms were monitored in dogs with brain and spinal disease until waveforms with characteristic peaks were acquired. All the recorded signals were amplified, filtered and digitalized, by the device, and then transferred to a computer for analysis.

RESULTS

Normal pulse waveforms indicating normal brain complacency were observed in eight neurologically normal dogs. In six dogs with brain disease, abnormal pulse waveforms were observed suggesting increased ICP and decreased brain complacency. Four dogs with spinal disease undergoing myelography, had normal waveforms before contrast medium injection and abnormal pulse waveforms during contrast medium injection, indicating a potential increase in ICP.

CLINICAL SIGNIFICANCE

Based on these preliminary observations, this method was capable of detecting abnormal pulse waveforms that suggested increased ICP.

Cerebrospinal fluid dynamics coupled to the global circulation in holistic setting: Mathematical models, numerical methods and applications

This paper presents a mathematical model of the global, arterio-venous circulation in the entire human body, coupled to a refined description of the cerebrospinal fluid (CSF) dynamics in the craniospinal cavity. The present model represents a substantially revised version of the original Müller-Toro mathematical model. It includes one-dimensional (1D), non-linear systems of partial differential equations for 323 major blood vessels and 85 zero-dimensional, differential-algebraic systems for the remaining components. Highlights include the myogenic mechanism of cerebral blood regulation; refined vasculature for the inner ear, the brainstem and the cerebellum; and viscoelastic, rather than purely elastic, models for all blood vessels, arterial and venous. The derived 1D parabolic systems of partial differential equations for all major vessels are approximated by hyperbolic systems with stiff source terms following a relaxation approach. A major novelty of this paper is the coupling of the circulation, as described, to a refined description of the CSF dynamics in the craniospinal cavity, following Linninger et al. The numerical solution methodology employed to approximate the hyperbolic non-linear systems of partial differential equations with stiff source terms is based on the Arbitrary DERivative Riemann problem finite volume framework, supplemented with a well-balanced formulation, and a local time stepping procedure. The full model is validated through comparison of computational results against published data and bespoke MRI measurements. Then we present two medical applications: (i) transverse sinus stenoses and their relation to Idiopathic Intracranial Hypertension; and (ii) extra-cranial venous strictures and their impact in the inner ear circulation, and its implications for Ménière's disease.

Photoacoustic imaging for the monitoring of local changes in oxygen saturation following an adrenaline injection in human forearm skin

Clinical monitoring of blood oxygen saturation (sO₂) is traditionally performed using optical techniques, such as pulse oximetry and diffuse reflectance spectroscopy (DRS), which lack spatial resolution. Photoacoustic imaging (PAI) is a rapidly developing biomedical imaging technique that is superior to previous techniques in that it combines optical excitation and acoustic detection, providing a map of chromophore distribution in the tissue. Hitherto, PAI has primarily been used in preclinical studies, and only a few studies have been performed in patients. Its ability to measure sO₂ with spatial resolution during local vasoconstriction after adrenaline injection has not yet been investigated. Using PAI and spectral unmixing we characterize the heterogeneous change in sO₂ after injecting a local anesthetic containing adrenaline into the dermis on the forearm of seven healthy subjects. In comparison to results obtained using DRS, we highlight contrasting results obtained between the two methods arising due to the so-called 'window effect' caused by a reduced blood flow in the superficial vascular plexus. The results demonstrate the importance of spatially resolving sO₂ and the ability of PAI to assess the tissue composition in different layers of the skin.

Efficiency of using a neurofeedback device in determining ischaemic early electroencephalography indicators in rabbits with acute brain ischaemia

OBJECTIVES

Continuous electroencephalography (EEG) monitoring is a useful method in surgical procedures in which brain circulation is at risk. Providing this function using neurofeedback devices reduced to small dimensions may provide ease of use in the early diagnosis of brain ischaemia. The goal of this study was to demonstrate the efficiency of using a neurofeedback device in determining the early EEG indicators of ischaemia in a rabbit model of acute brain ischaemia.

METHODS

Three randomized groups-carotid ischaemia (CI), global ischaemia (GI) and a sham group-each comprising 8 rabbits, were created. In the CI group, the bilateral main carotid artery was clamped; in the GI group, the bilateral subclavian and main carotid arteries were clamped and brain ischaemia was created for 15 min. Brain reperfusion was then achieved for 30 min. In the sham group, the same surgical preparation was performed but no ischaemia occurred. The brain EEG wave activities of all subjects were recorded during the experiment. At the end of the procedure, all brain tissue was removed and apoptotic indexes were determined by histopathological examination. The statistical significance of the histopathological results and the EEG wave activities among the groups was examined.

RESULTS

There was a significant difference between the sham, CI and GI average amplitude ratios, delta (1.02, 0.69, 0.16; P < 0.001) and total wave (0.99, 0.78, 0.49; P < 0.001), respectively. There was no significant difference between the sham and CI groups in delta (sham, CI, 1.01, 0.87; P = 0.1), total wave (sham, CI, 1.22, 0.98; P = 0.2) and amplitude standard deviation rates. However, there was a significant difference in the GI group (P < 0.001). There was a significant difference between all groups in apoptotic index (sham, 17.88; CI, 40.75; GI, 55.88; P < 0.001).

CONCLUSIONS

Significant EEG wave changes resulting from experimental brain ischaemia were analysed with the use of a neurofeedback device. The results indicated that the change in the delta and the total wave standard deviations may be an additional indicator in the formation of permanent brain damage.

A Systemic Review of Functional Near-Infrared Spectroscopy for Stroke: Current Application and Future Directions

Background: Survivors of stroke often experience significant disability and impaired quality of life. The recovery of motor or cognitive function requires long periods. Neuroimaging could measure changes in the brain and monitor recovery process in order to offer timely treatment and assess the effects of therapy. A non-invasive neuroimaging technique near-infrared spectroscopy (NIRS) with its ambulatory, portable, low-cost nature without fixation of subjects has attracted extensive attention. Methods: We conducted a comprehensive literature review in order to review the use of NIRS in stroke or post-stroke patients in July 2018. NCBI Pubmed database, EMBASE database, Cochrane Library and ScienceDirect database were searched. Results: Overall, we reviewed 66 papers. NIRS has a wide range of application, including in monitoring upper limb, lower limb recovery, motor learning, cortical function recovery, cerebral hemodynamic changes, cerebral oxygenation, as well as in therapeutic method, clinical researches, and evaluation of the risk for stroke. Conclusions: This study provides a preliminary evidence of the application of NIRS in stroke patients as a monitoring, therapeutic, and research tool. Further studies could give more emphasize on the combination of NIRS with other techniques and its utility in the prevention of stroke.

An Update on Pediatric Stroke Protocol

Pediatric stroke is relatively rare, with approximately 1000 childhood strokes in the United States per year. However, the occurrence of stroke in children leads to significant morbidity and mortality, warranting the development proven screening tools, protocols, and treatment options. Because significant delays in seeking medical attention can occur, time to recognition of pediatric stroke in the emergency department is uniquely challenging and critical. Once recognized, a trained multidisciplinary team with a multifaceted approach is needed to provide the best possible outcome for the patient. Key elements of the pediatric stroke protocol should include recognition tools, stroke alert mechanism, stroke order sets, timely imaging, laboratory evaluation, and treatment options. Substantial advancements have been made in the field of pediatric stroke protocols mainly due to formation of international consortiums and clinical trial. Despite significant progress, treatment options remain controversial.

Management of Intracranial Pressure

PURPOSE OF REVIEW

Intracranial pressure (ICP) can be elevated in traumatic brain injury, large artery acute ischemic stroke, intracranial hemorrhage, intracranial neoplasms, and diffuse cerebral disorders such as meningitis, encephalitis, and acute hepatic failure. Raised ICP is also known as intracranial hypertension and is defined as a sustained ICP of greater than 20 mm Hg.

RECENT FINDINGS

ICP must be measured through an invasive brain catheter, typically an external ventricular catheter that can drain CSF and measure ICP, or through an intraparenchymal ICP probe. Proper recognition of the clinical signs of elevated ICP is essential for timely diagnosis and treatment to prevent cerebral hypoperfusion and possible brain death. Clinical signs of elevated ICP include headache, papilledema, nausea, and vomiting in the early phases, followed by stupor and coma, pupillary changes, hemiparesis or quadriparesis, posturing and respiratory abnormalities, and eventually cardiopulmonary arrest.

SUMMARY

Management of elevated ICP is, in part, dependent on the underlying cause. Medical options for treating elevated ICP include head of bed elevation, IV mannitol, hypertonic saline, transient hyperventilation, barbiturates, and, if ICP remains refractory, sedation, endotracheal intubation, mechanical ventilation, and neuromuscular paralysis. Surgical options include CSF drainage if hydrocephalus is present and decompression of a surgical lesion, such as an intracranial hematoma/large infarct or tumor, if the patient's condition is deemed salvageable. Future research should continue investigating medical and surgical options for the treatment of raised ICP, such as hypothermia, drugs that reduce cerebral edema, and operations aimed at reducing intracranial mass effect.

Wavelength-Modulated Differential Photoacoustic Spectroscopy (WM-DPAS) for noninvasive early cancer detection and tissue hypoxia monitoring

This study introduces a novel noninvasive differential photoacoustic method, Wavelength Modulated Differential Photoacoustic Spectroscopy (WM-DPAS), for noninvasive early cancer detection and continuous hypoxia monitoring through ultrasensitive measurements of hemoglobin oxygenation levels (StO2 ). Unlike conventional photoacoustic spectroscopy, WM-DPAS measures simultaneously two signals induced from square-wave modulated laser beams at two different wavelengths where the absorption difference between maximum deoxy- and oxy-hemoglobin is 680 nm, and minimum (zero) 808 nm (the isosbestic point). The two-wavelength measurement efficiently suppresses background, greatly enhances the signal to noise ratio and thus enables WM-DPAS to detect very small changes in total hemoglobin concentration (CHb ) and oxygenation levels, thereby identifying pre-malignant tumors before they are anatomically apparent. The non-invasive nature also makes WM-DPAS the best candidate for ICU bedside hypoxia monitoring in stroke patients. Sensitivity tunability is another special feature of the technology: WM-DPAS can be tuned for different applications such as quick cancer screening and accurate StO2 quantification by selecting a pair of parameters, signal amplitude ratio and phase shift. The WM-DPAS theory has been validated with sheep blood phantom measurements. Sensitivity comparison between conventional single-ended signal and differential signal.

Accuracy, Precision, Sensitivity, and Specificity of Noninvasive ICP Absolute Value Measurements

An innovative absolute intracranial pressure (ICP) value measurement method has been validated by multicenter comparative clinical studies. The method is based on two-depth transcranial Doppler (TCD) technology and uses intracranial and extracranial segments of the ophthalmic artery as pressure sensors. The ophthalmic artery is used as a natural pair of "scales" that compares ICP with controlled pressure Pe, which is externally applied to the orbit. To balance the scales, ICP = Pe a special two-depth TCD device was used as a pressure balance indicator. The proposed method is the only noninvasive ICP measurement method that does not need patient-specific calibration.

Brachial-ankle pulse wave velocity and ankle-brachial index are complementary tools for transcranial Doppler ultrasonography in early diagnosis of intracranial arterial stenosis/occlusion in patients with acute ischemic stroke

The aim of this study was to explore whether brachial-ankle pulse wave velocity (baPWV) and ankle-brachial index (ABI) are suitable to serve as complementary tools for TCD in early diagnosis of intracranial arterial stenosis/occlusion in patients with acute ischemic stroke (AIS). A total of 52 patients with AIS onset and 52 age-matched healthy controls were included in this study. All participants received TCD detection, and baPWV and ABI were measured. Computed topography (CT)/magnetic resonance imaging (MRI) was applied to confirm diagnosis. TCD data from all participants was collected and reviewed to diagnose stenosis and occlusion of the major intracranial arteries. Receiver operating characteristic (ROC) analysis and logistic regression analysis were used to assess and compare the diagnostic accuracy of the various diagnostic approaches. We found that a combination of TCD with either baPWV or ABI, or a combination of the three provided a significantly higher area under the curve (AUC) in detecting stenosis or occlusion in various intracranial arteries, excluding the anterior cerebral artery (ACA), when compared to TCD alone, thereby demonstrating that these combined approaches provide improved diagnostic accuracy. In conclusion, our findings suggest that both baPWV and ABI are suitable complementary tools for TCD in early diagnosis of intracranial arterial stenosis/occlusion in AIS patients and that these combinations may assist in facilitating the diagnostic process associated with this disease.

Calibration-free quantification of absolute oxygen saturation based on the dynamics of photoacoustic signals

Photoacoustic tomography (PAT) is a hybrid imaging technique that has broad preclinical and clinical applications. Based on the photoacoustic effect, PAT directly measures specific optical absorption, which is the product of the tissue-intrinsic optical absorption coefficient and the local optical fluence. Therefore, quantitative PAT, such as absolute oxygen saturation (sO₂) quantification, requires knowledge of the local optical fluence, which can only be estimated through invasive measurements or sophisticated modeling of light transportation. In this Letter, we circumvent this requirement by taking advantage of the dynamics in sO₂. The new method works when the sO₂ transition can be simultaneously monitored with multiple wavelengths. For each wavelength, the ratio of photoacoustic amplitudes measured at different sO₂ states is utilized. Using the ratio cancels the contribution from optical fluence and allows calibration-free quantification of absolute sO₂. The new method was validated through both phantom and in vivo experiments.