Non-invasive assessment of intracranial pressure

Modelling midline shift and ventricle collapse in cerebral oedema following acute ischaemic stroke

In ischaemic stroke, a large reduction in blood supply can lead to the breakdown of the blood-brain barrier and to cerebral oedema after reperfusion therapy. The resulting fluid accumulation in the brain may contribute to a significant rise in intracranial pressure (ICP) and tissue deformation. Changes in the level of ICP are essential for clinical decision-making and therapeutic strategies. However, the measurement of ICP is constrained by clinical techniques and obtaining the exact values of the ICP has proven challenging. In this study, we propose the first computational model for the simulation of cerebral oedema following acute ischaemic stroke for the investigation of ICP and midline shift (MLS) relationship. The model consists of three components for the simulation of healthy blood flow, occluded blood flow and oedema, respectively. The healthy and occluded blood flow components are utilized to obtain oedema core geometry and then imported into the oedema model for the simulation of oedema growth. The simulation results of the model are compared with clinical data from 97 traumatic brain injury patients for the validation of major model parameters. Midline shift has been widely used for the diagnosis, clinical decision-making, and prognosis of oedema patients. Therefore, we focus on quantifying the relationship between ICP and midline shift (MLS) and identify the factors that can affect the ICP-MLS relationship. Three major factors are investigated, including the brain geometry, blood-brain barrier damage severity and the types of oedema (including rare types of oedema). Meanwhile, the two major types (stress and tension/compression) of mechanical brain damage are also presented and the differences in the stress, tension, and compression between the intraparenchymal and periventricular regions are discussed. This work helps to predict ICP precisely and therefore provides improved clinical guidance for the treatment of brain oedema.

Cerebral hemodynamics and optic nerve sheath diameter acquired via neurosonology in critical patients with severe coronavirus disease: experience of a national referral hospital in Peru

Aim

We aimed to describe the neurosonological findings related to cerebral hemodynamics acquired using transcranial Doppler and to determine the frequency of elevated ICP by optic nerve sheath diameter (ONSD) measurement in patients with severe coronavirus disease (COVID-19) hospitalized in the intensive care unit of a national referral hospital in Peru.

Methods

We included a retrospective cohort of adult patients hospitalized with severe COVID-19 and acute respiratory failure within the first 7 days of mechanical ventilation under deep sedoanalgesia, with or without neuromuscular blockade who underwent ocular ultrasound and transcranial Doppler. We determine the frequency of elevated ICP by measuring the diameter of the optic nerve sheath, choosing as best cut-off value a diameter equal to or >5.8 mm. We also determine the frequency of sonographic patterns obtained by transcranial Doppler. Through insonation of the middle cerebral artery. Likewise, we evaluated the associations of clinical, mechanical ventilator, and arterial blood gas variables with ONSD ≥5.8 mm and pulsatility index (PI) ≥1.1. We also evaluated the associations of hemodynamic findings and ONSD with mortality the effect size was estimated using Poisson regression models with robust variance.

Results

This study included 142 patients. The mean age was 51.39 ± 13.3 years, and 78.9% of patients were male. Vasopressors were used in 45.1% of patients, and mean arterial pressure was 81.87 ± 10.64 mmHg. The mean partial pressure of carbon dioxide (PaCO2) was elevated (54.08 ± 16.01 mmHg). Elevated intracranial pressure was seen in 83.1% of patients, as estimated based on ONSD ≥5.8 mm. A mortality rate of 16.2% was reported. In the multivariate analysis, age was associated with elevated ONSD (risk ratio [RR] = 1.07). PaCO2 was a protective factor (RR = 0.64) in the cases of PI ≥ 1.1. In the mortality analysis, the mean velocity was a risk factor for mortality (RR = 1.15).

Conclusions

A high rate of intracranial hypertension was reported, with ONSD measurement being the most reliable method for estimation. The increase in ICP measured by ONSD in patients with severe COVID-19 on mechanical ventilation is not associated to hypercapnia or elevated intrathoracic pressures derived from protective mechanical ventilation.

Using EEG total energy as a noninvasively tracking of intracranial (and cerebral perfussion) pressure in an animal model: A pilot study

PURPOSE

This study aims to describe the total EEG energy during episodes of intracranial hypertension (IH) and evaluate its potential as a classification feature for IH.

NEW METHODS

We computed the sample correlation coefficient between intracranial pressure (ICP) and the total EEG energy. Additionally, a generalized additive model was employed to assess the relationship between arterial blood pressure (ABP), total EEG energy, and the odds of IH.

RESULTS

The median sample cross-correlation between total EEG energy and ICP was 0.7, and for cerebral perfusion pressure (CPP) was 0.55. Moreover, the proposed model exhibited an accuracy of 0.70, sensitivity of 0.53, specificity of 0.79, precision of 0.54, F1-score of 0.54, and an AUC of 0.7.

COMPARISON WITH EXISTING METHODS

The only existing comparable methods, up to our knowledge, use 13 variables as predictor of IH, our model uses only 3, our model, as it is an extension of the generalized model is interpretable and it achieves the same performance.

CONCLUSION

These findings hold promise for the advancement of multimodal monitoring systems in neurocritical care and the development of a non-invasive ICP monitoring tool, particularly in resource-constrained environments.

Non-Invasive Methods for Intracranial Pressure Monitoring in Traumatic Brain Injury Using Transcranial Doppler: A Scoping Review

Intracranial pressure (ICP) monitoring is necessary for managing patients with traumatic brain injury (TBI). Although gold-standard methods include intraventricular or intraparenchymal transducers, these systems cannot be used in patients with coagulopathies or in those who are at high risk of catheter-related infections, nor can they be used in resource-constrained settings. Therefore, a non-invasive modality that is more widely available, cost effective, and safe would have tremendous impact. Among such non-invasive choices, transcranial Doppler (TCD) provides indirect ICP estimates through waveform analysis of cerebral hemodynamic changes. The objective of this scoping review is to describe the existing evidence for the use of TCD-derived methods in estimating ICP in adult TBI patients as compared with gold-standard invasive methods. This review was conducted in accordance with the Joanna Briggs Institute methodology for scoping reviews, with a main search of PubMed and Embase. The search was limited to studies conducted in adult TBI patients published in any language between 2012 and 2022. Twenty-two studies were included for analysis, with most being prospective studies conducted in high-income countries. TCD-derived non-invasive ICP (nICP) methods are either mathematical or non-mathematical, with the former having slightly better correlation with invasive methods, especially when using time-trending ICP dynamics over one-time estimated values. Nevertheless, mathematical methods are associated with greater cost and complexity in their application. Formula-based methods showed promise in excluding elevated ICP, exhibiting a high negative predictive value. Therefore, TCD-derived methods could be useful in assessing ICP changes instead of absolute ICP values for high-risk patients, especially in low-resource settings.

"NeuroVanguard": a contemporary strategy in neuromonitoring for severe adult brain injury patients

Severe acute brain injuries, stemming from trauma, ischemia or hemorrhage, remain a significant global healthcare concern due to their association with high morbidity and mortality rates. Accurate assessment of secondary brain injuries severity is pivotal for tailor adequate therapies in such patients. Together with neurological examination and brain imaging, monitoring of systemic secondary brain injuries is relatively straightforward and should be implemented in all patients, according to local resources. Cerebral secondary injuries involve factors like brain compliance loss, tissue hypoxia, seizures, metabolic disturbances and neuroinflammation. In this viewpoint, we have considered the combination of specific noninvasive and invasive monitoring tools to better understand the mechanisms behind the occurrence of these events and enhance treatment customization, such as intracranial pressure monitoring, brain oxygenation assessment and metabolic monitoring. These tools enable precise intervention, contributing to improved care quality for severe brain injury patients. The future entails more sophisticated technologies, necessitating knowledge, interdisciplinary collaboration and resource allocation, with a focus on patient-centered care and rigorous validation through clinical trials.

The Role of ICP Monitoring in Minimally Invasive Surgery for the Management of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is the second major stroke type, with high incidence, high disability rate, and high mortality. At present, there is no effective and reliable treatment for ICH. As a result, most patients have a poor prognosis. Minimally invasive surgery (MIS) is the fastest treatment method to remove hematoma, which is characterized by less trauma and easy operation. Some studies have confirmed the safety of MIS, but there are still no reports showing that it can significantly improve the functional outcome of ICH patients. Intracranial pressure (ICP) monitoring is considered to be an important part of successful treatment in traumatic brain diseases. By monitoring ICP in real time, keeping stable ICP could help patients with craniocerebral injury get a good prognosis. In the course of MIS treatment of ICH patients, keeping ICP stable may also promote patient recovery. In this review, we will take ICP monitoring as the starting point for an in-depth discussion.

Late-Presenting Sagittal Craniosynostosis: An Update to a Standardized Treatment Protocol

BACKGROUND

The authors previously published their protocol to treat patients who present with sagittal craniosynostosis after the age of 1 year. The purpose of this article is to present a follow-up and update of this cohort to evaluate outcomes of their treatment protocol.

METHODS

Patients with isolated sagittal craniosynostosis who presented after the age of 1 year between July of 2013 and April of 2021 were included.

RESULTS

A total of 108 patients met inclusion criteria. The average age at presentation was 5.2 ± 3.4 years, and 79 patients (73.1%) were male. The indications for imaging were head shape (54.6%), headache (14.8%), trauma (9.3%), seizure (4.6%), papilledema (2.8%), and other (13.9%). Of the 108 patients, 12 (11.1%) underwent surgery following their initial consultation: five for papilledema, four for elevated intracranial pressure, two for severely scaphocephalic head shapes, and one for abnormal funduscopic findings. Two of these patients underwent additional reconstructive surgery, one for the recurrence of papilledema and headache and the other for progressive scaphocephaly. The average length of time between operations was 4.9 years. Of the 96 patients who were managed conservatively, four (4.2%) underwent surgery at an average of 1.2 ± 0.5 years later (average age, 4.4 ± 1.5 years) for brain growth restriction ( n = 2), aesthetic concerns ( n = 1), and refractory headaches ( n = 1). The average follow-up of all patients with craniofacial surgery was 2.7 ± 2.3 years (median, 2.1 years; interquartile range, 3.7 years).

CONCLUSIONS

Patients with late-presenting sagittal craniosynostosis require surgical correction less often than younger patients, likely because of milder phenotype. Few patients in the conservative treatment arm ultimately required surgery (4%).

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Analysis of intracranial pressure pulse waveform in studies on cerebrospinal compliance: a narrative review

Continuous monitoring of mean intracranial pressure (ICP) has been an essential part of neurocritical care for more than half a century. Cerebrospinal pressure-volume compensation, i.e. the ability of the cerebrospinal system to buffer changes in volume without substantial increases in ICP, is considered an important factor in preventing adverse effects on the patient's condition that are associated with ICP elevation. However, existing assessment methods are poorly suited to the management of brain injured patients as they require external manipulation of intracranial volume. In the 1980s, studies suggested that spontaneous short-term variations in the ICP signal over a single cardiac cycle, called the ICP pulse waveform, may provide information on cerebrospinal compensatory reserve. In this review we discuss the approaches that have been proposed so far to derive this information, from pulse amplitude estimation and spectral techniques to most recent advances in morphological analysis based on artificial intelligence solutions. Each method is presented with focus on its clinical significance and the potential for application in standard clinical practice. Finally, we highlight the missing links that need to be addressed in future studies in order for ICP pulse waveform analysis to achieve widespread use in the neurocritical care setting.

EEG Correlates of Spikes in Intracranial Pressure Caused by Transient Ventriculoperitoneal Shunt Malfunction

SUMMARY

A 30-year-old man with recurrent headaches and seizure-like activity and a 26-year-old woman with worsening headaches were admitted to the hospital. Both had ventriculoperitoneal shunts and history of several shunt revisions for congenital hydrocephalus. The ventricle size visualized on computed tomography scans was unremarkable, and shunt series were negative in both cases. Both patients began to present with brief periods of unresponsiveness, and video electroencephalography at that time showed periods of diffuse delta slowing. Lumbar punctures revealed increased opening pressures. Despite normal imaging and shunt series, both patients ultimately had increased intracranial pressure caused by shunt malfunction. This series demonstrates the difficulty of diagnosing potential transient increases in intracranial pressure based on standard-of-care diagnostics/examination and the potentially critical role for EEG in the identification of shunt malfunction.

A review of invasive intracranial pressure monitoring following surgery for hypertensive cerebral hemorrhage

Hypertensive cerebral hemorrhage, the most common prevalent of spontaneous cerebral hemorrhage, poses a significant threat to patient mortality and morbidity, while therapeutic options remain limited, making the disease a burden not only for patients' families but also a major challenge for national healthcare systems. The elevation of intracranial pressure subsequent to hypertensive cerebral hemorrhage is a critical contributor to mortality. However, it often manifests before the onset of clinical symptoms, which are typically atypical, leading to delayed treatment and irreversible consequences for the patient. Hence, early detection of intracranial pressure variations can aid in timely, efficient, and precise treatment, reducing patient mortality. Invasive intracranial pressure monitoring enables real-time, accurate monitoring of intracranial pressure changes, providing clinicians with therapeutic guidance and overcoming the limitations of empirical treatment. This article aims to review the use of invasive intracranial pressure monitoring in postoperative hypertensive cerebral hemorrhage and hopes to contribute to clinical and scientific research.

Contrast-enhanced subharmonic aided pressure estimation for assessment of intracranial pressure in vivo

BACKGROUND

Intracranial pressure (ICP) monitoring in children currently requires invasive techniques. Subharmonic aided pressure estimation (SHAPE) uses contrast-enhanced ultrasound (CEUS) to measure intravascular and interstitial pressure, but utility in ICP measurements has yet to be explored.

OBJECTIVE

The objective of this study was to investigate SHAPE as a novel tool for noninvasive ICP measurements in fetal lambs.

MATERIALS AND METHODS

Eighteen fetal lambs at 107-139 days gestational age (term = 145 days) underwent subdural ICP catheter placement. The brain was imaged in the coronal plane in CEUS mode optimized for SHAPE, while infusing an US contrast agent into the fetal circulation. After SHAPE calibration, saline was infused via the subdural catheter to increase ICP. Five-second SHAPE cine clips were obtained at various ICPs. Subharmonic intensity values of the whole brain and thalami were correlated with ICP values using mixed effects linear regression analyses and the strength of the relationship was evaluated by Spearman's rank-order correlation.

RESULTS

Forty-nine experiments produced 723 datapoints, including SHAPE intensity values and mean ICP measurements. There was a statistically significant inverse relationship between SHAPE intensity values and ICP measurements in the whole brain and thalami (median rho value - 0.58 and - 0.56, respectively).

CONCLUSION

SHAPE intensity values of the brain demonstrate an inverse and statistically significant correlation with in vivo ICP measurements in an animal model.

Effects of pneumoperitoneum and Trendelenburg position on intracranial pressure and cerebral blood flow assessed using transcranial doppler: A prospective observational study

Background and Aims

Laparoscopic lower abdominal surgeries involve carbon dioxide (CO2) insufflation and Trendelenburg position. The raised intra-abdominal pressure can increase intracranial pressure (ICP) and alter cerebral blood flow. This study was conducted to determine the effect of pneumoperitoneum and Trendelenburg position on ICP and cerebral perfusion pressure (CPP) measured using transcranial Doppler (TCD).

Material and Methods

A prospective observational study was conducted in 43 patients of either sex, aged between 18 and 60 years with American Society of Anesthesiologists physical status I and II, undergoing elective laparoscopic surgery in Trendelenburg position. After standard anesthesia induction, pneumoperitoneum was created to facilitate surgery, maintaining an intra-abdominal pressure of 10-15 mmHg and Trendelenburg position of 25°-30°. End-tidal carbon dioxide (EtCO2) was maintained between 30 and 35 mmHg. The ICP was assessed non-invasively using TCD-based diastolic flow velocities (FVd) and pulsatility index (PI) of middle cerebral artery. Data was represented as mean ± standard deviation and compared using paired t test. A P value of < 0.05 was considered significant.

Results

Mean ICPPI at baseline was 14.02 ± 0.89 mmHg which increased to 14.54 ± 1.21 mmHg at pneumoperitoneum and Trendelenburg position (P = 0.005). Mean ICPFVd at baseline was 6.25 ± 2.47 mmHg which increased to 8.64 ± 3.79 mmHg at pneumoperitoneum and Trendelenburg position (P < 0.001). There was no statistically significant change in the CPP or mean arterial pressure values intraoperatively.

Conclusions

Laparoscopic procedures with CO2 pneumoperitoneum in Trendelenburg position increase ICP as measured using TCD ultrasonography. The CPP was not significantly altered when EtCO2 was maintained in the range of 30-35 mmHg.

Transcranial doppler in the non-invasive estimation of intracranial pressure in traumatic brain injury compared to other non-invasive methods in lower-middle income countries: Systematic review and meta-analysis

BACKGROUND

The prediction of raised Intracranial Pressure (ICP) with accuracy in Traumatic Brain Injury (TBI) patients is a clinically important decision and therapeutic tool. This study aimed to evaluate the existing methods used for non-invasive ICP monitoring in TBI patients in LMICs.

METHODS

Systematic searches of PubMed, Google Scholar, and ScienceDirect were performed from database inception to November 2021. Studies reporting the prediction of raised ICP in TBI patients by non-invasive means in LMICs were included. Pooled estimates of sensitivity, specificity, positive likelihood ratios, and negative likelihood ratios with 95 %CI were calculated for each index test consisting of the fifteen studies, using the MEDDECIDE module 0.0.2 for meta-analysis of diagnostic test accuracy, reliability, and decision studies in JAMOVI 2.2.5.

RESULTS

A total of 1032 studies were identified, of which, 15 included 3316 patients with male predominance (n = 2458, 74.13%). Patients' ages range from 15 to 96 years with 40-80 (n = 1205, 36.34%), the most represented population. The ICP measured by Transcranial Doppler (TCD) had a sensitivity of 92.3%, and a specificity of 70%. The positive predictive value was 66.67%, with a negative predictive value of 93.33%. Furthermore, the positive Likelihood Ratio (+LR) was 3.69; 2<+LR < 5 and the negative Likelihood Ratio (-LR) 0.103; 0.1 < -LR < 0.2. We carried out a "Medical Decision", "Plots", "Fagan Normogram" and the ROC curve to find the perfect discrimination point of all the five tests used for the non-invasive measurement of ICP in the TBI patients in LMICs.

CONCLUSION

The TCD had shown high performance in its sensitivity and specificity, placing it on top of the other four different tests used in LMICs for the management of patients with TBI.

Non-Invasive Intracranial Pressure Monitoring

(1) Background: Intracranial pressure (ICP) monitoring plays a key role in the treatment of patients in intensive care units, as well as during long-term surgeries and interventions. The gold standard is invasive measurement and monitoring via ventricular drainage or a parenchymal probe. In recent decades, numerous methods for non-invasive measurement have been evaluated but none have become established in routine clinical practice. The aim of this study was to reflect on the current state of research and shed light on relevant techniques for future clinical application. (2) Methods: We performed a PubMed search for “non-invasive AND ICP AND (measurement OR monitoring)” and identified 306 results. On the basis of these search results, we conducted an in-depth source analysis to identify additional methods. Studies were analyzed for design, patient type (e.g., infants, adults, and shunt patients), statistical evaluation (correlation, accuracy, and reliability), number of included measurements, and statistical assessment of accuracy and reliability. (3) Results: MRI-ICP and two-depth Doppler showed the most potential (and were the most complex methods). Tympanic membrane temperature, diffuse correlation spectroscopy, natural resonance frequency, and retinal vein approaches were also promising. (4) Conclusions: To date, no convincing evidence supports the use of a particular method for non-invasive intracranial pressure measurement. However, many new approaches are under development.

Optic Nerve Ultrasound Evaluation in Children: A Review

Managing patients with neurocritical illness requires monitoring and treating elevated intracranial pressure (ICP), especially in cases in children. In terms of precise and real-time measurements, invasive ICP measurements are presently the gold standard for the initial diagnosis and follow-up ICP assessments. As a rapid and non-invasive way to detect elevated ICP, point-of-care ultrasonography (POCUS) of optic nerve sheath diameter (ONSD) has been proposed. The utility of bedside POCUS of ONSD to detect elevated ICP with excellent diagnostic test accuracy in adults has already been demonstrated. Nonetheless, data on the relationship between POCUS of ONSD and ICP in children are scarce. Therefore, the purpose of this review is to point out the most recent findings from the pediatric published literature and briefly discuss what was assessed with ONSD ultrasound examination, and also to describe and discuss the diagnostic procedures available for optic nerve ultrasound appraisal. A search of the medical databases PubMed and Scopus was carried out. The terms such as "ocular ultrasonography", "ICP assessment", "children", "point-of-care ultrasound", and "POCUS" were searched. In conclusion, the use of the standardized A-scan technique coupled with the B-scan technique should be suggested to provide data that are as accurate, precise, repeatable, and objective as possible.

Noninvasive assessment of intracranial pressure using subharmonic-aided pressure estimation: An experimental study in canines

BACKGROUND

Intracranial hypertension is a common clinicopathological syndrome in neurosurgery, and a timely understanding of the intracranial pressure (ICP) may help guide clinical treatment. We aimed to investigate the correlation between subharmonic contrast-enhanced ultrasound (SHCEUS) parameters and ICP in experimental canines.

METHODS

A dynamic model of ICP change from 11 mm Hg to 50 mm Hg was established in experimental canines by placing a latex balloon into the epidural space and injecting saline into the balloon. In addition, a pressure sensor was placed in the brain parenchyma to record the changes in ICP. When the ICP stabilized after each increase, subharmonic-aided pressure estimation (SHAPE) technology was performed to obtain the SHCEUS parameters, including the basal venous and adjacent intracranial arterial subharmonic amplitude and SHAPE gradient (subharmonic amplitude in the intracranial artery minus that in the basal vein). The correlation between these parameters and ICP was analyzed.

RESULTS

The subharmonic amplitude of the basal vein was negatively correlated with the ICP (r = -0.798), and the SHAPE gradient was positively correlated with the ICP (r = 0.628). According to the guidelines for ICP monitoring in patients with traumatic brain injury, we defined 20 mm Hg, 25 mm Hg, and 30 mm Hg as the cutoff ICP levels. The area under the receiver operating characteristic curve of the basal venous subharmonic amplitude for diagnosing intracranial hypertension ≥20 mm Hg, ≥25 mm Hg, and ≥30 mm Hg was 0.867 (95% confidence interval [CI], 0.750-0.943), 0.884 (95% CI, 0.770-0.954), and 0.875 (95% CI, 0.759-0.948), respectively. The area under the receiver operating characteristic curve of the SHAPE gradient for diagnosing intracranial hypertension ≥20 mm Hg, ≥25 mm Hg, and ≥30 mm Hg was 0.839 (95% CI, 0.716-0.924), 0.842 (95% CI, 0.720-0.926), and 0.794 (95% CI, 0.665-0.890), respectively.

CONCLUSION

SHCEUS parameters are correlated with ICP. The SHAPE technique can assist in evaluating ICP changes in canines, which provides a new idea and method for evaluating ICP.

Computational modelling of cerebral oedema and osmotherapy following ischaemic stroke

In ischaemic stroke, a large reduction in blood supply can lead to the breakdown of the blood brain barrier and to cerebral oedema after reperfusion therapy. Cerebral oedema is marked by elevated intracranial pressure (ICP), tissue herniation and reduced cerebral perfusion pressure. In clinical settings, osmotherapy has been a common practice to decrease ICP. However, there are no guidelines on the choice of administration protocol parameters such as injection doses, infusion time and retention time. Most importantly, the effects of osmotherapy have been proven controversial since the infusion of osmotic agents can lead to a range of side effects. Here, a new Finite Element model of brain oedema and osmotherapy is thus proposed to predict treatment outcome. The model consists of three components that simulate blood perfusion, oedema, and osmotherapy, respectively. In the perfusion model (comprising arteriolar, venous, and capillary blood compartments), an anatomically accurate brain geometry is used to identify regions with a perfusion reduction and potential oedema occurrence in stroke. The oedema model is then used to predict ICP using a porous circulation model with four fluid compartments (arteriolar blood, venular blood, capillary blood, and interstitial fluid). In the osmotherapy model, the osmotic pressure is varied and the changes in ICP during different osmotherapy episodes are quantified. The simulation results of the model show excellent agreement with available clinical data and the model is employed to study osmotherapy under various parameters. Consequently, it is demonstrated how therapeutic strategies can be proposed for patients with different pathological parameters based on simulations.

Clinical translation of noninvasive intracranial pressure sensing with diffuse correlation spectroscopy

OBJECTIVE

Intracranial pressure (ICP) is an important therapeutic target in many critical neuropathologies. The current tools for ICP measurements are invasive; hence, these are only selectively applied in critical cases where the benefits surpass the risks. To address the need for low-risk ICP monitoring, the authors developed a noninvasive alternative.

METHODS

The authors recently demonstrated noninvasive quantification of ICP in an animal model by using morphological analysis of microvascular cerebral blood flow (CBF) measured with diffuse correlation spectroscopy (DCS). The current prospective observational study expanded on this preclinical study by translating the method to pediatric patients. Here, the CBF features, along with mean arterial pressure (MAP) and heart rate (HR) data, were used to build a random decision forest, machine learning model for estimation of ICP; the results of this model were compared with those of invasive monitoring.

RESULTS

Fifteen patients (mean age ± SD [range] 9.8 ± 5.1 [0.3-17.5] years; median age [interquartile range] 11 [7.4] years; 10 males and 5 females) who underwent invasive neuromonitoring for any purpose were enrolled. Estimated ICP (ICPest) very closely matched invasive ICP (ICPinv), with a root mean square error (RMSE) of 1.01 mm Hg and 95% limit of agreement of ≤ 1.99 mm Hg for ICPinv 0.01-41.25 mm Hg. When the ICP range (ICPinv 0.01-29.05 mm Hg) was narrowed on the basis of the sample population, both RMSE and limit of agreement improved to 0.81 mm Hg and ≤ 1.6 mm Hg, respectively. In addition, 0.3% of the test samples for ICPinv ≤ 20 mm Hg and 5.4% of the test samples for ICPinv > 20 mm Hg had a limit of agreement > 5 mm Hg, which may be considered the acceptable limit of agreement for clinical validity of ICP sensing. For the narrower case, 0.1% of test samples for ICPinv ≤ 20 mm Hg and 1.1% of the test samples for ICPinv > 20 mm Hg had a limit of agreement > 5 mm Hg. Although the CBF features were crucial, the best prediction accuracy was achieved when these features were combined with MAP and HR data. Lastly, preliminary leave-one-out analysis showed model accuracy with an RMSE of 6 mm Hg and limit of agreement of ≤ 7 mm Hg.

CONCLUSIONS

The authors have shown that DCS may enable ICP monitoring with additional clinical validation. The lower risk of such monitoring would allow ICP to be estimated for a wide spectrum of indications, thereby both reducing the use of invasive monitors and increasing the types of patients who may benefit from ICP-directed therapies.

Does MARPE therapy have effects on intracranial pressure? a clinical study

Background

We aimed to evaluate possible intracranial pressure (ICP) changes caused by screw activations during active microimplant-assisted rapid palatal expansion (MARPE) therapy of post-pubertal individuals by measuring the optic nerve sheath diameter (ONSD) under ultrasonography (US) guidance.

Methods

This study’s participants comprised 15 patients (7 males, 8 females) with posterior crossbite and a mean age of 16.7 years (14.25–20.08 years). The Maxillary Skeletal Expander (MSE) appliance was used to perform MARPE in all patients. Their vital signs (heart rate, mean arterial pressure (MAP), and peripheral oxygen saturation (SpO₂)) were recorded. The ONSD was measured by US immediately before the first screw activation (T0), and the measurements were repeated 1 min (T1) and 10 min (T2) after the first activation. In the last session of active MARPE therapy, the same measurement protocol was performed as in the first activation session (T3, T4, and T5). The patients’ perceptions of pain during the screw activation were also noted at T1 and T4 using a four-category verbal rating scale (VRS-4). The significant differences among different time intervals performed with the Friedman test (for all tested variables; SpO2, MAP, Heart Rate, VRS-4 and ONSD). Spearman correlation test was used for VRS-4 and ONSD comparisons. The statistical significance level was accepted as p < 0.05.

Results

The ONSD values ​​(T1 and T4) relatively increased within 1 min after screw activation but did not reach a statistically significant level (p > 0.05). There was also no significant difference between the initial (T0) and the final (T5) ONSD values ​​during the active MARPE therapy (p > 0.05).

Conclusion

There is no changes or alterations in intracranial pressure in late adolescents during active MARPE therapy.

Supplementary information

The online version contains supplementary material available at 10.1186/s12903-022-02482-x.

Intracranial pressure: current perspectives on physiology and monitoring

Intracranial pressure (ICP) monitoring is now viewed as integral to the clinical care of many life-threatening brain insults, such as severe traumatic brain injury, subarachnoid hemorrhage, and malignant stroke. It serves to warn of expanding intracranial mass lesions, to prevent or treat herniation events as well as pressure elevation which impedes nutrient delivery to the brain. It facilitates the calculation of cerebral perfusion pressure (CPP) and the estimation of cerebrovascular autoregulatory status. Despite advancements in our knowledge emanating from a half century of experience with this technology, important controversies remain related even to fundamental aspects of ICP measurements, including indications for monitoring, ICP treatment thresholds, and management of intracranial hypertension. Here, we review the history of ICP monitoring, the underlying pathophysiology as well as current perspectives on why, when and how ICP monitoring is best used. ICP is typically assessed invasively but a number of emerging, non-invasive technologies with inherently lower risk are showing promise. In selected cases, additional neuromonitoring can be used to assist in the interpretation of ICP monitoring information and adapt directed treatment accordingly. Additional efforts to expand the evidence base relevant to ICP monitoring, related technologies and management remain a high priority in neurosurgery and neurocritical care.

Lateral Ventricular Volume Asymmetry and Optic Nerve Sheath Diameter Predict Intracranial Pressure in Traumatic Brain Injury Patients

Background

Various noninvasive methods of intracranial pressure (ICP) measurement have been proposed. Each has unique advantages and limitations. This study was aimed at investigating the relationships between lateral ventricular asymmetry on admission computed tomography, optic nerve sheath diameter (ONSD), and ICP in traumatic brain injury (TBI) patients.

Methods

A prospective observational study was conducted in the patients admitted to our department between October 2018 and October 2020. 20 patients with moderate-severe TBI with a Glasgow Coma Scale of 3-12 were enrolled. Lateral ventricle volume (LVV) value measurements were conducted using ITK-SNAP software. The lateral ventricular volume ratio (LVR) was quantified by dividing the larger LVV by the smaller.

Results

ONSD and LVR had a good correlation with ICP. Admission LVR of >1.735 was shown to have a sensitivity of 90.9% and a specificity of 88.9% for prediction of ICP increase (AUC = 0.879; standard error = 0.091; 95% CI = 0.701 to 1.0; significance level p < 0.004). Admission ONSD of >5.55 mm was shown to have a sensitivity of 81.8% and a specificity of 88.9% for prediction of ICP increase (AUC = 0.919; standard error = 0.062; 95% CI = 0.798 to 1.0; significance level p < 0.002). Combining the ONSD and LVR, the sensitivity could be improved to 90.9% in parallel test, and the specificity could be improved to 100% in serial test.

Conclusion

ONSD and LVR measurements can diagnose elevated ICP in traumatic brain injury patients. ONSD combining with LVR may further improve the diagnostic evaluation.

Zero retinal vein pulsation amplitude extrapolated model in non-invasive intracranial pressure estimation

Intracranial pressure (ICP) includes the brain, optic nerve, and spinal cord pressures; it influences blood flow to those structures. Pathological elevation in ICP results in structural damage through various mechanisms, which adversely affects outcomes in traumatic brain injury and stroke. Currently, invasive procedures which tap directly into the cerebrospinal fluid are required to measure this pressure. Recent fluidic engineering modelling analogous to the ocular vascular flow suggests that retinal venous pulse amplitudes are predictably influenced by downstream pressures, suggesting that ICP could be estimated by analysing this pulse signal. We used this modelling theory and our photoplethysmographic (PPG) retinal venous pulse amplitude measurement system to measure amplitudes in 30 subjects undergoing invasive ICP measurements by lumbar puncture (LP) or external ventricular drain (EVD). We estimated ICP from these amplitudes using this modelling and found it to be accurate with a mean absolute error of 3.0 mmHg and a slope of 1.00 (r = 0.91). Ninety-four percent of differences between the PPG and invasive method were between − 5.5 and + 4.0 mmHg, which compares favourably to comparisons between LP and EVD. This type of modelling may be useful for understanding retinal vessel pulsatile fluid dynamics and may provide a method for non-invasive ICP measurement.

Optic Nerve Sheath Diameter Ultrasound: A Non-Invasive Approach to Evaluate Increased Intracranial Pressure in Critically Ill Pediatric Patients

Early diagnosis of increased intracranial pressure (ICP) is crucial for prompt diagnosis and treatment of intracranial hypertension in critically ill pediatric patients, preventing secondary brain damage and mortality. Although the placement of an external ventricular drain coupled to an external fluid-filled transducer remains the gold standard for continuous ICP monitoring, other non-invasive approaches are constantly being improved and can provide reliable estimates. The use of point-of-care ultrasound (POCUS) for the assessment of ICP has recently become widespread in pediatric emergency and critical care settings, representing a valuable extension of the physical examination. The aim of this manuscript is to review and discuss the basic principles of ultra-sound measurement of the optic nerve sheath diameter (ONSD) and summarize current evidence on its diagnostic value in pediatric patients with ICP. There is increasing evidence that POCUS measurement of the ONSD correlates with ICP, thus appearing as a useful extension of the physical examination in pediatrics, especially in emergency medicine and critical care settings for the initial non-invasive assessment of patients with suspected raised ICP. Its role could be of value even to assess the response to therapy and in the follow-up of patients with diagnosed intracranial hypertension if invasive ICP monitoring is not available. Further studies on more homogeneous and extensive study populations should be performed to establish ONSD reference ranges in the different pediatric ages and to define cut-off values in predicting elevated ICP compared to invasive ICP measurement.

Reversible focal intracranial hypertension swine model with continuous multimodal neuromonitoring

BACKGROUND

Intracranial hypertension (HI) is associated with worse neurological outcomes and higher mortality. Although there are several experimental models of HI, in this article we present a reproducible, reversible, and reliable model of intracranial hypertension, with continuous multimodal monitoring.

NEW METHOD

A reversible intracranial hypertension model in swine with multimodal monitoring including intracranial pressure, arterial blood pressure, heart rate variation, brain tissue oxygenation, and electroencephalogram is developed to understand the relationship of ICP and EEG. By inflating and deflating a balloon, located 20 mm anterior to the coronal suture and a 15 mm sagittal suture, we generate intracranial hypertension events and simultaneously measure intracranial pressure and oxygenation in the contralateral hemisphere and the EEG, simulating the usual configuration in humans.

RESULTS

We completed 5 experiments and in all of them, we were able to complete at least 6 events of intracranial hypertension in a stable and safe way. For events of 20-40 mmHg of ICP we need an median (IQR) of 4.2 (3.64) ml of saline solution into the Foley balloon, a median (IQR) infusion time of 226 (185) second in each event and for events of 40-50 mmHg of ICP we need a median (IQR) of 5.1 (4.66) ml of saline solution, a median (IQR) infusion time of 280 (48) seconds and a median (IQR). The median (IQR) maintenance time was 352 (77) seconds and 392 (166) seconds for 20-40 mmHg and 40-50 mmHg of ICP, respectively.

COMPARISON WITH EXISTING METHOD(S)

Existing methods do not include EEG measures and do not present the reversibility of intracranial hypertension.

CONCLUSIONS

Our model is fully reproducible, it is capable of generating reversible focal intracranial hypertension through strict control of the injected volume, it is possible to generate different infusion rates of the volume in the balloon, in order to generate different scenarios, the data obtained are sufficient to determine the brain complacency in real time. and useful for understanding the pathophysiology of ICP and the relationship between ICP (CPP) and EEG.

Evaluation of cerebral hemodynamics by transcranial Doppler ultrasonography and its correlation with intracranial pressure in an animal model of intracranial hypertension

BACKGROUND

Transcranial Doppler has been tested in the evaluation of cerebral hemodynamics as a non-invasive assessment of intracranial pressure (ICP), but there is controversy in the literature about its actual benefit and usefulness in this situation.

OBJECTIVE

To investigate cerebral blood flow assessed by Doppler technique and correlate with the variations of the ICP in the acute phase of intracranial hypertension in an animal model.

METHODS

An experimental animal model of intracranial hypertension was used. The experiment consisted of two groups of animals in which intracranial balloons were implanted and inflated with 4 mL (A) and 7 mL (B) for controlled simulation of different volumes of hematoma. The values of ICP and Doppler parameters (systolic [FVs], diastolic [FVd], and mean [FVm] cerebral blood flow velocities and pulsatility index [PI]) were collected during the entire procedure (before and during hematoma simulations and venous hypertonic saline infusion intervention). Comparisons between Doppler parameters and ICP monitoring were performed.

RESULTS

Twenty pigs were studied, 10 in group A and 10 in group B. A significant correlation between PI and ICP was obtained, especially shortly after abrupt elevation of ICP. There was no correlation between ICP and FVs, FVd or FVm separately. There was also no significant change in ICP after intravenous infusion of hypertonic saline solution.

CONCLUSIONS

These results demonstrate the potential of PI as a parameter for the evaluation of patients with suspected ICP elevation.

Big data and predictive analytics in neurocritical care

PURPOSE OF REVIEW

To describe predictive data and workflow in the intensive care unit when managing neurologically ill patients.

RECENT FINDINGS

In the era of Big Data in medicine, intensive critical care units are data-rich environments. Neurocritical care adds another layer of data with advanced multimodal monitoring to prevent secondary brain injury from ischemia, tissue hypoxia, and a cascade of ongoing metabolic events. A step closer toward personalized medicine is the application of multimodal monitoring of cerebral hemodynamics, bran oxygenation, brain metabolism, and electrophysiologic indices, all of which have complex and dynamic interactions. These data are acquired and visualized using different tools and monitors facing multiple challenges toward the goal of the optimal decision support system. In this review, we highlight some of the predictive data used to diagnose, treat, and prognosticate the neurologically ill patients. We describe information management in neurocritical care units including data acquisition, wrangling, analysis, and visualization.

The association between intracranial pressure and optic nerve sheath diameter on patients with head trauma

BACKGROUND

Although intracranial pressure (ICP) monitoring is the gold standard method for measuring intracranial pressure after traumatic brain injury, optic nerve sheath diameter (ONSD) measurement with ultrasound (US) is also used in the evaluation of ICP.

OBJECTIVE

To investigate the association between a series of OSND measurements by US and changes in clinical presentation of the patient.

METHODS

Prospective study including 162 patients with traumatic brain injury. Age, sex, cerebral CT findings, ONSD levels by US at minutes 0, 60, and 120, Glasgow Coma Scale (GCS) within same period, change of consciousness, treatment, and mortality data were reviewed. The association of ONSD levels with GCS, change of consciousness, treatment, and mortality was evaluated.

RESULTS

There was no difference in ONSD changes in the patients' sample within the period (p=0.326). ONSD significantly increased in patients who died (p<0.001), but not in those who survived (p=0.938). There was no significant change in ONSD of the patients who received anti-edema therapy (p=801), but significantly increased ONSD values were found in those who received anti-edema therapy (p=0.03). Patients without change of consciousness did not have any significant change in ONSD (p=0.672), but ONSD values increased in patients who consciousness became worse, and decreased in those who presented a recovery (respectively, p<0.001, p=0.002). A negative correlation was detected between ONSD values and GSC values measured at primary, secondary, and tertiary time periods (for all p<0.001).

CONCLUSIONS

ONSD follow-up may be useful to monitor ICP increase in patients with acute traumatic brain injury.

The Pre-Lumbar puncture Intracranial Hypertension Scale (PLIHS): A practical scale to identify subjects with normal cerebrospinal fluid pressure in the management of idiopathic intracranial hypertension

BACKGROUND

Idiopathic Intracranial Hypertension (IIH) diagnosis requires lumbar puncture to measure cerebrospinal fluid (CSF) pressure. The Pre-Lumbar puncture Intracranial Hypertension Scale (PLIHS) is aimed to detect cases that will show raised or normal CSF opening pressure.

METHODS

Retrospective analysis of records of patients who underwent lumbar puncture for suspect IIH. The target was CSF opening pressure ≥ 250 mmH2O, whereas a set of known neurological, neuro-ophthalmological and neuro-radiological parameters, plus obesity, were used as predictors in a logistic regression model. The PLIHS was based on significant predictors and a cut-off was validated using chi-squared test around CSF opening pressure ≥ 250 and < 200 mmH2O.

RESULTS

Records of 162 patients were included: CSF opening pressure was <200 mmH2O in 40 and ≥ 250 mmH2O in 95 patients; 85 fulfilled IIH diagnosis. PLIHS is based on Frisén grade 2 or higher papilledema, tinnitus, empty sella, perioptic subarachnoid space distension, and obesity. Score range is 0-7: correlation with CSF opening pressure is 0.508 (p < .001), and PLIHS score is different between subjects not diagnosed with IIH, and those diagnosed with IIH both with and without papilledema (p < .001). PLIHS score ≤ 2 identifies cerebrospinal fluid pressure < 200 mmH2O; PLIHS score ≥ 3 identifies CSF opening pressure ≥ 250 mmH2O, IIH diagnosis, visual acuity ≤0.7, and optic nerve atrophy.

CONCLUSIONS

The PLIHS, can be used to identify patients who will particularly need LP, thus helping with the organization of the diagnostic work-up by optimising healthcare resources and potentially limit the likelihood to incur in LP-related adverse events.

The evaluation of intracranial pressure evaluation by optic nerve sheath diameter measurement on bedside ultrasonography after ischemic stroke

INTRODUCTION

We aimed to predict intracranial pressure(ICP)after cerebral ischemic stroke by measuring diameter of the optic nerve sheath(ONSD)with bedside ultrasonography(US). In order to see the ICP changes,it was planned to record delta ICP changes at the 3rd and 5th day follow-up of the patients METHOTS: Patients aged 18 years or older who were admitted to the emergency department(ED)with stroke symptoms for one year were included.Demographic data,time elapsed since the onset of symptoms,neurogical status assesment scales,ONSD values measured by US in three time periods(the day the patient was admitted to the ED,the 3rd and 5th days of hospitalization),MDCT findings when the patient was admitted,ONSD values in MDCT,whether they received tissue plasminogen activator(tPA)and whether they underwent decompression surgery were recorded.

RESULTS

The average age of the 82 patients was 67.5(range 33-89)years.Forty-two patients(51.2%)were male.On both the right and left sides,ONSD on the 3rd day was larger(>5 mm)than on first day(p < 0.05). ONSD on the 5th day was larger than on the first day(p > 0.05). All ONSD results measured using both US and MDCT showed a positive correlation between the same eye and contralateral eye measurements(p < 0.05).

DISCUSSION

CT is the most critical radiological method for stroke patients.Transport to radyology unit in unstable patients carries risk and is not recommended.Optic nerve US can be used in the early diagnosis of ICP increase and provides early treatment.The ease of use and safety in unstable patients have increased its popularity.

CONCLUSION

We believe that measuring ONSD using US is an appropriate choice on ICP management in stroke patients.

Noninvasive intracranial pressure monitoring methods: a critical review

BACKGROUND

Intracranial pressure (ICP) monitoring has been used for decades in management of various neurological conditions. The gold standard for measuring ICP is a ventricular catheter connected to an external strain gauge, which is an invasive system associated with a number of complications. Despite its limitations, no noninvasive ICP monitoring (niICP) method fulfilling the technical requirements for replacing invasive techniques has yet been developed, not even in cases requiring only ICP monitoring without cerebrospinal fluid (CSF) drainage.

OBJECTIVES

Here, we review the current methods for niICP monitoring.

METHODS

The different methods and approaches were grouped according to the mechanism used for detecting elevated ICP or its associated consequences.

RESULTS

The main approaches reviewed here were: physical examination, brain imaging (magnetic resonance imaging, computed tomography), indirect ICP estimation techniques (fundoscopy, tympanic membrane displacement, skull elasticity, optic nerve sheath ultrasound), cerebral blood flow evaluation (transcranial Doppler, ophthalmic artery Doppler), metabolic changes measurements (near-infrared spectroscopy) and neurophysiological studies (electroencephalogram, visual evoked potential, otoacoustic emissions).

CONCLUSION

In terms of accuracy, reliability and therapeutic options, intraventricular catheter systems still remain the gold standard method. However, with advances in technology, noninvasive monitoring methods have become more relevant. Further evidence is needed before noninvasive methods for ICP monitoring or estimation become a more widespread alternative to invasive techniques.

Effects of Cranioplasty After Decompressive Craniectomy on Neurological Function and Cerebral Hemodynamics in Traumatic Versus Nontraumatic Brain Injury

After decompressive craniectomy (DC), cranioplasty (CP) can help to normalize vascular and cerebrospinal fluid circulation besides improving the patient's neurological status. The aim of this study was to investigate the effects of CP on cerebral hemodynamics and on cognitive and functional outcomes in patients with and without a traumatic brain injury (TBI). Over a period of 3 years, 51 patients were included in the study: 37 TBI patients and 14 non-TBI patients. The TBI group was younger (28.86 ± 9.71 versus 45.64 ± 9.55 years, P = 0.0001), with a greater proportion of men than the non-TBI group (31 versus 6, P = 0.011). Both groups had improved cognitive outcomes (as assessed by the Mini-Mental State Examination) and functional outcomes (as assessed by the Barthel Index and Modified Rankin Scale) 90 days after CP. In the TBI group, the mean velocity of blood flow in the middle cerebral artery ipsilateral to the cranial defect increased between the time point before CP and 90 days after CP (34.24 ± 11.02 versus 42.14 ± 10.19 cm/s, P = 0.0001). In conclusion, CP improved the neurological status in TBI and non-TBI patients, but an increment in cerebral blood flow velocity after CP occurred only in TBI patients.

Comparison of the effects of normal and low blood pressure regulation on the optic nerve sheath diameter in robot assisted laparoscopic radical prostatectomy

Background

Robot-assisted laparoscopic radical prostatectomy is an advanced and popular surgical technique. However, increased intracranial pressure which is caused by CO₂ pneumoperitoneum and Trendelenburg position is the main cerebrovascular effect. Measurement of optic nerve sheath diameter using ocular ultrasound is a noninvasive and reliable method for the assessment of intracranial pressure. The primary endpoint of this study was to identify whether low blood pressure regulation has any benefit in attenuating an increase of optic nerve sheath diameter during robot-assisted laparoscopic radical prostatectomy.

Methods

Optic nerve sheath diameter and cerebral oxygen saturation were measured at baseline (supine position), one and two hours after pneumoperitoneum and Trendelenburg position respectively, and after return to supine position in normal (n = 27) and low blood pressure groups (n = 24).

Results

Mean optic nerve sheath diameter values measured at one and two hours after pneumoperitoneum and Trendelenburg position were significantly increased compared to the baseline value (P < 0.001 in normal blood pressure group; P = 0.003 in low blood pressure group). However, the mean optic nerve sheath diameter and cerebral oxygen saturation measured at any of the time points as well as degrees of change between the two groups did not show any significant changes. The peak values of optic nerve sheath diameter in normal and low blood pressure groups demonstrated 14.9% and 9.2% increases, respectively.

Conclusions

Low blood pressure group demonstrated an effect in maintaining an increase of optic nerve sheath diameter less than 10% during CO₂ pneumoperitoneum and Trendelenburg position.

Intracranial pressure waveform changes in Alzheimer's disease and mild cognitive impairment

Background:

Alzheimer’s disease (AD) is known to cause an enormous impairment to the quality of life and impact in the health system; meanwhile, studies show that in the coming years, the number of affected individuals will continue to grow. It is also believed that amnestic mild cognitive impairment (MCI) could represent an early symptomatic form of AD, which precedes dementia.

Methods:

The present study aimed to evaluate the intracranial pressure (ICP) through a noninvasive method in patients with AD and MCI, seeking for differences when compared to healthy elderlies. This is a cross-sectional, correlational, and observational study of a quantitative character, carried out in a Brazilian city, with patients from the ANEC of the UFSCar.

Results:

It was found a statistically significant difference between the ICP morphology when analyzing the results in patients with AD and MCI, compared to healthy volunteers. It is known that dementias means a progressive disorder that leads to the loss of independency and function of the patient, although, it is believed that it can be found early ICP alterations in these patients. Nevertheless, considering this is an unprecedent study, it was not possible to compare results with previous studies and literatures. However, the study has a limitation related to the sample size; an expansion of it could possibility lead to different findings.

Conclusion:

The findings through the ICP measurement could indicate an early diagnosis, which would lead to an early treatment and an improvement in the quality of life of patients with AD. Thus, further investigation and widening studies are encouraged.

The effect of robotic surgery on intraocular pressure and optic nerve sheath diameter: a prospective study

Background and objectives

To investigate the effect of the steep Trendelenburg position (35° to 45°) and carbon dioxide (CO2) insufflation on optic nerve sheath diameter (ONSD), intraocular pressure (IOP), and hemodynamic parameters in patients undergoing robot-assisted laparoscopic prostatectomy (RALP), and to evaluate possible correlations between these parameters.

Methods

A total of 34 patients were included in this study. ONSD was measured using ultrasonography and IOP was measured using a tonometer at four time points: T1 (5 minutes after intubation in the supine position); T2 (30 minutes after CO2 insufflation); T3 (120 minutes in steep Trendelenburg position); and T4 (in the supine position, after abdominal exsufflation). Systolic and diastolic arterial pressure, heart rate, and end-tidal CO2 (etCO2) were also evaluated.

Results

The mean IOP was 12.4 mmHg at T1, 20 mmHg at T2, 21.8 mmHg at T3, and 15.6 mmHg at T4. The mean ONSD was 4.87 mm at T1, 5.21 mm at T2, 5.30 mm at T3, and 5.08 at T4. There was a statistically significant increase and decrease in IOP and ONSD between measurements at T1 and T4, respectively. However, no significant correlation was found between IOP and ONSD. A significant positive correlation was found only between ONSD and diastolic arterial pressure. Mean arterial pressure, heart rate, and etCO2 were not correlated with IOP or ONSD.

Conclusions

A significant increase in IOP and ONSD were evident during RALP; however, there was no significant correlation between the two parameters.

Structure and Outcomes of Educational Programs for Training Non-electroencephalographers in Performing and Screening Adult EEG: A Systematic Review

OBJECTIVE

To qualitatively and quantitatively summarize curricula, teaching methods, and effectiveness of educational programs for training bedside care providers (non-experts) in the performance and screening of adult electroencephalography (EEG) for nonconvulsive seizures and other patterns.

METHODS

PRISMA methodological standards were followed. MEDLINE, EMBASE, Cochrane, CINAHL, WOS, Scopus, and MedEdPORTAL databases were searched from inception until February 26, 2020 with no restrictions. Abstract and full-text review was completed in duplicate. Studies were included if they were original research; involved non-experts performing, troubleshooting, or screening adult EEG; and provided qualitative descriptions of curricula and teaching methods and/or quantitative assessment of non-experts (vs gold standard EEG performance by neurodiagnostic technologists or interpretation by neurophysiologists). Data were extracted in duplicate. A content analysis and a meta-narrative review were performed.

RESULTS

Of 2430 abstracts, 35 studies were included. Sensitivity and specificity of seizure identification varied from 38 to 100% and 65 to 100% for raw EEG; 40 to 93% and 38 to 95% for quantitative EEG, and 95 to 100% and 65 to 85% for sonified EEG, respectively. Non-expert performance of EEG resulted in statistically significant reduced delay (86 min, p < 0.0001; 196 min, p < 0.0001; 667 min, p < 0.005) in EEG completion and changes in management in approximately 40% of patients. Non-experts who were trained included physicians, nurses, neurodiagnostic technicians, and medical students. Numerous teaching methods were utilized and often combined, with instructional and hands-on training being most common.

CONCLUSIONS

Several different bedside providers can be educated to perform and screen adult EEG, particularly for the purpose of diagnosing nonconvulsive seizures. While further rigorous research is warranted, this review demonstrates several potential bridges by which EEG may be integrated into the care of critically ill patients.

Intracranial pressure monitoring following traumatic brain injury: evaluation of indications, complications, and significance of follow-up imaging-an exploratory, retrospective study of consecutive patients at a level I trauma center

Background

Measurement of intracranial pressure (ICP) is an essential part of clinical management of severe traumatic brain injury (TBI). However, clinical utility and impact on clinical outcome of ICP monitoring remain controversial. Follow-up imaging using cranial computed tomography (CCT) is commonly performed in these patients. This retrospective cohort study reports on complication rates of ICP measurement in severe TBI patients, as well as on findings and clinical consequences of follow-up CCT.

Methods

We performed a retrospective clinical chart review of severe TBI patients with invasive ICP measurement treated at an urban level I trauma center between January 2007 and September 2017.

Results

Clinical records of 213 patients were analyzed. The mean Glasgow Coma Scale (GCS) on admission was 6 with an intra-hospital mortality of 20.7%. Overall, complications in 12 patients (5.6%) related to the invasive ICP-measurement were recorded of which 5 necessitated surgical intervention. Follow-up CCT scans were performed in 192 patients (89.7%). Indications for follow-up CCTs included routine imaging without clinical deterioration (n = 137, 64.3%), and increased ICP values and/or clinical deterioration (n = 55, 25.8%). Follow-up imaging based on clinical deterioration and increased ICP values were associated with significantly increased likelihoods of worsening of CCT findings compared to routinely performed CCT scans with an odds ratio of 5.524 (95% CI 1.625–18.773) and 6.977 (95% CI 3.262–14.926), respectively. Readings of follow-up CCT imaging resulted in subsequent surgical intervention in six patients (3.1%).

Conclusions

Invasive ICP-monitoring in severe TBI patients was safe in our study population with an acceptable complication rate. We found a high number of follow-up CCT. Our results indicate that CCT imaging in patients with invasive ICP monitoring should only be considered in patients with elevated ICP values and/or clinical deterioration.

Neurological Complications and Noninvasive Multimodal Neuromonitoring in Critically Ill Mechanically Ventilated COVID-19 Patients

Purpose: The incidence and the clinical presentation of neurological manifestations of coronavirus disease-2019 (COVID-19) remain unclear. No data regarding the use of neuromonitoring tools in this group of patients are available. Methods: This is a retrospective study of prospectively collected data. The primary aim was to assess the incidence and the type of neurological complications in critically ill COVID-19 patients and their effect on survival as well as on hospital and intensive care unit (ICU) length of stay. The secondary aim was to describe cerebral hemodynamic changes detected by noninvasive neuromonitoring modalities such as transcranial Doppler, optic nerve sheath diameter (ONSD), and automated pupillometry. Results: Ninety-four patients with COVID-19 admitted to an ICU from February 28 to June 30, 2020, were included in this study. Fifty-three patients underwent noninvasive neuromonitoring. Neurological complications were detected in 50% of patients, with delirium as the most common manifestation. Patients with neurological complications, compared to those without, had longer hospital (36.8 ± 25.1 vs. 19.4 ± 16.9 days, p < 0.001) and ICU (31.5 ± 22.6 vs. 11.5±10.1 days, p < 0.001) stay. The duration of mechanical ventilation was independently associated with the risk of developing neurological complications (odds ratio 1.100, 95% CI 1.046-1.175, p = 0.001). Patients with increased intracranial pressure measured by ONSD (19% of the overall population) had longer ICU stay. Conclusions: Neurological complications are common in critically ill patients with COVID-19 receiving invasive mechanical ventilation and are associated with prolonged ICU length of stay. Multimodal noninvasive neuromonitoring systems are useful tools for the early detection of variations in cerebrovascular parameters in COVID-19.

Escalation therapy in severe traumatic brain injury: how long is intracranial pressure monitoring necessary?

Traumatic brain injury frequently causes an elevation of intracranial pressure (ICP) that could lead to reduction of cerebral perfusion pressure and cause brain ischemia. Invasive ICP monitoring is recommended by international guidelines, in order to reduce the incidence of secondary brain injury; although rare, the complications related to ICP probes could be dependent on the duration of monitoring. The aim of this manuscript is to clarify the appropriate timing for removal and management of invasive ICP monitoring, in order to reduce the risk of related complications and guarantee adequate cerebral autoregulatory control. There is no universal consensus concerning the duration of invasive ICP monitoring and its related complications, although the pertinent literature seems to show that the longer is the monitoring maintenance, the higher is the risk of technical issues. Besides, upon 72 h of normal ICP values or less than 72 h if the first computed tomography scan is normal (none or minimal signs of injury) and the neurological exam is available (allowing to observe variations and possible occurrence of new-onset pathological response), the removal of invasive ICP monitoring can be justified. The availability of non-invasive monitoring systems should be considered to follow up patients' clinical course after invasive ICP probe removal or for substituting the invasive monitoring in case of contraindication to its placement. Recently, optic nerve sheath diameter and straight sinus systolic flow velocity evaluation through ultrasound methods showed a good correlation with ICP values, demonstrating their potential role in place of invasive monitoring or in the early weaning phase from the invasive ICP monitoring.

Advantages of Small Bone-Window Craniotomy Under Microscope Combined Postoperative Intracranial Pressure Monitoring in the Treatment of Hypertensive Intracerebral Hemorrhage

OBJECTIVE

The aim of this study is to analyze the clinical effect of small bone-window craniotomy with microscope combined postoperative ICP monitoring, and further explore an appropriate treatment for HICH patients.

METHODS

One hundred fifty patients with HICH were selected according to inclusion and exclusion criteria and divided into 3 groups at random, 50 each group. Patients in 3 groups were treated with conventional craniotomy, small bone-window craniotomy and small bone-window craniotomy combined ICP monitoring respectively. The surgical efficiency, treatment effect and outcomes were recorded and analyzed.

RESULTS

The intraoperative blood loss and operation time of small window groups were significantly less than that of conventional group, and the hematoma clearance rate in small window groups were significantly higher than in conventional group (P < 0.05). Compared with conventional group, the hospital stays and mannitol dose used were less in small window groups and least in small window combined ICP monitoring group (P < 0.05). The complication rate in small window combined ICP monitoring group was 10%, which was significantly lower than in conventional group (26%, P < 0.05), while no significant difference was found between small window group (18%) compared with the other 2 groups respectively (P > 0.05). The difference of morality rate between 3 groups wasn't significant (P > 0.05). Three treatment significantly increased the Barthel index score, and the improvement of small window combined ICP monitoring group was significantly higher than in other 2 groups respectively (P < 0.05), while the difference between this two groups wasn't significant (P > 0.05).

CONCLUSION

Small bone-window craniotomy is more efficient and convenient than conventional craniotomy in the treatment of HICH. In the meantime, small bone-window craniotomy simultaneous with ICP monitoring significantly improved clinical effect and treatment outcomes of HICH patients.

Effects of Age and Sex on Optic Nerve Sheath Diameter in Healthy Volunteers and Patients With Traumatic Brain Injury

The measurement of optic nerve sheath diameter (ONSD) has been reported as a non-invasive marker for intracranial pressure (ICP). Nevertheless, it is uncertain whether possible ONSD differences occur with age and sex in healthy and brain-injured populations. The aim of this study was to investigate the effects of sex and age on ONSD in healthy volunteers and patients with traumatic brain injury. We prospectively included 122 healthy adult volunteers (Galliera Hospital, Genova, Italy), and compared age/sex dependence of ONSD to 95 adult patients (Addenbrooke's Hospital, Cambridge, UK) with severe traumatic brain injury (TBI) requiring intubation and invasive ICP monitoring. The two groups were stratified for sex and age. Age was divided into 3 subgroups: (1) young adults: 18–44 years; (2) middle-aged adults: 45–64 years; (3) old adults: >65 years. In healthy volunteers, ONSD was significantly different between males and females [median (interquartile range): 4.2 (3.9–4.6) mm vs. 4.1 (3.6–4.2) mm (p = 0.01), respectively] and was correlated with age (R = 0.50, p < 0.0001). ONSD was significantly increased in group 3 compared to groups 2 and 1, indicating that ONSD values are higher in elderly subjects. In TBI patients, no differences in ONSD were found for sex and the correlation between ONSD and age was non-significant (R = 0.13, p = 0.20). ONSD increases with age and is significantly larger for males in healthy volunteers but not in TBI patients. Different ONSD cut-off values need not be age- or sex-adjusted for the assessment of increased ICP in TBI patients.

Non-Invasive Estimation of Intracranial Pressure by Diffuse Optics: A Proof-of-Concept Study

Intracranial pressure (ICP) is an important parameter to monitor in several neuropathologies. However, because current clinically accepted methods are invasive, its monitoring is limited to patients in critical conditions. On the other hand, there are other less critical conditions for which ICP monitoring could still be useful; therefore, there is a need to develop non-invasive methods. We propose a new method to estimate ICP based on the analysis of the non-invasive measurement of pulsatile, microvascular cerebral blood flow with diffuse correlation spectroscopy. This is achieved by training a recurrent neural network using only the cerebral blood flow as the input. The method is validated using a 50% split sample method using the data from a proof-of-concept study. The study involved a population of infants (n = 6) with external hydrocephalus (initially diagnosed as benign enlargement of subarachnoid spaces) as well as a population of adults (n = 6) with traumatic brain injury. The algorithm was applied to each cohort individually to obtain a model and an ICP estimate. In both diverse cohorts, the non-invasive estimation of ICP was achieved with an accuracy of <4 mm Hg and a negligible small bias. Further, we have achieved a good correlation (Pearson's correlation coefficient >0.9) and good concordance (Lin's concordance correlation coefficient >0.9) in comparison with standard clinical, invasive ICP monitoring. This preliminary work paves the way for further investigations of this tool for the non-invasive, bedside assessment of ICP.

Multimodal non-invasive assessment of intracranial hypertension: an observational study

BACKGROUND

Although placement of an intra-cerebral catheter remains the gold standard method for measuring intracranial pressure (ICP), several non-invasive techniques can provide useful estimates. The aim of this study was to compare the accuracy of four non-invasive methods to assess intracranial hypertension.

METHODS

We reviewed prospectively collected data on adult intensive care unit (ICU) patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), or intracerebral hemorrhage (ICH) in whom invasive ICP monitoring had been initiated and estimates had been simultaneously collected from the following non-invasive indices: optic nerve sheath diameter (ONSD), pulsatility index (PI), estimated ICP (eICP) using transcranial Doppler, and the neurological pupil index (NPI) measured using automated pupillometry. Intracranial hypertension was defined as an invasively measured ICP > 20 mmHg.

RESULTS

We studied 100 patients (TBI = 30; SAH = 47; ICH = 23) with a median age of 52 years. The median invasively measured ICP was 17 [12-25] mmHg and intracranial hypertension was present in 37 patients. Median values from the non-invasive techniques were ONSD 5.2 [4.8-5.8] mm, PI 1.1 [0.9-1.4], eICP 21 [14-29] mmHg, and NPI 4.2 [3.8-4.6]. There was a significant correlation between all the non-invasive techniques and invasive ICP (ONSD, r = 0.54; PI, r = 0.50; eICP, r = 0.61; NPI, r = - 0.41-p < 0.001 for all). The area under the curve (AUC) to estimate intracranial hypertension was 0.78 [CIs = 0.68-0.88] for ONSD, 0.85 [95% CIs 0.77-0.93] for PI, 0.86 [95% CIs 0.77-0.93] for eICP, and 0.71 [95% CIs 0.60-0.82] for NPI. When the various techniques were combined, the highest AUC (0.91 [0.84-0.97]) was obtained with the combination of ONSD with eICP.

CONCLUSIONS

Non-invasive techniques are correlated with ICP and have an acceptable accuracy to estimate intracranial hypertension. The multimodal combination of ONSD and eICP may increase the accuracy to estimate the occurrence of intracranial hypertension.

Automatic Optic Nerve Measurement: A New Tool to Standardize Optic Nerve Assessment in Ultrasound B-Mode Images

Transorbital sonography provides reliable information about the estimation of intra-cranial pressure by measuring the optic nerve sheath diameter (ONSD), whereas the optic nerve (ON) diameter (OND) may reveal ON atrophy in patients with multiple sclerosis. Here, an AUTomatic Optic Nerve MeAsurement (AUTONoMA) system for OND and ONSD assessment in ultrasound B-mode images based on deformable models is presented. The automated measurements were compared with manual ones obtained by two operators, with no significant differences. AUTONoMA correctly segmented the ON and its sheath in 71 out of 75 images. The mean error compared with the expert operator was 0.06 ± 0.52 mm and 0.06 ± 0.35 mm for the ONSD and OND, respectively. The agreement between operators and AUTONoMA was good and a positive correlation was found between the readers and the algorithm with errors comparable with the inter-operator variability. The AUTONoMA system may allow for standardization of OND and ONSD measurements, reducing manual evaluation variability.

Telemetric Intracranial Pressure Monitoring: A Systematic Review

Telemetric intracranial pressure (ICP) monitoring is a new method of measuring ICP which eliminates some of the shortcomings of previous methods. However, there are limited data on specific characteristics, including the advantages and disadvantages of this method. The main aim of this study was to demonstrate the indications, benefits, and complications of telemetric ICP monitoring. PubMed, MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for relevant studies without language or date restriction in May 2019. Human studies in which telemetric ICP monitoring was the main subject of the study were included. Our initial search resulted in 1650 articles from which 50 studies were included. There were no randomized controlled trials. The majority of the studies were case reports or case series (68%). The most common aim of studies was testing of the device (52%), and monitoring the disease progression or recovery (46%). The most common indications for telemetric ICP monitoring in these studies were testing cerebrospinal fluid shunt function (46%), ICP control after the procedure (36%), and diagnosing intracranial hypertension (22%) and hydrocephalus (12%). In total, 1423 brain disease patients had been monitored in studies. The possibility of long-term ICP monitoring as the main benefit was reported in 38 (76%) studies. The associated complication rate was 7.1%. Despite the increasing application of telemetric monitoring devices, studies to evaluate specific characteristics of this method have been infrequent and inadequate. Future research using a higher level of scientific methods is needed to evaluate advantage and disadvantages.

Optic nerve sheath diameter ultrasonography for elevated intracranial pressure detection

Ultrasonographically measured optic nerve sheath diameter measurement has become a common noninvasive approach for detecting elevated intracranial pressure. We present a case of aneurysmal subarachnoid hemorrhage with elevated intracranial pressure. Postoperative arachnoiditis developed, and lumbar puncture revealed low intracranial pressure. However, ultrasonography revealed a dilated optic nerve sheath, denoting elevated intracranial pressure. This was confirmed by computed tomography showing ventricular dilation. Ophthalmoscopy revealed papilledema and hemorrhage. This case study demonstrated that noninvasive bedside ultrasonographic optic nerve sheath diameter measurement can detect elevated intracranial pressure more accurately than lumbar puncture, especially in cases with intracranial infection.

Measuring intracranial pressure by invasive, less invasive or non-invasive means: limitations and avenues for improvement

Sixty years have passed since neurosurgeon Nils Lundberg presented his thesis about intracranial pressure (ICP) monitoring, which represents a milestone for its clinical introduction. Monitoring of ICP has since become a clinical routine worldwide, and today represents a cornerstone in surveillance of patients with acute brain injury or disease, and a diagnostic of individuals with chronic neurological disease. There is, however, controversy regarding indications, clinical usefulness and the clinical role of the various ICP scores. In this paper, we critically review limitations and weaknesses with the current ICP measurement approaches for invasive, less invasive and non-invasive ICP monitoring. While risk related to the invasiveness of ICP monitoring is extensively covered in the literature, we highlight other limitations in current ICP measurement technologies, including limited ICP source signal quality control, shifts and drifts in zero pressure reference level, affecting mean ICP scores and mean ICP-derived indices. Control of the quality of the ICP source signal is particularly important for non-invasive and less invasive ICP measurements. We conclude that we need more focus on mitigation of the current limitations of today's ICP modalities if we are to improve the clinical utility of ICP monitoring.

Point-of-care ultrasound of optic nerve sheath diameter to detect intracranial pressure in neurocritically ill children - A narrative review

The rapid diagnosis of increased intracranial pressure is urgently needed for therapeutic reasons in neurocritically ill children, however this can rarely be achieved without invasive procedures. Point-of-care ultrasound of the optic nerve sheath diameter has been proposed as a non-invasive and reliable means to detect increased intracranial pressure in adults. Accordingly, clinicians may be able to use this technique to initiate early treatment and monitor the effectiveness of treatment in conjunction with other clinical examination and diagnostic modalities. Two meta-analyses and a systematic review have been published on this topic in adults. However, data on the correlation between optic nerve sheath diameter and intracranial pressure in neurocritically ill children are scarce. The aim of this review was to briefly describe what is being measured with point-of-care ultrasound of the optic nerve sheath diameter, summarize the most recent findings from adult literature, and provide an update of current work in children.

Optic Nerve Sheath Diameter is not Related to Intracranial Pressure in Subarachnoid Hemorrhage Patients

BACKGROUND

Intracranial pressure (ICP) monitoring is essential after subarachnoid hemorrhage (SAH) to prevent secondary brain insults and to tailor individualized treatments. Optic nerve sheath diameter (ONSD), measured using ultrasound (US), could serve as a noninvasive bedside tool to estimate ICP, avoiding the risks of hemorrhage or infection related to intracranial catheters. The aims of this study were twofold: first, to explore the reliability of US for measuring ONSD; second, to establish whether the US-ONSD can be considered a proxy for ICP in SAH patients early after bleeding. For the first aim, we compared the ONSD measurements given by magnetic resonance imaging (MRI-ONSD) with the US-ONSD findings. For the second aim, we analyzed the relationship between US-ONSD measurements and ICP values.

METHODS

Adult patients with diagnosis of aneurysmal SAH and external ventricular drainage system (EVD) were included. Ten patients were examined by MRI to assess ONSD, and the results were compared to the diameter given by US. In 20 patients, the US-ONSD values were related to ICP measured simultaneously through EVD. In ten of these patients, we explored the changes in the US-ONSD at the time of controlled and fairly rapid changes in ICP after cerebrospinal fluid (CSF) drainage.

RESULTS

US-ONSD measurements at the bedside were accurate, very similar to the diameters measured by MRI (the mean difference in the Bland-Altman plot was 0.08 mm, 95% limits of agreement: - 1.13; + 1.23 mm). No clear relationship was detectable between the ICP and US-ONSD, and a linear regression model showed an angular coefficient very close to 0 (p > 0.05). US-ONSD and ICP values were in agreement after CSF drainage and shifts in ICP in a limited number of patients.

CONCLUSIONS

US-ONSD measurement does not accurately estimate ICP in SAH patients in the intensive care unit.