Intracranial pressure monitoring: Gold standard and recent innovations

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.

Methods of Monitoring Intracranial Pressure: A Review

Monitoring intracranial pressure (ICP) is important in a variety of neurologic conditions, including aneurysmal subarachnoid hemorrhage and traumatic brain injury. Monitoring and controlling ICP can mitigate secondary injury of the brain. Of the invasive methods of monitoring ICP, the external ventricular drain is still considered the gold standard. However, microtransducers have been shown to be a reliable option with significantly lower risks of complications. Due to their reproducibility, and their limitations, they are not ready to replace invasive ICP monitoring techniques. This article reviews the commonly used invasive and non-invasive methods of monitoring ICP.

A prospective observational study on intracranial pressure management: A comparison of three ultrasound techniques

OBJECTIVE

This prospective observational study aimed to assess the effectiveness of B-mode ultrasound, color-coded Doppler, and shear-wave elastography in predicting intracranial pressure (ICP) and their capability to evaluate the efficacy of ICP lowering therapy.

MATERIALS AND METHODS

Forty-eight neuro-critical care patients were enrolled and categorized into 2 groups based on ICP measurements obtained through external ventricular drainage: the intracranial hypertension (IH) and normal ICP groups. The optic nerve (ON) sheath diameter (ONSD), end diastolic velocity, peak systolic velocity, resistance index of the central retinal artery (CRA), and Young's modulus (YM) of the ON were recorded after external ventricular drainage placement and following ICP lowering treatment in the IH group.

RESULTS

The median values of ONSD (5.35 mm [IQR 5.03, 5.80 mm] vs. 4.38 mm [IQR 4.25, 4.60 mm]) and YM of the ON (23.69 kPa [IQR 18.83, 30.90 kPa] vs. 10.48 kPa [IQR 9.84, 12.41 kPa]) were remarkably higher in the IH group than in the normal ICP group (both P < 0.001). However, no obvious differences were observed in end diastolic velocity, peak systolic velocity, or resistance index of the CRA between the two groups (all P > 0.05). Additionally, analysis of the differences in ultrasound parameters before and after treatment revealed that ΔYM of the ON exhibited higher sensitivity and specificity in detecting successful treatment of IH compared to ΔONSD.

CONCLUSION

ΔYM of the ON may serve as a more valuable parameter for reflecting changes in ICP and predicting the efficacy of treatment. In contrast, the color-coded Doppler indices of the CRA had limited values in evaluating ICP.

Prognostic role of quantitative pupillometry in traumatic brain injury: a scoping review

BACKGROUND

Traumatic brain injury (TBI) is a major cause of global mortality and disability, leading to primary and secondary brain injuries that can result in severe neurological, cognitive, and psychological impairments. Accurate and early prognosis of TBI outcomes is critical, particularly in assessing the risk of neurological decline, intracranial pressure (ICP) changes, and mortality.

OBJECTIVE

This systematic review aims to evaluate the prognostic value of quantitative pupillometry, particularly the Neurological Pupil Index (NPi), in predicting long-term outcomes in TBI patients.

METHODS

A systematic review was conducted following PRISMA guidelines, with the protocol registered on PROSPERO (CRD42023489079). Databases including PubMed, Scopus, and Embase were searched. Studies were included based on predefined inclusion criteria, focusing on the prognostic accuracy of automated pupillometry in TBI patients. Risk of bias was assessed using the Joanna Briggs Institute (JBI) tool, and evidence quality was evaluated using the Best-Evidence Synthesis approach.

RESULTS

Thirteen studies met the inclusion criteria, with sample sizes ranging from 36 to 2258 participants. The studies demonstrated a consistent association between lower NPi values and increased mortality, poorer functional outcomes, elevated ICP, and the need for emergency interventions. Despite variability in study design and sample sizes, strong evidence supported the use of NPi as a reliable prognostic tool in TBI management.

CONCLUSION

Automated infrared pupillometry, particularly through NPi measurement, offers important prognostic value in TBI patients. Incorporating NPi into routine clinical practice could improve the accuracy of prognosis and enhance patient management. Future research should focus on standardizing measurement protocols and validating these findings in larger, more diverse cohorts.

Intracranial pressure estimated non-invasively and postoperative outcomes in surgery in the Trendelenburg position with pneumoperitoneum

BACKGROUND

Surgery in the Trendelenburg position (TP) with pneumoperitoneum (PP) is beneficial in several aspects but is associated with postoperative complications, such as postoperative nausea and vomiting (PONV). The mechanism behind this is unknown, but an increase in intracranial pressure (ICP) has been suggested. There are several studies of non-invasively estimated ICP during surgery in TP with PP. The association between perioperative estimated ICP and postoperative complications has not yet been reviewed.

METHODS

We performed a scoping review of peer-reviewed clinical studies reporting on both perioperative estimation of ICP and postoperative complications in patients undergoing surgery in TP with PP. The literature search was performed in February 2025 on PubMed, CINAHL, and Web of Science.

RESULTS AND CONCLUSIONS

Ten of 12 included studies suggested associations between perioperative elevation of estimated ICP and postoperative complications, most notably PONV. This may have clinical implications since elevated ICP can be treated. Future research should focus on the association between perioperative ICP estimation and postoperative complications and the effects of ICP-lowering strategies on postoperative outcomes.

Clinical implications of real-time optic nerve sheath diameter assessment via critical care ultrasound in intracranial hypertension

Objectives

This study aims to assess the clinical value of dynamic monitoring of optic nerve sheath diameter using critical care ultrasound in the management of patients with intracranial hypertension.

Methods

A total of 130 patients with craniocerebral injuries, treated at the Department of Critical Care Medicine of the Affiliated Hospital of Hebei University from January 2021 to November 2022, were selected and randomly assigned to either the control group (65 patients) or the observation group (65 patients). Patients in both groups were monitored based on clinical symptoms, cranial CT findings, and optic nerve sheath diameter (ONSD). The control group received standard osmotic therapy to manage intracranial pressure (ICP), while the observation group was guided accordingly. Comparative analyses were conducted on Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, Glasgow Coma Scale (GCS) scores, duration of ICU stay, and mechanical ventilation time between the two groups.

Results

On the 28th day, the APACHE II scores of patients with craniocerebral injuries in both groups were significantly lower compared to admission scores, while GCS scores were higher (P < 0.05). Compared to conventional management, the observation group showed a 15% reduction in APACHE II scores, a 20% decrease in ICU stay duration, and a 25% reduction in mechanical ventilation time by day 28 post-admission. The observation group also showed a higher proportion of patients with favorable prognoses and a significant reduction in severe disability and vegetative survival rates (P < 0.05).

Conclusion

Dynamic monitoring of ONSD using bedside critical care ultrasound has proven effective in guiding osmotic therapy for patients with intracranial hypertension. This approach significantly reduces ICP, offers a reliable basis to opt for subsequent treatments, and effectively lowers the rate of disability while improving patient prognosis.

Non-invasive fundoscopy as a tool to estimate intracranial pressure: a large animal model

PURPOSE

Intracranial pressure (ICP) monitoring is in most studies considered essential in avoiding secondary brain injury in patients with intracranial pathologies. Invasive monitoring of ICP is accurate but is unavailable in many clinical and prehospital settings. Non-invasive modalities have historically been difficult to implement clinically. The retinal arteriovenous ratio (A/V ratio) has shown promise through its relationship with ICP. This study aimed to further elucidate the relationship between ICP, A/V ratio and the intraocular pressure (IOP) measured with non-invasive fundoscopy in a porcine model.

METHODS

We achieved controlled values of ICP ranging from normal (5-15 mmHg) to elevated (> 20 mmHg) within the same animal subject. Six pigs were included. ICP and IOP was measured using an intraparenchymal pressure monitor and a tonometer, respectively. Fundoscopy was performed at baseline and at predefined ICP values.

RESULTS

Mixed-effects linear regression revealed a significant inverse correlation between A/V ratio and ICP ≥ 20 mmHg (slope coefficient - 0.0026734 [95%-CI: -0.0039347 - (-0.0014121)], p < 0.001). For ICP < 20 mmHg there was no change in A/V ratio (p = 0.987). Similar results were seen for ICP > IOP with a mean IOP of 10 mmHg. A Wald test showed no significant difference between ICP > IOP and ICP ≥ 20 mmHg. ROC curve analysis revealed an AUC of 0.64 for ICP ≥ 20 mmHg and 0.71 for ICP > IOP.

CONCLUSION

The results support the hypothesis that an increase in ICP was associated with a decrease in A/V ratio. Although a slightly better fit, the model of ICP > IOP was deemed less clinically relevant than ICP ≥ 20 mmHg because of the subjects' IOP. Further research integrating multifactorial models and machine learning is needed to enhance the diagnostic accuracy of A/V ratio via fundoscopy, enabling it to serve as a cost-effective screening tool.

Intraoperative Intracranial Pressure Monitoring as an Intraoperative Guide During Operations for Relieving Elevated Intracranial Pressure

BACKGROUND

Intracranial pressure (ICP) is a well-established measure in managing not only traumatic brain injury but also nontraumatic intracranial bleeding or edema. When ICP increases despite nursing or medical management, ICP may be reduced via surgical measures. Deciding whether to perform a craniotomy vs. craniectomy (whether the bone flap is replaced or not, respectively) is commonly made intraoperatively following preoperative planning. While ICP monitoring (ICPm) is standard pre- and postoperatively, its intraoperative utility remains understudied.

METHODS

We conducted a study utilizing prospectively gathered and retrospectively analyzed data from 25 traumatic brain injury surgical decompression cases at a single center. All cases had intraoperative ICPm throughout surgery.

RESULTS

Our findings indicate that ICPm significantly influenced real-time intraoperative decision-making, diverging from preoperative.

CONCLUSIONS

These results bring forward the potential pivotal role of intraoperative ICPm in guiding surgical strategies for elevated ICP, suggesting a novel data-driven approach to intraoperative management of decompression surgery.

The Neurological and Hemodynamics Safety of an Airway Clearance Technique in Patients with Acute Brain Injury: An Analysis of Intracranial Pressure Pulse Morphology Using a Non-Invasive Sensor

Patients with acute brain injury (ACI) often require mechanical ventilation (MV) and are subject to pulmonary complications, thus justifying the use of Airway Clearance Techniques (ACTs), but their effects on intracranial pressure (ICP) are unknown. This study investigates the neurological and hemodynamics safety of an ACT called ventilator hyperinflation (VHI) in patients with ACI. This was a randomized clinical equivalence trial, which included patients aged ≥ 18 years with a clinical diagnosis of hemorrhagic stroke, with symptom onset within 48 h. The participants were randomly allocated to the Experimental Group (EG, n = 15), which underwent VHI followed by tracheal aspiration (TA), and the Control Group (CG, n = 15), which underwent TA only. Neurological safety was verified by analyzing the morphology of the ICP wave through the non-invasive B4C sensor, which detects bone deformation of the skull, resulting in a P2/P1 ratio and TTP, and hemodynamics through a multi-parameter monitor. Evaluations were recorded during five instances: T1 (baseline/pre-VHI), T2 (post-VHI and before TA), T3 (post-TA), T4 and T5 (monitoring 10 and 20 min after T3). The comparison between groups showed that there was no effect of the technique on the neurological variables with a mean P2/P1 ratio [F (4,112) = 1.871; p = 0.120; np2 = 0.063] and TTP [F (4,112) = 2.252; p = 0.068; np2 = 0.074], and for hemodynamics, heart rate [F (4,112) = 1.920; p = 0.112; np2 = 0.064] and mean arterial pressure [F(2.73, 76.57) = 0.799; p = 0.488; np2 = 0.028]. Our results showed that VHI did not pose a neurological or hemodynamics risk in neurocritical patients after ACI.

Analysis of Cerebral Spinal Fluid Drainage and Intracranial Pressure Peaks in Patients with Subarachnoid Hemorrhage

BACKGROUND

After aneurysmal subarachnoid hemorrhage (aSAH), elevated intracranial pressure (ICP) due to disrupted cerebrospinal fluid (CSF) dynamics is a critical concern. An external ventricular drainage (EVD) is commonly employed for management; however, optimal strategies remain debated. The randomized controlled Earlydrain trial showed that an additional prophylactic lumbar drainage (LD) after aneurysm treatment improves neurological outcome. We performed a post hoc investigation on the impact of drainage volumes and critical ICP values on patient outcomes after aSAH.

METHODS

Using raw patient data from Earlydrain, we analyzed CSF drainage amounts and ICP measurements in the first 8 days after aSAH. Outcomes were the occurrence of secondary infarctions and the score on the modified Rankin scale after 6 months, dichotomized in values of 0-2 as favorable and 3-6 as unfavorable. Repeated measurements were considered with generalized estimation equations.

RESULTS

Earlydrain recruited 287 patients, of whom 221 received an EVD and 140 received an LD. Higher EVD volumes showed a trend to more secondary infarctions (p = 0.09), whereas higher LD volumes were associated with less secondary infarctions (p = 0.009). The mean total CSF drainage was 1052 ± 659 mL and did not differ concerning infarction and neurological outcome. Maximum ICP values were higher in patients with poor outcomes but not related to drainage volumes via EVD. After adjustment for aSAH severity and total CSF drainage, higher LD volume was linked to favorable outcome (per 100 mL: odds ratio 0.61 (95% confidence interval 0.39-0.95), p = 0.03), whereas higher EVD amounts were associated with unfavorable outcome (per 100 mL: odds ratio 1.63 (95% confidence interval 1.05-2.54), p = 0.03).

CONCLUSIONS

Findings indicate that effects of CSF drainage via EVD and LD differ. Higher amounts and higher proportions of LD volumes were associated with better outcomes, suggesting a potential quantity-dependent protective effect. Optimizing LD volume and mitigating ICP spikes may be a strategy to improve patient outcomes after aSAH.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01258257.

Suspected intracranial hypertension in COVID-19 patients with severe respiratory failure

BACKGROUND

COVID-19 patients may exhibit neurological symptoms due to direct viral damage, systemic inflammatory syndrome, or treatment side effects. Mechanical ventilation in patients with severe respiratory failure often requires sedation and neuromuscular blockade, hindering thorough clinical examinations. This study aimed to investigate neurological involvement through clinical and noninvasive techniques and to detect signs of intracranial hypertension in these patients.

METHOD

We conducted a prospective observational study on mechanically ventilated COVID-19 adult patients admitted to our ICU, following standard of care protocols for ventilation and permissive hypercapnia. Data were collected at three time points: admission day (T1), day seven (T7), and day fourteen (T14). At each time point, patients underwent multimodal noninvasive neurological monitoring, including clinical examination, pupillary reactivity, transcranial color doppler of the middle cerebral artery (MCA), and optic nerve sheath diameter (ONSD) assessed via ultrasound (US). Head computer tomography (CT) was performed at T1 and T14. A limited subset of patients had a follow-up examination six months after ICU discharge.

RESULTS

Seventy-nine patients were recruited; most were under deep sedation and neuromuscular blockade at T1. Pupillary size, symmetry, and reactivity were normal, as was the MCA mean velocity. However, ONSD, assessed by both US and CT, appeared enlarged, suggesting raised intracranial pressure (ICP). In a subgroup of 12 patients, increased minute ventilation was associated with a significant decrease in US-ONSD, corresponding to a drop in paCO2. At follow-up, twelve patients showed no long-term neurological sequelae, and US-ONSD was decreased in all of them.

DISCUSSION AND CONCLUSIONS

In this cohort, enlarged ONSD was detected during non-invasive neurological monitoring, suggesting a raised ICP, with hypercapnia playing a prominent role. Further studies are needed to explore ONSD behavior in other samples of mechanically ventilated, hypercapnic patients.

Global traumatic brain injury intracranial pressure: from monitoring to surgical decision

Traumatic brain injury (TBI) is a significant global public health issue, heavily impacting human health, especially in low-and middle-income areas. Despite numerous guidelines and consensus statements, TBI fatality rates remain high. The pathogenesis of severe TBI is closely linked to rising intracranial pressure (ICP). Elevated intracranial pressure can lead to cerebral herniation, resulting in respiratory and circulatory collapse, and ultimately, death. Managing intracranial pressure (ICP) is crucial in neuro-intensive care. Timely diagnosis and precise treatment of elevated ICP are essential. ICP monitoring provides real-time insights into a patient's condition, offering invaluable guidance for comprehensive management. ICP monitoring and standardization can effectively reduce secondary nerve damage, lowering morbidity and mortality rates. Accurately assessing and using true ICP values to manage TBI patients still depends on doctors' clinical experience. This review discusses: (a) Epidemiological disparities of traumatic brain injuries across countries with different income levels worldwide; (b) The significance and function of ICP monitoring; (c) Current status and challenges of ICP monitoring; (d) The impact of decompressive craniectomy on reducing intracranial pressure; and (e) Management of TBI in diverse income countries. We suggest a thorough evaluation of ICP monitoring, head CT findings, and GCS scores before deciding on decompressive craniectomy. Personalized treatment should be emphasized to assess the need for surgical decompression in TBI patients, offering crucial insights for clinical decision-making.

Moderate Traumatic Brain Injury in Adult Population: The Latin American Brain Injury Consortium Consensus for Definition and Categorization

Moderate traumatic brain injury (TBI) is a diagnosis that describes diverse patients with heterogeneity of primary injuries. Defined by a Glasgow Coma Scale between 9 and 12, this category includes patients who may neurologically worsen and require increasing intensive care resources and/or emergency neurosurgery. Despite the unique characteristics of these patients, there have not been specific guidelines published before this effort to support decision-making in these patients. A Delphi consensus group from the Latin American Brain Injury Consortium was established to generate recommendations related to the definition and categorization of moderate TBI. Before an in-person meeting, a systematic review of the literature was performed identifying evidence relevant to planned topics. Blinded voting assessed support for each recommendation. A priori the threshold for consensus was set at 80% agreement. Nine PICOT questions were generated by the panel, including definition, categorization, grouping, and diagnosis of moderate TBI. Here, we report the results of our work including relevant consensus statements and discussion for each question. Moderate TBI is an entity for which there is little published evidence available supporting definition, diagnosis, and management. Recommendations based on experts' opinion were informed by available evidence and aim to refine the definition and categorization of moderate TBI. Further studies evaluating the impact of these recommendations will be required.

The Current State of Non-Invasive Measurement of Intracranial Pressure in Patients with Craniosynostosis: A Systematic Review

Introduction:

Despite being invasive, direct measurements remain the gold standard to measure intra-cranial pressure (ICP) in patients with craniosynostosis. However, there has been persistent effort to develop non-invasive modalities to measure ICP, possibly avoiding some of the risks of direct measurements. Here, we conduct a systematic review of the evidence behind various non-invasive modalities to monitor ICP in patients with craniosynostosis.

Methods:

A systematic review was conducted using PubMed, Cochrane, and Web of Science databases to identify studies describing the use of non-invasive ICP measurements in patients with craniosynostosis. Studies were included if they assessed a non-invasive method of ICP monitoring against a direct/invasive ICP monitoring technique in patients with craniosynostosis. Non-English and non-human studies were excluded.

Results:

A total of 735 studies were screened, of which 52 were included in the study. Nine methods of non-invasive ICP measurement were identified, with varying sensitivities and specificities in detecting elevated ICP. Specifically, optical coherence tomography (OCT), and ocular ultrasonography demonstrated ability to accurately measure ICP when compared to direct measurements.

Conclusion:

Here, we present the first systemic-review of the current literature surrounding non-invasive modalities to measure ICP in patients with craniosynostosis. While direct measurement remains the gold-standard, multiple reviewed modalities have shown promise in accurately measuring ICP. Of these, OCT has the most rigorous evidence supporting its use. Ocular sonography has also shown promise, albeit without as robust evidence supporting its use. Regardless, further investigation is required before any modality is able to obviate the need for invasive, direct measurements.

Intracranial Pressure Monitoring Location: A Pilot Study on the Validation of Subdural Site with the Intraventricular Site

Introduction  Knowledge of preoperative and intraoperative intracranial pressure (ICP) enables the neuroanesthesiologist to optimize cerebral perfusion pressure. However, ICP is rarely monitored during the intraoperative period. In this report, subdural site ICP measurement is validated with intraventricular ICP measurement, and the feasibility of subdural ICP monitoring during the intraoperative period is discussed. Materials and Methods  In this prospective pilot study, ICP measurement at the subdural site was achieved with an intravenous cannula and the ventricular site with a ventricular cannula. Both were transduced using a fluid-filled pressure transducer and connected to the monitor for display of the number and the waveforms. Monitoring of intraoperative ICP using both the techniques was done in all patients recruited into the study. The correlation between the two modalities of measurement was studied by the Spearman correlation test and their limits of agreement were studied using the Bland-Altman plot. A case series describing the perioperative management based on the subdural ICP values are also described. Results  Subdural ICP showed a strong correlation with intraventricular ICP ( r s  = 0.93, p  = 0.01). Agreement analysis using the Bland-Altman plot showed that the mean difference of ICP between the modalities was 1.44 mm Hg (95% confidence interval, -0.6 to 3.49, p  = 0.122). Discussion  This study validates the ICP values measured at the subdural site with the intraventricular site. Subdural site ICP monitoring can be achieved rapidly with readily available systems and helps in making intraoperative clinical decisions. Conclusion  Cannula-based subdural ICP is a satisfactory alternative to intraventricular ICP monitoring in the intraoperative period.

The Current Update of Conventional and Innovative Treatment Strategies for Central Nervous System Injury

This review explores the complex challenges and advancements in the treatment of traumatic brain injury (TBI) and spinal cord injury (SCI). Traumatic injuries to the central nervous system (CNS) trigger intricate pathophysiological responses, frequently leading to profound and enduring disabilities. This article delves into the dual phases of injury-primary impacts and the subsequent secondary biochemical cascades-that worsen initial damage. Conventional treatments have traditionally prioritized immediate stabilization, surgical interventions, and supportive medical care to manage both the primary and secondary damage associated with central nervous system injuries. We explore current surgical and medical management strategies, emphasizing the crucial role of rehabilitation and the promising potential of stem cell therapies and immune modulation. Advances in stem cell therapy, gene editing, and neuroprosthetics are revolutionizing treatment approaches, providing opportunities not just for recovery but also for the regeneration of impaired neural tissues. This review aims to emphasize emerging therapeutic strategies that hold promise for enhancing outcomes and improving the quality of life for affected individuals worldwide.

ICP wave morphology as a screening test to exclude intracranial hypertension in brain-injured patients: a non-invasive perspective

Intracranial hypertension (IH) is a life-threating condition especially for the brain injured patient. In such cases, an external ventricular drain (EVD) or an intraparenchymal bolt are the conventional gold standard for intracranial pressure (ICPi) monitoring. However, these techniques have several limitations. Therefore, identifying an ideal screening method for IH is important to avoid the unnecessary placement of ICPi and expedite its introduction in patients who require it. A potential screening tool is the ICP wave morphology (ICPW) which changes according to the intracranial volume-pressure curve. Specifically, the P2/P1 ratio of the ICPW has shown promise as a triage test to indicate normal ICP. In this study, we propose evaluating the noninvasive ICPW (nICPW-B4C sensor) as a screening method for ICPi monitoring in patients with moderate to high probability of IH. This is a retrospective analysis of a prospective, multicenter study that recruited adult patients requiring ICPi monitoring from both Federal University of São Paulo and University of São Paulo Medical School Hospitals. ICPi values and the nICPW parameters were obtained from both the invasive and the noninvasive methods simultaneously 5 min after the closure of the EVD drainage. ICP assessment was performed using a catheter inserted into the ventricle and connected to a pressure transducer and a drainage system. The B4C sensor was positioned on the patient's scalp without the need for trichotomy, surgical incision or trepanation, and the morphology of the ICP waves acquired through a strain sensor that can detect and monitor skull bone deformations caused by changes in ICP. All patients were monitored using this noninvasive system for at least 10 min per session. The area under the curve (AUC) was used to describe discriminatory power of the P2/P1 ratio for IH, with emphasis in the Negative Predictive value (NPV), based on the Youden index, and the negative likelihood ratio [LR-]. Recruitment occurred from August 2017 to March 2020. A total of 69 patients fulfilled inclusion and exclusion criteria in the two centers and a total of 111 monitorizations were performed. The mean P2/P1 ratio value in the sample was 1.12. The mean P2/P1 value in the no IH population was 1.01 meanwhile in the IH population was 1.32 (p < 0.01). The best Youden index for the mean P2/P1 ratio was with a cut-off value of 1.13 showing a sensitivity of 93%, specificity of 60%, and a NPV of 97%, as well as an AUC of 0.83 to predict IH. With the 1.13 cut-off value for P2/P1 ratio, the LR- for IH was 0.11, corresponding to a strong performance in ruling out the condition (IH), with an approximate 45% reduction in condition probability after a negative test (ICPW). To conclude, the P2/P1 ratio of the noninvasive ICP waveform showed in this study a high Negative Predictive Value and Likelihood Ratio in different acute neurological conditions to rule out IH. As a result, this parameter may be beneficial in situations where invasive methods are not feasible or unavailable and to screen high-risk patients for potential invasive ICP monitoring.Trial registration: At clinicaltrials.gov under numbers NCT05121155 (Registered 16 November 2021-retrospectively registered) and NCT03144219 (Registered 30 September 2022-retrospectively registered).

Optic nerve sheath diameter and eyeball transverse diameter in severe head injury and its correlation with intracranial pressure

BACKGROUND

Gold standard for determining intracranial pressure (ICP), intraventricular catheter, is invasive with associated risks. Non-invasive investigations like magnetic resonance imaging and ultrasonography have demonstrated correlation between optic nerve sheath diameter (ONSD) and raised ICP. However, computed tomography (CT) is accessible and less operator-dependent. Literature shows variable results regarding correlations between ICP and ONSD on CT. The study aimed to investigate correlations between raised ICP and ONSD, eyeball transverse diameter (ETD), and ONSD/ETD ratios on CT scan(s) of severe head injuries.

METHODS

A retrospective review of a three-year prospectively-maintained database of severe traumatic head injuries in patients who had ICP measurements and CT scans was conducted. Glasgow Coma Score (GCS), ICP, ONSD 3 mm and 9 mm behind the globe, ETD, ONSD/ETD ratios, CT Marshall Grade, and Glasgow Outcome Score (GOS) were recorded. Statistical analysis assessed correlations between ICP and CT measurements.

RESULTS

Seventy-four patients were assessed; mortality rate: 36.5 %. Assault (48.6 %) and pedestrian-vehicle collisions (21.6 %) were the most common mechanisms. CT Marshall Grade correlated significantly with 3 mm and 9 mm ONSD, ONSD/ETD ratios, GCS, and GCS motor score, which correlated significantly with GOS. No significant correlation was found between ICP and ONSD, ETD or ONSD/ETD ratios. Marshall Grade was not significantly associated with ICP measurements but correlated with injury severity.

CONCLUSIONS

Unlike previous studies, our study not only investigated the correlation between ICP and single variables (ONSD and ETD) but also the ONSD/ETD ratios. No correlations were observed between raised ICP and ONSD, ETD or ONSD/ETD ratio on CT in neurotrauma patients.

Diagnostic evaluation of optic nerve sheath diameter in predicting elevated intracranial pressure among neurocritically ill patients: A prospective observational study

Background

Optic nerve sheath diameter (ONSD) is used as a surrogate for intracranial pressure (ICP) with a marked variation in its optimal cutoff in various subgroups of neurocritical illnesses. Real-world data on ultrasound (US)-ONSD performance among a diverse population and its trend corresponding with clinical deterioration are scarce. We aim to determine the diagnostic performance of ONSD compared to computed tomography (CT) in predicting elevated ICP in a mixed population of neurocritical patients.

Methods

Baseline ONSD measurements (T1) using B-mode US were recorded among eligible patients. Follow-up ONSD (T2) was recorded during clinical deterioration defined by ≥2 drops in Glasgow Coma Scale/Full Outline of UnResponsiveness (GCS/FOUR) scores. Its diagnostic performance in predicting elevated ICP was assessed by comparing it with the concurrently taken CT findings as a reference standard. The difference between the two ONSD measurements was termed delta ONSD.

Results

In the final analysis, 129 participants were included. The population comprised traumatic brain injury, stroke (hemorrhagic and ischemic), intracranial space-occupying lesions, and other medical conditions. The optimal ONSD (T2) cutoff of 5.23 mm had a diagnostic accuracy of 80.73% to predict elevated ICP (sensitivity: 82%; specificity: 78%; area under the curve: 0.88; and 95% confidence interval [CI]: 0.819-0.941). Each unit increase in delta ONSD was associated with increased odds of need for surgical intervention (odds ratio [OR]: 3.91; 95% CI: 1.31-12.6, P = 0.017) and death at intensive care unit discharge (OR: 8.24; 95% CI: 1.78-41.15, P = 0.007).

Conclusions

ONSD cutoff of 5.23 mm has a good diagnostic accuracy in predicting elevated ICP compared to CT during clinical deterioration. ONSD measurements correlate well with corresponding GCS/FOUR scores.

Intracranial pressure following surgery of an unruptured intracranial aneurysm-a model for normal intracranial pressure in humans

OBJECTIVE

Optimizing the treatment of several neurosurgical and neurological disorders relies on knowledge of the intracranial pressure (ICP). However, exploration of normal ICP and intracranial pressure pulse wave amplitude (PWA) values in healthy individuals poses ethical challenges, and thus the current documentation remains scarce. This study explores ICP and PWA values for healthy adults without intracranial pathology expected to influence ICP.

METHODS

Adult patients (age > 18 years) undergoing surgery for an unruptured intracranial aneurysm without any other neurological co-morbidities were included. Patients had a telemetric ICP sensor inserted, and ICP was measured in four different positions: supine, lateral recumbent, standing upright, and 45-degree sitting, at day 1, 14, 30, and 90 following the surgery.

RESULTS

ICP in each position did not change with time after surgery. Median ICP was 6.7 mmHg and median PWA 2.1 mmHg in the supine position, while in the upright standing position median ICP was - 3.4 mmHg and median PWA was 1.9 mmHg. After standardization of the measurements from the transducer site to the external acoustic meatus, the median ICPmidbrain was 8.3 mmHg in the supine position and 1.2 mmHg in the upright standing position.

CONCLUSION

Our study provides insights into normal ICP dynamics in healthy adults following a uncomplicated surgery for an unruptured aneurysm. These results suggest a slightly wider normal reference range for invasive intracranial pressure than previously suggested, and present the first normal values for PWA in different positions. Further studies are, however, essential to enhance our understanding of normal ICP. Trial registration The study was preregistered at www.

CLINICALTRIALS

gov (NCT03594136) (11 July 2018).

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.

Sex differences in the diagnostic value of optic nerve sheath diameter for assessing intracranial pressure

The optic nerve sheath diameter (ONSD) can predict elevated intracranial pressure (ICP) but it is not known whether diagnostic characteristics differ between men and women. This observational study was performed at the Karolinska University Hospital in Sweden to assess sex differences in diagnostic accuracy for ONSD. We included 139 patients (65 women), unconscious and/or sedated, with invasive ICP monitoring. Commonly used ONSD derived measurements and associated ICP measurements were collected. Linear regression analyses were performed with ICP as dependent variable and ONSD as independent variable. Area under the receiver operator characteristics curve (AUROC) analyses were performed with a threshold for elevated ICP ≥ 20 mmHg. Analyses were stratified by sex. Optimal cut-offs and diagnostic characteristics were estimated. The ONSD was associated with ICP in women. The AUROCs in women ranged from 0.70 to 0.83. In men, the ONSD was not associated with ICP and none of the AUROCs were significantly larger than 0.5. This study suggests that ONSD is a useful predictor of ICP in women but may not be so in men. If this finding is verified in further studies, this would call for a re-evaluation of the usage and interpretation of ONSD to estimate ICP.

Rapid versus gradual external ventricular drain weaning: a general review of best practices

Rapid versus gradual external ventricular drain (EVD) weaning methods have been widely debated, aiming to establish a standard clinical practice. The techniques used in each approach offer their own set of benefits and associated risks. Many published works continue to deliberate and dispute each other on the topic, as many believe gradual weaning is preferable due to its perceived potential to decrease ventriculoperitoneal shunt (VPS) dependency. In contrast, rapid weaning is known to have benefits such as a reduction in ventriculostomy-associated infections. Additionally, both weaning methods have been further debated due to the perception of the risks associated, which for gradual weaning includes a longer hospital stay. This literature review explores both sides of this debate, providing pros and cons to each weaning method to better unify the disconnect within the field. Based on the current research available, it is clear that due to a lengthy and more consistent list of benefits as well as overall decreased associated risks, rapid weaning is the superior form of EVD treatment method and should become the standard for clinical practice when performing EVDs on patients suffering from aneurysmal subarachnoid hemorrhages.

The current status of noninvasive intracranial pressure monitoring: A literature review

Elevated intracranial pressure (ICP) is a life-threatening condition that must be promptly diagnosed. However, the gold standard methods for ICP monitoring are invasive, time-consuming, and they involve certain risks. To address these risks, many noninvasive approaches have been proposed. This study undertakes a literature review of the existing noninvasive methods, which have reported promising results. The experimental base on which they are established, however, prevents their application in emergency conditions and thus none of them are capable of replacing the traditional invasive methods to date. On the other hand, contemporary methods leverage Machine Learning (ML) which has already shown unprecedented results in several medical research areas. That said, only a few publications exist on ML-based approaches for ICP estimation, which are not appropriate for emergency conditions due to their restricted capability of employing the medical imaging data available in intensive care units. The lack of such image-based ML models to estimate ICP is attributed to the scarcity of annotated datasets requiring directly measured ICP data. This ascertainment highlights an active and unexplored scientific frontier, calling for further research and development in the field of ICP estimation, particularly leveraging the untapped potential of ML techniques.

Comprehensive analysis of brain injury parameters in a preclinical porcine model of acute liver failure

Introduction

Acute liver failure (ALF) is defined as acute loss of liver function leading to hepatic encephalopathy associated with a high risk of patient death. Brain injury markers in serum and tissue can help detect and monitor ALF-associated brain injury. This study compares different brain injury parameters in plasma and tissue along with the progression of ALF.

Method

ALF was induced by performing an 85% liver resection. Following the resection, animals were recovered and monitored for up to 48 h or until reaching the predefined endpoint of receiving standard medical therapy (SMT). Blood and serum samples were taken at Tbaseline, T24, and upon reaching the endpoint (Tend). Control animals were euthanized by exsanguination following plasma sampling. Postmortem brain tissue samples were collected from the frontal cortex (FCTx) and cerebellum (Cb) of all animals. Glial fibrillary acidic protein (GFAP) and tau protein and mRNA levels were quantified using ELISA and qRT-PCR in all plasma and brain samples. Plasma neurofilament light (NFL) was also measured using ELISA.

Results

All ALF animals (n = 4) were euthanized upon showing signs of brain herniation. Evaluation of brain injury biomarkers revealed that GFAP was elevated in ALF animals at T24h and Tend, while Tau and NFL concentrations were unchanged. Moreover, plasma glial fibrillary acidic protein (GFAP) levels were negatively correlated with total protein and positively correlated with both aspartate transaminase (AST) and alkaline phosphatase (AP). Additionally, lower GFAP and tau RNA expressions were observed in the FCTx of the ALF group but not in the CB tissue.

Conclusion

The current large animal study has identified a strong correlation between GFAP concentration in the blood and markers of ALF. Additionally, the protein and gene expression analyses in the FCTx revealed that this area appears to be susceptible, while the CB is protected from the detrimental impacts of ALF-associated brain swelling. These results warrant further studies to investigate the mechanisms behind this process.

In Situ Polymer-Solution-Processed Graphene-PDMS Nanocomposites for Application in Intracranial Pressure Sensors

Polydimethylsiloxane (PDMS) has emerged as a promising candidate for the dielectric layer in implantable sensors due to its exceptional biocompatibility, stability, and flexibility. This study introduces an innovative approach to produce graphene-reinforced PDMS (Gr-PDMS), where graphite powders are exfoliated into mono- and few-layer graphene sheets within the polymer solution, concurrently forming cross-linkages with PDMS. This method yields a uniformly distributed graphene within the polymer matrix with improved interfaces between graphene and PDMS, significantly reducing the percolation threshold of graphene dispersed in PDMS from 10% to 5%. As-synthesized Gr-PDMS exhibits improved mechanical and electrical properties, tested for potential use in capacitive pressure sensors. The results demonstrate an impressive pressure sensitivity up to 0.0273 kpa-1, 45 times higher than that of pristine PDMS and 2.5 times higher than the reported literature value. The Gr-PDMS showcases excellent pressure sensing ability and stability, fulfilling the requirements for implantable intracranial pressure (ICP) sensors.

Current practice of intracranial pressure monitoring in children with severe traumatic brain injury-a nationwide prospective surveillance study in Germany

Background

For management of severe traumatic brain injuries (sTBI) in children, the overall level of evidence to guide diagnostic and therapeutic procedures is low. Since 2016, international guidelines have subsequently suggested invasive intracranial pressure (ICP) monitoring in patients with initial Glasgow Coma Scale (GCS) ≤8. In Germany, ICP monitoring was an individual case decision from 2011 until the 2022 update of the German pediatric TBI guideline. The aim of this study was to evaluate current clinical practice of invasive ICP monitoring in Germany in children <10 years with respect to guideline recommendations.

Methods

Anonymized clinical data on sTBI cases <10 years of age were collected in a nationwide prospective surveillance study via the German Pediatric Surveillance Unit ESPED from July 2019 until June 2022. Inclusion criteria for the surveillance study were sTBI (initial GCS ≤8) or neurosurgery following TBI. For this analysis, only cases with GCS ≤8 were subject to the present analysis. Descriptive analyses were performed to assess the proportion of ICP monitored patients and describe the cohort.

Results

Out of 217 reported cases, 102 cases met the inclusion criteria and thus qualified for ICP monitoring. Of these, 37 (36%) received ICP monitoring. Monitored patients were older, had lower median GCS values at presentation (4 vs. 5), higher mortality (32% vs. 22%), and were more frequently diagnosed with cerebral edema (68% vs. 37%).

Conclusion

In children <10 years with sTBI, the present clinical management regarding ICP monitoring deviates from the current German national and international guidelines. The reasons remain unclear, with the low level of evidence in the field of ICP monitoring and the recency of changes in guideline recommendations as potential contributors. Prospective interventional studies should elucidate the benefit of ICP monitoring and ICP directed therapies to provide evidence-based recommendations on ICP monitoring.

Critical ICP thresholds in relation to outcome: Is 22 mmHg really the answer?

PURPOSE

Intensive care for patients with traumatic brain injury (TBI) aims, among other tasks, at avoiding high intracranial pressure (ICP), which is perceived to worsen motor and cognitive deficits and increase mortality. International recommendations for threshold values for ICP were increased from 20 to 22 mmHg in 2016 following the findings in a study by Sorrentino et al., which were based on an observational study of patients with TBI of averaged ICP values. We aimed to reproduce their approach and validate the findings in a separate cohort.

METHODS

Three hundred thirty-one patients with TBI were included and categorised according to survival/death and favourable/unfavourable outcome at 6 months (based on Glasgow Outcome Score-Extended of 6-8 and 1-5, respectively). Repeated chi-square tests of survival and death (or favourable and unfavourable outcome) vs. high and low ICP were conducted with discrimination between high and low ICP sets at increasing values (integers) between 10 and 35 mmHg, using the average ICP for the entire monitoring period. The ICP limit returning the highest chi-square score was assumed to be the threshold with best discriminative ability. This approach was repeated after stratification by sex, age, and initial Glasgow Coma Score (GCS).

RESULTS

An ICP limit of 18 mmHg was found for both mortality and unfavourable outcome for the entire cohort. The female and the low GCS subgroups both had threshold values of 18 mmHg; for all other subgroups, the threshold varied between 16 and 30 mmHg. According to a multiple logistic regression analysis, age, initial GCS, and average ICP are independently associated with mortality and outcome.

CONCLUSIONS

Using identical methods and closely comparable cohorts, the critical thresholds for ICP found in the study by Sorrentino et al. could not be reproduced.

Estimating intracranial parameters using an inverse mathematical model with viscoelastic elements that closely predicts complex ICP morphologies

The quantitative relationship between arterial blood pressure (ABP) and intracranial pressure (ICP) waveforms has not been adequately explained. We hypothesized that the ICP waveform results from interferences between propagating and reflected pressure waves occurring in the cranium following the initiating arterial waveform. To demonstrate cranial effects on interferences between waves and generation of an ICP waveform morphology, we modified our previously reported mathematical model to include viscoelastic elements that affect propagation velocity. Using patient data, we implemented an inverse model methodology to generate simulated ICP waveforms in response to given ABP waveforms. We used an open database of traumatic brain injury patients and studied 65 pairs of ICP and ABP waveforms from 13 patients (five pairs from each). Incorporating viscoelastic elements into the model resulted in model-generated ICP waveforms that very closely resembled the measured waveforms with a 16-fold increase in similarity index relative to the model with only pure elasticity elements. The mean similarity index for the pure elasticity model was 0.06 ± 0.12 SD, compared to 0.96 ± 0.28 SD for the model with viscoelastic components. The normalized root mean squared error (NRMSE) improved substantially for the model with viscoelastic elements compared to the model with pure elastic elements (NRMSE of 2.09% ± 0.62 vs. 15.2% ± 4.8, respectively). The ability of the model to generate complex ICP waveforms indicates that the model may indeed reflect intracranial dynamics. Our results suggest that the model may allow the estimation of intracranial biomechanical parameters with potential clinical significance. It represents a first step in the estimation of inaccessible intracranial parameters.

A simplified cranial cavity model to understand the relationship between intracranial pressure and dural sinus pressure

Although accurate intracranial pressure (ICP) monitoring is essential for the diagnosis and treatment of severe brain diseases, current methods are performed invasively. Therefore, a safe and less invasive ICP measurement is required. The purpose of our study was to develop a simplified cranial cavity model for a better understanding of the relationship between the ICP and the pressure measurement within the dural venous sinus (DVS) to support the validity of using sinus pressure as the surrogate of the ICP. The in-house cranial cavity model had three components: the brain part, the DVS part, and the subarachnoid space (SAS) part. Pressure in other parts was measured when the pressure in the SAS part and, separately, brain part was increased from 0 (baseline) to 50 mmHg at intervals of 10 mmHg. When the pressure in the SAS part was increased from 10 to 50 mmHg at 10 mmHg interval, pressures of both the brain and DVS parts increased without significant difference (all P > 0.05). However, pressures in both the SAS and DVS parts differed while the pressure in the brain part was increased. The pressures in both parts showed about 70% of the increase in the brain part. Nevertheless, the pressures in the SAS and DVS parts were not significantly different (P > 0.05). A simplified in-house cranial cavity model was developed consisting of three compartments to represent the actual intracranial spaces. The pressure measurement within the DVS was feasible to use as a surrogate for the ICP measurement.

A Novel Method for Prediction of Raised Intracranial Pressure Through Automated ONSD and ETD Ratio Measurement From Ocular Ultrasound

The paper presents a novel framework for the prediction of the raised Intracranial Pressure (ICP) from ocular ultrasound images of traumatic patients through automated measurement of Optic Nerve Sheath Diameter (ONSD) and Eyeball Transverse Diameter (ETD). The measurement of ONSD using an ocular ultrasound scan is non-invasive and correlates with the raised ICP. However, the existing studies suggested that the ONSD value alone is insufficient to indicate the ICP condition. Since the ONSD and ETD values may vary among patients belonging to different ethnicity/origins, there is a need for developing an independent global biomarker for predicting raised ICP condition. The proposed work develops an automated framework for the prediction of raised ICP by developing algorithms for the automated measurement of ONSD and ETD values. It is established that the ONSD and ETD ratio (OER) is a potential biomarker for ICP prediction independent of ethnicity and origin. The OER threshold value is determined by performing statistical analysis on the data of 57 trauma patients obtained from the AIIMS, New Delhi. The automated OER is computed and compared with the conventionally measured ICP by determining suitable correlation coefficients. It is found that there is a significant correlation of OER with ICP (r = .81, p ≤ .01), whereas the correlation of ONSD alone with ICP is relatively less (r = .69, p = .004). These correlation values indicate that OER is a better parameter for the prediction of ICP. Further, the threshold value of OER is found to be 0.21 for predicting raised ICP conditions in this study. Scatter plot and Heat map analysis of OER and corresponding ICP reveal that patients with OER ≥ 0.21, have ICP in the range of 17 to 35 mm Hg. In the data available for this research work, OER ranges from 0.17 to 0.35.

Astrocytoma Mimicking Herpetic Meningoencephalitis: The Role of Non-Invasive Multimodal Monitoring in Neurointensivism

Neuromonitoring is a critical tool for emergency rooms and intensive care units to promptly identify and treat brain injuries. The case report of a patient with status epilepticus necessitating orotracheal intubation and intravenous lorazepam administration is presented. A pattern of epileptiform activity was detected in the left temporal region, and intravenous Acyclovir was administered based on the diagnostic hypothesis of herpetic meningoencephalitis. The neurointensivist opted for multimodal non-invasive bedside neuromonitoring due to the complexity of the patient's condition. A Brain4care (B4C) non-invasive intracranial compliance monitor was utilized alongside the assessment of an optic nerve sheath diameter (ONSD) and transcranial Doppler (TCD). Based on the collected data, a diagnosis of intracranial hypertension (ICH) was made and a treatment plan was developed. After the neurosurgery team's evaluation, a stereotaxic biopsy of the temporal lesion revealed a grade 2 diffuse astrocytoma, and an urgent total resection was performed. Research suggests that monitoring patients in a dedicated neurologic intensive care unit (Neuro ICU) can lead to improved outcomes and shorter hospital stays. In addition to being useful for patients with a primary brain injury, neuromonitoring may also be advantageous for those at risk of cerebral hemodynamic impairment. Lastly, it is essential to note that neuromonitoring technologies are non-invasive, less expensive, safe, and bedside-accessible approaches with significant diagnostic and monitoring potential for patients at risk of brain abnormalities. Multimodal neuromonitoring is a vital tool in critical care units for the identification and management of acute brain trauma as well as for patients at risk of cerebral hemodynamic impairment.

Non-invasive intracranial pressure estimation using ultrasonographic measurement of area of optic nerve subarachnoid space

OBJECTIVE

To verify whether the area of the ONSAS (ONSASA) obtained by transorbital ultrasonography can be used to accurately evaluate the intracranial pressure (ICP).

METHODS

The recorded indexes included the optic nerve diameter, the optic nerve sheath diameter (ONSD), the width of both sides of the ONSAS (ONSASW) at 3 mm from the optic nerve head and the entire ONSASA outlined between 3 and 7 mm. After exploring and comparing five models to describe the relationship between body mass index (BMI), mean arterial blood pressure (MABP), ONSASA and ICP, the best model was determined.

RESULTS

In all, 90 patients with neurological diseases undergoing continuous invasive ICP monitoring were included in the study. In the training group, the correlation coefficient for the association between the ICP and ONSASA (Pearson's correlation r=0.953) was higher than that for the association of the ICP with the ONSD (r=0.672; p<0.0001) and ONSASW at 3 mm behind the globe (r=0.691; p<0.0001). In the training group, the weighting function for prediction of the ICP was as follows: non-invasive ICP=2.050×ONSASA-0.051×BMI +0.036*MABP-5.837. With 20 mm Hg as the cut-off point for a high or low ICP, the sensitivity and specificity of ONSASA predicting ICP was 1.00 and 0.92. Receiver operator curve analysis revealed that the calculated cut-off value for predicting elevated ICP was 19.96 (area under curve= 0.960, 95% CI 0.865 to 1.00).

CONCLUSION

Measurement of the ONSASA using ultrasonography can serve as a practical method for rapid and non-invasive quantification for evaluating ICP through an accurate mathematical formula with the BMI and MABP considered as contributing parameters.

TRIAL REGISTRATION NUMBER

The study was registered in the Chinese Clinical Trial Registry (Study no ChiCTR2100045274).

Frontiers of Wearable Biosensors for Human Health Monitoring

Wearable biosensors offer noninvasive, real-time, and continuous monitoring of diverse human health data, making them invaluable for remote patient tracking, early diagnosis, and personalized medicine [...].

Multimodal monitoring intracranial pressure by invasive and noninvasive means

Although the placement of an intraventricular catheter remains the gold standard method for the diagnosis of intracranial hypertension (ICH), the technique has several limitations including but not limited to its invasiveness. Current noninvasive methods, however, still lack robust evidence to support their clinical use. We aimed to estimate, as an exploratory hypothesis generating analysis, the discriminative power of four noninvasive methods to diagnose ICH. We prospectively collected data from adult intensive care unit (ICU) patients with subarachnoid hemorrhage (SAH), intraparenchymal hemorrhage (IPH), and ischemic stroke (IS) in whom invasive intracranial pressure (ICP) monitoring had been placed. Measures were simultaneously collected from the following noninvasive methods: optic nerve sheath diameter (ONSD), pulsatility index (PI) using transcranial Doppler (TCD), a 5-point visual scale designed for brain Computed Tomography (CT), and two parameters (time-to-peak [TTP] and P2/P1 ratio) of a noninvasive ICP wave morphology monitor (Brain4Care[B4c]). ICH was defined as a sustained ICP > 20 mmHg for at least 5 min. We studied 18 patients (SAH = 14; ICH = 3; IS = 1) on 60 occasions with a mean age of 52 ± 14.3 years. All methods were recorded simultaneously, except for the CT, which was performed within 24 h of the other methods. The median ICP was 13 [9.8-16.2] mmHg, and intracranial hypertension was present on 18 occasions (30%). Median values from the noninvasive techniques were ONSD 4.9 [4.40-5.41] mm, PI 1.22 [1.04-1.43], CT scale 3 points [IQR: 3.0], P2/P1 ratio 1.16 [1.09-1.23], and TTP 0.215 [0.193-0.237]. There was a significant statistical correlation between all the noninvasive techniques and invasive ICP (ONSD, r = 0.29; PI, r = 0.62; CT, r = 0.21; P2/P1 ratio, r = 0.35; TTP, r = 0.35, p < 0.001 for all comparisons). The area under the curve (AUC) to estimate intracranial hypertension was 0.69 [CIs = 0.62-0.78] for the ONSD, 0.75 [95% CIs 0.69-0.83] for the PI, 0.64 [95%Cis 0.59-069] for CT, 0.79 [95% CIs 0.72-0.93] for P2/P1 ratio, and 0.69 [95% CIs 0.60-0.74] for TTP. When the various techniques were combined, an AUC of 0.86 [0.76-0.93]) was obtained. The best pair of methods was the TCD and B4cth an AUC of 0.80 (0.72-0.88). Noninvasive technique measurements correlate with ICP and have an acceptable discrimination ability in diagnosing ICH. The multimodal combination of PI (TCD) and wave morphology monitor may improve the ability of the noninvasive methods to diagnose ICH. The observed variability in non-invasive ICP estimations underscores the need for comprehensive investigations to elucidate the optimal method-application alignment across distinct clinical scenarios.

Ventriculostomy Associated with Reduced Mortality in Severe Traumatic Brain Injury Compared to Parenchymal ICP Monitoring: A Propensity Score-Adjusted Analysis

BACKGROUND

There is a lack of data on whether intracranial pressure (ICP)-guided therapy with an intraparenchymal fiberoptic monitor (IPM) or an external ventricular drain (EVD) leads to superior outcomes. Our goal is to determine the relationship between ICP-guided therapy with an EVD or IPM and mortality.

METHODS

Retrospective analysis of severe traumatic brain injury cases that required IPM or EVD placement for ICP-guided therapy from January 1, 2010 to December 31, 2020. The data were obtained from the Pennsylvania Trauma Systems Foundation registry.

RESULTS

A total of 2305 patients met the inclusion criteria, with 1048 (45.5%) IPM and 1257 (54.5%) EVD placed. Inpatient mortality occurred in 337 (32.2%) and 334 (26.6%) patients in the IPM and EVD cohorts, respectively (P = 0.003). Even among those treated medically only, inpatient mortality occurred in 171 (30.8%) of those with an IPM and in 100 (23.4%) of those with an EVD (P = 0.010). Multivariable logistic regression analysis showed that older age (odds ratio [OR] 1.03, P < 0.001), lower Glasgow Coma Scale (GCS) score (OR 1.16, P < 0.001), requiring surgery (OR 1.22, P = 0.049), and an IPM (OR 1.40, P = 0.001) were significant predictors of mortality. Propensity score-adjusted analysis using inverse probability of treatment weighted method revealed a 28% decrease in mortality and a 14% decrease in length of hospital stay with EVD use when adjusting for age, sex, GCS, Injury Severity Score, surgery, and Hispanic ethnicity.

CONCLUSIONS

A significant mortality benefit was associated with the use of EVD compared to IPM. This mortality benefit was observed regardless of whether patients required surgery or not.

Optic nerve sheath diameter and pulsatility index for the diagnosis and follow-up in pediatric traumatic brain injury: a prospective observational cohort study

PURPOSE

Invasive neuromonitoring could be difficult in children with traumatic brain injury (TBI). This study aimed to determine whether noninvasive intracranial pressure (nICP), calculated via pulsatility index (PI) and optic nerve sheath diameter (ONSD) had correlated with each other and patient outcome.

METHODS

All moderate-severe TBI patients were eligible. Patients with a diagnosis of intoxication that did not affect the mental status or cardiovascular system were enrolled as controls. The PI measurements were routinely performed bilaterally on the middle cerebral artery. A software (QLAB's Q-Apps) was used to calculate PI, which further placed the ICP equation of Bellner et al. Linear probe with a 10 MHz frequency transducer to measure ONSD, which further placed the ICP equation of Robba et al. All measurements were performed by a point-of-care ultrasound certified pediatric intensivist under the supervision of a neurocritical care specialist, before and 30 min after a hypertonic saline (HTS) infusion for every 6 h when the patient's mean arterial pressure, heart rate, body temperature, hemoglobin, and blood CO2 levels were within normal ranges. The secondary outcome was the effect of hypertonic saline (HTS) on nICP. Delta-sodium values of each HTS infusion were calculated as a difference between pre- and post-measurements.

RESULTS

Twenty-five TBI patients (200 measurements) and 19 controls (57 measurements) were included. Median nICP-PI and nICP-ONSD on admission were significantly higher in the TBI group (11.03 (9.98-12.63), p = 0.004, and 13.14 (12.27-14.64), p < 0.001, respectively). Median nICP-ONSD of severe TBI patients were higher than moderate TBI patients (13.58 (13.14-15.71) and 12.30 (9.83-13.14), respectively, p = 0.013). The median nICP-PI was the same across the type of injury (falls and motor vehicle accidents), while the median nICP-ONSD of the motor vehicle accident group was higher than falls. The first nICP-PI and nICP-ONSD measurements in PICU and admission pGCS were negatively correlated (r =  - 0.562, p = 0.003 and r =  - 0.582, p = 0.002, respectively). The mean nICP-ONSD during the study period and admission pGCS and GOS-E peds score significantly correlated. However, the Bland-Altman plots showed significant bias between the two methods of ICP except after 5th dose of HTS. All nICP values significantly decreased in time, and it was most obvious after the 5th dose of HTS. No significant correlations were found between delta sodium levels and nICP.

CONCLUSION

Noninvasive estimation of ICP is helpful for the management of pediatric severe TBI patients. nICP driven by ONSD is more consistent with clinical findings of increased ICP but not useful as a follow-up tool in acute management because of slow circulation of CSF around the optic sheath. The correlation between admission GCS scores and GOS-E peds score favors ONSD as a good candidate for determining disease severity and predicting long-term outcomes.

Intracranial Pressure Monitoring and Treatment Thresholds in Acute Neural Injury: A Narrative Review of the Historical Achievements, Current State, and Future Perspectives

Since its introduction in the 1960s, intracranial pressure (ICP) monitoring has become an indispensable tool in neurocritical care practice and a key component of the management of moderate/severe traumatic brain injury (TBI). The primary utility of ICP monitoring is to guide therapeutic interventions aimed at maintaining physiological ICP and preventing intracranial hypertension. The rationale for such ICP maintenance is to prevent secondary brain injury arising from brain herniation and inadequate cerebral blood flow. There exists a large body of evidence indicating that elevated ICP is associated with mortality and that aggressive ICP control protocols improve outcomes in severe TBI patients. Therefore, current management guidelines recommend a cerebral perfusion pressure (CPP) target range of 60-70 mm Hg and an ICP threshold of >20 or >22 mm Hg, beyond which therapeutic intervention should be initiated. Though our ability to achieve these thresholds has drastically improved over the past decades, there has been little to no change in the mortality and morbidity associated with moderate-severe TBI. This is a result of the "one treatment fits all" dogma of current guideline-based care that fails to take individual phenotype into account. The way forward in moderate-severe TBI care is through the development of continuously derived individualized ICP thresholds. This narrative review covers the topic of ICP monitoring in TBI care, including historical context/achievements, current monitoring technologies and indications, treatment methods, associations with patient outcome and multi-modal cerebral physiology, present controversies surrounding treatment thresholds, and future perspectives on personalized approaches to ICP-directed therapy.

Risk factors and cerebrospinal fluid indexes analysis of intracranial infection by Acinetobacter baumannii after neurosurgery

Background

Intracranial infection by Acinetobacter baumannii (A. baumannii) after neurosurgery has always been a difficult problem for neurosurgeons. This study analyzed risk factors that discriminated A. baumannii from other bacteria causing intracranial infection after neurosurgery. It also examined the differences in the cerebrospinal fluid (CSF) indexes to explore their value in the early diagnosis of intracranial infection by A. baumannii.

Methods

We retrospectively reviewed ten years (January 2011 to May 2021) of postoperative central nervous system (CNS) infections in the First Hospital of China Medical University. According to the pathogen, CNS infections were divided into A. baumannii group and other species of bacteria group. We collected clinical and laboratory information of patients, and statistical analysis was performed with SPSS 26.0. Risk factors were screened by univariate analysis, and independent risk factors were screened by multiple logistic regression analysis. Finally, CSF-Pro, CSF-Glu, CSF-Cl, CSF-monocytes (%), CSF-multinucleated cells (%) levels, and CSF multinucleated cells%/monocytes% in the different groups were analyzed.

Results

A total of 155 patients were included, 62 cases (40%) of intracranial infection by A. baumannii and 93 cases (60%) by other species of bacteria. The analysis showed that indwelling nasogastric tubes (P＜0.001, OR = 4.231), indwelling peripherally inserted central catheters (PICCs) (P = 0.041, OR = 2.765), and CSF drainage obstruction (P = 0.003, OR = 3.765) were independent risk factors for intracranial infection by A. baumannii after neurosurgery. Indwelling ventriculoperitoneal shunt (VPS) was a protective factor (P = 0.033, OR = 0.22). In addition, compared with other bacterial groups, the A. baumannii group had higher CSF-pro and CSF- multinucleated cells (%) levels and lower CSF-Glu and CSF- monocytes (%) levels, and the difference was statistically significant (P < 0.01).

Conclusions

Our results elucidate risk factors and differences in CSF indexes for intracranial infection by A. baumannii after neurosurgery that could be detected and prevented early to reduce mortality.

Noninvasive intracranial pressure monitoring throughout brain compliance guiding a ventriculoperitoneal shunt replacement in hydrocephalus-case report

INTRODUCTION

Ventriculoperitoneal (VP) shunt is the primary therapy for hydrocephalus in children; however, this technique is amenable to malfunctions, which could be detected through an assessment of clinical signs and imaging results. Furthermore, early detection can prevent patient deterioration and guide clinical and surgical treatment.

CASE PRESENTATION

A 5-year-old female with a premedical history of neonatal IVH, secondary hydrocephalus, multiple VP shunts revisions, and slit ventricle syndrome was evaluated using a noninvasive intracranial pressure monitor device at the early stages of the clinical symptoms, evidencing increased intracranial pressure and poor brain compliance. Serial MRI images demonstrated a slight ventricular enlargement, leading to the use of a gravitational VP shunt, promoting progressive improvement. On the follow-up visits, we used the noninvasive ICP monitoring device to guide the shunt adjustments until symptom resolution. Furthermore, the patient has been asymptomatic for the past 3 years without requiring new shunt revisions.

DISCUSSION

Slit ventricle syndrome and VP shunt dysfunctions are challenging diagnoses for the neurosurgeon. The noninvasive intracranial monitoring has allowed a closer follow-up assisting early assessment of brain compliance changes related to a patient's symptomatology. Furthermore, this technique has high sensitivity and specificity in detecting alterations in the intracranial pressure, serving as a guide for the adjustments of programmable VP shunts, which may improve the patient's quality of life.

CONCLUSION

Noninvasive ICP monitoring may lead to a less invasive assessment of patients with slit ventricle syndrome and could be used as a guide for adjustments of programmable shunts.

Associations between intracranial pressure thresholds and multimodal monitoring in acute traumatic neural injury: a scoping review

BACKGROUND

Current moderate/severe traumatic brain injury (TBI) guidelines suggest the use of an intracranial pressure (ICP) treatment threshold of 20 mmHg or 22 mmHg. Over the past decade, the use of various cerebral physiology monitoring devices has been incorporated into neurocritical care practice and termed "multimodal monitoring." Such modalities include those that monitor systemic hemodynamics, systemic and brain oxygenation, cerebral blood flow (CBF), cerebral autoregulation, electrophysiology, and cerebral metabolism. Given that the relationship between ICP and outcomes is not yet entirely understood, a comprehensive review of the literature on the associations between ICP thresholds and multimodal monitoring is still needed.

METHODS

We conducted a scoping review of the literature for studies that present an objective statistical association between ICP above/below threshold and any multimodal monitoring variable. MEDLINE, BIOSIS, Cochrane library, EMBASE, Global Health, and SCOPUS were searched from inception to July 2022 for relevant articles. Full-length, peer-reviewed, original works with a sample size of ≥50 moderate-severe TBI patients were included in this study.

RESULTS

A total of 13 articles were deemed eligible for final inclusion. The included articles were significantly heterogenous in terms of their designs, demographics, and results, making it difficult to draw any definitive conclusions. No literature describing the association between guideline-based ICP thresholds and measures of brain electrophysiology, cerebral metabolism, or direct metrics of CBF was found.

CONCLUSION

There is currently little literature that presents objective statistical associations between ICP thresholds and multimodal monitoring physiology. However, overall, the literature indicates that having ICP above guideline based thresholds is associated with increased blood pressure, increased cardiac decoupling, reduced parenchymal brain oxygen tension, and impaired cerebral autoregulation, with no association with CBF velocity within the therapeutic range of ICP. There was insufficient literature to comment on other multimodal monitoring measures.

A novel approach to CSF pressure measurement via lumbar puncture that shortens the measurement time with a high level of accuracy

Intracranial pressure (ICP) is an important parameter in clinical management and diagnosis of several neurological diseases which is indirectly measured via lumbar puncture (LP). In routine measurements of cerebrospinal fluid pressure (P_CSF) from lumbar region, a spinal needle and a spinal manometer are used. P_CSF measurement via LP with the use of a spinal manometer may not yield correct P_CSF results due to prolonged times required to obtain an accurate pressure value. Equilibrium pressure may be underestimated in circumstances where spinal manometry procedure is terminated prematurely, with the wrong assumption that equilibrium pressure is reached. Elevated P_CSF levels can lead to visual loss and brain damage when go undiagnosed. In this study, the spinal needle-spinal manometer combination was modelled with a first-order differential equation and a time constant (τ) was defined as the product of the resistance to flow of the needle with the bore area of the manometer divided by the dynamic viscosity of CSF, i.e. τ= RA/ρ_CSF. Each needle/manometer combination had a unique constant as a predictor of the equilibrium pressure. The fluid pressure in the manometer rose in an exponential manner which was tested in a simulated environment using 22G spinal needles namely Braun-Spinocan, Pajunk-Sprotte and M.Schilling. Curve fitting of the manometer readings were obtained with regression coefficients of R² ≥ 0.99 to determine measurement time constants. The residual differences between predicted and true values were less than 1.18 cmH₂O. For a given needle/manometer combination, time required to reach equilibrium pressure was identical for all pressure levels. P_CSF measured at reduced times can easily be interpolated to their equilibrium level allowing clinicians to obtain P_CSF values with high accuracy within seconds. This method can be used as an indirect estimation of ICP in routine clinical practice.

Intracranial pressure monitoring in the perioperative period of patients with acute liver failure undergoing orthotopic liver transplantation

Acute liver failure (ALF) may result in severe neurological complications caused by cerebral edema and elevated intracranial pressure (ICP). Multiple pathogenic mechanisms explain the elevated ICP, and newer hypotheses have been descri bed. While invasive ICP monitoring (ICPM) may have a role in ALF management, these patients are typically coagulopathic and at risk for intracranial hemorrhage. ICPM is the subject of much debate, and significant heterogeneity exists in clinical practice regarding its use. Contemporary ICPM techniques and coagulopathy reversal strategies may be associated with a lower risk of hemor rhage; however, most of the evidence is limited by its retrospective nature and relatively small sample size.

Ultrasound detected increase in optic disk height to identify elevated intracranial pressure: a systematic review

BACKGROUND

Elevated intracranial pressure (eICP) is a serious medical emergency that requires prompt identification and monitoring. The current gold standards of eICP detection require patient transportation, radiation, and can be invasive. Ocular ultrasound has emerged as a rapid, non-invasive, bedside tool to measure correlates of eICP. This systematic review seeks to explore the utility of ultrasound detected optic disc elevation (ODE) as an ultrasonographic finding of eICP and to study its sensitivity and specificity as a marker of eICP.

METHODS

This systematic review followed the preferred reporting items for systematic reviews and meta-analyses guidelines. We systematically searched PubMed, EMBASE, and Cochrane Central for English articles published before April 2023; yielding 1,919 total citations. After eliminating duplicates, and screening the records, we identified 29 articles that addressed ultrasonographically detected ODE.

RESULTS

The 29 articles included a total of 1249 adult and pediatric participants. In patients with papilledema, the mean ODE ranged between 0.6 mm and 1.2 mm. Proposed cutoff values for ODE ranged between 0.3 mm and 1 mm. The majority of studies reported a sensitivity between 70 and 90%, and specificity ranged from 69 to 100%, with a majority of studies reporting a specificity of 100%.

CONCLUSIONS

ODE and ultrasonographic characteristics of the optic disc may aid in differentiating papilledema from other conditions. Further research on ODE elevation and its correlation with other ultrasonographic signs is warranted as a means to increase the diagnostic accuracy of ultrasound in the setting of eICP.