Quantitative pupillometry for the monitoring of intracranial hypertension in patients with severe traumatic brain injury

Automated Pupillometry Is Able to Discriminate Patients with Acute Stroke from Healthy Subjects: An Observational, Cross-Sectional Study

BACKGROUND

Automated pupillometry (AP) is a handheld, non-invasive tool that is able to assess pupillary light reflex dynamics and is useful for the detection of intracranial hypertension. Limited evidence is available on acute ischemic stroke (AIS) patients. The primary objective was to evaluate the ability of AP to discriminate AIS patients from healthy subjects (HS). Secondly, we aimed to compute a predictive score for AIS diagnosis based on clinical, demographic, and AP variables.

METHODS

We included 200 consecutive patients admitted to a comprehensive stroke center who underwent AP assessment through NPi-200 (NeurOptics®) within 72 h of stroke onset and 200 HS. The mean values of AP parameters and the absolute differences between the AP parameters of the two eyes were considered in the analyses. Predictors of stroke diagnosis were identified through univariate and multivariate logistic regressions; we then computed a nomogram based on each variable's β coefficient. Finally, we developed a web app capable of displaying the probability of stroke diagnosis based on the predictive algorithm.

RESULTS

A high percentage of pupil constriction (CH, p < 0.001), a low constriction velocity (CV, p = 0.002), and high differences between these two parameters (p = 0.036 and p = 0.004, respectively) were independent predictors of AIS. The highest contribution in the predictive score was provided by CH, the Neurological Pupil Index, CV, and CV absolute difference, disclosing the important role of AP in the discrimination of stroke patients.

CONCLUSIONS

The results of our study suggest that AP parameters, and in particular, those concerning pupillary constriction, may be useful for the early diagnosis of AIS.

The Neurocritical Care Examination and Workup

OBJECTIVE

This article provides an overview of the evaluation of patients in neurocritical care settings and a structured approach to recognizing and localizing acute neurologic emergencies, performing a focused examination, and pursuing workup to identify critical findings requiring urgent management.

LATEST DEVELOPMENTS

After identifying and stabilizing imminent threats to survival, including respiratory and hemodynamic compromise, the initial differential diagnosis for patients in neurocritical care is built on a focused history and clinical examination, always keeping in mind critical "must-not-miss" pathologies. A key priority is to identify processes warranting time-sensitive therapeutic interventions, including signs of elevated intracranial pressure and herniation, acute neurovascular emergencies, clinical or subclinical seizures, infections of the central nervous system, spinal cord compression, and acute neuromuscular respiratory failure. Prompt neuroimaging to identify structural abnormalities should be obtained, complemented by laboratory findings to assess for underlying systemic causes. The indication for EEG and lumbar puncture should be considered early based on clinical suspicion.

ESSENTIAL POINTS

In neurocritical care, the initial evaluation is often fast paced, requiring assessment and management to happen in parallel. History, clinical examination, and workup should be obtained while considering therapeutic implications and the need for lifesaving interventions.

Update in Pediatric Neurocritical Care: What a Neurologist Caring for Critically Ill Children Needs to Know

Currently nearly one-quarter of admissions to pediatric intensive care units (PICUs) worldwide are for neurocritical care diagnoses that are associated with significant morbidity and mortality. Pediatric neurocritical care is a rapidly evolving field with unique challenges due to not only age-related responses to primary neurologic insults and their treatments but also the rarity of pediatric neurocritical care conditions at any given institution. The structure of pediatric neurocritical care services therefore is most commonly a collaborative model where critical care medicine physicians coordinate care and are supported by a multidisciplinary team of pediatric subspecialists, including neurologists. While pediatric neurocritical care lies at the intersection between critical care and the neurosciences, this narrative review focuses on the most common clinical scenarios encountered by pediatric neurologists as consultants in the PICU and synthesizes the recent evidence, best practices, and ongoing research in these cases. We provide an in-depth review of (1) the evaluation and management of abnormal movements (seizures/status epilepticus and status dystonicus); (2) acute weakness and paralysis (focusing on pediatric stroke and select pediatric neuroimmune conditions); (3) neuromonitoring modalities using a pathophysiology-driven approach; (4) neuroprotective strategies for which there is evidence (e.g., pediatric severe traumatic brain injury, post-cardiac arrest care, and ischemic stroke and hemorrhagic stroke); and (5) best practices for neuroprognostication in pediatric traumatic brain injury, cardiac arrest, and disorders of consciousness, with highlights of the 2023 updates on Brain Death/Death by Neurological Criteria. Our review of the current state of pediatric neurocritical care from the viewpoint of what a pediatric neurologist in the PICU needs to know is intended to improve knowledge for providers at the bedside with the goal of better patient care and outcomes.

Improved Transcranial Doppler Waveform Analysis for Intracranial Hypertension Assessment in Patients with Traumatic Brain Injury

BACKGROUND

Transcranial Doppler (TCD) is a noninvasive bedside tool for cerebral hemodynamic assessments in multiple clinical scenarios. TCD, by means of measuring systolic and diastolic blood velocities, allows the calculation of the pulsatility index (PI), a parameter that is correlated with intracranial pressure (ICP). Nevertheless, the predictive value of the PI for raised ICP appears to be low, as it is subjected to several, often confounding, factors not related to ICP. Recently, the pulsatile apparent resistance (PaR) index was developed as a PI corrected for arterial blood pressure, reducing some of the confounding factors influencing PI. This study compares the predictive value of PaR versus PI for intracranial hypertension (IH) (ICP > 20 mm Hg) in patients with traumatic brain injury.

METHODS

Patients with traumatic brain injury admitted to the neurocritical care unit who required invasive ICP monitoring were included prospectively within 5 days of admission. TCD measurements were performed in both middle cerebral arteries, allowing calculations of the PI and PaR. The optimal cutoff, discriminative power of these parameters for ICP ≥ 20 mm Hg, was assessed by calculating the area under the receiver operator characteristics curve (AUC).

RESULTS

In total, 93 patients were included. A total of 20 (22%) patients experienced IH during the recording sessions. The discriminative power was low for PI (AUC 0.63) but slightly higher for PaR (AUC 0.77). Nonparametric analysis indicated significant difference for PaR when comparing patients with (median 0.169) and without IH (median - 0.052, p = 0.001), whereas PI medians for patients with and without IH were 0.86 and 0.77, respectively (p =  0.041). Regarding subanalyses, the discriminative power of these parameters increased after exclusion of patients who had undergone a neurosurgical procedure. This was especially true for the PaR (AUC 0.89) and PI (AUC 0.72). Among these patients, a PaR cutoff value of - 0.023 had 100% sensitivity and 52.9% specificity.

CONCLUSIONS

In the present study, discriminative power of the PaR for discriminating IH was superior to the PI. The PaR seems to be a reliable noninvasive parameter for detecting IH. Further studies are warranted to define its clinical application, especially in aiding neurosurgical decision making, following up in intensive care units, and defining its ability to indicate responses according to the therapies administered.

Exploring the feasibility of pupillometry training and perceptions of potential use for intracranial pressure monitoring in Uganda: A mixed methods study

INTRODUCTION

Traumatic brain injury (TBI) accounts for the majority of Uganda's neurosurgical disease burden; however, invasive intracranial pressure (ICP) monitoring is infrequently used. Noninvasive monitoring could change the care of patients in such a setting through quick detection of elevated ICP.

PURPOSE

Given the novelty of pupillometry in Uganda, this mixed methods study assessed the feasibility of pupillometry for noninvasive ICP monitoring for patients with TBI.

METHODS

Twenty-two healthcare workers in Kampala, Uganda received education on pupillometry, practiced using the device on healthy volunteers, and completed interviews discussing pupillometry and its implementation. Interviews were assessed with qualitative analysis, while quantitative analysis evaluated learning time, measurement time, and accuracy of measurements by participants compared to a trainer's measurements.

RESULTS

Most participants (79%) reported a positive perception of pupillometry. Participants described the value of pupillometry in the care of patients during examination, monitoring, and intervention delivery. Commonly discussed concerns included pupillometry's cost, understanding, and maintenance needs. Perceived implementation challenges included device availability and contraindications for use. Participants suggested offering continued education and engaging hospital leadership as implementation strategies. During training, the average learning time was 13.5 minutes (IQR 3.5), and the measurement time was 50.6 seconds (IQR 11.8). Paired t-tests to evaluate accuracy showed no statistically significant difference in comparison measurements.

CONCLUSION

Pupillometry was considered acceptable for noninvasive ICP monitoring of patients with TBI, and pupillometer use was shown to be feasible during training. However, key concerns would need to be addressed during implementation to aid device utilization.

Quantitative Pupillometry: Clinical Applications for the Internist

From the time of Galen, examination of the pupillary light reflex has been a standard of care across the continuum of health care. The growing body of evidence overwhelmingly supports the use of quantitative pupillometry over subjective examination with flashlight or penlight. At current time, pupillometers have become standard of care in many hospitals across 6 continents. This review paper provides an overview and rationale for pupillometer use and highlights literature supporting pupillometer-derived measures of the pupillary light reflex in both neurological and non-neurological patients across the health care continuum.

Prediction for the prognosis of diffuse axonal injury using automated pupillometry

OBJECTIVE

Previous studies have reported various predictive indicators of diffuse axonal injury (DAI), but no consensus has not been reached. Although the efficiency of automated pupillometry in patients with consciousness disorder has been widely reported, there are few reports of its use in patients with DAI. This study aimed to investigate the significance of pupillary findings in predicting the prognosis of DAI.

PATIENTS AND METHODS

We included patients admitted to our center with a diagnosis of DAI from June 1, 2021 to June 30, 2022. Pupillary findings in both eyes were quantitatively measured by automated pupillometry every 2 hours after admission. We statistically examined the correlations between automated pupillometry parameters, the patients' characteristics, and outcomes such as the Glasgow Outcome Scale Extended (GOSE) after 6 months from injury, the time to follow command, and so on.

RESULTS

Among 22 patients included in this study, five had oculomotor nerve palsy. Oculomotor nerve palsy was correlated with all outcomes, whereas Marshall computed tomography (CT) classification, Injury severity score (ISS) and DAI grade were correlated with few outcomes. Some of the automated pupillometry parameters were significantly correlated with GOSE at 6 months after injury, and many during the first 24 hours of measurement were correlated with the time to follow command. Most of these results were not affected by adjustment using sedation period, ISS or Marshall CT classification. A subgroup analysis of patients without oculomotor nerve palsy revealed that many of the automated pupillometry parameters during the first 24 hours of measurement were significantly correlated with most of the outcomes. The cutoff values that differentiated a good prognosis (GOSE 5-8) from a poor prognosis (GOSE 1-4) were constriction velocity (CV) 1.43 (AUC = 0.81(0.62-1), p = 0.037) and maximum constriction velocity (MCV) 2.345 (AUC = 0.78 (0.58-0.98), p = 0.04). The cutoff values that differentiated the time to follow command into within 7 days and over 8 days were percentage of constriction 8 (AUC = 0.89 (0.68-1), p = 0.011), CV 0.63 (AUC = 0.92 (0.78-1), p = 0.013), MCV 0.855 (AUC = 0.9 (0.74-1), p = 0.017) and average dilation velocity 0.175 (AUC = 0.95 (0.86-1), p = 0.018).

CONCLUSIONS

The present results indicate that pupillary findings in DAI are a strong predictive indicator of the prognosis, and that quantitative measurement of them using automated pupillometry could facilitate enhanced prediction for the prognosis of DAI.

The use of quantitative pupillometry in brain death determination: preliminary findings

PURPOSE

Quantitative pupillometry (QP) has been increasingly applied in neurocritical care as an easy-to-use and reliable technique for evaluating the pupillary light reflex (PLR). Here, we report our preliminary findings on using QP for clinical brain death (BD) determination.

MATERIALS

This retrospective study included 17 patients ≥ 18 years (mean age, 57.3 years; standard deviation, 15.8 years) with confirmed BD, as defined by German Guidelines for the determination of BD. The PLR was tested using the NPi®-200 Pupillometer (Neuroptics, Laguna Hill, USA), a handheld infrared device automatically tracking and analyzing pupil dynamics over 3 s. In addition, pupil diameter and neurological pupil index (NPi) were also evaluated.

RESULTS

Intracerebral bleeding, subarachnoid hemorrhage, and hypoxic encephalopathy were the most prevalent causes of BD. In all patients, the NPi was 0 for both eyes, indicating the cessation of mid-brain function. The mean diameter was 4.9 mm (± 1.3) for the right pupil and 5.2 mm (±1.2) for the left pupil.

CONCLUSIONS

QP is a valuable tool for the BD certification process to assess the loss of PLR due to the cessation of brain stem function. Furthermore, implementing QP before the withdrawal of life-sustaining therapy in brain-injured patients may reduce the rate of missed organ donation opportunities. Further studies are warranted to substantiate the feasibility and potential of this technique in treating patients and identify suitable candidates for this technique during the BD certification process.

"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.

Neuromonitoring in the ICU - what, how and why?

PURPOSE OF REVIEW

We selectively review emerging noninvasive neuromonitoring techniques and the evidence that supports their use in the ICU setting. The focus is on neuromonitoring research in patients with acute brain injury.

RECENT FINDINGS

Noninvasive intracranial pressure evaluation with optic nerve sheath diameter measurements, transcranial Doppler waveform analysis, or skull mechanical extensometer waveform recordings have potential safety and resource-intensity advantages when compared to standard invasive monitors, however each of these techniques has limitations. Quantitative electroencephalography can be applied for detection of cerebral ischemia and states of covert consciousness. Near-infrared spectroscopy may be leveraged for cerebral oxygenation and autoregulation computation. Automated quantitative pupillometry and heart rate variability analysis have been shown to have diagnostic and/or prognostic significance in selected subtypes of acute brain injury. Finally, artificial intelligence is likely to transform interpretation and deployment of neuromonitoring paradigms individually and when integrated in multimodal paradigms.

SUMMARY

The ability to detect brain dysfunction and injury in critically ill patients is being enriched thanks to remarkable advances in neuromonitoring data acquisition and analysis. Studies are needed to validate the accuracy and reliability of these new approaches, and their feasibility and implementation within existing intensive care workflows.

Evaluating the utility of quantitative pupillometry in a neuro-critical care setting for the monitoring of intracranial pressure: A prospective cohort study

INTRODUCTION

Assessment of the pupillary light reflex (PLR) is key in intensive care monitoring of neurosurgical patients, particularly for monitoring intracranial pressure (ICP). Quantitative pupillometry using a handheld pupillometer is a reliable method for PLR assessment. However, many variables are derived from such devices. We therefore aimed to assess the performance of these variables at monitoring ICP.

METHODS

Sedated patients admitted to neurocritical care in a tertiary neurosurgical centre with invasive ICP monitoring were included. Hourly measurement of ICP, subjective pupillometry (SP) using a pen torch device, and quantitative pupillometry (QP) using a handheld pupillometer were performed.

RESULTS

561 paired ICP, SP and QP pupillary observations from nine patients were obtained (1122 total pupillary observations). SP and QP had a moderate concordance for pupillary size (κ=0.62). SP performed poorly at detecting pupillary size changes (sensitivity=24%). In 40 (3.6%) observations, SP failed to detect a pupillary response whereas QP did. Moderate correlations with ICP were detected for maximum constriction velocity (MCV), dilation velocity (DV), and percentage change in pupillary diameter (%C). Discriminatory ability at an ICP threshold of >22 mmHg was moderate for MCV (AUC=0.631), DV (AUC=0.616), %C (AUC=0.602), and pupillary maximum size (AUC=0.625).

CONCLUSION

QP is superior to SP at monitoring pupillary reactivity and changes to pupillary size. Although effect sizes were moderate to weak across assessed variables, our data indicates MCV and %C as the most sensitive variables for monitoring ICP. Further study is required to validate these findings and to establish normal range cut-offs for clinical use.

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.

Critical Care Management of Patients After Cardiac Arrest: A Scientific Statement from the American Heart Association and Neurocritical Care Society

The critical care management of patients after cardiac arrest is burdened by a lack of high-quality clinical studies and the resultant lack of high-certainty evidence. This results in limited practice guideline recommendations, which may lead to uncertainty and variability in management. Critical care management is crucial in patients after cardiac arrest and affects outcome. Although guidelines address some relevant topics (including temperature control and neurological prognostication of comatose survivors, 2 topics for which there are more robust clinical studies), many important subject areas have limited or nonexistent clinical studies, leading to the absence of guidelines or low-certainty evidence. The American Heart Association Emergency Cardiovascular Care Committee and the Neurocritical Care Society collaborated to address this gap by organizing an expert consensus panel and conference. Twenty-four experienced practitioners (including physicians, nurses, pharmacists, and a respiratory therapist) from multiple medical specialties, levels, institutions, and countries made up the panel. Topics were identified and prioritized by the panel and arranged by organ system to facilitate discussion, debate, and consensus building. Statements related to postarrest management were generated, and 80% agreement was required to approve a statement. Voting was anonymous and web based. Topics addressed include neurological, cardiac, pulmonary, hematological, infectious, gastrointestinal, endocrine, and general critical care management. Areas of uncertainty, areas for which no consensus was reached, and future research directions are also included. Until high-quality studies that inform practice guidelines in these areas are available, the expert panel consensus statements that are provided can advise clinicians on the critical care management of patients after cardiac arrest.

The Role of Automated Infrared Pupillometry in Traumatic Brain Injury: A Narrative Review

Pupillometry, an integral component of neurological examination, serves to evaluate both pupil size and reactivity. The conventional manual assessment exhibits inherent limitations, thereby necessitating the development of portable automated infrared pupillometers (PAIPs). Leveraging infrared technology, these devices provide an objective assessment, proving valuable in the context of brain injury for the detection of neuro-worsening and the facilitation of patient monitoring. In cases of mild brain trauma particularly, traditional methods face constraints. Conversely, in severe brain trauma scenarios, PAIPs contribute to neuro-prognostication and non-invasive neuromonitoring. Parameters derived from PAIPs exhibit correlations with changes in intracranial pressure. It is important to acknowledge, however, that PAIPs cannot replace invasive intracranial pressure monitoring while their widespread adoption awaits robust support from clinical studies. Ongoing research endeavors delve into the role of PAIPs in managing critical neuro-worsening in brain trauma patients, underscoring the non-invasive monitoring advantages while emphasizing the imperative for further clinical validation. Future advancements in this domain encompass sophisticated pupillary assessment tools and the integration of smartphone applications, emblematic of a continually evolving landscape.

Prediction of neurocritical care intensity through automated infrared pupillometry and transcranial doppler in blunt traumatic brain injury: the NOPE study

PURPOSE

This pilot study aimed to determine the capacity of automated infrared pupillometry (AIP) alone and in combination with transcranial doppler (TCD) on admission to rule out need for intense neuroAQ2 critical care (INCC) in severe traumatic brain injury (TBI).

METHODS

In this observational pilot study clinicians performed AIP and TCD measurements on admission in blunt TBI patients with a Glasgow Coma Score (GCS) < 9 and/or motor score < 6. A Neurological Pupil index (NPi) < 3, Pulsatility Index (PI) > 1,4 or diastolic blood flow velocity (dV) of < 20 cm/s were used to rule out the need for INCC (exceeding the tier 0 Seattle Consensus Conference). The primary outcome was the negative likelihood ratio (nLR) of NPi < 3 alone or in combination with TCD to detect need for INCC.

RESULTS

A total of 69 TBI patients were included from May 2019 to September 2020. Of those, 52/69 (75%) median age was 45 [28-67], median prehospital GCS of 7 [5-8], median Injury Severity Scale of 13.0 [6.5-25.5], median Marshall Score of 4 [3-5], the median Glasgow Outcome Scale at discharge was 3 [1-5]. NPi < 3 was an independent predictor of INCC. NPi demonstrated a nLR of 0,6 (95%CI 0.4-0.9; AUROC, 0.65, 95% CI 0.51-0.79), a combination of NPi and TCD showed a nLR of 0.6 (95% CI 0.4-1.0; AUROC 0.67 95% CI 0.52-0.83) to predict INCC.

CONCLUSION

This pilot study suggests a possible useful contribution of NPi to determine the need for INCC in severe blunt TBI patients on admission.

Critical Care Management of Patients After Cardiac Arrest: A Scientific Statement From the American Heart Association and Neurocritical Care Society

The critical care management of patients after cardiac arrest is burdened by a lack of high-quality clinical studies and the resultant lack of high-certainty evidence. This results in limited practice guideline recommendations, which may lead to uncertainty and variability in management. Critical care management is crucial in patients after cardiac arrest and affects outcome. Although guidelines address some relevant topics (including temperature control and neurological prognostication of comatose survivors, 2 topics for which there are more robust clinical studies), many important subject areas have limited or nonexistent clinical studies, leading to the absence of guidelines or low-certainty evidence. The American Heart Association Emergency Cardiovascular Care Committee and the Neurocritical Care Society collaborated to address this gap by organizing an expert consensus panel and conference. Twenty-four experienced practitioners (including physicians, nurses, pharmacists, and a respiratory therapist) from multiple medical specialties, levels, institutions, and countries made up the panel. Topics were identified and prioritized by the panel and arranged by organ system to facilitate discussion, debate, and consensus building. Statements related to postarrest management were generated, and 80% agreement was required to approve a statement. Voting was anonymous and web based. Topics addressed include neurological, cardiac, pulmonary, hematological, infectious, gastrointestinal, endocrine, and general critical care management. Areas of uncertainty, areas for which no consensus was reached, and future research directions are also included. Until high-quality studies that inform practice guidelines in these areas are available, the expert panel consensus statements that are provided can advise clinicians on the critical care management of patients after cardiac arrest.

Describing Anisocoria in Neurocritically Ill Patients

BACKGROUND

Anisocoria (unequal pupil size) has been defined using cut points ranging from greater than 0.3 mm to greater than 2.0 mm for absolute difference in pupil size. This study explored different pupil diameter cut points for assessing anisocoria as measured by quantitative pupillometry before and after light stimulus.

METHODS

An exploratory descriptive study of international registry data was performed. The first observations in patients with paired left and right quantitative pupillometry measurements were included. Measurements of pupil size before and after stimulus with a fixed light source were used to calculate anisocoria.

RESULTS

The sample included 5769 patients (mean [SD] age, 57.5 [17.6] years; female sex, 2558 patients [51.5%]; White race, 3669 patients [75.5%]). Anisocoria defined as pupil size difference of greater than 0.5 mm was present in 1624 patients (28.2%) before light stimulus; 645 of these patients (39.7%) also had anisocoria after light stimulus (P < .001). Anisocoria defined as pupil size difference of greater than 2.0 mm was present in 79 patients (1.4%) before light stimulus; 42 of these patients (53.2%) also had anisocoria after light stimulus (P < .001).

DISCUSSION

The finding of anisocoria significantly differed before and after light stimulus and according to the cut point used. At most cut points, fewer than half of the patients who had anisocoria before light stimulus also had anisocoria after light stimulus.

CONCLUSION

The profound difference in the number of patients adjudicated as having anisocoria using different cut points reinforces the need to develop a universal definition for anisocoria.

Automated pupillometry and optic nerve sheath diameter ultrasound to define tuberculous meningitis disease severity and prognosis

BACKGROUND

Tuberculous meningitis (TBM) causes high mortality and morbidity, in part due to raised intracranial pressure (ICP). Automated pupillometry (NPi) and optic nerve sheath diameter (ONSD) are both low-cost, easy-to-use and non-invasive techniques that correlate with ICP and neurological status. However, it is uncertain how to apply these techniques in the management of TBM.

METHODS

We conducted a pilot study enrolling 20 adults with TBM in the Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam. Our objective was to investigate the relationships between baseline and serial measurements of NPi and ONSD and disease severity and outcome. Serial NPi and ONSD were performed for 30 days, at discharge, and at 3-months, with measurements correlated with clinical progression and outcomes.

RESULTS

ONSD and NPi measurements had an inverse relationship. Higher ONSD and lower NPi values were associated with lower Glasgow coma score. Baseline NPi was a strong predictor 3-month outcome (median NPi 4.55, interquartile range 4.35-4.65 for good outcomes versus 2.60, IQR 0.65-3.95 for poor outcomes, p = 0.002). Pupil inequality (NPi ≥0.7) was also strongly associated with poor 3-month outcomes (p = 0.006). Individual participants' serial NPi and ONSD were variable during initial treatment and correlated with clinical condition and outcome.

CONCLUSION

Pupillometry and ONSD may be used to predict clinical deterioration and outcome from TBM. Future, larger studies are need explore the optimal timing of measurements and to define how they might be used to optimise treatments and improve outcomes from TBM.

The Neurological Pupil index for outcome prognostication in people with acute brain injury (ORANGE): a prospective, observational, multicentre cohort study

BACKGROUND

Improving the prognostication of acute brain injury is a key element of critical care. Standard assessment includes pupillary light reactivity testing with a hand-held light source, but findings are interpreted subjectively; automated pupillometry might be more precise and reproducible. We aimed to assess the association of the Neurological Pupil index (NPi)-a quantitative measure of pupillary reactivity computed by automated pupillometry-with outcomes of patients with severe non-anoxic acute brain injury.

METHODS

ORANGE is a multicentre, prospective, observational cohort study at 13 hospitals in eight countries in Europe and North America. Patients admitted to the intensive care unit after traumatic brain injury, aneurysmal subarachnoid haemorrhage, or intracerebral haemorrhage were eligible for the study. Patients underwent automated infrared pupillometry assessment every 4 h during the first 7 days after admission to compute NPi, with values ranging from 0 to 5 (with abnormal NPi being <3). The co-primary outcomes of the study were neurological outcome (assessed with the extended Glasgow Outcome Scale [GOSE]) and mortality at 6 months. We used logistic regression to model the association between NPi and poor neurological outcome (GOSE ≤4) at 6 months and Cox regression to model the relation of NPi with 6-month mortality. This study is registered with ClinicalTrials.gov, NCT04490005.

FINDINGS

Between Nov 1, 2020, and May 3, 2022, 514 patients (224 with traumatic brain injury, 139 with aneurysmal subarachnoid haemorrhage, and 151 with intracerebral haemorrhage) were enrolled. The median age of patients was 61 years (IQR 46-71), and the median Glasgow Coma Scale score on admission was 8 (5-11). 40 071 NPi measurements were taken (median 40 per patient [20-50]). The 6-month outcome was assessed in 497 (97%) patients, of whom 160 (32%) patients died, and 241 (47%) patients had at least one recording of abnormal NPi, which was associated with poor neurological outcome (for each 10% increase in the frequency of abnormal NPi, adjusted odds ratio 1·42 [95% CI 1·27-1·64]; p<0·0001) and in-hospital mortality (adjusted hazard ratio 5·58 [95% CI 3·92-7·95]; p<0·0001).

INTERPRETATION

NPi has clinically and statistically significant prognostic value for neurological outcome and mortality after acute brain injury. Simple, automatic, repeat automated pupillometry assessment could improve the continuous monitoring of disease progression and the dynamics of outcome prediction at the bedside.

FUNDING

NeurOptics.

Neurological Pupillary Index (NPi) Measurement Using Pupillometry and Outcomes in Critically Ill Children

Aim/objective Neurological Pupil Index (NPi), measured by automated pupillometry (AP), allows the objective assessment of pupillary light reflex (PLR). NPi ranges from 0 (non-reactive) to 5 (normal). In this study, we aimed to compare neurologic and functional outcomes in children admitted for neurologic injury with normal (≥3) versus abnormal (<3) NPi measured during their pediatric intensive care unit (PICU) stay. Materials and methods We conducted a retrospective chart review of children between one month and 18 years admitted to our PICU with a diagnosis of neurologic injury between January 2019 and June 2022. We collected demographic, clinical, pupillometer, and outcome data, including mortality, Pediatric Cerebral Performance Category (PCPC), Pediatric Overall Performance Category (POPC), and Functional Status Score (FSS) at admission, at discharge, and at the three to six-month follow-up. We defined abnormal pupil response as any NPi <3 at any point during the PICU stay. Using the student's t-test and chi-square test, we compared the short-term and long-term outcomes of children with abnormal NPi (<3) versus those with normal NPi (≥3). Results There were 49 children who met the inclusion criteria and who had pupillometry data available for analysis. The mean (SD) Glasgow Coma Scale (GCS) in the study cohort was 5.6 (4.3), and 61% had low (<3) NPi during ICU stay. Mortality was significantly higher among patients with an abnormal NPi as compared to those with normal NPi. Children with abnormal NPi exhibited significant worsening of neurologic and functional status (ΔPCPC, ΔPOPC, and ΔFSS) from admission to discharge (mean (SD): 3.55(1.5), 3.45(1.43), 16.75(7.85), p<0.001) as compared to those with normal NPi (mean (SD): 1.45(0.93), 1.73(0.90), 3.55(2.07), p>0.05). The significant difference in neurologic and functional status persisted at the three to six-month follow-up between the two groups - children with abnormal NPi (mean (SD): 2.0(1.41), 2.08(1.38), 6.92(6.83), p<0.01) and children with normal NPi (mean (SD): 0.82(1.01), 0.94(1.03), 1.53(1.70), p>0.05). Conclusion In our retrospective cohort study, children admitted to the PICU for a neuro injury and with abnormal NPi (< 3) have higher mortality, and worse short-term and long-term neurologic and functional outcomes as compared to those with normal NPi (≥ 3) measured during the PICU course. AP provides an objective assessment of PLR and has potential applications for neuro-prognostication. More research needs to be done to elucidate the prognostic value of NPi in pediatrics.

Racially fair pupillometry measurements for RGB smartphone cameras using the far red spectrum

Pupillometry is a measurement of pupil dilation commonly performed as part of neurological assessments. Prior work have demonstrated the potential for pupillometry in screening or diagnosing a number of neurological disorders including Alzheimer's Disease, Schizophrenia, and Traumatic Brain Injury. Unfortunately, the expense and inaccessibility of specialized pupilometers that image in the near infrared spectrum limit the measurement to high resource clinics or institutions. Ideally, this measurement could be available via ubiquitous devices like smartphones or tablets with integrated visible spectrum imaging systems. In the visible spectrum of RGB cameras, the melanin in the iris absorbs light such that it is difficult to distinguish the pupil aperature that appears black. In this paper, we propose a novel pupillometry technique to enable smartphone RGB cameras to effectively differentiate the pupil from the iris. The proposed system utilizes a 630 nm long-pass filter to image in the far red (630-700 nm) spectrum, where the melanin in the iris reflects light to appear brighter in constrast to the dark pupil. Using a convolutional neural network, the proposed system measures pupil diameter as it dynamically changes in a frame by frame video. Comparing across 4 different smartphone models, the pupil-iris contrast of N = 12 participants increases by an average of 451% with the proposed system. In a validation study of N = 11 participants comparing the relative pupil change in the proposed system to a Neuroptics PLR-3000 Pupillometer during a pupillary light response test, the prototype system acheived a mean absolute error of 2.4%.

The impact of Alzheimer's disease risk factors on the pupillary light response

Alzheimer's disease (AD) is the leading cause of dementia, and its prevalence is increasing and is expected to continue to increase over the next few decades. Because of this, there is an urgent requirement to determine a way to diagnose the disease, and to target interventions to delay and ideally stop the onset of symptoms, specifically those impacting cognition and daily livelihood. The pupillary light response (PLR) is controlled by the sympathetic and parasympathetic branches of the autonomic nervous system, and impairments to the pupillary light response (PLR) have been related to AD. However, most of these studies that assess the PLR occur in patients who have already been diagnosed with AD, rather than those who are at a higher risk for the disease but without a diagnosis. Determining whether the PLR is similarly impaired in subjects before an AD diagnosis is made and before cognitive symptoms of the disease begin, is an important step before using the PLR as a diagnostic tool. Specifically, identifying whether the PLR is impaired in specific at-risk groups, considering both genetic and non-genetic risk factors, is imperative. It is possible that the PLR may be impaired in association with some risk factors but not others, potentially indicating different pathways to neurodegeneration that could be distinguished using PLR. In this work, we review the most common genetic and lifestyle-based risk factors for AD and identify established relationships between these risk factors and the PLR. The evidence here shows that many AD risk factors, including traumatic brain injury, ocular and intracranial hypertension, alcohol consumption, depression, and diabetes, are directly related to changes in the PLR. Other risk factors currently lack sufficient literature to make any conclusions relating directly to the PLR but have shown links to impairments in the parasympathetic nervous system; further research should be conducted in these risk factors and their relation to the PLR.

Extended reality quantification of pupil reactivity as a non-invasive assessment for the pathogenesis of spaceflight associated neuro-ocular syndrome: A technology validation study for astronaut health

The National Aeronautics and Space Administration (NASA) has rigorously documented a group of neuro-ophthalmic findings in astronauts during and after long-duration spaceflight known as spaceflight associated neuro-ocular syndrome (SANS). For astronaut safety and mission effectiveness, understanding SANS and countermeasure development are of utmost importance. Although the pathogenesis of SANS is not well defined, a leading hypothesis is that SANS might relate to a sub-clinical increased intracranial pressure (ICP) from cephalad fluid shifts in microgravity. However, no direct ICP measurements are available during spaceflight. To further understand the role of ICP in SANS, pupillometry can serve as a promising non-invasive biomarker for spaceflight environment as ICP is correlated with the pupil variables under illumination. Extended reality (XR) can help to address certain limitations in current methods for efficient pupil testing during spaceflight. We designed a protocol to quantify parameters of pupil reactivity in XR with an equivalent time duration of illumination on each eye compared to pre-existing, non-XR methods. Throughout the assessment, the pupil diameter data was collected using HTC Vive Pro-VR headset, thanks to its eye-tracking capabilities. Finally, the data was used to compute several pupil variables. We applied our methods to 36 control subjects. Pupil variables such as maximum and minimum pupil size, constriction amplitude, average constriction amplitude, maximum constriction velocity, latency and dilation velocity were computed for each control data. We compared our methods of calculation of pupil variables with the non-XR methods existing in the literature. Distributions of the pupil variables such as latency, constriction amplitude, and velocity of 36 control data displayed near-identical results from the non-XR literature for normal subjects. We propose a new method to evaluate pupil reactivity with XR technology to further understand ICP's role in SANS and provide further insight into SANS countermeasure development for future spaceflight.

PupillOmetry for preDIction of DeliriUM in ICU (PODIUM): protocol for a prospective multicentre cohort study

INTRODUCTION

Delirium is a severe complication that is associated with short-term adverse events, prolonged hospital stay and neurological sequelae in survivors. Automated pupillometry is an easy-to-use device that allows for accurate objective assessment of the pupillary light responses in comatose patients in the intensive care unit (ICU). Whether automated pupillometry might predict delirium in critically ill patients is not known. We hypothesise that automated pupillometry could predict the occurrence of delirium in critically ill patients without primary brain injury, requiring more than 48 hours of invasive mechanical ventilation in the ICU.

METHODS AND ANALYSIS

The PupillOmetry for preDIction of DeliriUM in ICU (PODIUM) study is a prospective cohort study, which will be conducted in eight French ICUs in the Paris area. We aim to recruit 213 adult patients requiring invasive mechanical ventilation for more than 48 hours. Automated pupillometry (Neurological Pupil Index; NPi-200, Neuroptics) will be assessed two times per day for 7 days. Delirium will be assessed using the Confusion Assessment Method in ICU two times per day over 14 days in non-comatose patients (Richmond Agitation and Sedation Scale ≥-3).The predictive performances of the seven automated pupillometry parameters (ie, pupillary diameter, variation of the pupillary diameter, pupillary constriction speed, pupillary dilatation speed, photomotor reflex latency, NPi and symmetry of pupillary responses) measured to detect the delirium occurrence within 14 days will be the main outcomes. Secondary outcomes will be the predictive performances of the seven automated pupillometry parameters to detect complications related to delirium, ICU length of stay, mortality, functional and cognitive outcomes at 90 days.

ETHICS AND DISSEMINATION

The PODIUM study has been approved by an independent ethics committee, the Comité de Protection des Personnes (CPP) OUEST IV-NANTES (CPP21.02.15.45239 32/21_3) on 06 April 2021). Participant recruitment started on 15 April 2022. Results will be published in international peer-reviewed medical journals and presented at conferences.

TRIAL REGISTRATION NUMBER

NCT05248035; clinicaltrials.gov.

Application of Pupillometry in Neurocritical Patients

Pupillary light reflex (PLR) assessment is a crucial examination for evaluating brainstem function, particularly in patients with acute brain injury and neurosurgical conditions. The PLR is controlled by neural pathways modulated by both the sympathetic and parasympathetic nervous systems. Altered PLR is a strong predictor of adverse outcomes after traumatic and ischemic brain injuries. However, the assessment of PLR needs to take many factors into account since it can be modulated by various medications, alcohol consumption, and neurodegenerative diseases. The development of devices capable of measuring pupil size and assessing PLR quantitatively has revolutionized the non-invasive neurological examination. Automated pupillometry, which is more accurate and precise, is widely used in diverse clinical situations. This review presents our current understanding of the anatomical and physiological basis of the PLR and the application of automated pupillometry in managing neurocritical patients. We also discuss new technologies that are being developed, such as smartphone-based pupillometry devices, which are particularly beneficial in low-resource settings.

Intracranial pressure monitoring in neurosurgery: the present situation and prospects

Intracranial pressure (ICP) is one of the most important indexes in neurosurgery. It is essential for doctors to determine the numeric value and changes of ICP, whether before or after an operation. Although external ventricular drainage (EVD) is the gold standard for monitoring ICP, more and more novel monitoring methods are being applied clinically.Invasive wired ICP monitoring is still the most commonly used in practice. Meanwhile, with the rise and development of various novel technologies, non-invasive types and invasive wireless types are gradually being used clinically or in the testing phase, as a complimentary approach of ICP management. By choosing appropriate monitoring methods, clinical neurosurgeons are able to obtain ICP values safely and effectively under particular conditions.This article introduces diverse monitoring methods and compares the advantages and disadvantages of different monitoring methods. Moreover, this review may enable clinical neurosurgeons to have a broader view of ICP monitoring.

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.

Noninvasive methods to monitor intracranial pressure

PURPOSE OF REVIEW

Intracranial pressure (ICP) is determined by the production of and outflow facility of cerebrospinal fluid. Since alterations in ICP are implicated in several vision-threatening and life-threatening diseases, measurement of ICP is necessary and common. All current clinical methods to measure ICP are invasive and carry the risk for significant side effects. Therefore, the development of accurate, reliable, objective, and portal noninvasive devices to measure ICP has the potential to change the practice of medicine. This review discusses recent advances and barriers to the clinical implementation of noninvasive devices to determine ICP.

RECENT FINDINGS

Many noninvasive methods to determine ICP have been developed. Although most have significant limitations limiting their clinical utility, several noninvasive methods have shown strong correlations with invasively obtained ICP and have excellent potential to be developed further to accurately quantify ICP and ICP changes.

SUMMARY

Although invasive methods remain the mainstay for ICP determination and monitoring, several noninvasive biomarkers have shown promise to quantitatively assess and monitor ICP. With further refinement and advancement of these techniques, it is highly possible that noninvasive methods will become more commonplace and may complement or even supplant invasively obtained methods to determine ICP in certain situations.

Traumatic brain injury: Mechanisms, manifestations, and visual sequelae

Traumatic brain injury (TBI) results when external physical forces impact the head with sufficient intensity to cause damage to the brain. TBI can be mild, moderate, or severe and may have long-term consequences including visual difficulties, cognitive deficits, headache, pain, sleep disturbances, and post-traumatic epilepsy. Disruption of the normal functioning of the brain leads to a cascade of effects with molecular and anatomical changes, persistent neuronal hyperexcitation, neuroinflammation, and neuronal loss. Destructive processes that occur at the cellular and molecular level lead to inflammation, oxidative stress, calcium dysregulation, and apoptosis. Vascular damage, ischemia and loss of blood brain barrier integrity contribute to destruction of brain tissue. This review focuses on the cellular damage incited during TBI and the frequently life-altering lasting effects of this destruction on vision, cognition, balance, and sleep. The wide range of visual complaints associated with TBI are addressed and repair processes where there is potential for intervention and neuronal preservation are highlighted.

Noninvasive intracranial pressure waveforms for estimation of intracranial hypertension and outcome prediction in acute brain-injured patients

Analysis of intracranial pressure waveforms (ICPW) provides information on intracranial compliance. We aimed to assess the correlation between noninvasive ICPW (NICPW) and invasively measured intracranial pressure (ICP) and to assess the NICPW prognostic value in this population. In this cohort, acute brain-injured (ABI) patients were included within 5 days from admission in six Intensive Care Units. Mean ICP (mICP) values and the P2/P1 ratio derived from NICPW were analyzed and correlated with outcome, which was defined as: (a) early death (ED); survivors on spontaneous breathing (SB) or survivors on mechanical ventilation (MV) at 7 days from inclusion. Intracranial hypertension (IHT) was defined by ICP > 20 mmHg. A total of 72 patients were included (mean age 39, 68% TBI). mICP and P2/P1 values were significantly correlated (r = 0.49, p < 0.001). P2/P1 ratio was significantly higher in patients with IHT and had an area under the receiving operator curve (AUROC) to predict IHT of 0.88 (95% CI 0.78–0.98). mICP and P2/P1 ratio was also significantly higher for ED group (n = 10) than the other groups. The AUROC of P2/P1 to predict ED was 0.71 [95% CI 0.53–0.87], and the threshold P2/P1 > 1.2 showed a sensitivity of 60% [95% CI 31–83%] and a specificity of 69% [95% CI 57–79%]. Similar results were observed when decompressive craniectomy patients were excluded. In this study, P2/P1 derived from noninvasive ICPW assessment was well correlated with IHT. This information seems to be as associated with ABI patients outcomes as ICP.

Trial registration: NCT03144219, Registered 01 May 2017 Retrospectively registered, https://www.clinicaltrials.gov/ct2/show/NCT03144219.

Impact of acute intoxication on quantitative pupillometry assessment in the emergency department

Study Hypothesis/Objective

This prospective cohort study aimed to assess whether and to what extent different quantitative pupillometry (QP) metrics are associated with different intoxicant drug classes as well as investigate the potential benefit of QP as a tool in the rapid assessment of clinically intoxicated patients in the emergency department (ED).

Methods

Between February 25, 2019 and April 24, 2021, 325 patients were enrolled in the EDs of the Hospital of the University of Pennsylvania (HUP) and Penn Presbyterian Medical Center (PPMC). Patients deemed clinically intoxicated or in withdrawal by an attending emergency physician were considered for eligibility. Patients <18 years old, with a chief complaint indicative of head trauma or stroke or without a urine drug screen (UDS) positive for drugs of abuse were excluded. QP data were also collected from a cohort of 82 healthy control subjects.

Results

Neurological Pupil index (NPi) values did not vary significantly between control and study groups nor between study group patients with a UDS positive for opioids. With exception of latency of constriction, all other QP metrics for the study group were depressed relative to controls (P < 0.005).

Conclusions

This work demonstrated the feasibility of QP measurement in the ED, finding that NPi remains unaffected by clinical intoxication and therefore can potentially be used for ED patient evaluation without risk of confounding by key intoxicants of abuse. Future work will evaluate the value of QP as a means of rapid and reproducible neurological assessment to identify various pathologies.

The Next Frontier in Neurocritical Care in Resource-Constrained Settings

Neurocritical care (NCC) is an emerging field within critical care medicine, reflecting the widespread prevalence of neurologic injury in critically ill patients. Morbidity and mortality from neurocritical illness (NCI) have been reduced substantially in resource-rich settings (RRS), owing to the development of advanced technologies, neuro-specific units, and subspecialized medical training. Despite shouldering much of the burden of NCI worldwide, resource-limited settings (RLS) face immense hurdles when implementing guidelines generated in RRS. This review summarizes the current epidemiology, management, and outcomes of the most common NCIs in RLS and offers commentary on future directions in NCC practiced in RLS.

Automated Pupillometry as an Assessment Tool for Intracranial Hemodynamics in Septic Patients

Impaired cerebral autoregulation (CA) may increase the risk of brain hypoperfusion in septic patients. Sepsis dysregulates the autonomic nervous system (ANS), potentially affecting CA. ANS function can be assessed through the pupillary light reflex (PLR). The aim of this prospective, observational study was to investigate the association between CA and PLR in adult septic patients. Transcranial Doppler was used to assess CA and calculate estimated cerebral perfusion pressure (eCPP) and intracranial pressure (eICP). An automated pupillometer (AP) was used to record Neurological Pupil Index (NPi), constriction (CV) and dilation (DV) velocities. The primary outcome was the relationship between AP-derived variables with CA; the secondary outcome was the association between AP-derived variables with eCPP and/or eICP. Among 40 included patients, 21 (53%) had impaired CA, 22 (55%) had low eCPP (<60 mmHg) and 15 (38%) had high eICP (>16 mmHg). DV was lower in patients with impaired CA compared to others; DV predicted impaired CA with area under the curve, AUROC= 0.78 [95% Confidence Interval, CI 0.63−0.94]; DV < 2.2 mm/s had sensitivity 85% and specificity 69% for impaired CA. Patients with low eCPP or high eICP had lower NPi values than others. NPi was correlated with eCPP (r = 0.77, p < 0.01) and eICP (r = −0.87, p < 0.01). Automated pupillometry may play a role to assess brain hemodynamics in septic patients.

Harmonization of Physiological Data in Neurocritical Care: Challenges and a Path Forward

Continuous multimodal monitoring in neurocritical care provides valuable insights into the dynamics of the injured brain. Unfortunately, the "readiness" of this data for robust artificial intelligence (AI) and machine learning (ML) applications is low and presents a significant barrier for advancement. Harmonization standards and tools to implement those standards are key to overcoming existing barriers. Consensus in our professional community is essential for success.

Prognostic Value of the Neurological Pupil Index in Patients With Acute Subarachnoid Hemorrhage

BACKGROUND

The Neurological Pupil index (NPi) provides a quantitative assessment of pupil reactivity and may have prognostic value in patients with subarachnoid hemorrhage (SAH). We aimed to explore associations between the NPi and clinical outcomes in patients with SAH.

METHODS

A retrospective analysis of 79 consecutive patients with acute SAH. Age, sex, Acute Physiology and Chronic Health Evaluation-II score, and respiratory failure and NPi in each eye were recorded at admission. The primary outcomes included death and poor clinical outcome (defined as inpatient death, care withdrawal, or discharge Glasgow Outcome Score <4). Groups were compared using the Fisher exact test, and predictive models developed with fast-and-frugal trees (FFTs).

RESULTS

A total of 53 patients were included: 21 (40%) had poor clinical outcomes and 2 (4%) died. Univariate analysis found that only APACHE-II score (P < 0.001) and respiratory failure (P = 0.04) were significantly associated with poor clinical outcomes. NPi was lower among patients with poor clinical outcomes (mean 4.3 in the right eye and 4.2 in the left eye) vs those without (mean 4.5 in the right eye and 4.5 in the left eye), but neither was significant. However, the most accurate FFTs for death and poor clinical outcome included NPi after accounting for age in the death FFT and APACHE-II score in the poor outcome FFT (sensitivity [sn] = 100%, specificity [sp] = 94%, and accuracy (ac) = 94% in a model for death; sn = 100%, sp = 50%, and ac = 70%) in a model for poor clinical outcome.

CONCLUSIONS

Our study supports the NPi as a useful prognostic marker for poor outcomes in acute SAH after accounting for age and APACHE-II score.

Optic Disc Edema and Elevated Intracranial Pressure (ICP): A Comprehensive Review of Papilledema

Papilledema is a swelling of the optic disc secondary to elevated intracranial pressure (ICP). We analyzed 79 peer-review journal articles and provided a concise summary of the etiology, epidemiology, pathophysiology, clinical presentation, evaluation, natural history, differential diagnosis, treatment, and prognosis of papilledema. Only studies written in English with the full text available were included. Although many etiologies of papilledema exist, idiopathic intracranial hypertension is the most common and, thus, a large focus of this review.

Neurological Pupil Index for the Early Prediction of Outcome in Severe Acute Brain Injury Patients

In this study, we examined the early value of automated quantitative pupillary examination, using the Neurological Pupil index (NPi), to predict the long-term outcome of acute brain injured (ABI) patients. We performed a single-centre retrospective study (October 2016−March 2019) in ABI patients who underwent NPi measurement during the first 3 days following brain insult. We examined the performance of NPi—alone or in combination with other baseline demographic (age) and radiologic (CT midline shift) predictors—to prognosticate unfavourable 6-month outcome (Glasgow Outcome Scale 1−3). A total of 145 severely brain-injured subjects (65 traumatic brain injury, TBI; 80 non-TBI) were studied. At each time point tested, NPi <3 was highly predictive of unfavourable outcome, with highest specificity (100% (90−100)) at day 3 (sensitivity 24% (15−35), negative predictive value 36% (34−39)). The addition of NPi, from day 1 following ABI to age and cerebral CT scan, provided the best prognostic performance (AUROC curve 0.85 vs. 0.78 without NPi, p = 0.008; DeLong test) for 6-month neurological outcome prediction. NPi, assessed at the early post-injury phase, has a superior ability to predict unfavourable long-term neurological outcomes in severely brain-injured patients. The added prognostic value of NPi was most significant when complemented with baseline demographic and radiologic information.

Pilot Study of Neurologic Pupil Index as A Predictor of External Ventricular Drain Clamp Trial Failure After Subarachnoid Hemorrhage

BACKGROUND

External ventricular drains (EVDs) provide a temporary egress for cerebrospinal fluid (CSF) in patients with symptomatic hydrocephalus following aneurysmal subarachnoid hemorrhage. Before EVD removal, a wean trial, which involves clamping the EVD, is typically attempted to ensure that CSF self-regulation is achieved. Automated infrared pupillometry (AIP) has been shown to detect early neurologic decline. We sought to explore the use of AIP to detect early EVD clamping trial failure.

METHODS

This prospective observational pilot study enrolled aneurysmal subarachnoid hemorrhage patients before an EVD clamp trial. On initiating the clamp trial, nurses included hourly AIP assessment in documentation. Clamp trial outcome was based on neurologic examination and neuroimaging. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) models were constructed to explore computed tomography (CT) versus AIP as predictors of clamp trial outcome.

RESULTS

Among the 30 subjects enrolled, there were 38 clamping trials and 22 successful EVD removals. CT scan as a predictor of clamp trial was found to have a sensitivity of 68.8% and specificity of 89.5% (PPV = 84.6%, NPV = 77.3%). AIP assessment as a predictor of wean trial outcome was found to have a sensitivity of 58.3% and specificity of 100% (PPV = 100%, NPV = 63.2%).

CONCLUSIONS

The pilot study data support that Neurological Pupil index <3 is a potential indicator of early clamp trial failure, but a CT scan has a higher sensitivity and NPV for predicting successful EVD removal. This finding suggests the benefits of including AIP assessments during clamping trials.

Multimodal Neurologic Monitoring in Children With Acute Brain Injury

Children with acute neurologic illness are at high risk of mortality and long-term neurologic disability. Severe traumatic brain injury, cardiac arrest, stroke, and central nervous system infection are often complicated by cerebral hypoxia, hypoperfusion, and edema, leading to secondary neurologic injury and worse outcome. Owing to the paucity of targeted neuroprotective therapies for these conditions, management emphasizes close physiologic monitoring and supportive care. In this review, we will discuss advanced neurologic monitoring strategies in pediatric acute neurologic illness, emphasizing the physiologic concepts underlying each tool. We will also highlight recent innovations including novel monitoring modalities, and the application of neurologic monitoring in critically ill patients at risk of developing neurologic sequelae.

How to manage traumatic brain injury without invasive monitoring?

PURPOSE OF REVIEW

Severe traumatic brain injury (TBI) is an extremely serious health problem, especially in low-middle income countries (LMICs). The prevalence of severe TBI continues to increase in LMICs. Major limitations in the chain of care for TBI patients are common in LMICs including suboptimal or nonexistent prehospital care, overburdened emergency services, lack of trained human resources and limited availability of ICUs. Basic neuromonitoring, such as intracranial pressure, are unavailable or underutilized and advanced techniques are not available.

RECENT FINDINGS

Attention to fundamental principles of TBI care in LMICs, including early categorization, prevention and treatment of secondary insults, use of low-cost technology for evaluation of intracranial bleeding and neuromonitoring, and emphasis on education of human resources and multidisciplinary work, are particularly important in LMICs. Institutional collaborations between high-income and LMICs have developed evidence focused on available resources. Accordingly, an expert group have proposed consensus recommendations for centers without availability of invasive brain monitoring.

SUMMARY

Severe TBI is very prevalent in LMIC and neuromonitoring is often not available in these environments. When intracranial pressure monitors are not available, careful attention to changes on clinical examination, serial imaging and noninvasive monitoring techniques can help recognize intracranial hypertension and effectively guide treatment decisions.

Endotypes and the Path to Precision in Moderate and Severe Traumatic Brain Injury

Heterogeneity is recognized as a major barrier in efforts to improve the care and outcomes of patients with traumatic brain injury (TBI). Even within the narrower stratum of moderate and severe TBI, current management approaches do not capture the complexity of this condition characterized by manifold clinical, anatomical, and pathophysiologic features. One approach to heterogeneity may be to resolve undifferentiated TBI populations into endotypes, subclasses that are distinguished by shared biological characteristics. The endotype paradigm has been explored in a range of medical domains, including psychiatry, oncology, immunology, and pulmonology. In intensive care, endotypes are being investigated for syndromes such as sepsis and acute respiratory distress syndrome. This review provides an overview of the endotype paradigm as well as some of its methods and use cases. A conceptual framework is proposed for endotype research in moderate and severe TBI, together with a scientific road map for endotype discovery and validation in this population.

Prognostic role of automatic pupillometry in sepsis: a retrospective study

BACKGROUND

Sepsis-associated brain dysfunction is a frequent disorder in septic patients and has a multifactorial pathophysiology. Cholinergic pathways and brainstem dysfunction may result in pupillary alterations. The aim of this study was to evaluate whether early assessment of the Neurological Pupil Index (NPiTM) derived from an automated pupillometry could predict mortality in critically ill septic patients.

METHODS

Retrospective cohort study of adult critically ill septic patients admitted to the intensive care unit of an University Hospital; patients with acute or known brain damage were excluded. The severity of the patients was assessed by the daily Sequential Organ Failure Assessment score and the SOFAmax (i.e. highest SOFA score during the first 5 days) was computed. The worst NPi (i.e. lowest value from one eye) was collected daily and then computed over the first 5 days of assessment. Mortality was assessed at hospital discharge.

RESULTS

A total of 75 patients were included over the study period (median age 67 [53-75] years and median SOFA score at admission 10 [8-12]); 64 (85%) presented septic shock; 48 (64%) died at hospital discharge. The worst NPi during the first 5 days of sepsis was significantly lower in non-survivors compared to survivors (4.4 [3.6-4.6] vs. 4.5 [4.2-4.7]; p=0.042). The worst NPi was also significantly lower in high severity group (i.e. SOFAmax≥12) when compared to others (4.4 [3.2- 4.5] vs 4.5 [4.0-4.7] p=0.01). However, in the multivariate analyses, the NPi value was not independently associated with in-hospital mortality or high SOFAmax.

CONCLUSIONS

In this study, no independent prognostic role of NPi was observed in septic patients. Further larger prospective studies are needed to better evaluate the role of automated pupillometry in this setting.

Early Pupillometry Assessment in Traumatic Brain Injury Patients: A Retrospective Study

BACKGROUND

The aim of this study was to evaluate whether the early assessment of neurological pupil index (NPi) values derived from automated pupillometry could predict neurological outcome after traumatic brain injury (TBI).

METHODS

Retrospective observational study including adult (>18 years) TBI patients admitted from January 2018 to December 2020, with available NPi on admission. Abnormal NPi was considered if <3. Unfavorable neurological outcome (UO) at hospital discharge was considered for a Glasgow Outcome Scale of 1-3.

RESULTS

100 patients were included over the study period (median age 48 (34-69) years and median GCS on admission 11 (6-15)); 49 (49%) patients had UO. On admission, 20 (20%) patients had an abnormal NPi (NPi < 3); median worst (i.e., from both eyes) NPi was 4.2 (3.2-4.5). Median worst and mean NPi on admission were significantly lower in the UO group than others (3.9 (1.7-4.4) vs. 4.4 (3.7-4.6); p = 0.005-4.0 (2.6-4.5) vs. 4.5 (3.9-4.7); p = 0.002, respectively). The ROC curve for the worst and mean NPi showed a moderate accuracy to predict UO (AUC 0.66 (0.56-0.77); p = 0.005 and 0.68 (0.57-0.78); p = 0.002). However, in a generalized linear model, the prognostic role of NPi on admission was limited.

CONCLUSIONS

Low NPi on admission has limited prognostic value in TBI.

Epidemiology, patterns of care and outcomes of traumatic brain injury in deployed military settings: implications for future military operations

BACKGROUND

Traumatic brain injury (TBI) is prevalent and highly morbid among Service Members. A better understanding of TBI epidemiology, outcomes, and care patterns in deployed settings could inform potential approaches to improve TBI diagnosis and management.

METHODS

A retrospective cohort analysis of Service Members who sustained a TBI in deployed settings between 2001 and 2018 was conducted. Among individuals hospitalized with TBI, we compared the demographic characteristics, mechanism of injury, injury type, and severity between combat and non-combat injuries. We compared diagnostic tests and procedures, evacuation patterns, return to duty rates and days in care between individuals with concussion and those with severe TBI.

RESULTS

There were 46,309 Service Members with TBI and 9,412 who were hospitalized; of those hospitalized, 55% (4,343) had isolated concussion and 9% (796) had severe TBI, of whom 17% (132/796) had polytrauma. Overall mortality was 2% and ranged from 0.1% for isolated concussion to 18% for severe TBI. The vast majority of TBI were evacuated by rotary wing to Role 3 or higher, including those with isolated concussion. As compared to severe TBI, individuals with isolated concussion had fewer diagnostic or surgical procedures performed. Only 6% of Service Members with severe TBI were able to return to duty as compared to 54% of those with isolated concussion. TBI resulted in 123,677 lost duty days; individuals with isolated concussion spent a median of 2 days in care and those with severe TBI spent a median of 17 days in care and a median of 6 days in the intensive care unit.

CONCLUSIONS

While most TBI in the deployed setting is mild, TBI is frequently associated with hospitalization and polytrauma. Over-triage of mild TBI is common. Improved TBI capabilities applicable to forward settings will be critical to the success of future multi-domain operations with limitations in air superiority.

LEVEL OF EVIDENCE

Prognostic, Level III.

Fixed, Dilated, and Conversing—Unreactive Pupil With Preserved Consciousness Indicating Acutely Rising Intracranial Pressure due to Traumatic Intraparenchymal Contusions: Case Report and Review of the Literature

Patients with fixed and dilated pupils (FDPs) due to rising intracranial pressure (ICP) typically experience a deterioration in consciousness. We describe an exceptional case of a patient with bifrontal contusions who developed worsening edema and a unilaterally FDP while maintaining consciousness and the ability to communicate. A 58-year-old man with history of hypertension and diabetes mellitus type II presented after being assaulted, with bifrontal contusions and right frontal intraparenchymal hemorrhage. On hospital day 8, his right pupil became fixed (NPi 0) and dilated (4.8 mm). The patient was drowsy, arousable to tactile stimuli, answering questions, oriented to place and time, following commands on his right side, maintaining Glasgow Coma Scale of 14 (E4, V5, M6). He described complete loss of vision and could not identify objects or count fingers. His gaze was dysconjugate with impaired vertical excursion and inability to fully abduct to the right side. Corneal reflexes were intact bilaterally. Hypertonic saline and mannitol produced no improvement in his pupillary exam. Head computed tomography showed worsening midline shift and interval increase in subfalcine herniation related to increased peri-hematoma edema. We performed an emergent right-sided decompressive hemicraniectomy with durotomy and duraplasty. His pupil became reactive 5 hours after surgery. While FDP without deterioration of consciousness has been described due to traumatic subdural and epidural hematomas, we report this unusual constellation as a sign of rising ICP and impeding herniation due to intraparenchymal contusions, highlighting that any pupillary change warrants prompt work-up and intervention.

Anisocoria Correlates With Injury Severity and Outcomes After Blunt Traumatic Brain Injury

ABSTRACT

BACKGROUND: Automated infrared pupillometry (AIP) has been shown to be helpful in the setting of aneurysmal subarachnoid hemorrhage and stroke as an indicator of imminent irreversible brain injury. We postulated that the early detection of pupillary dysfunction after light stimulation using AIP may be useful in patients with traumatic brain injury (TBI). METHODS: We performed a retrospective review of the Establishing Normative Data for Pupillometer Assessment in Neuroscience Intensive Care database, a prospectively populated multicenter registry of patients who had AIP measurements taken during their intensive care unit admission. The primary eligibility criterion was a diagnosis of blunt TBI. Ordinal logistic modeling was used to explore the association between anisocoria and daily Glasgow Coma Scale scores and discharge modified Rankin Scale scores from the intensive care unit and from the hospital. RESULTS: Among 118 subjects in the who met inclusion, there were 6187 pupillometer readings. Of these, anisocoria in ambient light was present in 12.8%, and that after light stimulation was present in 9.8%. Anisocoria after light stimulation was associated with worse injury severity (odds ratio [OR], 0.26 [95% confidence interval (CI), 0.14-0.46]), lower discharge Glasgow Coma Scale scores (OR, 0.28 [95% CI, 0.17-0.45]), and lower discharge modified Rankin Scale scores (OR, 0.28 [95% CI, 0.17-0.47]). Anisocoria in ambient light showed a similar but weaker association. CONCLUSION: Anisocoria correlates with injury severity and with patient outcomes after blunt TBI. Anisocoria after light stimulation seems to be a stronger predictor than does anisocoria in ambient light. These findings represent continued efforts to understand pupillary changes in the setting of TBI.