Average Intracranial Pressure Research Articles

Intracranial pulse pressure amplitude as an indicator of intracranial compliance: observations in symptomatic children with Chiari malformation type I.

Reduced intracranial compliance (ICC) may be an important factor in the pathophysiology of Chiari malformation type I (CM-I). However, direct measurement of ICC is controversial because of its invasiveness, particularly in children. Instead, ICC may be estimated from continuous measurements of intracranial pressure (ICP), where the metric mean wave amplitude (MWA) has been found to be more useful as a surrogate marker of ICC than mean ICP. This observational study investigated the distribution of MWA and mean ICP in symptomatic children with CM-I, as well as their association with clinical and radiological findings. From a consecutive series of children treated for CM-I at a single institution between 2006 and 2023, the authors analyzed ICP scores in those who underwent an overnight preoperative ICP recording in which MWA was calculated. Clinical and radiological data were retrieved from the patient records. Thirty-seven children (mean age 12.4 ± 3.6 years) with symptomatic CM-I were identified. From the overnight ICP measurements, the average MWA was 5.2 ± 1.3 mm Hg: 56% of children had an abnormal MWA (> 5 mm Hg) and 33% had a borderline MWA (4-5 mm Hg). In contrast, the average mean ICP was 9.7 ± 4.1 mm Hg: 8% of children had an abnormal mean ICP (> 15 mm Hg) and 41% had a borderline mean ICP (10-15 mm Hg). Thus, more children were found to have an abnormal MWA than an abnormal mean ICP (p < 0.001). MWA was significantly higher in the subgroup of children with medullary compression in the foramen magnum, as seen on MRI, than in those without (5.6 ± 1.0 mm Hg vs 4.7 ± 1.4 mm Hg, p = 0.03), whereas a similar difference was not observed for mean ICP (9.9 ± 4.6 mm Hg vs 9.7 ± 3.7 mm Hg, p = 0.889). In this cohort of symptomatic children with CM-I, MWA was more frequently abnormal than mean ICP, with a clinically significant discrepancy in half of the patients. Moreover, MWA was significantly higher in patients with medullary compression. Based on these findings, the authors' interpretation is that in children with CM-I, the ICC may be reduced, as indicated by increased MWA, even though the mean ICP is within normal thresholds.

Transcranial Transmission Ultrasound for Reliable Noninvasive Exclusion of Intracranial Hypertension in Traumatic Brain Injury Patients: A Proof of Concept Study.

For many years, noninvasive methods to measure intracranial pressure (ICP) have been unsuccessful. However, such methods are crucial for the assessment of patients with nonpenetrating traumatic brain injuries (TBIs) who are unconscious. In this study, we explored the use of transcranial transmission ultrasound (TTUS) to gather experimental data through brain pulsatility, assessing its effectiveness in detecting high ICP using machine learning analysis. We included patients with severe TBI under invasive ICP monitoring in our intensive care unit. During periods of both normal and elevated ICP, we simultaneously recorded ICP, arterial blood pressure, heart rate, and TTUS measurements. Our classification model was based on data from 9 patients, encompassing 387 instances of elevated ICP (>15 mmHg) and 345 instances of normal ICP (<10 mmHg), and validated through a leave-one-subject-out method. The study, conducted from October 2021 to October 2022, involved 25 patients with an average age of 61.6 ± 17.6 years, producing 279 datasets with an average ICP of 11.3 mmHg (1st quartile 6.1 mmHg; 3rd quartile 14.8 mmHg). The automated TTUS analysis effectively identified ICP values over 15 mmHg with 100% sensitivity and 47% specificity. It achieved a 100% negative predictive value and a 14% positive predictive value. This suggests that TTUS can accurately rule out high ICP above 15 mmHg in TBI patients, indicating patients who may need immediate imaging or intervention. These promising results, if confirmed and expanded in larger studies, could lead to the first reliable, noninvasive screening tool for detecting elevated ICP.

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

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

Intracranial Pressure Evaluation in Swine During Full-Endoscopic Lumbar Spine Surgery

Neurological complications during full-endoscopic spine surgery (FESS) might be attributed to intracranial pressure (ICP) increase due to continuous saline infusion (CSI). Understanding CSI and ICP correlation might modify irrigation pump usage. This study aimed to evaluate invasive ICP during interlaminar FESS; correlate ICP with irrigation pump parameters (IPPs); evaluate ICP during saline outflow occlusion, commonly used to control bleeding and improve the surgeon's view; and, after durotomy, simulate accidental dural tear. Five swine were monitored, submitted to total intravenous anesthesia, and positioned ventrally. A parenchymal catheter was installed through a skull burr for ICP monitoring. Lumbar interlaminar FESS was performed until exposure of neural structures. CSI was used within progressively higher IPPs (A [60 mm Hg, 350 mL/minute] to D [150 mm Hg, 700 mL/minute]), and ICP was documented. During each IPP, different situations were grouped: intact dura with open channels (A1-D1) or occlusion test (A2-D2); dural tear with open channels (Ax1-Dx1) or occlusion test (Ax2-Dx2). ICP <20 mm Hg was defined as safe. Basal average ICP was 8.1 mm Hg. Adjustment in total intravenous anesthesia or suspension of tests was necessary due to critical ICP or animal discomfort. It was safe to operate with all IPPs with opened drainage channels (A1-D1) even with dural tear (Ax1-Dx1). Several occlusion tests (A2-D2, Ax2-Dx2) caused ICP increase (e.g., 86.1 mm Hg) influenced by anesthetic state and hemodynamics. During FESS, CSI might critically raise ICP. Keeping drainage channels open, with ideal anesthetic state, ICP remains safe even with high IPPs, despite dural tear. Drainage occlusions can quickly raise ICP, being even more severe with higher IPPs. Total intravenous anesthesia may protect from ICP increase and may allow longer drainage occlusion or higher IPPs.

Analysis of intracranial pressure pulse waveform in traumatic brain injury patients: a CENTER-TBI study.

Intracranial pressure (ICP) pulse waveform analysis may provide valuable information about cerebrospinal pressure-volume compensation in patients with traumatic brain injury (TBI). The authors applied spectral methods to analyze ICP waveforms in terms of the pulse amplitude of ICP (AMP), high frequency centroid (HFC), and higher harmonics centroid (HHC) and also used a morphological classification approach to assess changes in the shape of ICP pulse waveforms using the pulse shape index (PSI). The authors included 184 patients from the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) High-Resolution Sub-Study in the analysis. HFC was calculated as the average power-weighted frequency within the 4- to 15-Hz frequency range of the ICP power density spectrum. HHC was defined as the center of mass of the ICP pulse waveform harmonics from the 2nd to the 10th. PSI was defined as the weighted sum of artificial intelligence-based ICP pulse class numbers from 1 (normal pulse waveform) to 4 (pathological waveform). AMP and PSI increased linearly with mean ICP. HFC increased proportionally to ICP until the upper breakpoint (average ICP of 31 mm Hg), whereas HHC slightly increased with ICP and then decreased significantly when ICP exceeded 25 mm Hg. AMP (p < 0.001), HFC (p = 0.003), and PSI (p < 0.001) were significantly greater in patients who died than in patients who survived. Among those patients with low ICP (< 15 mm Hg), AMP, PSI, and HFC were greater in those with poor outcome than in those with good outcome (all p < 0.001). Whereas HFC, AMP, and PSI could be used as predictors of mortality, HHC may potentially serve as an early warning sign of intracranial hypertension. Elevated HFC, AMP, and PSI were associated with poor outcome in TBI patients with low ICP.

Correlating Intracranial Pressure Following Decompressive Craniectomy With Neurological Outcomes in Severe Traumatic Brain Injury Patients: A Prospective Observational Study.

Introduction Decompressive craniectomies have been performed in settings with raised intracranial pressure (ICP) after severe traumatic brain injury (TBI). A decompressive craniectomy (DC) is an important salvage procedure for intracranial hypertension. The changes in the intracranial microenvironment after a primaryDC are significant in terms of the neurological outcome in the postoperative period. Materials and methods The study comprised 68 patients with severe TBIs who were undergoing primary DC; of these, 59% were male. Recorded data include demographic profiles, clinical features, and cranial computed tomography (CT) scans. All patients underwent a primary unilateral DC with augmentation duraplasty. Intracranial pressure was recorded in the first 24 hours at regular intervals, and the outcome was recorded using the Extended Glasgow Outcome Scale (GOS-E) at two-week and two-month intervals. Results Road traffic accidents (RTAs) are the most common cause of severe TBIs. Imaging studies and intraoperative findings suggest that acute subdural hematomas (SDHs) are the most common pathology leading to high ICP in the postoperative period. Mortality was strongly statistically associated with high ICP values postoperatively at all intervals. The average ICP for the patients who died was 11.871 mmHg higher than the patients who survived (p=0.0009). The Glasgow Coma Scale (GCS) at the time of admission is positively correlated with the neurological outcome at two weeks and two months, with a Pearson correlation coefficient of 0.4190 and 0.4235, respectively. There is a strong negative correlation between ICP in the postoperative period and the neurological outcome at two weeks and two months (Pearson correlation coefficients are -0.828 and -0.841, respectively). Conclusion The results indicate that RTAsare the most common cause of severe TBIs, and acute SDHsare the most common pathology leading to high ICPafter the surgery. ICP values in the postoperative period have a strong negative correlation with survival and neurological outcome.Preoperative GCS and postoperative ICP monitoring are important methods of prognostication and planning further management.

Blood Clots May Compromise Intracranial Pressure Measurement Using Air-Pouch Intracranial Pressure Probes.

Background: Air-pouch balloon-assisted probes have proven to be both simple and reliable tools for intracranial pressure (ICP) monitoring. However, we experienced reproducible falsely high ICP measurements when the ICP probe was inserted into the intracerebral hematoma cavity. Thus, the aim of the experimental and translational study was to analyze the influence of ICP probe placement with regard to measured ICP values. Methods: Two Spiegelberg 3PN sensors were simultaneously inserted into a closed drain system and were connected to two separate ICP monitors thereby allowing for simultaneous ICP measurements. This closed system was also engineered to allow for pressure to be gradually increased in a controlled fashion. Once the pressure was verified using two identical ICP probes, one of the probes was coated with blood in an effort to replicate placement within an intraparenchymal hematoma. Pressures recorded using the coated probe and control probe were then recorded and compared across a range of 0-60 mmHg. In an effort to further the translational relevance of our results, two ICP probes were inserted in a patient that presented with a large basal ganglia hemorrhage that met criteria for ICP monitoring. One probe was inserted into the hematoma and the other into brain parenchyma; ICP values were recorded from both probes and the results compared. Results: The experimental set-up demonstrated a reliable correlation between both control ICP probes. Interestingly, the ICP probe covered with clot displayed a significantly higher average ICP value when compared to the control probe between 0 mmHg and 50 mmHg (p < 0.001); at 60 mmHg, there was no significant difference noted. Critically, this trend in discordance was even more pronounced in the clinical setting with the ICP probe placed within the hematoma cavity having reported significantly higher ICP values as compared to the probe within brain parenchyma. Conclusions: Our experimental study and clinical pilot highlight a potential pitfall in ICP measurement that may result secondary to probe placement within hematoma. Such aberrant results may lead to inappropriate interventions in an effort to address falsely elevated ICPs.

Relationship between edema and intracranial pressure following intracerebral hemorrhage in rat

Elevated intracranial pressure (ICP) is a potentially fatal consequence of intracerebral hemorrhage (ICH). As the mass of the hematoma and regional edema builds, ICP rises and becomes increasingly variable acutely after stroke. High ICP may worsen cellular injury and edema by impairing local tissue perfusion, fueling a cycle that may ultimately cause fatality through ischemia and brain herniation. Time spent above an ICP of 20 mmHg often predicts a greater risk of death and disability following ICH. Compensatory mechanisms combat rising ICP. Classically, these include cerebrospinal fluid volume loss and cerebrovascular autoregulation, such as a reduction in the volume of venous blood. Additional mechanisms such as brain tissue compliance and skull volume compensation may also contribute. Compensatory compliance mechanisms are limited, and they vary by age and many other factors. Animal models of ICH are widely used to assess these variables and to gauge putative therapeutics. Most often those studies rely upon simple measures of edema, which may not accurately predict ICP data. Thus, we analyzed our past studies characterizing ICP, edema, and tissue compliance responses to striatal ICH in rat, including the collagenase (C-ICH) and whole blood models (WB-ICH). We found that both ICH models raised ICP, with greater effects in the C-ICH model, which may thus better reflect clinical findings of concern. Importantly, measures of edema, such as in the damaged hemisphere, on their own are not predictive of average or peak ICP response within either model, unless assessing across a very wide range of injury severities, or when including non-stroke animals. We caution against using edema data as a surrogate measure of mass effect and ICP following ICH.

Prognostic predictive value of intracranial pressure and cerebral oxygen metabolism monitoring in patients with spontaneous intracerebral hemorrhage

ObjectiveOur study aimed to investigate the predictive value of intracranial pressure (ICP) and cerebral oxygen metabolism monitoring in the postoperative prognosis of patients with spontaneous intracerebral hemorrhage (SICH).MethodsThe clinical data of 55 patients with SICH treated by neurosurgery were analyzed retrospectively. These patients were divided into two groups based on postoperative Glasgow Outcome Scale (GOS) scores, i.e., the poor prognosis group (GOS I-III) and the good prognosis group (GOS IV and V). Next, the ICP and cerebral oxygen metabolism indexes, such as brain temperature (BT), cerebral perfusion pressure (CPP), internal jugular venous oxygen saturation (SjvO2), and arterial partial pressure of carbon dioxide (PaCO2), were recorded after the operation. Further, the prognostic differences between the two groups were compared, and the predictive values were evaluated using the receiver operating characteristic curve (ROC) and area under the curve (AUC).ResultsThe results showed that the average ICP and BT in the good prognosis group were lower than those in the poor prognosis group. However, the CPP and SjvO2 in the good prognosis group were higher than those in the poor prognosis group. Moreover, the incidence of low PaCO2 in the poor prognosis group was higher than that in the good prognosis group.ConclusionsOur results demonstrated that the average ICP, BT, CPP, SjvO2, and arterial PaCO2 may reflect the changes in brain function and cerebral blood flow, which are significantly correlated with the prognosis of patients. Further, our findings indicated that the combined postoperative ICP levels with cerebral oxygen metabolism indexes could guide clinical treatments and predict prognosis.

Invasive brain tissue oxygen and intracranial pressure (ICP) monitoring versus ICP-only monitoring in pediatric severe traumatic brain injury.

Severe traumatic brain injury (TBI) is a leading cause of disability and death in the pediatric population. While intracranial pressure (ICP) monitoring is the gold standard in acute neurocritical care following pediatric severe TBI, brain tissue oxygen tension (PbtO2) monitoring may also help limit secondary brain injury and improve outcomes. The authors hypothesized that pediatric patients with severe TBI and ICP + PbtO2 monitoring and treatment would have better outcomes than those who underwent ICP-only monitoring and treatment. Patients ≤ 18 years of age with severe TBI who received ICP ± PbtO2 monitoring at a quaternary children's hospital between 1998 and 2021 were retrospectively reviewed. The relationships between conventional measurements of TBI were evaluated, i.e., ICP, cerebral perfusion pressure (CPP), and PbtO2. Differences were analyzed between patients with ICP + PbtO2 versus ICP-only monitoring on hospital and pediatric intensive care unit (PICU) length of stay (LOS), length of intubation, Pediatric Intensity Level of Therapy scale score, and functional outcome using the Glasgow Outcome Score-Extended (GOS-E) scale at 6 months postinjury. Forty-nine patients, including 19 with ICP + PbtO2 and 30 with ICP only, were analyzed. There was a weak negative association between ICP and PbtO2 (β = -0.04). Conversely, there was a strong positive correlation between CPP ≥ 40 mm Hg and PbtO2 ≥ 15 and ≥ 20 mm Hg (β = 0.30 and β = 0.29, p < 0.001, respectively). An increased number of events of cerebral PbtO2 < 15 mm Hg or < 20 mm Hg were associated with longer hospital (p = 0.01 and p = 0.022, respectively) and PICU (p = 0.015 and p = 0.007, respectively) LOS, increased duration of mechanical ventilation (p = 0.015 when PbtO2 < 15 mm Hg), and an unfavorable 6-month GOS-E score (p = 0.045 and p = 0.022, respectively). An increased number of intracranial hypertension episodes (ICP ≥ 20 mm Hg) were associated with longer hospital (p = 0.007) and PICU (p < 0.001) LOS and longer duration of mechanical ventilation (p < 0.001). Lower minimum hourly and average daily ICP values predicted favorable GOS-E scores (p < 0.001 for both). Patients with ICP + PbtO2 monitoring experienced longer PICU LOS (p = 0.018) compared to patients with ICP-only monitoring, with no significant GOS-E score difference between groups (p = 0.733). An increased number of cerebral hypoxic episodes and an increased number of intracranial hypertension episodes resulted in longer hospital LOS and longer duration of mechanical ventilator support. An increased number of cerebral hypoxic episodes also correlated with less favorable functional outcomes. In contrast, lower minimum hourly and average daily ICP values, but not the number of intracranial hypertension episodes, were associated with more favorable functional outcomes. There was a weak correlation between ICP and PbtO2, supporting the importance of multimodal invasive neuromonitoring in pediatric severe TBI.

Optic Nerve Sheath Viscoelastic Properties: Re-Examination of Biomechanical Behavior and Clinical Implications.

Meta-analyses show a variable relationship between optic nerve sheath diameter (ONSD) and the presence of raised intracranial pressure (ICP). Because optic nerve sheath (ONS) tissue can be deformed, it is possible that ONSD reflects not only the current ICP but also prior deforming biomechanical exposures. In this post hoc analysis of two published data sets, we characterize ONS Young's modulus (E, mechanical stress per unit of strain) and calculate threshold pressure for plastic deformation. The authors of two previously published articles contributed primary data for these unique post hoc analyses. Human cadaveric ex vivo measurements of ONSD (n = 10) and luminal distending pressure (range 5 to 65mm Hg) were used to calculate E and the threshold pressure for plastic deformation. Clinical in vivo measurements of ONSD and ICP during endotracheal tube suction from patients with traumatic brain injury (n = 15) were used to validate the ex vivo cadaveric findings. Ex vivo ONS estimate of E was 140 ± 1.3mm Hg (mean ± standard error), with evidence of plastic deformation occurring with distending pressure at 45mm Hg. Similar E (71 ± 10mm Hg) was estimated in vivo with an average ICP of 34 ± 2mm Hg. Ex vivo, ONS plastic deformation occurs at levels of pressure commonly seen in patients with raised ICP, leading to distortion of the ICP-ONSD relationship. This evidence of plastic deformation may illustrate why meta-analyses fail to identify a single threshold in ONSD associated with the presence of raised ICP. Future studies characterizing time-dependent viscous characteristics of the ONS will help determine the time course of ONS tissue biomechanical behavior.

Clinical effects of hypertonic saline boluses in children with severe traumatic brain injury.

To quantify the effects of 3% hypertonic saline (HTS) boluses on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in children. A retrospective study of patients admitted to a regional neurosurgical children's intensive care unit. A total of 156 HTS boluses were given to children with traumatic brain injury. ICP decreased 6 mmHg (P < 0.01) and CPP increased 4 mmHg (P=0.003) 1-h post-bolus. Effects persisted for 3 h post-dose ICP was 5 mmHg lower) and 4 h post-bolus CPP was 3 mmHg higher. ICP change was not associated with pre-bolus serum sodium concentration. Hypertonic saline 3% at 5 mL/kg is an effective osmolar therapy for reducing ICP and increasing CPP in children for up to 3 h. '53-53' is a suitable guide - 5 mL/kg of 3% HTS will on average decrease ICP by at least 5 mmHg for 3 h. Pre-bolus serum sodium concentration is not correlated with effect size.

Application of continuous monitoring of intracranial pressure and brain oxygen partial pressure in the treatment of patients with severe craniocerebral injury

To investigate the effects of continuous monitoring intracranial pressure (ICP) and brain oxygen partial pressure (PbtO2) on the prognosis of patients with severe craniocerebral injury. A prospective randomized controlled trial was conducted. Seventy patients with severe craniocerebral injury with a Glasgow coma score (GCS) 4-8 admitted to the neurosurgical intensive care unit (NICU) of the People's Hospital of Inner Mongolia Autonomous Region from January 2017 to May 2020 were enrolled, and they were divided into ICP monitoring group and ICP+PbtO2 monitoring group by random number table. Patients in ICP monitoring group received ICP monitoring and were given traditional treatment of controlling ICP and cerebral perfusion pressure (CPP), the therapeutic target was ICP < 20 mmHg (1 mmHg = 0.133 kPa) and CPP > 60 mmHg. Patients in ICP+PbtO2 monitoring group were given ICP and PbtO2 monitoring at the same time, and oxygen flow was adjusted on the basis of controlling ICP and CPP to maintain the PbtO2 > 20 mmHg, and the therapeutic target of ICP and CPP was the same as the ICP monitoring group. ICP and PbtO2 values were recorded during monitoring in the two groups, the results of CPP, GCS and arterial blood gas analysis were recorded, and the prognosis at 3 months and 6 months after injury was compared by Glasgow outcome scale (GOS) score between the two groups. GOS score > 3 was considered as good prognosis. Kaplan-Meier survival curve was drawn, and the 3-month and 6-month cumulative survival rates of the two groups were analyzed. Linear regression analysis was used to further evaluate the relationship between PbtO2 and GOS score. Finally, a total of 70 patients with severe craniocerebral injury were enrolled in the analysis, 34 patients received ICP combined with PbtO2 monitoring and guided therapy, and 36 patients received ICP monitoring alone. The average ICP of ICP+PbtO2 monitoring group was significantly lower than that of ICP monitoring group (mmHg: 13.4±3.2 vs. 18.2±8.3, P < 0.01). Although the CPP in both groups was great than 60 mmHg, the average CPP of ICP+PbtO2 monitoring group was significantly higher than that of ICP monitoring group (mmHg: 82.1±10.5 vs. 74.5±11.6, P < 0.01). No significant difference was found in average GCS score or arterial partial pressure of carbon dioxide (PaCO2) between the ICP+PbtO2 monitoring group and ICP monitoring group [GCS score: 5.3±2.3 vs. 5.2±2.2, PaCO2 (mmHg): 33.5±4.8 vs. 32.6±5.2, both P > 0.05]. The average arterial partial pressure of oxygen (PaO2) of ICP+PbtO2 monitoring group was obviously higher than that of ICP monitoring group (mmHg: 228.4±93.6 vs. 167.3±81.2, P < 0.01). Compared with the ICP monitoring group, the good outcome rates of 3 months and 6 months after injury in the ICP+PbtO2 monitoring group were significantly higher (3 months: 67.6% vs. 38.9%, 6 months: 70.6% vs. 41.7%, both P < 0.05). Kaplan-Meier survival curve showed that the 3-month and 6-month cumulative survival rates of ICP+PbtO2 monitoring group were significantly higher than those of ICP monitoring group (3 months: 85.3% vs. 61.1%, Log-Rank test: χ2 = 5.171, P = 0.023; 6 months: 79.4% vs. 55.6%, Log-Rank test: χ2 = 4.511, P = 0.034). Linear regression analysis showed that PbtO2 was significantly correlated with GOS score at 3 months and 6 months after injury in patients with severe craniocerebral injury (r values were 0.951 and 0.933, both P < 0.01). PbtO2 compared with ICP monitoring guiding therapy is valuable in improving the prognosis of patients with severe craniocerebral injury. It can improve the prognosis at 3-6 months after injury.

The role of pulsatile and static intracranial pressure measurements in the management of children with craniosynostosis-an institutional experience from 49 patients.

Although measurement of intracranial pressure (ICP) has occasionally been utilized in children with craniosynostosis (CSS), data on parameters of pulsatile ICP in CSS are still lacking, and the role of pulsatile ICP measurements in the management of CSS is not well established. From our department's database, we retrieved the data from children in whom the measurement of static and pulsatile ICP was a part of the diagnostic work-up in different clinical situations related to CSS. Both clinical and ICP data were retrospectively reviewed and analyzed. We identified 49 children with CSS, median age 4.4years (range 0.2-18.9), in whom a total of 67 diagnostic ICP measurements were undertaken between 2002 and 2014. The CSS was syndromal in 23 cases. The rationale for ICP measurement was a question of indication for cranial vault expansion surgery (CVES) in 12 patients (Group 1), of its timing in 10 patients (Group 2), of suspected abnormally elevated ICP or hydrocephalus in 11 patients (Group 3), of indication for repeated CVES in 13 patients (Group 4), or shunt dysfunction in three patients (Group 5). The average mean ICP for the whole cohort was 15.1 ± 5.5mmHg and mean wave amplitude (MWA) 5.3 ± 2.2mmHg. There was no significant difference in ICP parameters when compared between Groups 1-5. Fundoscopy revealed papilledema in five out of 32 children (15.6%). There were significantly higher parameters of pulsatile ICP (MWA) in patients with papilledema, but no statistically significant difference in parameters of static ICP. In this cohort of pediatric patients with CSS presenting with various diagnostic challenges, we found the diagnostic measurement of static and pulsatile ICP useful in selecting the optimal treatment modality and timing of surgery. Papilledema was associated with elevated pulsatile ICP, a parameter that in previous studies has been shown to correlate with impaired intracranial compliance.

Randomized Clinical Trial of 20% Mannitol Versus 3% Hypertonic Saline in Children With Raised Intracranial Pressure Due to Acute CNS Infections.

Mannitol is a commonly used osmotherapy agent in raised intracranial pressure. However, the side effects of mannitol are significant. In traumatic brain injury (adult and pediatric), hypertonic saline (3%) shows varied results in comparison with 20% mannitol. We compared the effect of 3% hypertonic saline versus 20% mannitol (using common dosing strategies) on raised intracranial pressure in pediatric acute CNS infections. Open-label randomized controlled trial. PICU of a quaternary care academic institute. Children 1-12 years old, with raised intracranial pressure and modified-Glasgow Coma Scale scores less than or equal to 8, were enrolled. Patients were randomly assigned to 20%-mannitol (n = 28), 0.5 gram/kg/dose versus 3%-hypertonic saline (n = 29), 10 mL/kg loading followed by 0.5-1 mL/kg/hr infusion. An intraparenchymal catheter was used to monitor the intracranial pressure. The primary outcome was the proportion of patients achieved target average intracranial pressure less than 20 mm Hg during 72 hours. Secondary outcomes were interventions, morbidity, and mortality. The proportion of patients with target average intracranial pressure (< 20 mm Hg) was higher in hypertonic saline-group as compared to mannitol-group (79.3% vs 53.6%; adjusted hazard ratio 2.63; 95% CI: 1.23-5.61). Mean (± SE) reduction of intracranial pressure (-14.3 ± 1.7 vs -5.4 ± 1.7 mm Hg; p ≤ 0.001) and elevation of cerebral perfusion pressure (15.4 ± 2.4 vs 6 ± 2.4 mm Hg; p = 0.007) from baseline were significant in hypertonic saline-group. Mean (± SE) intracranial pressure over 72 hours was lower (14 ± 2 vs 22 ± 2 mm Hg; p = 0.009), and cerebral perfusion pressure was higher (65 ± 2.2 vs 58 ± 2.2; p = 0.032) in hypertonic saline-group. Hypertonic saline-group had higher modified-Glasgow Coma Scale score at 72 hours (median, interquartile range 10; 7-11 vs 7; 3-9; p = 0.003), lower mortality (20.7% vs 35.7%; p = 0.21), shorter duration of mechanical ventilation (5 vs 15 d; p = 0.002), and PICU stay (11 vs 19 d; p = 0.016) and less severe neurodisability at discharge (31% vs 61%; p = 0.049). In pediatric acute CNS infections, 3%-hypertonic saline was associated with a greater reduction of intracranial pressure as compared to 20% mannitol.

The Effects of Acute Intracranial Pressure Changes on the Episcleral Venous Pressure, Retinal Vein Diameter and Intraocular Pressure in a Pig Model

ABSTRACT Purpose Orbital veins such as the retinal veins and episcleral veins drain into the cavernous sinus, an intracranial venous structure. We studied the effects of acute intracranial pressure (ICP) elevation on episcleral venous pressure, intraocular pressure and retinal vein diameter in an established non-survival pig model. Methods In six adult female domestic pigs, we increased ICP in 5 mm Hg increments using saline infusion through a lumbar drain. We measured ICP (using parenchymal pressure monitor), intraocular pressure (using pneumatonometer), episcleral venous pressure (using venomanometer), retinal vein diameter (using OCT images) and arterial blood pressure at each stable ICP increment. The average baseline ICP was 5.4 mm Hg (range 1.5–9 mm Hg) and the maximum stable ICP ranged from 18 to 40 mm Hg. Linear mixed models with random intercepts were used to evaluate the effect of acute ICP increase on outcome variables. Results With acute ICP elevation, we found loss of retinal venous pulsation and increased episcleral venous pressure, intraocular pressure and retinal vein pressure in all animals. Specifically, acute ICP increase was significantly associated with episcleral venous pressure (β = 0.31; 95% CI 0.14–0.48, p < .001), intraocular pressure (β = 0.37, 95%CI 0.24–0.50; p < .001) and retinal vein diameter (β = 11.29, 95%CI 1.57–21.00; p = .03) after controlling for the effects of arterial blood pressure. Conclusion We believe that the ophthalmic effects of acute ICP elevation are mediated by increased intracranial venous pressure producing upstream pressure changes within the orbital and retinal veins. These results offer exciting possibilities for the development of non-invasive ophthalmic biomarkers to estimate acute ICP elevations following significant neuro-trauma.

Significance of ICP-related parameters for the treatment and outcome of severe traumatic brain injury.

ObjectiveTo analyze the significance of intracranial pressure (ICP)-related parameters on outcome in patients with severe traumatic brain injury. The ICP-related parameters included ICP, ICP dose (DICP), regression of the correlation coefficient between amplitude and pressure (RAP), pressure reactivity index (PRx), and cerebral perfusion pressure (CPP).MethodsA retrospective analysis was performed using clinical information from 29 patients with severe traumatic brain injury who were admitted to the Department of Neurosurgery from January 2018 to January 2019. All patients underwent ICP probe implantation after admission. Patients were followed up for 6 months after discharge, and were categorized into either the favorable or unfavorable outcome group based on their Glasgow Outcome Scale score. The differences in ICP, DICP, RAP, PRx, and CPP between the two groups were analyzed for their effects on outcome.ResultsThe average ICP, DICP, PRx, and RAP values in patients with favorable outcomes were significantly lower than in patients with unfavorable outcomes, while CPP values were significantly higher in the favorable outcome group.ConclusionAverage ICP, DICP, PRx, RAP, and CPP values may indicate disease status and relate to patient outcomes. It is important to use multiple parameters to predict patients’ disease severity and prognosis.

Implementation of cisternostomy as adjuvant to decompressive craniectomy for the management of severe brain trauma

ObjectiveTo evaluate the value of an adjuvant cisternostomy (AC) to decompressive craniectomy (DC) for the management of patients with severe traumatic brain injury (sTBI).MethodsA single-center retrospective quality control analysis of a consecutive series of sTBI patients surgically treated with AC or DC alone between 2013 and 2018. A subgroup analysis, “primary procedure” and “secondary procedure”, was also performed. We examined the impact of AC vs. DC on clinical outcome, including long-term (6 months) extended Glasgow outcome scale (GOS-E), the duration of postoperative ventilation, and intensive care unit (ICU) stay, mortality, Glasgow coma scale at discharge, and time to cranioplasty. We also evaluated and analyzed the impact of AC vs. DC on post-procedural intracranial pressure (ICP) and brain tissue oxygen (PbO2) values as well as the need for additional osmotherapy and CSF drainage.ResultsForty patients were examined, 22 patients in the DC group, and 18 in the AC group. Compared with DC alone, AC was associated with significant shorter duration of mechanical ventilation and ICU stay, as well as better Glasgow coma scale at discharge. Mortality rate was similar. At 6-month, the proportion of patients with favorable outcome (GOS-E ≥ 5) was higher in patients with AC vs. DC [10/18 patients (61%) vs. 7/20 (35%)]. The outcome difference was particularly relevant when AC was performed as primary procedure (61.5% vs. 18.2%; p = 0.04). Patients in the AC group also had significant lower average post-surgical ICP values, higher PbO2 values and required less osmotic treatments as compared with those treated with DC alone.ConclusionOur preliminary single-center retrospective data indicate that AC may be beneficial for the management of severe TBI and is associated with better clinical outcome. These promising results need further confirmation by larger multicenter clinical studies. The potential benefits of cisternostomy should not encourage its universal implementation across trauma care centers by surgeons that do not have the expertise and instrumentation necessary for cisternal microsurgery. Training in skull base and vascular surgery techniques for trauma care surgeons would avoid the potential complications associated with this delicate procedure.

A preliminary exploration of acute intracranial pressure-cerebrospinal fluid production relationships in experimental hydrocephalus.

CONTEXT:By occluding the fourth ventricle simultaneously obtaining telemetric data on intracranial pressure (ICP) and cerebrospinal fluid (CSF) production, the authors of this study investigate a variety of physiologic parameters in cases of experimental hydrocephalus.AIMS:The aim of this study is to provide a new context on the disrupted homeostasis in hydrocephalus and guide toward improved treatment based on multiple physiological parameters.MATERIALS AND METHODS:Hydrocephalus was induced in ten 21-day-old Sprague–Dawley rats by blocking the flow of CSF to the fourth ventricle with kaolin. Ten days post induction, when physical signs of ventriculomegaly reached Evan's ratio (ER) of ≥0.46, CSF flow and ICP were measured while manipulating body position (0°, 45°, 90°) and heart rate.RESULTS:In hydrocephalic animals (ER ≥0.46), we found a near-steady average acute ICP (13.638 ± 2.331) compared to age-matched controls (ER <0.30) (13.068 ± 8.781), whose ICP fluctuated with the position. Hydrocephalic and controls exhibited an insignificant degree of parabolic shifts in CSF production when body position was changed from prone to 90° and again when moved back to the prone position, a trend more noteworthy in controls (P = 0.1322 and 0.2772). A Pearson's Correlation found CSF production and ICP to be correlated at baseline 0° posture (P = 0.05) in the control group, but not the hydrocephalic group. Weight appeared to play a role when animals were held at 90°. No significant changes in ICP or CSF flow patterns were observed when the heart rate was increased within either group.CONCLUSIONS:These preliminary findings suggest that our standard assumptions of posture-dependent changes in ICP created using data from physiologic data may be inaccurate in the hydrocephalic patient, and thus describe a need to further explore these relationships.

Abstract 410: Early Imaging Incompletely Predicts Subsequent Cerebral Physiological Derangements After Cardiac Arrest

Introduction: Decreased grey-white matter ratio (GWR) on early head CT scans correlates with poor outcome after cardiac arrest. However, it is unknown if early imaging features fully predict of subsequent derangments in cerebral physiology that cause secondary brain injury. Hypothesis: GWR on early head CT correlates with average intracranial pressure (ICP), brain tissue oxygen (PbtO2), and pressure reactivity (a proxy for cerebral autoregulation) after cardiac arrest. Methods: A total of 30 post-arrest patients were identified over a 3-year period who underwent head CT within 1 day of arrest as well as intracranial monitoring (IM) during hospitalization. 5 patients were excluded either due to unavailable IM recordings (n=1) or motion degraded head CTs (n=4). ICP, P bt O 2 , and mean arterial pressure (MAP) were recorded continuously using a bedside recording unit (CNS Monitor, Moberg Research Inc). Pressure reactivity index (PRx), was calculated as the Pearson correlation coefficient between ICP and MAP over 5 minute intervals, updated every minute. GWR was measured for the basal ganglia from Hounsfield unit measurements made from initial head CT. Relationships between average ICP, PRx, P bt O 2 and GWR was calculated using linear regression. Results: Average GWR for the cohort was 1.2154. Average ICP was weakly correlated with initial GWR (R 2 =0.257, p=0.01). A trend towards higher PRx values was seen with lower initial GWR; however, this did not reach statistical significance (R 2 =0.15, p=0.07). There was no relation between average P bt O 2 and GWR (R 2 =0.02, p=0.56). Conclusions: Lower initial GWR is associated with higher average ICP, and may also be associated with disorderd cerebral autoregulation. However, no relationship could be identified between initial imaging findings and average brain oxygen levels. These data imply that physiological stressors such as brain hypoxia are not predicted by initial imaging findings and suggests a role for invasive neuromonitoring to identify and treat processes that promote secondary brain injury.