Changes In Intracranial Pressure Research Articles

Cerebral haemodynamics and intracranial pressure during haemorrhagic shock and resuscitation with total endovascular balloon occlusion of the aorta in an animal model.

To assess changes of cerebral haemodynamic and intracranial pressure (ICP) in animals, with or without elevated ICP, during controlled haemorrhagic shock and resuscitation with Total REBOA (tREBOA). In 22 anaesthetized and normoventilated pigs, after placement of catheters for monitoring invasive proximal blood pressure (pMAP), ICP, and vital parameters, and 60min stabilisation phase, a controlled haemorrhagic shock (HS), was conducted. In 11 pigs (EICPG), an elevated ICP of 25-30 mmHg at the end HS was achieved by simulating an epidural mass. In 11 pigs (NICPG), the ICP was normal. tREBOA was then applied for 120min. The changes of pMAP and ICP were followed, and cerebral perfusion pressure (CPP) calculated. The integrity of the autoregulation was estimated using a calculated Modified-Long Pressure Reactivity Index (mL-PRx). After stabilisation, hemodynamics and physiological parameters were similar and normal in both groups. At the end of the HS, ICP was 16 mmHg in NICPG vs. 32 in EICPG (p = 0.0010). CPP was 30 mmHg in NICPG vs. 6 mmHg in EICPG (p = 0.0254). After aorta occlusion CPP increased immediately in both groups reaching after 15min up to104 mmHg in NICPG vs. 126 mmHg in EICPG. Cerebrovascular reactivity seems to be altered during bleeding and occlusion phases in both groups with positive mL-PRx. The alteration was more pronounced in EICPG, but reversible in both groups. tREBOA is lifesaving by restoration the cerebral circulation defined as CPP in animals with HS with normal or elevated ICP. Despite the observation of short episodes of cerebral autoregulation impairment during the occlusion, mainly in EICPG, tREBOA seems to be an effective tool for improving cerebral perfusion in HS that extends the crucial early window sometimes known as the "golden hour" for resuscitation even after a traumatic brain injury.

The correlation between intracranial pressure and venous sinus pressures changes after venous sinus stenting

BackgroundThe pathophysiology of idiopathic intracranial hypertension (IIH) and other cerebral venous outflow disorders (CVD) has largely been unexplored. While a correlation between venous sinus pressure and opening pressure (OP) has...

Computational modeling of predicting cerebrovascular injury in traumatic brain injury patients

Despite significant progress in understanding traumatic brain injury (TBI) and subsequent outcomes, predicting and preventing cerebrovascular injury (CVI) remains challenging. We introduces a novel computational modeling approach using advanced fluid-structure interaction (FSI) models, which incorporate high-resolution magnetic resonance imaging (MRI) data to analyze changes in intracranial pressure and blood flow in cerebral arteries post-TBI. We analyzed the mechanical fields between the PCOMA, ICA, PCA, and ACA areas by conducting a region of interest analysis in this research. The approach uniquely integrates detailed patient-specific brain vasculature geometries and dynamic boundary conditions to enhance predictive accuracy. The model indicates that peak pressure in the anterior cerebral artery (ACA) reaches 130 kPa within the first hour post-injury, with a 20% increase observed at 2 milliseconds. Wall shear stress (WSS) in the posterior communicating artery (PCOMA) reaches 140 kPa, which exceeds the typical physiological range of 10–20 kPa and may lead to endothelial damage. Regions such as the PCOMA and ACA are identified as particularly vulnerable to high mechanical stress and strain, which suggests the need for timely medical intervention to reduce the risk of CVI. Further validation with clinical data is required to improve the predictive accuracy of the model.

Effect Of Gravity-induced Intracranial Pressure Changes On Cerebral Blood Flow Regulation During Resistance Exercise

Effect Of Gravity-induced Intracranial Pressure Changes On Cerebral Blood Flow Regulation During Resistance Exercise

The Implication of Photodynamic Therapy Applied to the Level of Tumor Resection on Postoperative Cerebral Edema and Intracranial Pressure Changes in Gliomas.

The aim of our study was to explore the factors influencing cerebral edema and intracranial pressure in glioblastoma multiforme (GBM) patients who undergo photodynamic therapy (PDT) after resection. This was a retrospective controlled study of GBM patients treated with PDT-assisted resections of varying scope from May 2021 to August 2023. The baseline clinical data, cerebral edema volumes, intracranial pressure values, and imaging data of the GBM patients were collected for statistical analysis. A total of 56 GBM patients were included. Thirty of the patients underwent gross total resection (GTR), and the other 26 patients underwent subtotal resection (STR). We found that the cerebral edema volume and the mean intracranial pressure in patients who underwent GTR were lower than those in patients who underwent STR. Moreover, univariate analysis showed that the scope of tumor resection was an independent factor affecting cerebral edema and intracranial pressure after PDT. Compared with STR, PDT combined with GTR significantly reduced postoperative brain edema volume and intracranial pressure in GBM patients.

Intracranial pressure changes in traumatic brain injury patients undergoing unilateral decompressive craniectomy with dural expansion

BackgroundThe aim of this study is to assess the ICP changes induced by a unilateral fronto-temporo-parietal DC with dural expansion after moderate to severe TBI. The effect of different bone flap sizes on ICP and the neurological outcomes were also evaluated after the decompressive surgery. Methods52 TBI patients with clinical and radiological evidences of increased ICP were included in this prospective study. All patients received unilateral fronto-temporo-parietal DC with dural expansion and ventriculostomy at contralateral Kocher's point. Postoperatively, ICP values and the largest antero-posterior (AP) diameter of bone flap removed was measured, and the clinical outcomes were assessed using Extended Glasgow Outcome Scale (GOS-E) at discharge and 6 months after DC. ResultsThe median ICP significantly decreased with an average of 56.7 % reduction from the initial opening ICP. Similar ICP changes were observed in all groups. This study also found that the large bone flap group (AP diameter >15 cm) demonstrated better postoperative ICP control as compared to the small bone flap group (AP diameter 12–15 cm), although not statistically significant. The SDH and cerebral swelling groups did better in the GOS-E at 6 months after TBI compared with cerebral contusion group. ConclusionThe ICP reduction in moderate to severe TBI patients undergoing unilateral fronto-temporo-parietal DC with dural expansion occurred in accordance with decompressive steps, regardless of intracranial lesions and the surgical procedure should be performed with the bone flap size of at least 12 cm in AP diameter for adequate and sustained ICP control.

Noninvasive Method Using Mechanical Extensometer for the Estimation of Intracranial Compliance by Repeated Measures Agreement Analysis.

Intracranial compliance refers to the relationship between changes in volume and the resultant changes in intracranial pressure (ICP). This study aimed to assess the agreement of a noninvasive ICP waveform device for the estimation of compliance compared with invasive ICP monitoring employing three distinct methods. We conducted a retrospective analysis of ICP waveform morphology recorded through both invasive (external ventricular drain) and noninvasive (mechanical extensometer) methods in adult patients with acute brain injury admitted to a neurointensive care unit between August 2021 and August 2022. Compliance was calculated as the amplitude of the fundamental component of cerebral arterial blood volume (estimated with concurrent Transcranial Doppler [TCD] recordings), divided by the amplitude of the fundamental component of the invasive and noninvasive ICP waveforms. Subsequently, we assessed the agreement between invasive and noninvasive intracranial compliance by repeated measures correlation coefficient analysis using three methods: TCD-derived, P2/P1 ratio, and time-to-peak (TTP). A linear mixed-effects model was used to compute the concordance correlation coefficient, total deviation index, and coefficient of individual agreement. Coverage probability plot was calculated to estimate the percent of observations within different cut points for each of the three methods. A total of 21 patients were identified for this study. Repeated measures correlation analysis showed a strong correlation (R = 0.982, 95% confidence interval [0.980-0.984], p < 0.0001) between log-transformed noninvasive and invasive compliance. Agreement statistics for TCD, P2/P1 ratio, and TTP indicated that although the concordance correlation coefficient was highest for log(TCD) values, TTP and P2:P1 ratio measures had better agreement with total deviation index and coverage probability plot analyses. Repeated measures correlations suggest that ICP waveform analyses may offer a more accurate estimate of compliance than TCD-derived methods for noninvasive ICP monitoring. Further validations studies are warranted to confidently establish this method as an indicator of intracranial compliance.

Combined effects of alcohol and lead on cerebrospinal fluid production

Currently, due to the development of industry, a high incidence of heavy metal salt poisoning is observed, especially in people with alcohol dependence. The study aims to investigate the combined effects of these pathogens on the central nervous system. The study demonstrates changes in intracranial pressure and cerebrospinal fluid production in isolated and combined poisoning of lead and ethanol based on experimental models on 10 and 40 days of exposure, 3 main groups were formed – the group of lead salts, ethanol, combined intoxication, after which the main indicators were measured. The effect of separate and combined action of alcohol and lead on cerebrospinal fluid production and haemodynamic indices in experimental animals was studied. It was found at 40-day intoxication indices remained above normal, systemic arterial pressure was 131.8 mmHg, and the rate of cerebrospinal fluid production was 0.073±0.002 ml/min. Combined 10-day combined action of alcohol and lead enhances their excitatory effect, which is characterised by an increase in systemic arterial pressure (to the level of 135.6 mmHg) and general psycho-somatic agitation, the rate of cerebrospinal fluid production was 0.077±0.008 ml/min. The 40-day co-exposure manifested mainly toxic effects of lead, as shown by a decrease in cerebrospinal fluid production of 0.049±0.001 ml/min, and a decrease in blood pressure to a level of 93.6 mmHg. The results of this study will make it possible to develop treatment protocols for patients with ethanol and heavy metal salt poisoning, especially in the field of anti-oedema therapy

Otoacoustic Estimate of Astronauts' Intracranial Pressure Changes During Spaceflight.

To investigate the potential correlation between prolonged exposure to microgravity on the International Space Station and increased intracranial fluid pressure, which is considered a risk factor for the astronauts' vision, and to explore the feasibility of using distortion product otoacoustic emissions as a non-invasive in-flight monitor for intracranial pressure changes. Distortion product otoacoustic emission phase measurements were taken from both ears of five astronauts pre-flight, in-flight, and post-flight. These measurements served as indirect indicators of intracranial pressure changes, given their high sensitivity to middle ear transmission alterations. The baseline pre-flight ground measurements were taken in the seated upright position. In-flight measurements revealed a significant systematic increase in otoacoustic phase, indicating elevated intracranial pressure during spaceflight compared to seated upright pre-flight ground baseline. Noteworthy, in two astronauts, strong agreement was also observed between the time course of the phase changes measured in the two ears during and after the mission. Reproducibility and stability of the probe placement in the ear canal were recognized as a critical issue. The study suggests that distortion product otoacoustic emissions hold promise as a non-invasive tool for monitoring intracranial pressure changes in astronauts during space missions. Pre-flight measurements in different body postures and probe fitting strategies based on the individual ear morphology are needed to validate and refine this approach.

Safety of labor, Valsalva maneuver, and neuraxial anesthesia for pregnant women after decompressive craniectomy: Case series and review of the literature.

Decompressive craniectomies are a neurosurgical operation aimed at normalizing intracranial pressure (ICP). Occasionally, there is delayed replacement of the skull resulting in an acquired skull defect. When managing laboring patients with an acquired skull defect there is often fear associated with traditional labor involving the Valsalva maneuver and with neuraxial anesthesia. These fears typically stem from potential ICP changes and risk of herniation. In reviewing the literature, only 15 cases are described detailing labor management after decompressive craniectomy (DC), mostly with incomplete labor histories. We aim to expand that literature by reporting two cases of safe labor with epidural anesthesia in patients with large skull defects. The first described patient underwent a cranioplasty during pregnancy because of trauma. Later, because of concerns for pre-eclampsia, induction of labor was initiated and she received neuraxial anesthesia via epidural. The patient ultimately underwent cesarean delivery 48 h after induction began due to nonreassuring fetal heart tones. The second patient underwent a cranioplasty because of infection prior to pregnancy. Once in labor, she was cleared by neurosurgery and the anesthesia team placed her epidural. She later underwent an uncomplicated standard vaginal delivery. The existing literature on labor following DC is sparse. Retrospective review of case reports can advance discussion and standardization regarding care for laboring women with a history of DC. We advocate that the Valsalva maneuver and epidural anesthesia is safe for pregnant women who are neurologically asymptomatic.

Optimal target mean arterial pressure for patients with sepsis-associated encephalopathy: a retrospective cohort study

BackgroundSepsis-associated encephalopathy (SAE) patients often experience changes in intracranial pressure and impaired cerebral autoregulation. Mean arterial pressure (MAP) plays a crucial role in cerebral perfusion pressure, but its relationship with mortality in SAE patients remains unclear. This study aims to investigate the relationship between MAP and the risk of 28-day and in-hospital mortality in SAE patients, providing clinicians with the optimal MAP target.MethodsWe retrospectively collected clinical data of patients diagnosed with SAE on the first day of ICU admission from the MIMIC-IV (v2.2) database. Patients were divided into four groups based on MAP quartiles. Kruskal-Wallis H test and Chi-square test were used to compare clinical characteristics among the groups. Restricted cubic spline and segmented Cox regression models, both unadjusted and adjusted for multiple variables, were employed to elucidate the relationship between MAP and the risk of 28-day and in-hospital mortality in SAE patients and to identify the optimal MAP. Subgroup analyses were conducted to assess the stability of the results.ResultsA total of 3,816 SAE patients were included. The Q1 group had higher rates of acute kidney injury and vasoactive drug use on the first day of ICU admission compared to other groups (P < 0.01). The Q1 and Q4 groups had longer ICU and hospital stays (P < 0.01). The 28-day and in-hospital mortality rates were highest in the Q1 group and lowest in the Q3 group. Multivariable adjustment restricted cubic spline curves indicated a nonlinear relationship between MAP and mortality risk (P for nonlinearity < 0.05). The MAP ranges associated with HRs below 1 for 28-day and in-hospital mortality were 74.6–90.2 mmHg and 74.6–89.3 mmHg, respectively.The inflection point for mortality risk, determined by the minimum hazard ratio (HR), was identified at a MAP of 81.5 mmHg. The multivariable adjusted segmented Cox regression models showed that for MAP < 81.5 mmHg, an increase in MAP was associated with a decreased risk of 28-day and in-hospital mortality (P < 0.05). In Model 4, each 5 mmHg increase in MAP was associated with a 15% decrease in 28-day mortality risk (HR: 0.85, 95% CI: 0.79–0.91, p < 0.05) and a 14% decrease in in-hospital mortality risk (HR: 0.86, 95% CI: 0.80–0.93, p < 0.05). However, for MAP ≥ 81.5 mmHg, there was no significant association between MAP and mortality risk (P > 0.05). Subgroup analyses based on age, congestive heart failure, use of vasoactive drugs, and acute kidney injury showed consistent results across different subgroups.Subsequent analysis of SAE patients with septic shock also showed results similar to those of the original cohort.However, for comatose SAE patients (GCS ≤ 8), there was a negative correlation between MAP and the risk of 28-day and in-hospital mortality when MAP was < 81.5 mmHg, but a positive correlation when MAP was ≥ 81.5 mmHg in adjusted models 2 and 4.ConclusionThere is a nonlinear relationship between MAP and the risk of 28-day and in-hospital mortality in SAE patients. The optimal MAP target for SAE patients in clinical practice appears to be 81.5 mmHg.

Evaluation of optic nerve sheath diameter in patients undergoing laparoscopic surgery in the Trendelenburg position: a prospective observational study.

The Trendelenburg position and pneumoperitoneum may cause cerebral edema and increased intracranial pressure. Non-invasive measurement of the diameter of the optic nerve sheath by ultrasonography can provide early recognition of intracranial pressure. Evaluate the optic nerve sheath diameter (ONSD) changes in patients who undergo laparoscopic surgery in the Trendelenburg position and make indirect conclusions about changes in intracranial pressure. Prospective, observational. Laparoscopic surgeries. Patients aged 18-75 years who underwent laparoscopic surgery in the Trendelenburg position under general anesthesia were included in our study. The ONSD was measured four times: Immediately after tracheal intubation, in the neutral position (baseline value) (T0), 10 minutes after pneumoperitoneum and Trendelenburg position (T1), 60 minutes after pneumoperitoneum and Trendelenburg position (T2), and 10 minutes after the pneumoperitoneum is terminated and placed in the neutral position (T3). Compare ONSD measured by ultrasonography at different times of surgery. 40. Arterial carbon dioxide pressure increased with laparoscopy and Trendelenburg position in parallel with ONSD measurements and decreased again after returning to the neutral position. It was still higher than the baseline value at the T3. There was also a significant difference[a] between the measurement made at the T2 and the measurement made at T1. This difference showed that the prolongation of the Trendelenburg time was associated with an increase in ONSD. At the end of the operation it was observed that the decreased statistically significantly (T3) 10 minutes after the pneumoperitoneum was terminated and the position was corrected. However, the ONSD was still higher at the end of the operation (T3) compared to the baseline value measured at the beginning of the operation (T0). The ONSD increased in relation to Trendelenburg position and pneumoperitoneum. With these results, we think the ultrasonographic measurement of ONSD, a non-invasive method, can be used for clinical follow-up when performing laparoscopic surgery in the Trendelenburg position in cases requiring intracranial pressure monitoring. There may be variations in the measurement of ONSD, even in the measurements of the same practitioner, as in all imaging with an ultrasonography device.

P049 RENOVASCULAR HYPERTENSIVE RATS (2K1C) HAVE REDUCED INTRACRANIAL COMPLIANCE INDUCED BY RAISED VENTRICULAR VOLUME COMPARED TO NORMOTENSIVE RATS

Background and Objective: Intracerebroventricular (ICV) infusions of increased volumes of saline can be used to study intracranial compliance (ICC). Since the two-kidneys,1-clip (2K1C) rat model of renovascular hypertension has an enhanced baseline level of intracranial pressure (ICP), the present study aimed to verify the effect of ICV infusions of 0.15 M NaCl on ICP and ICC in 2K1C rats. Methods: Male Holtzman rats (180-210 g) were randomly separated to be normotensive (NT; sham surgery, n = 5) or with 2K1C (n = 5), done by a partial left renal artery occlusion. Six weeks after, rats were anaesthetized with urethane (1.2 g/kg body weight, i.v.), tracheostomized, placed under artificial ventilation, and had an ICP sensor and a needle inserted into the lateral ventricle for, respectively, ICP recording and ICV 0.15 M infusions (30, 60 and 90 μL, at 100 μL/min). There was a 20-minute interval between each infusion. ICC was calculated by the ratio of volume change to ICP change [ICC = ΔV (μL)/Δ ICP (mmHg)]. Results: Baseline MAP, ICP, and P2/P1 ratio of 2K1C rats (166 ± 6 mmHg; 15.7 ± 1.7 mmHg; 1.6 ± 0.1, respectively) were higher than the ones in NT rats (94 ± 5 mmHg; 10.1 ±1.4 mmHg; 0.7 ± 0.1 respectively; p&lt;0.05 vs 2K-1C). ICV infusions induced increased ICP in 2K1C rats (19 ±0.5; 42 ±1.2 and 55 ±5.5 mmHg, vs NT: 8 ±0.6; 25 ±3.2 and 36 ± 4.9 mmHg, respectively at 30, 60 and 90 μL infusion; p&lt;0.05). In addition, 2K1C rats presented a reduced ICC only at 30 μl infusion (5.6 ±1.4, vs NT: 11.4 ±0.9; p&lt;0.05). Conclusions: These findings suggest that renovascular hypertension impairs ICC to the well-documented increase in ICP. Support: FAPESP, CNPq.

Intraoperative Intracranial Pressure Changes in Children With Craniosynostosis Undergoing Endoscopic-Assisted Strip Craniectomy.

Craniosynostosis can lead to progressive cranial and skull base deformities and can be associated with increased intracranial pressure (ICP), ophthalmological manifestations, behavioral changes, and developmental delay. Most published data on the incidence of elevated ICP include older children undergoing open surgical correction. Endoscopic-assisted release of fused sutures with postoperative helmet therapy is an established method for managing craniosynostosis presenting at an early age; however, the immediate effect of this approach on ICP in a young cohort has not been previously reported. Prospective data on 52 children undergoing endoscopic-assisted release of stenosed cranial sutures were included. Individuals were excluded if they underwent open correction or had previous cranial surgery. Individuals underwent a standardized endoscopic approach for each suture type. ICP was measured using an intraparenchymal sensor both before creation of the neosuture and after complete release of the stenosed suture. An ICP reading of >10 mm Hg was considered elevated. The mean age was 5.3 months, range 1 to 32 months, and 94% was younger than 12 months. The mean opening pressure was 12.7 mm Hg, and the mean closing pressure was 2.9 mm Hg. Opening ICP ≥10 mm Hg was present in 58%, ≥15 mm Hg was present in 31%, and ≥20 mm Hg was present in 23%. No patient had an ICP above 10 mm Hg at closing. The mean percentage change in ICP among all craniosynostosis cases was a 64% decrease. Optic disk swelling was identified in 28 children preoperatively and improved in 22 children at follow-up. Elevated ICP may occur in infants with craniosynostosis at higher rates than previously reported. Endoscopic-assisted craniectomy has an immediate effect on lowering ICP and improving postoperative ophthalmological findings.

Intracranial compliance in patients with COVID-19: a multicenter observational study.

Patients with severe coronavirus disease-19 (COVID-19) may require the use of invasive mechanical ventilation (MV) for prolonged periods. Aggressive MV parameters have been associated with changes in intracranial pressure (ICP) in patients with acute intracranial disorders. Significant ICP elevation could compromise intracranial compliance (ICC) and cerebrovascular hemodynamics (CVH). However, the effects of these parameters in individuals without neurological disorders have not yet been evaluated. To evaluate ICC in patients on MV with COVID-19 infection compared to other diagnoses, to better characterize the effects of MV and COVID-19 upon ICC. We also compared between the ICC in patients with COVID-19 who did not require MV and healthy volunteers, to assess the isolated effect of COVID-19 upon ICC. This was an exploratory, observational study with a convenience sample. The ICC was evaluated with a noninvasive ICP monitoring device. The P2/P1 ratio was calculated by dividing the amplitude of these two points, being defined as "abnormal" when P2 > P1. The statistical analysis was performed using a mixed linear model with random effects to compare the P2/P1 ratio in all four groups on the first monitoring day. A convenience sample of 78 subjects (15 MV-COVID-19, 15 MV non-COVID-19, 24 non-MV-COVID-19, and 24 healthy participants) was prospectively enrolled. There was no difference in P2/P1 ratios between MV patients with and without COVID-19, nor between non-MV patients with COVID-19 and healthy volunteers. However, the P2/P1 ratio was higher in COVID-19 patients with MV use than in those without it. This exploratory analysis suggests that COVID-19 does not impair ICC.

Systematic quantitative evaluation of gene polymorphism and therapeutic effect of xingnaojing injection in patients with brain injury.

The incidence of brain injury is increasing year by year, and it has become one of the major diseases threatening human life in today's society. From the perspective of the causes of brain injury, it is mainly due to falls from high places, traffic accidents, etc. Severe brain injury patients often lose consciousness. In recent years, the emergence of integrated traditional Chinese and Western medicine has provided a new approach and new ideas for the treatment of craniocerebral trauma. The article systematically and scientifically expounded the role of Xingnaojing injection in the treatment of brain injury by comparing the GCS (Glasgow Coma Scale) score, changes in intracranial pressure, the incidence of complications after brain injury, the transformation from moderate brain injury to severe brain injury, and recovery of consciousness. For the problem of gene polymorphism in patients with brain injury, this article discussed the role of APOE2 (Apolipoprotein E2), ε3, ε4 in brain injury. All patients had a clear history of trauma and received strict nervous system examination and CT scanning when they were admitted to the hospital. After craniocerebral trauma surgery or conservative therapy, patients should take a Xingnaojing injection of 30 ml and a 0.9% sodium chloride injection of 250 ml after admission. After the operation, respiratory tract nursing should be strengthened, and patients who cannot eat should be given nasal feeding, acupuncture, and physiotherapy to prevent bedridden complications. The probability of epilepsy after brain injury was 27%. The article would help to evaluate the degree of brain damage and prognosis of patients.

Effects of moderate sedation induced by propofol or midazolam on intracranial pressure

Introduction: Propofol and midazolam are the main options for moderate sedation in clinical practice. In addition, these drugs are used to reduce intracranial pressure in cases of intracranial hypertension, and their use in these situations is guided by limited evidence. Objective: To compare the effects of propofol and midazolam on intracranial pressure wave morphology in moderate sedation in patients undergoing upper digestive endoscopy. Methods: Sixty patients were included in this study, being divided into two groups, propofol and midazolam group. Intracranial pressure was monitored during and after upper digestive endoscopy, using non-invasive monitoring equipment developed by the company Brain4care. Arterial pressure was measured before and after the exam. Results: The propofol group had lower intracranial pressure (p=0.037) during moderate sedation compared to intracranial pressure after endoscopy and a significant decrease in systolic (p=0.0001) and diastolic pressure (p=0.001) after sedation. Midazolam, on the other hand, reduced systolic pressure (p=0.001), but didn’t change the other parameters after the procedure. There wasn’t a significant difference between the propofol and midazolam groups. Conclusion: There was no significant difference between the groups studied, however, analyses within the propofol and midazolam groups indicate that propofol, but not midazolam, causes changes in intracranial pressure in moderate sedation.

Which compartments of the optic nerve and its sheath are associated with intracranial pressure? An exploratory study.

The optic nerve sheath diameter (ONSD) is a commonly used estimate of intracranial pressure (ICP). The rationale behind this is that pressure changes in the cerebrospinal fluid affect the optic nerve subarachnoid space (ONSAS) thickness. Still, possible effects on other compartments of the optic nerve sheath (ONS) have not been studied. This is the first study ever to analyze all measurable compartments of the ONS for associations with elevated ICP. We measured changes in ICP and changes in ONS compartments in 75 patients treated with invasive ICP monitoring at the Karolinska University Hospital. Associations between changes in ICP and changes in ONS compartments were estimated with generalized estimating equations. The potential to identify elevated ICP was assessed with the area under the receiver operating characteristic curve (AUROC) for ONS compartments associated with ICP changes. Both ONSAS and perioptic dura mater thickness were significantly associated with changes in ICP in multivariable modeling. ONSAS was the only compartment that independently predicted changes in ICP, with an AUROC of 0.69 for predicting ICP increase. Still, both the perioptic dura mater thickness and the optic nerve diameter added value in predicting ICP changes in multivariable modeling. The results from this study challenge the current understanding of the mechanism behind the association between ICP and ONSD. Contrary to the common opinion that ONSAS is the only affected compartment, this study shows a more complex picture. It suggests that all ONS compartments may add value in predicting changes in ICP.

Intracranial Pressure Thresholds for Cerebral Autoregulation Impairment: Age-Stratified Analysis of Ultra-Low-Frequency Pressure Reactivity Index (UL-PRx) in Traumatic Brain Injury.

The study investigated the effectiveness of low-frequency sampling in detecting alterations in cerebrovascular reactivity (CVR) associated with changes in intracranial pressure (ICP) in patients with traumatic brain injury (TBI) across different age groups. The primary objective was to investigate an ICP threshold that indicates a decrease in CVR as evidenced by a significant increase in the ultra-low-frequency pressure reactivity index (UL-PRx). Additionally, the study aimed to develop an age-based categorization method for patients with TBI to investigate the differences between these ICP thresholds in different age groups. In this retrospective analysis, data from 263 patients with TBI were prospectively collected. ICP and mean arterial pressure were extracted from the hospital database at 5-min intervals. Demographic details, clinical presentation, computed tomography scans, neurosurgical interventions, and 12-months outcome were recorded. ICP versus UL-PRx values were categorized into ICP bins and graphically represented with boxplots for each age group, illustrating how as ICP values rise, there is a bin (age-tailored ICP [AT-ICP]) beyond which UL-PRx shows a sudden increase, indicating CVR loss. Homogeneous age groups were established to obtain a consistent AT-ICP threshold. The discriminatory ability of the AT-ICP thresholds was compared with the guideline-recommended thresholds by calculating the area under the Receiver Operating Characteristic curve of the ICP-derived indices (dose above threshold, and the hourly dosage above threshold). Age groups 0-5, 6-20, 21-60, 61-70, and 71-85years were the best age subdivisions, corresponding to AT-ICP thresholds of 20, 30, 35, 25, and 30mmHg, respectively. The AT-ICP thresholds exhibited better discriminative ability compared with the guideline-recommended thresholds. The AT-ICP thresholds offer a novel approach for estimating CVR impairment and the developed method represents an alternative solution to address the age stratification issue in patients with TBI.

Orthostatic Hemifacial Spasm in Idiopathic Intracranial Hypertension.

Among the symptoms seen in idiopathic intracranial hypertension (IIH), hemifacial spasm (HFS) is rare. Orthostatic-induced HFS preceding lumbar puncture (LP) is previously unreported. We treated two patients with unusual IIH presentations. This case series reviews the few reports of HFS in IIH and proposes a mechanism for spasm occurrence. Case 1: A woman in her mid-40s with previously controlled IIH developed daily headache, pulsatile tinnitus, right-sided trigeminal paresthesia, and right-sided HFS. The latter 2 symptoms occurred exclusively when moving from a sitting to a standing position. Imaging was unremarkable; opening pressure (OP) on LP was 46 cmH2O with normal cerebrospinal fluid (CSF) components. Case 2: A woman in her late 40s presented with severe daily headache, pulsatile tinnitus, and left-sided HFS following weight gain. Imaging was unremarkable; OP on LP was 32 cmH2O with normal CSF components. HFS episodes persisted following LP in both patients. Increasing and initiating acetazolamide, respectively, resolved all symptoms. Earlier suggested mechanisms of HFS are based on elevated intracranial pressure (ICP) shifting the facial nerve into proximity of a vascular structure. HFS appearing upon standing and continuing after LP, and thus a lower ICP, contradicts this. We propose a mechanism based on the degree of ICP change. This theory is grounded in the lack of intracranial compliance in IIH, wherein substantial pressure changes occur following small volume changes.