Bedside ultrasonography of optic nerve sheath diameter for detection of raised intracranial pressure in nontraumatic neurocritically ill patients

BACKGROUND Delay in treatment of raised intracranial pressure(ICP)leads to poor clinical outcomes.Optic nerve sheath diameter(ONSD)by ultrasonography(US-ONSD)has shown good accuracy in traumatic brain injury and neurosurgical patients to diagnose raised ICP.However,there is a dearth of data in neuro-medical intensive care unit(ICU)where the spectrum of disease is different.AIM To validate the diagnostic accuracy of ONSD in non-traumatic neuro-critically ill patients.METHODS We prospectively enrolled 114 patients who had clinically suspected raised ICP due to non-traumatic causes admitted in neuro-medical ICU.US-ONSD was performed according to ALARA principles.A cut-off more than 5.7 mm was taken as significantly raised.Raised ONSD was corelated with raised ICP on radiological imaging.Clinical history,general and systemic examination findings,SOFA and APACHE 2 score and patient outcomes were recorded.RESULTS There was significant association between raised ONSD and raised ICP on imaging(P<0.001).The sensitivity,specificity,positive and negative predictive value at this cut-off was 77.55%,89.06%,84.44% and 83.82% respectively.The positive and negative likelihood ratio was 7.09 and 0.25.The area under the receiver operating characteristic curves was 0.844.Using Youden’s index the best cut off value for ONSD was 5.75 mm.Raised ONSD was associated with lower age(P=0.007),poorer Glasgow Coma Scale(P=0.009)and greater need for surgical intervention(P=0.006)whereas no statistically significant association was found between raised ONSD and SOFA score,APACHE II score or ICU mortality.Our limitations were that it was a single centre study and we did not perform serial measurements or ONSD pre-and post-treatment or procedures for raised ICP.CONCLUSION ONSD can be used as a screening a test to detect raised ICP in a medical ICU and as a trigger to initiate further management of raised ICP.ONSD can be beneficial in ruling out a diagnosis in a low-prevalence population and rule in a diagnosis in a high-prevalence population.

Epidural Blood Patches Performed with Miethke Sensor Reservoir for Continuous Intracranial Pressure Monitoring

An epidural blood patch (EBP) is a procedure performed by injecting autologous blood into a patient’s epidural space, usually at the site of a suspected CSF leak. It is typically performed in patients with characteristic postural headaches due to low intracranial pressure. We report a case of a young female with an implanted Miethke Sensor Reservoir, which was used for continuous intracranial pressure (ICP) monitoring during a two-level epidural blood patch. ICP increased only with thoracic injection, suggesting thoracic EBP may have greater efficacy than lumbar EBP in treating SIH and PDPH when the site of CSF leak is unknown.

Amendment on the strain measurement of thin-walled human skull shell as intracranial pressure changes

The human skull, composed of tabula extema, tabula intema, and a porous diploe sandwiched in between, is deformed with changing intracranial pressure （ICP）. Because the human skull＇s thickness is only 6 mm, it is simplified as a thin-walled shell. The objective of this article is to analyze the strain of the thin-wailed shell by the stress-strain calculation of a human skull with changing ICP. Under the same loading conditions, using finite element analysis （FEA）, the strains of the human skull were calculated and the results were compared with the measurements of the simulative experiment in vitro. It is demonstrated that the strain of the thin-walled shell is totally measured by pasting the one-way strain foils on the exterior surface of the shell with suitable amendment for data. The amendment scope of the measured strain values of the thin-walled shell is from 13.04% to 22.22%.

Outcomes of high-grade aneurysmal subarachnoid hemorrhage patients treated with coiling and ventricular intracranial pressure monitoring

BACKGROUND High-grade aneurysmal subarachnoid hemorrhage is a devastating disease with a low favorable outcome.Elevated intracranial pressure is a substantial feature of high-grade aneurysmal subarachnoid hemorrhage that can result to secondary brain injury.Early control of intracranial pressure including decompressive craniectomy and external ventricular drainage had been reported to be associated with improved outcomes.But in recent years,little is known whether external ventricular drainage and intracranial pressure monitoring after coiling could improve outcomes in high-grade aneurysmal subarachnoid hemorrhage.AIM To investigate the outcomes of high-grade aneurysmal subarachnoid hemorrhage patients with coiling and ventricular intracranial pressure monitoring.METHODS A retrospective analysis of a consecutive series of high-grade patients treated between Jan 2016 and Jun 2017 was performed.In our center,followed by continuous intracranial pressure monitoring,the use of ventricular pressure probe for endovascular coiling and invasive intracranial pressure monitoring in the acute phase is considered to be the first choice for the treatment of high-grade patients.We retrospectively analyzed patient characteristics,radiological features,intracranial pressure monitoring parameters,complications,mortality and outcome.RESULTS A total of 36 patients were included,and 32(88.89%)survived.The overall mortality rate was 11.11%.No patient suffered from aneurysm re-rupture.The intracranial pressure in 33 patients(91.67%)was maintained within the normal range by ventricular drainage during the treatment.A favorable outcome was achieved in 18 patients(50%)with 6 mo follow-up.Delayed cerebral ischemia and Glasgow coma scale were considered as significant predictors of outcome(2.066 and-0.296,respectively,P<0.05).CONCLUSION Ventricular intracranial pressure monitoring may effectively maintain the intracranial pressure within the normal range.Despite the small number of cases in the current work,high-grade patients may benefit from a combination therapy of early coiling and subsequent ventricular intracranial pressure monitoring.

Changes of Nitric Oxide and Its Relationship with Clinical Features,Intracranial Pressure and Outcome in Acute Head Injury

To investigate the content and dynamics of nitric oxide (NO) in the cerebrospinal fluid (CSF) of patients with acute head injury and to clarify the relationship of NO with clinical features and intracranial pressure (ICP) as well as outcomes, 38 adults with acute head injury were studied. Glasgow Coma Scale (GCS) obtained at admission and Glasgow Outcome Scale (GOS) 3 months after injury was assessed. ICP was surveyed via intraventricular catheter and lumbar puncture and CSF samples were obtained simultaneously. NO was determined with Griess reagents. Results showed that NO peak content in the head injury group was significantly higher than that of the control group. During dynamic research, no peak content of mildly injured cases and severely injured ones appeared in different time windows respectively. The peak value of NO was distinctly higher in the severe group than in the mild group. NO peak value of the raised ICP group was remarkably higher than that of the normal ICP group. The peak value of NO was considerately higher in the poor outcome group than in the good outcome group. When the content of NO was over 6. 5 μmol/L, the rate of poor outcome was increased. There existed a correlation between NO and GCS, ICP and GOS. It is concluded that the content of NO was increased in patients with acute head injury and the changes of NO had different time windows in severely injured patients and mildly injured ones. The more sever the injury, the higher the NO content; and the more serious the secondary brain injury and brain edema, the worse the outcomes. When NO is combined with GCS, GOS and ICP, it increases the accuracy of judgement to the degree of head injury and outcome.

Closed cranial window rodent model for investigating hemodynamic response to elevated intracranial pressure

Background:Elevated intracranial pressure(ICP)occurs in several physiological and pathological conditions,yet long-term sequellae are not common,which implies that blood flow is preserved above ischemic thresholds.Methods:This pilot study sought to confirm this hypothesis using a closed cranial window model in a rat in which ICP was elevated to 120 mmHg for 12 min,and superficial cortical perfusion was measured by laser Doppler flowmetry and laser speckle flowmetry.Results:Following a transient increase,cortical blood flow decreased to between 25%and 75%of baseline.These levels correspond to disrupted metabolism and decreased protein synthesis but did not exceed thresholds for electrical signaling or membrane integrity.This may partially explain how some episodes of elevated ICP remain benign.Conclusion:The closed cranial window model provides a platform for prospective study of physiologic responses to artificially elevated ICP during neurosurgery to promote hemostasis.

Research Progresses in Effects of Analgesics and Sedatives on Intracranial Pressure of Neurointensive Care Patients

At present, there are some concerns and problems to treat neurointensive care patients by using analgesics and sedatives. Conditions of neurointensive care patients change quickly. For neurointensive care patients who cannot have auxiliary examination timely, clinicians judge intracranial conditions mainly through relevant monitoring devices and consciousness and pupil changes of patients. The use of analgesics and sedatives is limited due to worry about influences on consciousness evaluation and judgment and different degrees of inhibition on cardiovascular system and respiratory system. Common sedatives (e.g. benzodiazepines) and common analgesics (e.g. morphine, fentanyl and sufentanil) both may inhibit respiration. The specification often provides taboos for the use of drugs by patients with increase intracranial pressure (ICP) and craniocerebral injuries. Through literature review, the author analyzed influences of analgesics and sedatives on ICP of neurointensive care patients comprehensively.

Clinical significance of large decompressive craniectomy to control intractable increased intracranial pressure in patients with traumatic brain injury

Objective To investigate the role of decompressive craniectomy (DC) to decrease intractable intracranial hypertension(ICH) due to diffuse brain swelling and / or cerebral edema after severe traumatic brain injury and the time window of DC to affect on prognosis. Methods The clinical record of 132 patients who underwent DC for posttraumatic intractable ICH in our hospital from July 2003 to

Effects of positive end-expiratory pressure on intracranial pressure,cerebral perfusion pressure,and brain oxygenation in acute brain injury:Friend or foe?A scoping review

Background Patients with acute brain injury(ABI)are a peculiar population because ABI does not only affect the brain but also other organs such as the lungs,as theorized in brain–lung crosstalk models.ABI patients often require mechanical ventilation(MV)to avoid the complications of impaired respiratory function that can follow ABI;MV should be settled with meticulousness owing to its effects on the intracranial compartment,especially regarding positive end-expiratory pressure(PEEP).This scoping review aimed to(1)describe the physiological basis and mechanisms related to the effects of PEEP in ABI;(2)examine how clinical research is conducted on this topic;(3)identify methods for setting PEEP in ABI;and(4)investigate the impact of the application of PEEP in ABI on the outcome.Methods The five-stage paradigm devised by Peters et al.and expanded by Arksey and O'Malley,Levac et al.,and the Joanna Briggs Institute was used for methodology.We also adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)extension criteria.Inclusion criteria:we compiled all scientific data from peer-reviewed journals and studies that discussed the application of PEEP and its impact on intracranial pressure,cerebral perfusion pressure,and brain oxygenation in adult patients with ABI.Exclusion criteria:studies that only examined a pediatric patient group(those under the age of 18),experiments conducted solely on animals;studies without intracranial pressure and/or cerebral perfusion pressure determinations,and studies with incomplete information.Two authors searched and screened for inclusion in papers published up to July 2023 using the PubMed-indexed online database.Data were presented in narrative and tubular form.Results The initial search yielded 330 references on the application of PEEP in ABI,of which 36 met our inclusion criteria.PEEP has recognized beneficial effects on gas exchange,but it produces hemodynamic changes that should be predicted to avoid undesired consequences on cerebral blood flow and intracranial pressure.Moreover,the elastic properties of the lungs influence the transmission of the forces applied by MV over the brain so they should be taken into consideration.Currently,there are no specific tools that can predict the effect of PEEP on the brain,but there is an established need for a comprehensive monitoring approach for these patients,acknowledging the etiology of ABI and the measurable variables to personalize MV.Conclusion PEEP can be safely used in patients with ABI to improve gas exchange keeping in mind its potentially harmful effects,which can be predicted with adequate monitoring supported by bedside non-invasive neuromonitoring tools.

Intracranial pressure is elevated at 24h post-stroke inmice

Background:It has long been assumed that post-stroke intracranial pressure(ICP)elevation occurs because of large infarct and edema volumes.However,we have repeatedly shown IcP elevation at 24 h post-stroke in the presence of little to no edema in rats.Biological processes are often conserved across species and types of injury.Therefore,we aimed to determine if an ICP rise occurs at 24 h post-stroke in the presence of small infarct and edema volumes in mice.Methods:Mice were randomized by random number table to either photothrombotic stroke or sham surgery(n=15).Epidural ICP was recorded using a fiber optic catheter at 1 h post-stroke(baseline)and between 23 and 24hpost-stroke.Results:ICP was significantly higher at 24 h compared to baseline in stroke animals(n=6;10.71±6.45mmHg vs.3.74±2.20mmHg,respec-tively;p=0.03).ICP at 24 h was also significantly higher in stroke mice compared to sham(n=6;3.45±1.43mmHg;p=0.02).There was no change in ICP in sham mice(p=0.9).Edema volumes in stroke animals were small(0.04±0.04 mm3)and unlikely to have caused significant ICP elevation.Conclusion:This study provides evidence of an edema-independent ICP elevation following small ischemic stroke in mice.The occurrence of this rise supports our findings in other species and suggests it is caused by a previously undescribed mechanism.

RELATIONS OF INTRACRANIAL PRESSURE, CREATINE KINASE AND BRAINSTEM AUDITORY EVOKED POTENTIAL IN PATIENTS WITH TRAUMATIC BRAIN EDEMA

We studied the relations of intracranial pressure (ICP),creatine kinase (CK) and bralnstem auditory evoked potential (BAEP) in 44 patients with traumatic brain edema who were admitted to our hospital from June 1990 to February 1991. There were 30 males and 14 females, with age range from 9 to 67 years. The results showed that the abnormal BAEP could reflect the severity of cerebral edema in acute head injury and was related to ICP and serum CK levels. When ICP>30 mmHg (4kPa), the abnormality of BAEP was more obvious than that of the control group (P<0.05); the serum CK levels were also elevated markedly. In patients with ICP over and below 4kPa, the rate of abnormal BAEP was 38.46% and 77.78% respectively (P<0.05). The serum CK level in the normal group or in the group with moderate abnormality of BAEP was significantly different from that in the group with severe abnormality or lack of BAEP (274.8± 98.24 U/L vs 705.3± 364.27 U/L; P<0.001). After treatment, the ICP returned to normal, and the BAEP norm

Effect of Tianhuang Granule(田黄冲剂) on Intracranial Pressure and Serum Matrix Metalloproteinase-9 in Patients with Acute Cerebral Hemorrhage

Objective： To study the effect and mechanism of Tianhuang Granule （田黄冲剂, THG） on hydrocephalus in the patients with acute cerebral hemorrhage （ACH） through intracranial pressure （ICP） monitoring, serum matrix metalloproteinase-9 （MMP-9） level observation, and National Institutes of Health Stroke Scale （NIHSS） scoring （for nerve function deficit）. Methods： Sixty patients with ACH were equally randomized into two groups by lottery, the control group and the THG group; all were treated with conventional therapy, but to the patients in the THG group, THG was given orally in addition for 28 days. Changes of ICP, MMP-9 expression, and NIHSS scores, as well as the degree of cerebral hematoma and hydrocephalus （by cranial CT scanning） in the patients, were estimated and compared. Results： （1） ICP was lowered more significantly in the THG group, showing a significant difference between groups on day 7 （P〈0.05）. （2） MMP-9 expression was down-regulated in the THG group more significantly and earlier than that in the control group. （3） The degrees of cerebral hematoma and hydrocephalus in the THG group on day 7 were reduced significantly as compared with those on day 3 （P〈0.05）, but in the control group, the day of significant reduction was delayed to day 14, and the degrees on day 7 and day 14 in the two groups were significantly different （P〈0.05 and P〈0.01）. （4） NIHSS score was significantly lower in the THG group than that in the control group on day 14 and day 28 （P〈0.05 and P〈0.01）. Conclusion： THG can effectively lower ICP, down-regulate MMP-9 expression, promote the absorption of cerebral hematoma and hydrocephalus, and improve the nerve function, showing a clinical effectiveness than conventional therapy.

Tiny MEMS-Based Pressure Sensors in the Measurement of Intracranial Pressure

This study presents a tiny pressure sensor which is used to measure the Intracranial Pressure （ICP）. The sensor is based on the piezoresistive effect. The piezoresistive pressure sensor is simulated and designed by using nonlinear programming optimizing and Finite Element Analysis （FEA） tools. Two kinds of sensor sizes are designed in the case of childhood and adult. The sensors are fabricated by Microelectro Mechanical Systems （MEMS） process. The test results yield sensitivities of 1.033x 10-2 mV/kPa for the childhood type detection and 1.257x 10-2 mV/kPa for the adult detection with sensor chip sizes of 0.40x0.40 mm2 and 0.50x0.50 mm2, respectively. A novel method for measuring ICP is proposed because of the tiny sizes. Furthermore, relative errors for sensitivity of pressure sensors are limited within 4.76%. Minimum Detectable Pressure （MDP） reaches 128.4 Pa in average.

Micro packaged MEMS pressure sensor for intracranial pressure measurement

This paper presents a micro packaged MEMS pressure sensor for intracranial pressure measurement which belongs to BioMEMS. It can be used in lumbar puncture surgery to measure intracranial pressure. Minia- turization is key for lumbar puncture surgery because the sensor must be small enough to allow it be placed in the reagent chamber of the lumbar puncture needle. The size of the sensor is decided by the size of the sensor chip and package. Our sensor chip is based on silicon piezoresistive effect and the size is 400 × 400 μm2. It is much smaller than the reported polymer intracranial pressure sensors such as liquid crystal polymer sensors. In terms of package, the traditional dual in-line package obviously could not match the size need, the minimal size of recently reported MEMS-based intracranial pressure sensors after packaging is 10 × 10 mm2. In this work, we are the first to introduce a quad flat no-lead package as the package form of piezoresistive intracranial pressure sensors, the whole size of the sensor is minimized to only 3 × 3 mm2. Considering the liquid measurement environment, the sensor is gummed and waterproof performance is tested; the sensitivity of the sensor is 0.9 × 10-2 mV/kPa.

Low-cost and miniature all-silica Fabry–Perot pressure sensor for intracranial pressure measurement

The monitoring of increased intracranial pressure（ICP） is necessary in the diagnosis and treatment of patients with neurological disease because it can provide an insight into the mechanism of the head injury. In this letter, we develop a novel miniature Fabry–Perot（F-P） sensor for ICP measurement. The proposed sensor is fabricated by using a commercially available fusion splicer and a fiber cleaver, by which many difficult art problems involved in fabrication are solved and the online monitoring of the F-P cavity is actualized. The sensor exhibits a linear response to the applied pressure over the range of 0–25 k Pa（ample for ICP measurement）, with a sensitivity of 10.18 nm/k Pa, a resolution of 0.1 k Pa, and a reduced thermal sensitivity of 0.068 nm/°C, which shows it can meet the requirements of ICP measurement.

The effect of increased intra-abdominal pressure on orbital subarachnoid space width and intraocular pressure

In accordance with the trans-lamina cribrosa pressure difference theory, decreasing the trans-lamina cribrosa pressure difference can re- lieve glaucomatous optic neuropathy. Increased intracranial pressure can also reduce optic nerve damage in glaucoma patients, and a safe, effective and noninvasive way to achieve this is by increasing the intra-abdominal pressure. The purpose of this study was to observe the changes in orbital subarachnoid space width and intraocular pressure at elevated intra-abdominal pressure. An inflatable abdominal belt was tied to each of 15 healthy volunteers, aged 22-30 years （12 females and 3 males）, at the navel level, without applying pressure to the abdomen, before they laid in the magnetic resonance imaging machine. The baseline orbital subarachnoid space width around the optic nerve was measured by magnetic resonance imaging at 1, 3, 9, and 15 mm behind the globe. The abdominal belt was inflated to increase the pressure to 40 mmHg （1 mmHg = 0.133 kPa）, then the orbital subarachnoid space width was measured every 10 minutes for 2 hours. After removal of the pressure, the measurement was repeated 10 and 20 minutes later. In a separate trial, the intraocular pressure was measured for all the subjects at the same time points, before, during and after elevated intra-abdominal pressure. Results showed that the baseline mean orbital subarachnoid space width was 0.88 ＋ 0.1 mm （range： 0.77-1.05 mm）, 0.77 ＋ 0.11 mm （range： 0.60-0.94 mm）, 0.70 ＋ 0.08 mm （range： 0.62-0.80 ram）, and 0.68 _＋ 0.08 mm （range： 0.57-0.77 mm） at 1, 3, 9, and 15 mm behind the globe, respectively. During the elevated intra-abdominal pressure, the orbital subarachnoid space width increased from the baseline and dilation of the optic nerve sheath was significant at 1, 3 and 9 mm behind the globe. After decompression of the abdominal pressure, the orbital subarachnoid space width normalized and returned to the baseline value. There was no significant difference in the intraocular pressure before, during and after the intra-abdominal pressure elevation. These results verified that the increased intra-abdominal pressure widens the orbital subarachnoid space in this acute trial, but does not alter the intraocular pressure, indicating that intraocular pressure is not affected by rapid increased in- tra-abdominal pressure. This study was registered in the Chinese Clinical Trial Registry （registration number： ChiCTR-ONRC-14004947）.

Effect of intracranial hypertension on cerebral hemorrhage induced autonomic nerve imbalance

BACKGROUND： Cerebral hemorrhage can cause the imbalance of nerve function, whereas its mechanism and main impact factors are still not quite clear. OBJECTIVE： To explore the rules about the changes of intracranial pressure in brainstem hemorrhage and internal capsule hemorrhage, and analyze the role of intracranial hypertension in the changes of nerve function caused by cerebral hemorrhage. DESIGN： A self-controlled trial. SETTING： Department of Physiology, Tianjin Medical University. MATERIALS： Sixty-five healthy male Japanese white rabbits with long ears （1.5-1.8 kg） were supplied and fed by the Department of Animal Experiment of Tianjin Medical University. The RM6240B biological signal collecting and processing system was used. METHODS： The experiments were conducted in the Department of Physiology, Tianjin Medical University from August 2001 to May 2006. ① The rabbits were anesthetized, then fixed onto the brain stereotaxic apparatus, and afterwards fenestration on skull and intubation to lateral ventricle were performed.The dynamic changes of intracranial pressure were monitored continuously. Rabbits were infused with autologous arterial blood （0.3 mL） into midbrain corpora quadrigemina inferior colliculus to induce model of acute brainstem hemorrhage; models of internal capsule hemorrhage were established by infusing autologous arterial blood into internal capsule. ② The dynamic intracranial pressures under the above conditions were recorded continuously with the RM6240B biological signal collecting and processing system. ③ An animal model of persistent intracranial hypertension was established by infusion of physiologic saline into lateral ventricle. ④ The changes of the intensity of autonomic nerve discharge were analyzed, using the biological signal collecting and processing system before and after hemorrhage and under persistent intracranial hypertension.⑤ Ten animal models of internal capsule hemorrhage and 10 of bminstem hemorrhage were selected respectively, then gross pathological samples were cut open, and the accuracy of hemorrhage models was affirmed. Histological sections in hemorrhage point and around this point were prepared for with hernatoxylin and eosin staining, and the pathological changes were observed under light microscope. MAIN OUTCOME MEASURES： ① Changes of intracranial pressures before and after internal capsule hemorrhage and brainstem hemorrhage; ②Changes of the discharge intensity of cervical vagus nerve trunk in animal models of internal capsule hemorrhage, brainstem hemorrhage and persistent intracranial hypertension without hemorrhage; ③ Accuracy of location of internal capsule hemorrhage and brainstem hemorrhage confirmed by gross pathological samples and sections. RESULTS： Totally 65 rabbits were involved in the analysis of results. ① Dynamic state of intracranial pressure： Intracranial pressure increased obviously at 45 minutes after internal capsule hemorrhage and brainstem hemorrhage, the intracranial pressures were （1.31 ±0.30）, （1.82±0.45） kPa, which were obviously higher than those before hemorrhage [（1,04±0.18）, （1.05±0.19） kPa, P 〈 0.01]. ② Discharge of vagus nerve： Under intracranial hypertension, the discharge of cervical vagus nerve trunk was enhanced, and the discharge intensity of vagus nerve trunk was significantly different before and after persistent intracranial hypertension [（364.28±78.55）, （1252.19±151.75）μ V·s, P 〈 0.01]. The discharges of cervical vagus nerve trunk were significantly enhanced after internal capsule hemorrhage and brainstem hemorrhage （P 〈 0.01）. ③ Validation of hemorrhage sites： The hemorrhage sites were internal capsule and brainstem on histopathological sections. CONCLUSION： Intracranial pressure may play an important role in the pathophysiological process of vagus nerve imbalance caused by cerebral hemorrhage.

Hydrocephalic cerebrospinal fluid flowing rotationally with pulsatile boundaries:A mathematical simulation of the thermodynamical approach

To study the kinematics of flow rate and ventricular dilatation,an analytical perturbation approach of hydrocephalus has been devised.This research provides a comprehensive investigation of the characteristics of cerebrospinal fluid(CSF)flow and pressure in a hydrocephalic patient.The influence of hydrocephalic CSF,flowing rotationally with realistic dynamical characteristics on pulsatile boundaries of subarachnoid space,was demonstrated using a nonlinear controlling system of CSF.An analytical perturbation method of hydrocephalus has been developed to investigate the biomechanics of fluid flow rate and the ventricular enlargement.In this paper presents a detailed analysis of CSF flow and pressure dynamics in a hydrocephalic patient.It was elaborated with a nonlinear governing model of CSF to show the influence of hydrocephalic CSF,flowing rotationally with realistic dynamical behaviors on pulsatile boundaries of subarachnoid space.In accordance with the suggested model,the elasticity factor changes depending on how much a porous layer,in this case the brain parenchyma,is stretched.It was improved to include the relaxation of internal mechanical stresses for various perturbation orders,modelling the potential plasticity of brain tissue.The initial geometry that was utilised to create the framework of CSF with pathological disease hydrocephalus and indeed the output of simulations using this model were compared to the actual progression of ventricular dimensions and shapes in patients.According to this observation,the non-linear and elastic mechanical phenomena incorporated into the current model are probably true.Further modelling of ventricular dilation at a normal pressure may benefit from the existence of a valid model whose parameters approximate genuine mechanical characteristics of the cerebral cortex.

Novel D-galactosamine-induced cynomolgus monkey model of acute liver failure

AIM To establish a simplified, reproducible D-galactosamineinduced cynomolgus monkey model of acute liver failure having an appropriate treatment window. METHODS Sixteen cynomolgus monkeys were randomly dividedinto four groups(A, B, C and D) after intracranial pressure(ICP) sensor implantation. D-galactosamine at 0.3, 0.25, 0.20 + 0.05(24 h interval), and 0.20 g/kg body weight, respectively, was injected via the small saphenous vein. Vital signs, ICP, biochemical indices, and inflammatory factors were recorded at 0, 12, 24, 36, 48, 72, 96, and 120 h after D-galactosamine administration. Progression of clinical manifestations, survival times, and results of H&E staining, TUNEL, and Masson staining were recorded. RESULTS Cynomolgus monkeys developed different degrees of debilitation, loss of appetite, and jaundice after D-galactosamine administration. Survival times of groups A, B, and C were 56 ± 8.7 h, 95 ± 5.5 h, and 99 ± 2.2 h, respectively, and in group D all monkeys survived the 144-h observation period except for one, which died at 136 h. Blood levels of ALT, AST, CK, LDH, TBi L, Cr, BUN, and ammonia, prothrombin time, ICP, endotoxin, and inflammatory markers [(tumor necrosis factor(TNF)-α, interleukin(IL)-1β, and IL-6)] significantly increased compared with baseline values in different groups(P < 0.05). Pathological results showed obvious liver cell necrosis that was positively correlated with the dose of D-galactosamine.CONCLUSION We successfully established a simplified, reproducible D-galactosamine-induced cynomolgus monkey model of acute liver failure, and the single or divided dosage of 0.25 g/kg is optimal for creating this model.

Optic nerve sheath diameters in healthy adults measured by computer tomography

AIMTo measure optic nerve sheath diameters (ONSD) in different locations by computer tomography (CT) and to recommend the best location for cases when ONSD is used for intracranial pressure monitoring.METHODSIn a prospective cohort study, CT data of 300 healthy adults were analyzed (600 eyes). In all cases, the CT investigation was performed at the Emergency Department because of the various conditions that proved not to be connected with ophthalmological or neurological pathology. The ONSD were measured at 3 mm and 8 mm distance from the globe, and 3 mm from the anterior opening of the optic canal. The correlation analysis was performed with gender, age, and ethnic background.RESULTSThe right/left ONSD are 4.94&#x000b1;1.51/5.17&#x000b1;1.34 mm at 3 mm, 4.35&#x000b1;0.76/4.45&#x000b1;0.62 mm at 8 mm from the globe, and 3.55&#x000b1;0.82/3.65&#x000b1;0.7 mm at 3 mm from the optic canal. No significant differences correlated with gender of the patients, their age, and ethnic background were found.CONCLUSIONIn healthy persons, the ONSD varies from 5.17&#x000b1;1.34 mm to 3.55&#x000b1;0.82 mm in different locations within the intraorbital space. The most stable results with lesser standard deviation can be obtained if it is measured 8-10 mm from the globe.