Intracranial Pressure Profile Research Articles

Revealing the Effect of Skull Deformation on Intracranial Pressure Variation During the Direct Interaction Between Blast Wave and Surrogate Head.

Intracranial pressure (ICP) during the interaction between blast wave and the head is a crucial evaluation criterion for blast-induced traumatic brain injury (bTBI). ICP variation is mainly induced by the blast wave transmission and skull deformation. However, how the skull deformation influences the ICP remains unclear, which is meaningful for mitigating bTBI. In this study, both experimental and numerical models are developed to elucidate the effect of skull deformation on ICP variation. Firstly, we performed the shock tube experiment of the high-fidelity surrogate head to measure the ICP, the blast overpressure, and the skull surface strain of specific positions. The results show that the ICP profiles of all measured points show oscillations with positive and negative change, and the variation is consistent with the skull surface strain. Further numerical analysis reveals that when the blast wave reaches the measured point, the peak overpressure transmits directly through the skull to the brain, forming the local positive ICP peak, and the impulse induces the local inward deformation of the skull. As the peak overpressure passes through, the blast impulse impacts the nearby skull supported by the soft and incompressible brain tissue and extrudes the skull outward in the initial position. The inward and outward skull deformation leads to the oscillation of ICP. These numerical analyses agree with experimental results, which explain the appearance of negative and positive ICP peaks and the synchronization of negative ICP with surface strain. The study has implications for medical injury diagnosis and protective equipment design.

Sulcal Cavitation in Linear Head Acceleration: Possible Correlation With Chronic Traumatic Encephalopathy.

Traumatic Brain Injury (TBI) is a significant public health and financial concern that is affecting tens of thousands of people in the United States annually. There were over a million hospital visits related to TBI in 2017. Along with immediate and short-term morbidity from TBI, chronic traumatic encephalopathy (CTE) can have life-altering, chronic morbidity, yet the direct linkage of how head impacts lead to this pathology remains unknown. A possible clue is that chronic traumatic encephalopathy appears to initiate in the depths of the sulci. The purpose of this study was to isolate the injury mechanism/s associated with blunt force impact events. To this end, drop tower experiments were performed on a human head phantom. Our phantom was fabricated into a three-dimensional extruded ellipsoid geometry made out of Polyacrylamide gelatin that incorporated gyri-sulci interaction. The phantom was assembled into a polylactic acid 3D-printed skull, surrounded with deionized water, and enclosed between two optical windows. The phantom received repetitive low-force impacts on the order of magnitude of an average boxing punch. Intracranial pressure profiles were recorded in conjunction with high-speed imaging, 25 k frames-per-second. Cavitation was observed in all trials. Cavitation is the spontaneous formation of vapor bubbles in the liquid phase resulting from a pressure drop that reaches the vapor pressure of the liquid. The observed cavitation was predominately located in the contrecoup during negative pressure phases of local intracranial pressure. To further investigate the cavitation interaction with the brain tissue phantom, a 2D plane strain computational model was built to simulate the deformation of gyrated tissue as a result from the initiation of cavitation bubbles seen in the phantom experiments. These computational experiments demonstrated a focusing of strain at the depths of the sulci from bubble expansion. Our results add further evidence that mechanical interactions could contribute to the development of chronic traumatic encephalopathy and also that fluid cavitation may play a role in this interaction.

A mechatronic test-bench to investigate the impact of ventricular pulsation in hydrocephalus

BackgroundIn vitro modelling of the intracranial pressure (ICP) profile is an important tool to test potential prototypes for the diagnosis and treatment of hydrocepahlus. ObjectiveHere, a novel feedback-controlled mechatronic test-bench, which replicates the pulsatile ICP wave, is presented. MethodsThe design is based on a MATLAB Simscape simulation of the intracranial system (ICS) and a test environment consisting of a linear actuator coupled to a metal bellows that deliver an ICP wave profile to the inner ventricular cavity of a silicon-gel-carbon brain phantom. The proposed approach applies the Lagrange formalism for the electromechanical modelling of the system. MATLAB’s Grey-Box system identification tool is used and a PID controller is implemented. The ICS simulation is adapted from existing models from literature. A physiological aortic pressure wave is the input of the system. ResultsThe ICS model is able to generate wave profiles of varying morphology according to model parameters such as vessel compliance, capillary resistance and cerebrospinal fluid production rate. The wave profile serves as the reference pressure, ICPref, for the controller. Finally, the hardware setup successfully delivers the ICP profile to the intracranial cavity, ICPmeas, measured by a pressure sensor connected to the internal cavity of the brain phantom. ConclusionThe detailed in silico ICS model with cardiovascular coupling integrated with a modular brain phantom allows for flexible test scenarios in contrast to purely hydraulic setups. Future work will focus on the optimization of the test-bench for the validation of specific prototypes in the field of hydrocephalus.

Can general anesthesia prevent adverse effects during full-endoscopic spine surgery? Non-invasive intracranial pressure profile in 31 patients submitted to full-endoscopic spine surgery

Can general anesthesia prevent adverse effects during full-endoscopic spine surgery? Non-invasive intracranial pressure profile in 31 patients submitted to full-endoscopic spine surgery

Home telemonitoring of intracranial pressure.

As technical progress advances, telemonitoring has become an important part of patient care in many areas of medical treatment. However, distanced surveillance of intracranial pressure (ICP) could not be established so far. With the recent introduction of a telemetric ICP measurement probe, new possibilities arise. Here, we report on a new home setup enabling home telemonitoring of intracranial pressure. Twenty patients suffering from disturbances of cerebrospinal fluid circulation, who underwent insertion of a telemetric ICP measurement probe, were provided with medical equipment to read ICP at home and save the data on an internet-enabled computer. Training in handling the equipment was performed during in-patient stay; recorded and uploaded ICP data was then analyzed online. Therefore, the treating medical team was able to access the ICP data via a secure internet connection while telephone conferencing with the patient. Almost 7400h of ICP data were recorded at home and evaluated via an internet connection according to the telemonitoring setup. This corresponds to an average record time of about 370h per patient. ICP profiles were observed following endoscopic treatment, shunting procedures, or valve adjustments. The mean distance between the patients' residence and the consulting hospital was 172km (range, 16-649km). ICP measurements have become accessible for telemonitoring purposes. This new management of hydrocephalus reflects an alternative method in patient care, especially for those who live far away from specialized centers.

Intracranial Pressure-Guided Shunt Valve Adjustments with the Miethke Sensor Reservoir.

Telemetric intracranial pressure (ICP) monitoring seems to be a promising therapy-supporting option in shunt-treated patients. Benefits become obvious when headaches are unspecific and clinical symptoms cannot be related to possible overdrainage or underdrainage. In this study, we evaluated a new telemetric device to individually adjust shunt valves according to ICP measurements. Between December 2015 and November 2016, 25 patients with suspected suboptimal shunt valve settings underwent insertion of a telemetric ICP sensor (Sensor Reservoir; Christoph Miethke, Potsdam, Germany). Over a 1-year period, a total of 183 telemetric ICP measurements and 85 shunt valve adjustments were carried out. Retrospective statistic analyses focused on valve adjustments, ICP values, and clinical outcomes. ICP-guided valve adjustments positively changed the clinical state in 18 out of 25 patients. Clinical improvement over time was associated with significant changes of the valve settings and ICP values. Interestingly, a therapeutically normalized ICP profile was not automatically associated with clinical improvement. The Sensor Reservoir is an important and valuable tool for shunt-treated patients suffering from drainage-related problems. The possibility to simultaneously recognize and solve shunt problems represents the decisive advantage. Nevertheless, measurements with the Sensor Reservoir did not allow for the determination of default valve settings or universal target ICP values.

Role of helmets in blast mitigation: insights from experiments on PMHS surrogate

Blast induced traumatic brain injury (bTBI) has emerged as the most significant injury to war fighters in recent conflicts. Interaction of the blast wave with the head and helmet are not well understood. In this work, the effects of blast were investigated on the post-mortem human subject (PMHS) head using a compression driven shock tube. The results suggest that the evolution of intracranial pressure profiles is strongly governed by the wave propagation through skin-skull-brain parenchyma. It is also observed that the sinus cavities naturally attenuate the blast overpressure. Performance of two helmet configurations (padded and suspension) in mitigating the blast is also evaluated. The results suggest that the amount of mitigation offered by each helmet varies with the helmet configuration. For helmets with the suspension system, the blast wave is intensified beneath the helmet. Further, the degree of blast wave mitigation is affected by the morphology of the PMHS itself. Overall, these results suggest that the blast wave interacts with the head and the helmet in a complex manner and these interaction effects must be taken into account while designing strategies for protection of the head against the blast.

Mortality and long-term functional outcome associated with intracranial pressure after traumatic brain injury

Elevated intracranial pressure (ICP) has been associated with increased mortality in patients with severe traumatic brain injury (TBI). We have examined whether raised ICP is independently associated with mortality, functional status and neuropsychological functioning in adult TBI patients. Data from a randomized trial of 499 participants were secondarily analyzed. The primary endpoints were mortality and a composite measure of functional status and neuropsychological function (memory, speed of information processing, executive function) over a 6-month period. The area under the curve of the ICP profile (average ICP) during the first 48 h of monitoring was the main predictor of interest. Multivariable regression was used to adjust for a priori defined confounders: age, Glasgow Coma Score, Abbreviated Injury Scale-head and hypoxia. Of the participants, 365 patients had complete 48-h ICP data. The overall 6-month mortality was 18 %. The adjusted odds ratio of mortality comparing 10-mmHg increases in average ICP was 3.12 (95 % confidence interval 1.79, 5.44; p < 0.01). Overall, higher average ICP was associated with decreased functional status and neuropsychological functioning (p < 0.01). Importantly, among survivors, increasing average ICP was not independently associated with worse performance on neuropsychological testing (p = 0.46). Average ICP in the first 48 h of monitoring was an independent predictor of mortality and of a composite endpoint of functional and neuropsychological outcome at the 6-month follow-up in moderate or severe TBI patients. However, there was no association between average ICP and neuropsychological functioning among survivors.

The Course of Intracranial Pressure in Traumatic Brain Injury: Relation with Outcome and CT-characteristics

One of the predictive factors of outcome in traumatic brain injury is high intracranial pressure (ICP). Recently, the time course of ICP has been described but few data are available on the relation of these ICP profiles and outcome. The aim of this study is to investigate the relation of the time course of ICP with CT-findings and outcome. Retrospective analysis of prospectively collected data of 246 patients with traumatic brain injury admitted to the neurosurgical intensive care unit. Early rise in ICP (within the first 2 days) was present in 32%, an intermediate rise (between days 3 and 5) in 34% and a late rise (after day 5) in 34% of patients. Half of the patients with a normal opening pressure (76%) developed intermediate or late ICP rise profiles. More mass lesions and sub/epidural hematomas were present in the late rise group. Patients with a late ICP rise required significant more intensive treatment (65% vs. 37 and 33%) when compared to the early and intermediate rise groups. In multiple regression analysis both ICP profiles and extracranial hematomas were related to outcome. With late ICP rise more unfavorable outcome (46 vs. 17%, P < 0.001) was seen although one in four patients showed a favorable outcome. During ICP monitoring different ICP profiles are present over time. These profiles are related to CT-characteristics and outcome. The importance of early and late monitoring of ICP is underlined.

Ultrasonography of the optic nerve sheath may be useful for detecting raised intracranial pressure after severe brain injury

To assess at admission to the ICU the relationship between optic nerve sheath diameter (ONSD) and intracranial pressure (ICP) and to investigate whether increased ONSD at patient admission is associated with raised ICP in the first 48[Symbol: see text]h after trauma. Prospective, blind, observational study in a surgical critical care unit, level 1 trauma center. 31 adult patients with severe traumatic brain injury (TBI; Glasgow coma scale <or=8) requiring sedation and ICP monitoring, and 31 control patients without brain injury requiring sedation. ONSD was measured with a 7.5-MHz linear ultrasound probe. Two TBI groups were defined on the basis of ICP profile. If ICP exceeded 20 mmHg for more than 30 min in the first 48 h (before any specific treatment), patients were considered to have high ICP; if not, they had normal ICP. The largest ONSD value (the highest value for the right and left eye) was significantly higher in high ICP patients (6.3 +/-0.6 vs. 5.1+/-0.7 mm in normal ICP patients and 4.9+/-0.3mm in control patients). There was a significant relationship between the largest ONSD and ICP at admission (r=0.68). The largest ONSD was a suitable predictor of high ICP (area under ROC curve 0.96). When ONSD was under 5.7 mm, the sensitivity and negative predictive values for high ICP were 100%. In the early posttraumatic period, ocular ultrasound scans may be useful for detecting high ICP after severe TBI.

811 Relationship between Valve Opening Pressure, Body Position, and Intracranial Pressure in Normal-pressure Hydrocephalus: Paradigm for Selection of Programmable Valve Pressure Setting

INTRODUCTION: There is little scientific basis for guidance in selecting the optimal valve for the treatment of normal-pressure hydrocephalus (NPH). The aim of this study was to determine the programmable valve opening pressure (OPV) setting that would result in a slight reduction in intracranial pressure (ICP) after a ventriculoperitoneal (VP) shunt. We also assessed whether shunt-induced ICP changes could be predicted on the basis of a simple hydrodynamic equation. METHODS: In this prospective study of 11 patients with NPH, ICP was measured before and after implantation of a shunt incorporating a programmable valve without an antisiphon device. Pressure measurements, including intraperitoneal pressure (IPP), and shunt hydrostatic column lengths (HC) were recorded at body angles ranging from 0 to 55 degrees and at valve settings ranging from 30 to 200 mm H2O. Measured ICP values were compared with values computed using a simple hydrodynamic equation (ICPPredicted = OPV − HC + IPP). RESULTS: Even at the highest OPV setting of 200 mm H2O, which exceeded the mean baseline ICP (164 ± 64 mm H2O), there was a significant reduction in the postoperative ICP in the supine position (125 ± 69 mm H2O, P = 0.04). The OPV did not equal the measured postoperative ICP. Linear regression revealed a nonunity slope (0.39) and a nonzero y intercept (47 mm H2O versus measured IPPSupine of 69 ± 23 mm H2O). A precipitous decline of ICP at upright body positions, predicted by so-called siphoning, was not seen. Instead, postural ICP profile nearly paralleled that of the baseline measurements. CONCLUSION: This study indicates that very high OPV settings may be optimal for the initial treatment of NPH. The relationship between ICP and OPV is linear but not predicted by simple hydrodynamics. In NPH, VP shunts seem to lower ICP in a “physiological” manner without significant siphoning.

Quantitative analysis of continuous intracranial pressure recordings in symptomatic patients with extracranial shunts

Objectives: To explore the outcome of management of possible shunt related symptoms using intracranial pressure (ICP) monitoring, and to identify potential methodological limitations with the current strategies of ICP assessment....

Decreased cholecystokinin levels in cerebrospinal fluid of patients with adult chronic hydrocephalus syndrome

Cholecystokinin (CCK) levels were measured in cerebrospinal fluid (CSF) of patients with adult chronic hydrocephalus syndrome (ACHS) (n = 16) and compared with levels from a control group (n = 11). The CSF concentration of CCK in the ACHS group (0.79 +/- 0.53 fmol/mL) was significantly reduced (p = .002) with respect to the controls (1.55 +/- 0.54 fmol/mL). As CCK-8, the most prevalent from of CCK in the central nervous system, has been demonstrated to play a significant role in several physiological and behavioral actions, the reduced octapeptide values found in ACHS could be involved in the disturbances associated with this disorder. Continuous monitoring of intracranial pressure (ICP) demonstrated different ICP profiles in ACHS. We found that all patients with abnormal ICP records except one showed CCK values under the detection limit. Three of the 4 patients with normal ICP had CCK levels within the normal range. These preliminary studies could evidence that ICP alterations are responsible for part of the loss of brain neuropeptide levels in ACHS.