Opening Pressure Research Articles

Subdural Hygroma After Management of Ruptured Intracranial Aneurysms: Incidence, Associated Factors, Clinical Course, and Management Options

To evaluate the incidence, associated factors, clinical course, and management options of subdural hygroma in patients treated for aneurysmal subarachnoid hemorrhage (aSAH). From January 2013 until June 2022, 336 consecutive patients with aSAH underwent treatment in our center. No one patient was excluded from the study cohort. Computed tomography (CT) examinations were performed at admission, immediately after surgery and on the first postoperative day, and subsequently in case of any neurologic deterioration or, at least, once per week until discharge from the hospital. Thereafter, CT examinations were at the discretion of specialists in the rehabilitation facility, referring physicians, or neurosurgeons at the outpatient clinic. The length of radiologic follow-up starting from CT at admission ranged from 1 to 3286 days (mean, 673 ± 895 days; median, 150 days). Subdural hygromas developed in 84 patients (25%). An average interval until this imaging finding from the initial CT examination was 25 ± 55 days (median, 8 days; range, 0-362 days). Evaluation in the multivariate model showed that patient age ≥72 years (P < 0.0001), cerebrospinal fluid (CSF) shunting (P < 0.0001), and microsurgical clipping of ruptured intracranial aneurysm (RIA; P < 0.0001) are independently associated with the development of subdural hygroma. In 54 of 84 cases (64%), subdural hygromas required observation only. Increase of the lesion size with (5 cases) or without (10 cases) appearance of midline shift was associated with patient age <72 years (P= 0.0398), decompressive craniotomy (P= 0.0192), and CSF shunting (P= 0.0009), whereas evaluation of these factors in the multivariate model confirmed independent association of only CSF shunting (P= 0.0003). Active management of subdural hygromas included adjustment of the shunt programmable valve opening pressure, cranioplasty, external subdural drainage, or their combination. Overall, during follow-up (mean, 531 ± 824 days; median,119 days; range, 2-3285 days) after the start of observation or applied treatment, subdural hygromas showed either decrease (50 cases) or stabilization (34 cases) of their sizes, and no one lesion showed progression again. The clinical course of subdural hygromas in patients treated for aSAH is generally favorable, but occasionally these lesions show progressive enlargement with or without the appearance of midline shift, which requires active management.

Determination of the Trans-Lamina Cribrosa Pressure Difference in a Community-Based Population and its Association with Open-Angle Glaucoma

To determine the trans-lamina cribrosa pressure difference (TLCPD) in a cohort of normal community-based patients and the relationship to primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG). Retrospective cohort study of the Mayo Clinic Study of Aging. The Mayo Clinic Study of Aging is a prospective study evaluating the normal aging population. Mayo Clinic Study of Aging patients who underwent routine lumbar puncture (LP) studies with eye examinations were reviewed. The trans-lamina cribrosa pressure difference was calculated in 2 contexts of intraocular pressure (IOP): (1) maximum IOP at eye visit closest in time to the LP (closest-in-time TLCPD); and (2) IOP before IOP-lowering treatment (pretreatment IOP and pretreatment TLCPD) in POAG and NTG patients. Glaucoma patients without POAG or NTG were excluded. Regression analyses were performed to determine the relationship with glaucoma. IOP, intracranial pressure, TLCPD, POAG, normal-tension glaucoma (NTG) diagnosis, glaucoma parameters. Five hundred forty-eight patients were analyzed. Of these, there were 38 treated glaucoma patients (14 POAG and 24 NTG) and 510 nonglaucomatous patients. Cerebral spinal fluid (CSF) opening pressure was 155.0 ± 42.2 mmH2O in nonglaucomatous patients, 144.0 ± 34.0 mmH2O in POAG (P= 0.15 vs. nonglaucomatous patients), and 136.6 ± 29.3 mmH2O in NTG (P= 0.017 vs. nonglaucomatous patients). Intraocular pressure was 15.47 ± 2.9 mmHg in nonglaucomatous patients, 26.6 ± 3.7 mmHg in POAG, and 17.4 ± 3.4 mmHg in NTG. The closest-in-time TLCPD in the nonglaucomatous cohort was 4.07 ± 4.22 mmHg, which was lower than both the POAG cohort (7.19 ± 3.6 mmHg) and the NTG cohort (5.79 ± 4.5 mmHg, P= 0.04). Pretreatment TLCPD for the overall glaucoma cohort was 10.57 ± 6.1 mmHg. The POAG cohort had a higher pretreatment TLCPD (16.05 ± 5.2 mmHg) than the NTG cohort (7.37 ± 4.1 mmHg; P < 0.0001). Closest-in-time TLCPD for the nonglaucoma cohort (4.07± 4.2 mmHg) was significantly lower than pretreatment TLCPDs for both POAG (16.05 ± 5.2 mmHg; P < 0.0001) and NTG (7.37 ± 4.1 mmHg; P < 0.0001) cohorts. This study establishes the baseline TLCPD in a large cohort of normal, community-based patients. The differences in regression analysis between TLCPD and IOP suggests NTG pathophysiology is partially driven by TLCPD, but is also likely multifactorial. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Dual positivity for anti-MOG and oligoclonal bands: Unveiling unique clinical profiles and implications

BackgroundDistinguishing between MOG-associated disease (MOGAD) and multiple sclerosis (MS) presents a considerable challenge, as there are instances of overlapping clinical presentations. This complexity is further magnified in cases where patients concurrently exhibit both anti-myelin oligodendrocyte glycoprotein (anti-MOG) positivity and detectable oligoclonal bands (OCBs) This retrospective study investigates the clinical and imaging attributes of dual-positive patients, those with both anti-MOG positivity and OCBs, The study aims to show potential areas of overlap between multiple sclerosis (MS) and MOGAD. MethodsUtilizing data gathered from three medical centers, we evaluated a cohort of 45 patients, stratifying them into two groups: those exclusively positive for anti-MOG antibodies and those displaying dual positivity. Our analysis encompassed a wide range of clinical and imaging parameters. The statistical techniques employed comprised Fisher's Exact Test along with Benjamini-Hochberg correction to ensure robustness of the findings. ResultsThe study involved 45 patients with anti-MOG antibodies; 30 exhibited isolated anti-MOG positivity without OCBs, while 15 were dual-positive. The first group's average age was 10±7 years, compared to 28±17 years in the double-positive group (p = 0.001). CSF analysis showed no significant differences in pleocytosis, protein levels, or opening pressure between the groups. In the exclusive anti-MOG positivity cohort, 9 out of 15 patients received IVIG treatment; a larger subgroup with dual positivity chose anti-CD20 treatment. Notably, papilledema incidence was higher in the single-positive group (p = 0.014). Optic nerve enhancement (p = 0.0038) and nerve thickening (p = 0.0017) were markedly elevated in the single-positive population, with a trend towards pre-chiasmatic lesions (p = 0.06). Double-positive cases exhibited more polyfocal presentation (p = 0.013) and higher attacks per case (p = 0.002, HR=10.2, 95 % CI: 2.19 to 49.23). The double-positive group had more brain lesions (p = 0.0063) but no significant distinctions in other aspects. ConclusionThe results emphasize the challenges inherent in differentiating between MS and a more MOGAD. While the data suggest two plausible scenarios—either falling within the spectrum of MS or representing an intensified MOGAD—we recognize the need for stronger evidence to definitively classify these instances. This study underscores the imperative for thorough investigations to ascertain whether these cases align with the MS spectrum or denote an inflammatory variant of MOGAD.

The effect of head of bed elevation on upper airway collapsibility during drug-induced sleep endoscopy.

Drug-induced sleep endoscopy with positive airway pressure evaluates the collapsibility of the upper airway. It is currently unknown whether body position affects this assessment. We sought to determine whether the collapsibility of the airway may change with head of bed elevation. A prospective, consecutive cohort study was performed by 2 sleep surgeons at a tertiary care center. Inclusion criteria included adults 18 years of age and older with obstructive sleep apnea who were intolerant to continuous positive airway pressure therapy. Patients underwent drug-induced sleep endoscopy with positive airway pressure to evaluate them for alternative treatment options. Patients were evaluated in supine position with the head of bed both level and elevated to 30°. The airway was evaluated using the standardized VOTE scoring system in both positions. The 61 patients included in the study were predominantly male (70.5%), middle-aged (51.2 years), and obese (body mass index, 30.2 kg/m2) with moderate-to-severe obstructive sleep apnea (apnea-hypopnea index, 34.1 events/h). The cohort consisted of predominantly positional obstructive sleep apnea (mean supine apnea-hypopnea index 48.7 events/h, nonsupine apnea-hypopnea index 20.8 events/h). All 4 sites of the upper airway demonstrated a significant decrease in airway opening pressures with the head of bed elevated compared to level (P < .01 for all sites). There was no significant difference in VOTE scoring between level and upright positions. Patients with the head of bed elevated to 30° have a significantly lower degree of airway collapsibility compared to patients in the level position but no significant change in VOTE scoring was observed. Owen GS, Talati VM, Zhang Y, LoSavio PS, Hutz MJ. The effect of head of bed elevation on upper airway collapsibility during drug-induced sleep endoscopy. J Clin Sleep Med. 2024;20(1):93-99.

The initial intracranial pressure spike phenomenon.

Elective use of intraparenchymal intracranial pressure (ICP) monitoring is a valuable resource in the investigation of hydrocephalus and other cerebrospinal fluid disorders. Our preliminary study aims to investigate ICP changes in the immediate period following dural breach, which has not yet been reported on. This is a prospective cohort study of patients undergoing elective ICP monitoring, recruited between March and May 2022. ICP readings were obtained at opening and then at 5-min intervals for a 30-min duration. Ten patients were recruited, mean age 45 years, with indications of a Chiari malformation (n = 5), idiopathic intracranial hypertension (n = 3) or other ICP-related pathology (n = 2). Patients received intermittent bolus sedation (80%) vs general anaesthesia (20%). Mean opening pressure was 22.9 mmHg [± 6.0], with statistically significant decreases present every 5 min, to a total reduction of 15.2 mmHg at 20 min (p = < 0.0001), whereafter the ICP plateaued with no further statistical change. Our results highlight an intracranial opening pressure 'spike' phenomenon. This spike was 15.2 mmHg higher than the plateau, which is reached at 20 min after insertion. Several possible causes exist which require further research in larger cohorts, including sedation and pain response. Regardless of causation, this study provides key information on the use of ICP monitoring devices, guiding interpretation and when to obtain measurements.

Predictors of disease course and long-term outcomes of idiopathic intracranial hypertension in children and adolescents.

This study provides insights into predictive factors for an unfavorable disease course, persistent headaches, and poor visual outcomes in patients with childhood IIH. Patients with persistent headaches may have a variant of a chronic pain syndrome warranting a different therapeutic approach. • Childhood-onset Idiopathic Intracranial hypertension (IIH) is a heterogenous disease. The knowledge on disease trajectory and long-term outcomes and its predictors is limited. • A higher opening pressure and factors suggestive of the metabolic syndrome predict an unfavorable disease coursewhereasfemale sex and disease recurrence are significantly associated with poor visual outcomes • A third of the patients diagnosed with IIH experience ongoing headachesdespite achieving favorable visual outcomes.This subset, characterized by lower disease-severity indicators at onset may represent a distinct subgroup warranting a different therapeutic approach.

Mass flow characteristics and correlations of R454C flow through an electrical expansion valve in a heat pump split system

The use of electronic expansion valves (EEVs) in heat pump systems has seen a rapid increase in recent years due to their advantages such as fast response, accurate control, and ability to improve seasonal performance. Modeling of the refrigerant flow characteristics through EEVs is needed during design for optimizing system performance and operation. Previous studies have not led to any generalized correlations for EEVs that accurately predict performance for different refrigerants. When working with a new refrigerant and/or EEV, it is necessary to perform mass flow measurements for the EEV over a wide range of operating conditions that are then used to develop and validate a refrigerant and EEV specific correlation. R454C, a low-GWP refrigerant mixture, is gaining attention as a potential replacement for R404A and R410A systems. However, there is currently no available EEV experimental data or correlation specifically for R454C in the literature. The objective of this paper is to present experimental results and characterization of R454C flowing through an EEV in a heat pump split system across a wide range of operational conditions. The impacts of valve opening, subcooling degree and inlet pressure on mass flow rate though the EEV were investigated. Two semi-empirical correlations were developed that map the experimental data based on the Buckingham π theorem and a polynomial function. Both mapping methods predicted mass flow rate for test data within 10%. The Buckingham π correlation was slightly more accurate. Both correlations were developed to enable mass flow rate predictions for R454C passing through EEVs with different valve sizes. Finally, a relationship between refrigerant molar mass and mass flow coefficient was observed that could be useful in developing a general EEV correlation that can be applied for different refrigerants. However, further investigation is needed to validate this relationship.

A solenoid injector based drop-on-demand system for generating large droplets.

This paper proposes a drop-on-demand (DOD) system that can produce single droplets of highly repeatable size in the order of 2mm. This system utilizes an on-the-shelf solenoid injector used in automotive applications. The design methodology is explained along with the necessary measurements and numerical simulations of droplet generation. The invention consists of a solenoid injector that produces monodisperse single or in-series droplets with the help of a developed pulse width modulated signal generator. Mass per injection is measured over a range of supply pressures and injection durations to find the operation window to generate 2mm droplets. Later, various nozzle geometries are designed and tested by flow simulations. The contracting nozzle is found suitable for generating single droplets, so the design is implemented at the tip of the solenoid injector. The effects of different opening times, pressures, and nozzle's orifice diameters were tested to observe the operating window of the newly designed DOD system and the repeatability of generated droplets by utilizing a coherent circular Hough transform image processing algorithm to measure droplet sizes. The standard deviation of measured diameters is less than 5% of the mean droplet diameter, which is in the range of 1.68-2.07mm. Next, the voltage and current signals are measured per injection, and exact instants for the initiation and ending for both opening and closing are determined to construct transient mass flow rate functions for flow simulations in which the dependence of droplet formation on the speed of closing is revealed. The numerical and experimental results indicate the repeatability and consistency of the invention.

Diagnostic Analysis of Exhaust Gas with A Quick-Changing Temperature from a Marine Diesel Engine Part II / Two Factor Analysis

Abstract The article presents a continuation of research carried out to determine the effect of input parameters (changes in engine structure parameters) on selected output parameters (diagnostic measures), based on quickly changing exhaust gas temperature. A method of determining the simultaneous influence of two input factors (the structure parameter and the engine load) on one output factor was presented, as well as an evaluation of which of the analysed input factors has a stronger influence on the output parameter. The article presents the stages of the experimental research conducted and statistical inference based on the results. Three changing parameters for the structure were reviewed: the active cross-sectional area of the inlet air channel, the injector opening pressure and the compression ratio. Based on the quickly changing temperatures of the exhaust gases, three diagnostic measures were defined and subjected to statistical tests. The following data were averaged over one cycle for a 4-stroke engine operation: the intensity of changes, the specific enthalpy and the peak-to-peak value of the exhaust gas temperature. The results of the two-factor analysis are presented. Conclusions on the analysis are given and a criterion for the selection of a diagnostic measure, depending on the analysed parameter of the structural design of the diesel engine, is proposed. The previous part of the article presented the results of the first stage of the elimination study: the one-factor statistical analysis (randomised complete plan). This paper presents the results of the second stage of the studies: two-factor analysis (block randomised plan), where the significance of the effect of changing the values of the structural parameters on the diagnostic measures were analysed in the background of a variable engine load. The next (third) part will present the results of the calculations and analysis of the interaction coefficient of significance.

The Vienna idiopathic intracranial hypertension database-An Austrian registry.

Idiopathic intracranial hypertension (IIH) is becoming increasingly more prevalent bearing the risk of visual impairment and affecting the quality of life. Clinical presentation and outcome are heterogeneous. Large, well-characterized cohorts are scarce. To characterize the clinical spectrum, diagnostic findings, therapeutic management, and outcome of IIH. We identified patients with IIH according to modified Friedman criteria treated at our center between 2014 and 2021. The Vienna IIH database is described in detail. Of 113 patients 89% were female (mean age 32.3years). Median body mass index (BMI) was 31.8, with 85% overweight (BMI > 25) and 5% were classified as IIH without papilledema. Headache was present in 84% and showed migraine features in 43%. Median opening pressure in lumbar puncture was 31 cmH2O. Pharmacotherapy (predominantly acetazolamide) was established in 99%, 56% required at least 1 therapeutic lumbar puncture and 13% a surgical intervention. After a median 3.7years follow-up, 57% had achieved significant weight loss, papilledema was present in 59% and headache in 76% (58% improved). Comparing initial presentation to follow-up, perimetry was abnormal in 67% vs. 50% (8% worsened, 24% improved) and transorbital sonography in 87% vs. 65% with amedian optic nerve sheath diameter of 5.4 mm vs. 4.9 mm. Median peripapillary retinal nerve fiber layer thickness decreased from 199 µm to 99 µm and ganglion cell layer volume from 1.13 mm3 to 1.05 mm3. The large representative Vienna IIH cohort characterizes IIH-related symptoms, diagnostic findings, treatment, and outcome emphasizing substantial long-term sequelae of IIH. Future analyses will aim to refine phenotyping and identify factors predicting outcome.

Hydraulic injection tests in the pilot EGS borehole PVGT-LT1 in Litoměřice, Czechia

Successful utilization of geothermal energy is conditioned by sufficient permeability of the rock formation as a heat exchanger. We present results of hydraulic injection tests carried out in 2020 in the pilot geothermal borehole PVGT-LT1 in Litoměřice, Czech Republic, which samples 800 m of Paleozoic and Mesozoic sediments on the top of a crystalline basement. The low hydraulic conductivity on the order of 10−11 m/s obtained by recovery tests was verified by large-scale injection tests monitored by DTS temperature logging. During the first test, 24 m3 of water were injected and a permeable fracture was created at 880 m depth, breaking through the ignimbrite layer. The opening pressure of 12.55 MPa corresponds to the lower estimate of the minimum stress at this depth. The second injection was performed 7 months later and 202 m3 were injected at flow rates reaching 50 l/min. It showed that the fracture had been preserved since the first injection, which was documented by a non-zero flow rate at the smallest injection pressures and also by a stabilized water level in the borehole, which dropped immediately after the fracture formation. No induced seismicity accompanied the injection, which indicates a possibly low seismogenic potential of this area of the Bohemian Massif. The model of finite conductive fracture fitted to the pressure decay curve during shut-in intervals gives an estimate of a fracture half-length exceeding 100 m.

Quantifying bladder outflow obstruction in men: A comparison of four approximation methods exploiting large data samples.

A pressure flow study (PFS), part of the International Continence Societystandard urodynamic test, is regarded gold standard for the classification and quantification of the urethral resistance (UR), expressed in the bladder outflow obstruction(BOO). For men with benign prostatic hyperplasia, the minimum urethral opening pressure (pmuo ), found at the end of the passive urethral resistance relation is considered the relevant parameter describing BOO. However, in clinical practice, direct measurements of pmuo are easily confounded by terminal dribbling. For that reason, alternative methods were developed to derive pmuo , and thereby assess BOO using the maximum urine flow rate (Qmax ) and the corresponding pressure (pdetQmax ) instead. These methods were never directly compared against a large data set. With the increasing variety of treatments becoming available more precise grading of UR may become of relevance. The current study compares four well-known methods to approximate pmuo and examines the relation between pmuo and pdetQmax . In total, 1717 high-quality PFS of men referred with lower urinary tract symptoms between2003 and 2020 without earlierlower urinary tractsurgery were included. From these recordings, pmuo was calculated according to three one-parameter methods. In addition, a three-parameter method(3PM) was used, based on a fit through the lowest pressure flank of the pressure-flow plot. The estimated pmuo 's were compared with a precisely assessed pmuo . A difference of <10 cmH2 O between an estimate and the actual pmuo was considered accurate. A comparison between the four approximation methods and the actual pmuo was visualized using a Bland-Altman plot. The differences between the actual and the estimated slope were assessed and dependency on pmuo was analyzed. A total of 1717 studies were analyzed. In 55 (3.2%) PFS, 3PM analysis was impossible because all pressures after Qmax were higher than pdetQmax . The 3PM model was superior in predicting pmuo , with 75.9% of the approximations within a range of +10 or -10 cmH2 O of the actual pmuo . Moreover, pmuo according to urethral resistance A(URA) and linearized passive urethral resistance relation (linPURR) appear equally reliable. Bladder outflow obstruction index (BOOI) was significantly less accurate when compared to all others. Bland-Altman analysis showed a tendency of BOOI to overestimate pmuo in men with higher grades of UR, while URA tended to underestimate pmuo in those cases. The slope between pmuo and pdetQmax -Qmax increased with larger pmuo , as opposed to the constant relation proposed within BOOI. Although significant differences were found, the clinical relevance of those differences is not known. Of the four methods to estimate pmuo and quantify BOO, 3PM was found the most accurate and BOOI the least accurate. As 3PM is not generally available and performance in lower quality PFS is unknown, linPURR is (for now) the most physiologically accurate.

Development and validation of a machine learning model to predict prognosis in HIV-negative cryptococcal meningitis patients: a multicenter study.

To predict prognosis in HIV-negative cryptococcal meningitis (CM)patients by developing and validating a machine learning (ML)model. This study involved 523 HIV-negative CM patients diagnosed between January 1, 1998, and August 31, 2022, by neurologists from 3 tertiary Chinese centers. Prognosis was evaluated at 10weeks after the initiation of antifungal therapy. The final prediction model for HIV-negative CM patients comprised 8 variables: Cerebrospinal fluid(CSF) cryptococcal count, CSF white blood cell (WBC), altered mental status, hearing impairment, CSF chloride levels, CSF opening pressure (OP), aspartate aminotransferase levels at admission, and decreased rate of CSF cryptococcal count within 2weeks after admission. The areas under the curve (AUCs) in the internal, temporal, and external validation sets were 0.87 (95% CI 0.794-0.944), 0.92 (95% CI 0.795-1.000), and 0.86 (95% CI 0.744-0.975), respectively. An artificial intelligence(AI) model was trained to detect and count cryptococci, and the mean average precision (mAP) was 0.993. A ML model for predicting prognosis in HIV-negative CM patients was built and validated, and the model might provide a reference for personalized treatment of HIV-negative CM patients. The change in the CSF cryptococcal count in the early phase of HIV-negative CM treatment can reflect the prognosis of the disease. In addition, utilizing AI to detect and count CSF cryptococci in HIV-negative CM patients can eliminate the interference of human factors in detecting cryptococci in CSF samples and reduce the workload of the examiner.

Computational fluid dynamics of upper airway aerodynamics for exercise-induced laryngeal obstruction: A feasibility study.

Use of computational fluid dynamic (CFD) simulations to measure the changes in upper airway geometry and aerodynamics during (a) an episode of Exercise-Induced Laryngeal Obstruction (EILO) and (b) speech therapy exercises commonly employed for patients with EILO. Magnetic resonance imaging stills of the upper airway including the nasal and oral cavities from an adult female were used to re-construct three-dimensional geometries of the upper airway. The CFD simulations were used to compute the maximum volume flow rate (l/s), pressure (Pa), airflow velocity (m/s) and area of cross-section opening in eight planes along the vocal tract, separately for inhalation and exhalation. Numerical predictions from three-dimensional geometrical modeling of the upper airway suggest that the technique of nose breathing for inhalation and pursed lip breathing for exhalation show most promising pressure conditions and cross-sectional diameters for rescue breathing exercises. Also, if EILO is due to the constriction at the vocal fold level, then a quick sniff may also be a proper rescue inhalation exercise. EILO affects both the inspiratory and the expiratory phases of breathing. A prior knowledge of the supraglottal aerodynamics and the corresponding upper airway geometry from CFD analysis has the potential to assist the clinician in choosing the most effective rescue breathing technique for optimal functional outcome of speech therapy intervention in patients with EILO and in understanding the pathophysiology of EILO on a case-by-case basis with future studies. 4.

Design and research of a valve-based piezoelectric pump with low forward resistance and high reverse shutoff

This paper proposes, designs, manufactures and experimentally studies a wedge valve piezoelectric pump driven by a double displacement amplifier vibrator (DDAV). A novel wedge valve is designed, manufactured and analyzed, and the static performance of the wedge valve is tested. The test results show that it has less forward resistance and high reverse shutoff. The DDAV and pump body are designed, and the test experimental platform is built. Results indicate that the static opening pressure of the wedge valve is 0.27 kPa, and the reverse shutoff pressure can reach 200 kPa. When the driving voltage is 700 Vpp and the driving frequency is 425 Hz, the maximum flow rate is 491.2 ml min−1 and the maximum output pressure is 160 kPa.

Successful Cervical Epidural Blood Patch as a Treatment of Spontaneous Intracranial Hypotension - A Case Report

Background: Spontaneous intracranial hypotension can be a source of headache due to a continuous cerebrospinal fluid leakage. Case: A 33-year-old male patient with unremarkable history was presented with a headache, accompanying posterior neck stiffness and tinnitus lasting for 4 days. The opening pressure from cerebrospinal fluid tapping was 60mmH2O. Magnetic resonance imaging of the neck showed fluid collection at right C1-2 level, suggesting spontaneous intracranial hypotension. The headache did not respond to conservative treatments. Epidural blood patch was performed at C4-5 level. On postoperative day 1, remnant headache was only 20 percent and patient was discharged the day after. Conclusions: In spontaneous intracranial hypotension with leakage site at high cervical level, an epidural blood patch at a different cervical level can be safely performed to relieve the symptoms.

Measuring, representing and analysing indoor soundscapes: A data collection campaign in residential buildings with natural and mechanical ventilation in England

A model for the assessment of perceived affective quality of indoor residential soundscapes is first applied in a field survey carried out in 61 dwellings in England. Objectives are i) to investigate measurement and indoor soundscape data representation, ii) to characterize soundscape appropriateness for home working and relaxation, iii) to test differences based on the ventilation strategy, and iv) to identify factors predicting indoor soundscapes. In dwellings with natural ventilation (N = 34) the survey was carried out with windows open, while in those with mechanical ventilation (N = 27) with windows closed and the system in operation. Parallel to the administration of the questionnaire, monaural and binaural measurements of the acoustic environments were performed. The study provides examples of data representation in the circumplex space defined by comfort and content dimensions. Soundscapes which are appropriate for work and relaxation are characterized by high comfort and low content, i.e., perceived as private and under control. Indoor soundscapes are strongly related to the perception of traffic noise, window opening, and sound pressure level, especially in the energy content of interference in speech perception through the Speech Interference Level parameter (SIL), factors that lead to reduced comfort and increased saturation of the environment. Moreover, aspects related to psychoacoustics (sharpness), contextual and building-related factors (ownership status and floor level) and cross-modal effects from other sensory modalities (perceived air quality and air temperature) have an impact. A threshold value of 32.7 dB for SIL was identified at which a neutral comfort is attained.

Empirical Equations Expressing the Effects of Measured Suction on the Compaction Curve for Sandy Soils Varying Fines Content

To effectively apply various soil types for embankments, understanding their compaction characteristics is crucial. One crucial factor affecting compaction is suction, which plays a significant role as it is typically performed under unsaturated conditions. Suction varies with soil density, water content, and fines content. This study directly measures suction after soil compaction using the triaxial apparatus, unlike the Soil water characteristic curve (SWCC), assessing its impact on compaction characteristics. Immediate suction measurement after compaction provides apparent suction, resembling on-site conditions with open pore air pressure. Comparing SWCC with apparent suction at each compacted state reveals that suction and air entry value increase with initial density, positively impacting compaction. Notably, apparent suction aligns better with wetting process suction from the SWCC due to added water during specimen preparation. Empirical equations are derived to obtain suction contours across various density and saturation ranges, aiding in understanding suction variations on the compaction curve. Even slight variations in saturation causes noticeable changes in apparent suction during higher compaction efforts, affecting soil compaction characteristics. Therefore, the precise control of saturation control is needed to achieve desired properties of compacted soil, especially at higher compaction efforts and with various soil types. This understanding significantly impacts the mechanical behavior of unsaturated soils.

Retinal hemorrhages due to intracranial hypertension, is it possible to differentiate them from those associated with abuse?

BackgroundRetinal hemorrhages (RHs) are suggestive of abusive head trauma (AHT). Even so, controversy persists about other possible causes, a fact that hinders the diagnosis of abuse. ObjectiveTo determine the prevalence and patterns of RHs associated with increased intracranial pressure (ICP) in young children. Participants and methodsProspective, single center study of children aged 29 days-3 years undergoing a lumbar puncture with opening pressure (OP) measured during routine clinical care in the emergency department, over a 4-year period. Children with known causes of RHs were excluded. All the children underwent a detailed ophthalmological examination within 72 h of admission. For children with RHs, an in-depth investigation was carried out to rule out AHT. ResultsThirty-four patients were included: 20(58.8 %) were boys, median age 11.7 months (range 1-33 months). Overall, 29(85.3 %) had clinical findings of increased ICP. The duration of symptoms was ≤4 days in all patients except one, in whom it was 1.5 months. The median OP was 27cmH2O (range 20-60cmH2O). One of the children was found to have RHs, with evaluation resulting in a diagnosis of AHT. No RHs were found in any of the others studied. Using the Wilson method, we can be confident to an upper limit of 95 % that the probability of RHs occurring secondary to increased ICP alone is at most 0.1. ConclusionsRHs were not detected in patients with isolated nontraumatic increased ICP, measured via OP and diagnosed in the ED. Therefore, if RHs are detected, investigation into the possibility of AHT is warranted.

Emergent cerebral venous stenting: A valid treatment option for fulminant idiopathic intracranial hypertension

BackgroundFulminant idiopathic intracranial hypertension (FIIH) is characterized by rapid, severe, progressive vision loss and often treated surgically. Cerebral transverse venous stenting (CTVS) is efficacious in IIH patients, but emergent CTVS in FIIH is rarely reported. We present our experience with emergent CTVS in patients with FIIH. MethodsSince 01/2019, an institutional protocol allowed emergent CTVS in FIIH patients with bilateral transverse sinus stenosis and gradient pressure > 15 on digital subtraction angiography (DSA). We retrospectively analyzed a prospective registry of all IIH patients with details of neurological and neuro-ophthalmological assessments before and after treatment, and subjective assessments of headache and tinnitus were made pre-and post-procedure. Results259 IIH patients, including 49 who underwent CTVS, were registered. Among them, five female patients met inclusion criteria for FIIH and underwent emergent CTVS. FIIH patients were younger (18.8 ± 1.64 vs 27.7 ± 4.85, p < 0.01), mean BMI was lower (30.8 ± 10.57 vs 34.6 ± 4.3, p < 0.01), and lumbar puncture opening pressure higher (454 ± vs 361 ± 99.4, p < 0.01) than that of IIH patients. They presented with acute visual loss, severe headache, papilledema, significant bilateral transverse sinus stenosis on CT-venography, and mean dominant side gradient pressure of 26.4 ± 6.2 on DSA. CTVS was performed without significant complications, resulting in remarkable improvement in headache, optical coherence tomography, and visual fields within 1 week. At 1-year follow-up (four patients) and 6-month follow-up (1 patient), there was complete resolution of papilledema and headache, and marked improvement in visual acuity. ConclusionsIn these patients, emergent-CTVS was a safe and effective treatment option for FIIH. Further evaluation is warranted.