Simple detecting of elevated ICP through liquor flow after lumbar puncture.

Elevated intracranial pressure (ICP) is defined as a cerebrospinal fluid (CSF) opening pressure (OP) greater than 25 cmH2O. When a diagnostic lumbar puncture is performed it is useful to estimate also intracranial pressure. To do this it is required a presence of pressure gauges, which are currently the gold standard, not available in most resource-constrained contexts. We decided to evaluate whether it is possible to estimate it simply by counting the drops of cerebrospinal liquor, which are collected after lumbar puncture, according to Poiseuille's law. Was examined a sample of 52 patients, aged between 18 and 85 years, belonging to the emergency room of "Santa Maria delle Grazie" Hospital in Pozzuoli (Naples) who needed a diagnostic lumbar puncture (LP). The ICP was initially measured using a standard narrow-gauge manometer by attaching it to the spinal needle. After removing the pressure gauge, the number of drops of cerebrospinal fluid flowing from the spinal needle in 30  seconds was counted. A statistical analysis was made with linear regression and ROC analysis. OP as measured by standard manometry was raised on 17 occasions with CSF drop rate median of 47 drops/30 seconds and range 30-74 drops/30 seconds. OP was normal on 35 occasions with CSF drop rate median of 23 drops/30 seconds  with range of 14-34 drops/30 seconds. A linear regression analysis was performed which resulted in a Pearson correlation of 0.936 an adjusted R square of 0.874 (see Fig. 1). Analysis through ANOVA documented an F of 355.301 with p < 0.01 and Dubin Watson of 1.642. The analysis through ROC showed an AUC of 0.980, with a sensitivity of 100% and a specificity of 91% if chosen as a limit, 29 drops in 30 seconds  (Youden Index of 0.9140). Therefore, we have concluded, that although there are several precautions, like patient's position, it is technically feasible to indirectly estimate cerebrospinal fluid pressure with good accuracy by counting the drops of cerebrospinal fluid flowing from a 22 G spinal needle.

Navigated bedside implantation of external ventricular drains with mobile health guidance: technical note and case series.

PURPOSE: External ventricular drain (EVD) implantation is one of the fundamental procedures of emergency neurosurgery usually performed freehand at bedside or in the operating room using anatomical landmarks. However, this technique is frequently associated with malpositioning leading to complications or dysfunction. Here, we describe a novel navigated bedside EVD insertion technique, which is evaluated in a clinical case series with the aim of safety, accuracy, and efficiency in neurosurgical emergency settings. METHODS: From 2021 to 2022, a mobile health-assisted navigation instrument (Thomale Guide, Christoph Miethke, Potsdam, Germany) was used alongside a battery-powered single-use drill (Phasor Health, Houston, USA) for bedside EVD placement in representative neurosurgical pathologies in emergency situations requiring ventricular cerebrospinal fluid (CSF) relief and intracranial pressure (ICP) monitoring. RESULTS: In all 12 patients (8 female and 4 male), navigated bedside EVDs were placed around the foramen of Monro at the first ventriculostomy attempt. The most frequent indication was aneurysmal subarachnoid hemorrhage. Mean operating time was 25.8 ± 15.0 min. None of the EVDs had to be revised due to malpositioning or dysfunction. Two EVDs were converted into a ventriculoperitoneal shunt. Drainage volume was 41.3 ± 37.1 ml per day in mean. Mean length of stay of an EVD was 6.25 ± 2.8 days. Complications included one postoperative subdural hematoma and cerebrospinal fluid infection, respectively. CONCLUSION: Combining a mobile health-assisted navigation instrument with a battery-powered drill and an appropriate ventricular catheter may enable and enhance safety, accuracy, and efficiency in bedside EVD implantation in various pathologies of emergency neurosurgery without adding relevant efforts.

Intra-dialytic intracranial pressure monitoring in a patient with lumbo-peritoneal shunt for idiopathic intracranial hypertension.

We present the case of a 25-year-old female with End-Stage Renal Disease (ESRD) and Idiopathic Intracranial Hypertension (IIH) who developed severe headaches during haemodialysis (HD). The headaches resolved several hours after each HD session. We were able to diagnose dialysis disequilibrium syndrome (DDS) following intracranial pressure (ICP) monitoring and use a novel strategy to treat her symptoms.

Utilization of Brain Tissue Oxygenation Monitoring and Association with Mortality Following Severe Traumatic Brain Injury.

BACKGROUND: The aim of this study was to describe the utilization patterns of brain tissue oxygen (PbtO2) monitoring following severe traumatic brain injury (TBI) and determine associations with mortality, health care use, and pulmonary toxicity. METHODS: We conducted a retrospective cohort study of patients from United States trauma centers participating in the American College of Surgeons National Trauma Databank between 2008 and 2016. We examined patients with severe TBI (defined by admission Glasgow Coma Scale score ≤ 8) over the age of 18 years who survived more than 24 h from admission and required intracranial pressure (ICP) monitoring. The primary exposure was PbtO2 monitor placement. The primary outcome was hospital mortality, defined as death during the hospitalization or discharge to hospice. Secondary outcomes were examined to determine the association of PbtO2 monitoring with health care use and pulmonary toxicity and included the following: (1) intensive care unit length of stay, (2) hospital length of stay, and (3) development of acute respiratory distress syndrome (ARDS). Regression analysis was used to assess differences in outcomes between patients exposed to PbtO2 monitor placement and those without exposure by using propensity weighting to address selection bias due to the nonrandom allocation of treatment groups and patient dropout. RESULTS: A total of 35,501 patients underwent placement of an ICP monitor. There were 1,346 (3.8%) patients who also underwent PbtO2 monitor placement, with significant variation regarding calendar year and hospital. Patients who underwent placement of a PbtO2 monitor had a crude in-hospital mortality of 31.1%, compared with 33.5% in patients who only underwent placement of an ICP monitor (adjusted risk ratio 0.84, 95% confidence interval 0.76-0.93). The development of the ARDS was comparable between patients who underwent placement of a PbtO2 monitor and patients who only underwent placement of an ICP monitor (9.2% vs. 9.8%, adjusted risk ratio 0.89, 95% confidence interval 0.73-1.09). CONCLUSIONS: PbtO2 monitor utilization varied widely throughout the study period by calendar year and hospital. PbtO2 monitoring in addition to ICP monitoring, compared with ICP monitoring alone, was associated with a decreased in-hospital mortality, a longer length of stay, and a similar risk of ARDS. These findings provide further guidance for clinicians caring for patients with severe TBI while awaiting completion of further randomized controlled trials.

Intracranial Pressure Monitoring in Moderate Traumatic Brain Injury: A Systematic Review and Meta-Analysis.

BACKGROUND: The principal aim of this study was to determine the prevalence of intracranial pressure (ICP) monitoring and intracranial hypertension (IHT) in patients treated for moderate traumatic brain injury (TBI). A secondary objective was to assess factors associated with ICP monitoring. METHODS: We conducted a systematic review of the literature to identify studies that assessed ICP monitoring in moderate TBI. The meta-analysis was performed by using a random-effects model. RESULTS: A total of 13 studies comprising 116,714 patients were pooled to estimate the overall prevalence of ICP monitoring and IHT (one episode or more of ICP > 20 mm Hg) after moderate TBI. The prevalence rate for ICP monitoring was 18.3% (95% confidence interval 8.1-36.1%), whereas the proportion of IHT was 44% (95% confidence interval 33.8-54.7%). Three studies were pooled to estimate the prevalence of ICP monitoring according to Glasgow Coma Scale (GCS) (≤ 10 vs. > 10). ICP monitoring was performed in 32.2% of patients with GCS ≤ 10 versus 15.2% of patients with GCS > 10 (p = 0.59). Both subgroups were highly heterogeneous. We found no other variables associated with ICP monitoring or IHT. CONCLUSIONS: The prevalence of ICP monitoring in moderate TBI is low, but the prevalence of IHT is high among patients undergoing ICP monitoring. Current literature is limited in size and quality and does not identify factors associated with ICP monitoring or IHT. Further research is needed to guide the optimal use of ICP monitoring in moderate TBI.

Patient's Clinical Presentation and CPPopt Availability: Any Association?

BACKGROUND: The 'optimal' CPP (CPPopt) concept is based on the vascular pressure reactivity index (PRx). The feasibility and effectiveness of CPPopt guided therapy in severe traumatic brain injury (TBI) patients is currently being investigated prospectively in the COGiTATE trial. At the moment there is no clear evidence that certain admission and treatment characteristics are associated with CPPopt availability (yield). OBJECTIVE: To test the relation between patients' admission and treatment characteristics and the average CPPopt yield. METHODS: Retrospective analysis of 230 patients from the CENTER-TBI high-resolution database with intracranial pressure (ICP) measured using an intraparenchymal probe. CPPopt was calculated using the algorithm set for the COGiTATE study. CPPopt yield was defined as the percentage of CPP monitored time (%) when CPPopt is available. The variables in the statistical model included age, admission Glasgow Coma Scale (GCS), gender, pupil response, hypoxia and hypotension at the scene, Marshall computed tomography (CT) score, decompressive craniectomy, injury severity score score and 24-h therapeutic intensity level (TIL) score. RESULTS: The median CPPopt yield was 80.7% (interquartile range 70.9-87.4%). None of the selected variables showed a significant statistical correlation with the CPPopt yield. CONCLUSION: In this retrospective multicenter study, none of the selected admission and treatment variables were related to the CPPopt yield.

Intracranial pulse pressure waveform analysis using the higher harmonics centroid.

BACKGROUND: The pulse waveform of intracranial pressure (ICP) is its distinctive feature almost always present in the clinical recordings. In most cases, it changes proportionally to rising ICP, and observation of these changes may be clinically useful. We introduce the higher harmonics centroid (HHC) which can be defined as the center of mass of harmonics of the ICP pulse waveform from the 2nd to 10th, where mass corresponds to amplitudes of these harmonics. We investigate the changes in HHC during ICP monitoring, including isolated episodes of ICP plateau waves. MATERIAL AND METHODS: Recordings from 325 patients treated between 2002 and 2010 were reviewed. Twenty-six patients with ICP plateau waves were identified. In the first step, the correlation between HHC and ICP was examined for the entire monitoring period. In the second step, the above relation was calculated separately for periods of elevated ICP during plateau wave and the baseline. RESULTS: For the values averaged over the whole monitoring period, ICP (22.3 ± 6.9 mm Hg) correlates significantly (R = 0.45, p = 0.022) with HHC (3.64 ± 0.46). During the ICP plateau waves (ICP increased from 20.9 ± 6.0 to 53.7 ± 9.7 mm Hg, p < 10-16), we found a significant decrease in HHC (from 3.65 ± 0.48 to 3.21 ± 0.33, p = 10-5). CONCLUSIONS: The good correlation between HHC and ICP supports the clinical application of pressure waveform analysis in addition to the recording of ICP number only. Mean ICP may be distorted by a zero drift, but HHC remains immune to this error. Further research is required to test whether a decline in HHC with elevated ICP can be an early warning sign of intracranial hypertension, whether individual breakpoints of correlation between ICP and its centroid are of clinical importance.

Posterior fossa ICP monitoring: a tale of two compartments.

AIM: Measuring the intracranial pressure (ICP) of the infra-tentorial, posterior fossa compartment has long been avoided due to a lack of precedent and interpretability, as well as concern of damage to the underlying vital structures. In cases of posterior fossa insults however, the supra-tentorial compartment ICPs can be falsely reassuring. We aimed to measure the posterior fossa ICP in such a case and analyse the resulting data. METHODS: We present a case of posterior fossa ICP monitoring and discuss its safety profile, rationale and possible indications. RESULTS: Our comparison of the supra and infra-tentorial ICPs showed that there was a statistically significant difference in the two compartments. The infra-tentorial compartment had ICPs averaging 11.02 ± 2.24 mmHg whilst the supra-tentorial compartment averaged 4.94 ± 1.80 mmHg in the first 72 hours post-op (p < .01 on paired t-testing). After 72 hours, the pressures seemed to equilibrate and were 4.71 ± 2.6 and 3.88 ± 2.89 for the infra and supra-tentorial compartments respectively. CONCLUSION: We propose that where a patient with a posterior fossa insult exhibits signs and symptoms consistent with raised ICP but the supra-tentorial readings are normal, posterior fossa ICP monitoring can be considered.

The role of ICP overnight monitoring (ONM) in children with suspected craniostenosis.

PURPOSE: Secondary craniostenosis is a relevant problem pediatric neurosurgeons are confronted with and poses challenges regarding reliable diagnosis of raised ICP, especially in case of absent or questionable papilledema. How to identify children with elevated ICP is still controversial and diagnostics vary. We report on our experience with computerized ICP ONM in relation to imaging derived parameters. METHODS: Thirty-four children with primary or secondary craniostenosis and clinical suspicion of raised ICP were investigated. We compared clinical signs, history, and radiographic assessment with the results of computerized ICP ONM. Differences were significant at a p < 0.05. RESULTS: Baseline ICP was significantly higher in patients with combined suture synostosis, who also had a higher rate of questionable papilledema. Children with narrowed external CSF spaces in MRI had significantly higher ICP levels during REM sleep. Mean RAP was significantly elevated in patients with multi-suture synostosis, indicating poor intracranial compensatory reserve. Syndromal craniostenosis was associated with elevated ICP, RAP was significantly lower, and skull X-rays showed more impressions (copper beaten skull). RAP increased with more severe impressions only to decline in most severe abnormalities, indicating exhaustion of cerebrovascular reserve at an upper ICP breakpoint of 23.9 mmHg. Headaches correlated to lower ICP and were not associated with more severe X-ray abnormalities. CONCLUSION: Narrowed external CSF spaces in MRI seem to be associated to elevated ICP. Skull X-rays can help to identify patients at risk for chronically elevated ICP. Severe X-ray changes correlate with exhausted cerebrovascular reserve as indicated by RAP decline. Only ICP monitoring clearly identifies raised ICP and low brain compliance. Thus, in cases with ambiguous imaging, ONM constitutes an effective tool to acquire objective data for identification of surgical candidates.

The role of ICP monitoring in paediatric IIH.

INTRODUCTION: Diagnosis of idiopathic intracranial hypertension (IIH) in children is an extrapolation of the guidelines suggested for adult population. Lumbar puncture (LP) plays a crucial role in the diagnosis. The diagnosis of IIH at times is solely dependent on the interpretation of the opening pressure (OP). Unfortunately, LP-OP can vary due circumstantial parameters and therefore may be an unreliable form of intracranial pressure (ICP) measurement. Confirming the diagnosis based (as suggested by guidelines) on LP-OP in a doubtful clinical situation would be inappropriate. The aim of our study was to analyse the reliability of LP-OP and importance of ICP monitoring in situations where diagnosis of IIH was questionable. METHODS: Retrospective review of all children with diagnosis of IIH over a 10-year period was conducted. Children who underwent ICP monitoring (ICPM) were selected. We considered 2 LP-OP values-last LP (lLP) and the mean LP (mLP) for analysis. ICPM and LP-OP were compared. Follow-up till last clinic visit was also considered for long-term outcome. RESULTS: Eleven children (male 3; female 8) were included in the study. Mean delay between LP and ICPM was 112.8 days (17-257 days). There was lack of correlation between LP-OP and ICP in 9 children. ICP monitoring refuted the diagnosis of IIH in 80% of children and prevented exposure to unnecessary medical and surgical intervention. There was 1complication with ICPM. In 90% of children, there was no progression of symptoms following a decision based on ICP monitoring on long-term follow-up (mean, 36.5 months). CONCLUSION: When the diagnosis of IIH is in doubt, LP may be unreliable and formal ICP monitoring is advised.

First clinical experience with the new noninvasive transfontanelle ICP monitoring device in management of children with premature IVH.

We previously introduced a novel noninvasive technique of intracranial pressure (ICP) monitoring in children with open fontanelles. Within this study, we describe the first clinical implementation and results of this new technique in management of children with hydrocephalus caused by intraventricular hemorrhage (IVH). In neonates with posthemorrhagic hydrocephalus (PHH), an Ommaya reservoir was implanted for initial treatment of hydrocephalus. The ICP obtained noninvasively with our new device was measured before and after CSF removal and correlated to cranial ultra-sonographies. Six children with a mean age of 27.3 weeks and mean weight of 1082.3 g suffering from PHH were included in this study. We performed an overall of 30 aspirations due to ventricular enlargement. Before CSF removal, the mean ICP was 15.3 mmHg and after removal of CSF the mean ICP measured noninvasively decreased to 3.4 mmHg, p = 0.0001. The anterior horn width (AHW), which reflects early expansion of the ventricles, was before and after CSF removal 15.1 mm and 5.5 mm, respectively, p < 0.0006. There was a strong correlation between noninvasively measured ICP values and sonographically obtained AHW, r = 0.81. Ultimately, all children underwent ventriculoperitoneal shunt procedures. This is the first study providing proof for a noninvasively ICP-based approach for management of posthemorrhagic hydrocephalus in newborn children.

ICP Monitoring and Phase-Contrast MRI to Investigate Intracranial Compliance.

OBJECTIVE: The amplitude of intracranial pressure (ICP) can be measured by ICP monitoring. Phase-contrast magnetic resonance imaging (PCMRI) can quantify blood and cerebrospinal fluid (CSF) flows. The aim of this work was to investigate intracranial compliance at rest by combining baseline ICP monitoring and PCMRI in hydrocephalus patients. MATERIALS AND METHODS: ICP monitoring was performed before infusion testing to quantify ΔICP_rest at the basal condition in 33 suspected hydrocephalus patients (74 years). The day before, patients had had a PCMRI to assess total cerebral blood flow (tCBF), intracranial blood volume change (stroke volume SVblood), and cervical CSF volume change (the stroke volume CSV). Global (blood and CSF) intracranial volume change (ΔIVC) during each cardiac cycle (CC) was calculated. Finally, Compliance: C_rest = ΔIVC/ΔICP_rest was calculated. The data set was postprocessed by two operators according to blind analysis. RESULTS: Bland-Altman plots showed that measurements presented no significant difference between the two operators. ΔICP_rest = 2.41 ± 1.21 mmHg, tCBF = 469.89 ± 127.54 mL/min, SVblood = 0.82 ± 0.32 mL/cc, CSV = 0.50 ± 0.22 mL/cc, ΔIVC = 0.44 ± 0.22 mL, and C_rest = 0.23 ± 0.15 mL/mmHg. There are significant relations between SVblood and CSV and also SVblood and tCBF. CONCLUSIONS: During "basal" condition, the compliance amplitude of the intracranial compartment is heterogeneous in suspected hydrocephalus patients, and its value is lower than expected! This new parameter could represent new information, complementary to conventional infusion tests. We hope that this information can be applied to improve the selection of patients for shunt surgery.

ICP Monitoring by Open Extraventricular Drainage: Common Practice but Not Suitable for Advanced Neuromonitoring and Prone to False Negativity.

OBJECTIVE: A drawback in the use of an external ventricular drain (EVD) originates in the fact that draining cerebrospinal fluid (CSF) (open system) and intracranial pressure (ICP) monitoring can be done at the same time but is considered to be unreliable regarding the ICP trace. Furthermore, with the more widespread use of autoregulation monitoring using blood pressure and ICP signals, the question arises of whether an ICP signal from an open EVD can be used for this purpose. Using an EVD system with an integrated parenchymal ICP probe we compared the different traces of an ICP signal and their derived parameters under opened and closed CSF drainage. METHODS: Twenty patients with either subarachnoid or intraventricular hemorrhage and indication for ventriculostomy plus ICP monitoring received an EVD in combination with an air-pouch-based ICP probe. ICP was monitored via an open ventricular catheter (ICP_evd) and ICP probe (ICP_probe) simultaneously. Neuromonitoring data (ICP, arterial blood pressure, cerebral perfusion pressure, pressure reactivity index (PRx)) were recorded by ICM+ software for the time of ICU intensive care treatment. Routinely (at least every 4 h) ICP was recorded with a closed CSF drainage system for at least 15 min. ICP, ICP amplitude, and the autoregulation parameters (PRx_probe, PRx_evd) were evaluated for every episode with closed CSF drainage and during the 3 h prior with an open drainage system. RESULTS: One hundred and forty-four episodes with open/closed drainage were evaluated. During open drainage, overall mean ICP_evd levels were nonsignificantly different from those of ICP_probe, with 9.8 + 3.3 versus 8.2 + 3.2 mmHg, respectively. Limits of agreement ranged between 5.2 and -8.3 mmHg. However, 51 increases of ICP >20 mmHg with a duration of 3-30 min were missed by ICP_evd, and in 101 episodes the difference between ICPs was greater than 10 mmHg. After closure of the EVD, ICP increased moderately using both methods. Mean PRx_evd was significantly higher (falsely indicating impaired autoregulation) and more subjected to fluctuations than PRx_probe. CONCLUSION: The general practice of draining CSF and monitoring ICP via a (usually open) EVD plus frequently performed catheter closure for ICP reading is feasible for assessment of overall ICP trends. However, it does have clinically relevant drawbacks, namely, a significant amount of undetected increases in ICP above thresholds, and continuous assessment of cerebrovascular autoregulation is less reliable. In conclusion, all patients who need CSF drainage plus ICP monitoring due to the severity of their brain insult need either an EVD with integrated ICP probe or an EVD line plus a separate ICP probe.

MRI capture of intermittent ventriculomegaly in a patient with ventriculo-peritoneal shunt.

Intermittent change in ventricular size in patients with ventriculo-peritoneal shunts is a recognised complication but definitive imaging evidence is rare. We report a 3 years old boy with a medullary astrocytoma and ventriculo-peritoneal shunt placement who demonstrated intermittent ventriculomegaly during a single MRI scan.

Pathophysiology and the Monitoring Methods for Cardiac Arrest Associated Brain Injury.

Cardiac arrest (CA) is a well-known cause of global brain ischemia. After CA and subsequent loss of consciousness, oxygen tension starts to decline and leads to a series of cellular changes that will lead to cellular death, if not reversed immediately, with brain edema as a result. The electroencephalographic activity starts to change as well. Although increased intracranial pressure (ICP) is not a direct result of cardiac arrest, it can still occur due to hypoxic-ischemic encephalopathy induced changes in brain tissue, and is a measure of brain edema after CA and ischemic brain injury. In this review, we will discuss the pathophysiology of brain edema after CA, some available techniques, and methods to monitor brain oxygen, electroencephalography (EEG), ICP (intracranial pressure), and microdialysis on its measurement of cerebral metabolism and its usefulness both in clinical practice and possible basic science research in development. With this review, we hope to gain knowledge of the more personalized information about patient status and specifics of their brain injury, and thus facilitating the physicians' decision making in terms of which treatments to pursue.

The relationship between transorbital ultrasound measurement of the optic nerve sheath diameter (ONSD) and invasively measured ICP in children. : Part II: age-related ONSD cut-off values and patency of the anterior fontanelle.

PURPOSE: To analyse the diagnostic accuracy of age-related optic nerve sheath diameter (ONSD) cut-off values in children for detecting raised intracranial pressure (ICP) and to assess the benefit of using patency of the anterior fontanelle in describing a different set of cut-off values. METHODS: The ONSD measurement was performed prior to invasive ICP measurement in children under general anesthesia. The diagnostic accuracy of the ONSD measurement was compared to ICP at thresholds of 20, 15, 10, and 5 mmHg. This was further analysed in children above and below the age of 1 year, with a subgroup analysis of age at 4 years, and assessment of the anterior fontanelle (AF) as a reliable physiological marker in part II of this study. RESULTS: Data from 174 children were analysed. In children ≤1 year old, the ONSD measurement with the best diagnostic accuracy for detecting ICP ≥ 20 mmHg was 5.16 mm, compared to 5.75 mm in children >1 year old (p < 0.001). In addition, patency of the anterior fontanelle (AF) was found to be a useful clinical marker for defining different ONSD cut-off values at ICP thresholds of 20, 15, 10 and 5 mmHg. CONCLUSION: Transorbital ultrasound measurement of the ONSD is a reliable non-invasive marker of ICP particularly at higher thresholds of 20 and 15 mmHg. Patency of the AF is a useful clinical marker for defining different ONSD cut-off values in children.

The relationship between transorbital ultrasound measurement of the optic nerve sheath diameter (ONSD) and invasively measured ICP in children : Part I: repeatability, observer variability and general analysis.

PURPOSE: The aim of this study was to investigate the relationship between optic nerve sheath diameter (ONSD) measurement and invasively measured intracranial pressure (ICP) in children. METHODS: ONSD measurement was performed prior to invasive measurement of ICP. The mean binocular ONSD measurement was compared to the ICP reading. Physiological variables including systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), pulse rate, temperature, respiratory rate and end tidal carbon dioxide (ETCO2) level were recorded at the time of ONSD measurement. Diagnostic accuracy analysis was performed at various ICP thresholds and  repeatability, intra- and inter-observer variability, correlation between measurements in different imaging planes as well the relationship over the entire patient cohort were examined in part I of this study. RESULTS: Data from 174 patients were analysed. Repeatability and intra-observer variability were excellent (α = 0.97-0.99). Testing for inter-observer variability revealed good correlation (r = 0.89, p < 0.001). Imaging in the sagittal plane demonstrated a slightly better correlation with ICP (r = 0.66, p < 0.001). The ONSD measurement with the best diagnostic accuracy for detecting an ICP ≥ 20 mmHg over the entire patient cohort was 5.5 mm, sensitivity 93.2 %, specificity 74 % and odds ratio (OR) of 39.3. CONCLUSION: Transorbital ultrasound measurement of the OSND is a reliable and reproducible technique, demonstrating a good relationship with ICP and high diagnostic accuracy for detecting raised ICP.

Characterization of ICP Behavior in an Experimental Model of Hemorrhagic Stroke in Rats.

Intracranial pressure (ICP) monitoring is sometimes required in clinical pictures of stroke, as extensive intraparenchymal hematomas and intracranial bleeding may severely increase ICP, which can lead to irreversible conditions, such as dementia and cognitive derangement. ICP monitoring has been accepted as a procedure for the safe diagnosis of increased ICP, and for the treatment of intracranial hypertension in some diseases. In this work, we evaluated ICP behavior during the induction of an experimental model of autologous blood injection in rats, simulating a hemorrhagic stroke. Rats were subjected to stereotactic surgery for the implantation of a unilateral cannula into the left striatal region of the brain. Autologous blood was infused into the left striatal region with an automatic microinfusion pump. ICP monitoring was performed throughout the procedure of hemorrhagic stroke induction. Analyses consisted of short-time Fourier transform for ICP before and after stroke induction and the histological processing of the animals' brains. Short-time Fourier transform analysis demonstrated oscillations in the ICP frequency components throughout time after the microinjections compared with data before them. Histological analysis revealed neuropathological changes in the striatum in all microinjected animals.

Characterization of Intracranial Pressure Behavior in Chronic Epileptic Animals: A Preliminary Study.

Intracranial pressure (ICP) is a major neurological parameter in animals and humans. ICP is a function of the relationship between the contents of the cranium (brain parenchyma, cerebrospinal fluid, and blood) and the volume of the skull. Increased ICP can cause serious physiological effects or even death in patients who do not quickly receive proper care, which includes ICP monitoring. Epilepsies are a set of central nervous system disorders resulting from abnormal and excessive neuronal discharges, usually associated with hypersynchronism and/or hyperexcitability. Temporal lobe epilepsy (TLE) is one of the most common forms of epilepsy and is also refractory to medication. ICP characteristics of subjects with epilepsy have not been elucidated because there are few studies associating these two important neurological factors. In this work, an invasive (ICPi) and the new minimally invasive (ICPmi) methods were used to evaluate ICP features in rats with chronic epilepsy, induced by the experimental model of pilocarpine, capable of generating the main features of human TLE in these animals.

Assessment of non-invasive ICP during CSF infusion test: an approach with transcranial Doppler.

BACKGROUND: This study aimed to compare four non-invasive intracranial pressure (nICP) methods in a prospective cohort of hydrocephalus patients whose cerebrospinal fluid dynamics was investigated using infusion tests involving controllable test-rise of ICP. METHOD: Cerebral blood flow velocity (FV), ICP and non-invasive arterial blood pressure (ABP) were recorded in 53 patients diagnosed for hydrocephalus. Non-invasive ICP methods were based on: (1) interaction between FV and ABP using black-box model (nICP_BB); (2) diastolic FV (nICP_FVd); (3) critical closing pressure (nICP_CrCP); (4) transcranial Doppler-derived pulsatility index (nICP_PI). Correlation between rise in ICP (∆ICP) and ∆nICP and averaged correlations for changes in time between ICP and nICP during infusion test were investigated. RESULTS: From baseline to plateau, all nICP estimators increased significantly. Correlations between ∆ICP and ∆nICP were better represented by nICP_PI and nICP_BB: 0.45 and 0.30 (p < 0.05). nICP_FVd and nICP_CrCP presented non-significant correlations: -0.17 (p = 0.21), 0.21 (p = 0.13). For changes in ICP during individual infusion test nICP_PI, nICP_BB and nICP_FVd presented similar correlations with ICP: 0.39 ± 0.40, 0.39 ± 0.43 and 0.35 ± 0.41 respectively. However, nICP_CrCP presented a weaker correlation (R = 0.29 ± 0.24). CONCLUSIONS: Out of the four methods, nICP_PI was the one with best performance for predicting changes in ∆ICP during infusion test, followed by nICP_BB. Unreliable correlations were shown by nICP_FVd and nICP_CrCP. Changes of ICP observed during the test were expressed by nICP values with only moderate correlations.