Intracranial Pressure Increase

In modern medicine, doctors attempt to monitor all physiological variables to assess their evolution and to decide, based on their changes, the therapeutic attitudes to adopt. Furthermore, this helps to establish a forecast of the evolution to be expected. The measurement of Intracranial Pressure (ICP) has become indispensable for managing brain pathology at the anterior and middle fossa level. Doctors generally carry out this measurement at the frontal level. However, experimental and clinical studies have shown that supra-tentorial ICP measurement does not precisely predict the ICP situation in the posterior fossa. The increased ICP in the posterior fossa is directly responsible for the clinical deterioration and eventual death in patients with tumour, hemorrhagic, or ischemic pathology of the posterior fossa structures. Some of these lesions are treatable, and their effects reversible if the increase in ICP in the posterior fossa is controlled by pharmacological or even surgical means, preventing it from reaching high levels. This need for on-time ICP control is genuine in the cerebellar hemispheres' lesions, not so much in lesions involving the brainstem. Therefore, the increase in ICP in the posterior fossa needs to be known and documented to facilitate decision-making regarding the therapy to be adopted, be it medical or surgical. It is known what the abnormal ICP levels are at the supratentorial level, but what is not known whether these same levels apply to the posterior fossa. In other words, what it is not know with certainty is whether the same levels of ICP in the posterior fossa and its elevation during the same time are going to have equally pernicious effects or these effects are greater or lesser. Doctors need to have tables of ICP values in the posterior fossa to help them decide when these values are in the physiological range. When posterior fossa intracranial pressure lye in the pathological range, and patients need pharmacological treatment or surgical decompression, knowing for sure the posterior fossa ICP is essential. Finally, when doctors also need to know when any therapeutic attempt is useless. Currently, doctors only monitor the ICP at the supra-tentorial level and deduce the changes in the posterior fossa from the CT and MRI images, that is, the size of the lesions, the occlusion of the cisterns, the internal cerebral hernias (cerebellar tonsils, trans-tentorial hernia from bottom to top). However, doctors do not have a tool that can objectify the pathophysiological situation of the posterior fossa's structures in real-time. Monitoring the posterior fossa ICP will help doctors in decision-making in patients with traumatic, hemorrhagic, ischemic, or tumour pathologies (in the latter case, in the postoperative period of posterior fossa tumours). This posterior fossa ICP measurement will lead to improvements in morbidity/mortality in this subgroup of patients.

This research protocol focuses on the pre- and post-operative evaluation of ICP using non-invasive methods, particularly in the context of surgery for brain tumor removal. By utilizing ocular ultrasound to measure ONSD and ONSD/ETD ratios, this study hypothesizes that the utility of these parameters in monitoring ICP pre- and post-operative periods could be effective.

This study will test the use of video ophthalmoscope to provide information about intracranial pressure without the use of invasive methods, anesthesia or contact with the eye.

The aim of this study is to investigate the effects of low and normal intraperitoneal pressures on intraoperative optic nerve sheath diameter in laparoscopic gyneco-oncologic surgeries.

This is a prospectively recruiting, database development study collecting images and videos of the spontaneous venous pulsation at the back of people's eyes - this is a pulse one can see on examination of the back of the eye, originating from the blood vessels around the nerve that connects the eye to the brain (the optic nerve), and is present in most people who have normal pressure around the brain. However, in people with raised pressure in the brain, this pulse disappears as the pressure rises. Many things can cause the pressure around the brain to increase, including tumours, swellings and trauma. The investigators want to test if high-quality images and videos of this pulse, taken using both hand-held and larger, fixed-platform machines, can be used to train a software tool to automatically detect this pulse. The investigators want to collect these images and videos in 2 groups of patients: those with no known or suspected brain pressure problems, and those who are suspected to have raised pressure and/or are due to undergo measurement of the pressure around the brain, called lumbar punctures or intracranial pressure bolt monitoring. These tests to check the pressure around the brain are invasive - they involve inserting needles in the back or directly into the brain to measure the pressure, and carry risks. The value of these two groups of people will be to help train the software to reasonably say whether a pulse is present or absent and, hopefully, estimate what the pressure around the brain may be without the need for an invasive test.

The purpose of this clinical research project is to employ Mespere LifeSciences NeurOs Cerebral Oximetry system, equipped with noninvasive sensors approved by the FDA, to monitor and investigate the correlation within a cohort of patients suffering from traumatic brain injury (TBI), stroke, brain tumor, and brain bleeding. This study aims to investigate and establish the correlation between blood vessel functionality parameters-specifically, Vasodilation/Constriction Index (VDC), Vascular Resistance Index (VR), and Volume Reactivity Index (VRx)-with the crucial physiological indicators, Intracranial Pressure (ICP) and Mean Arterial Pressure (MAP). By doing so, the investigators seek to address fundamental questions surrounding cerebral hemodynamics and autoregulation in various neurological conditions.

High positive end-expiratory pressure (PEEP) levels required to achieve clinical benefits may increase ICP and reduce cerebral perfusion pressure (CPP) in patients at risk of intracranial hypertension. However, individualizing ventilation parameters is essential for each patient. Among protective ventilation strategies, PEEP is key to preventing alveolar collapse. The PEEP level that minimizes alveolar collapse while avoiding overdistension of the pulmonary parenchyma is known as the Best PEEP. This study aims to evaluate the application of Best PEEP in cranial neurosurgery.

ASTIM is a multicenter, prospective, randomised, blinded end-point assessed trial, to investigate the efficacy and safety of treatment based on intracranial pressure monitoring in improving the prognosis of patients with aneurysmal subarachnoid hemorrhage.

In this study, the effect of increased venous return and increased intra-abdominal pressure on intracranial pressure in the lithotomy position was evaluated.

Preeclampsia is a serious condition associated with complications such as pulmonary edema, placental abruption, hemolysis, thrombocytopenia, and cardiac, renal, and neurological complications, occurring at a rate of 2.7-8% in pregnant women (1,2). Neurological complications are believed to be associated with reversible cerebral vasoconstriction syndrome (3,4) and/or posterior leukoencephalopathy syndrome (4,5,6), sharing a common pathophysiology. Cerebral edema is primarily vasogenic, potentially linked to hyperperfusion resulting from impaired cerebral autoregulation, blood-brain barrier disruption, and endothelial cell dysfunction. In some eclampsia cases, computed tomography and magnetic resonance imaging may reveal signs consistent with significantly increased intracranial pressure (ICP) (7). However, the true incidence of elevated ICP in preeclampsia is unknown, clinical symptoms are nonspecific, and interpretation, especially during pregnancy and preeclampsia, can be challenging (2). Cesarean section, currently one of the most frequently performed surgeries worldwide, is conducted in 21.1% of women (8). Anesthesia for cesarean section can be divided into neuraxial and general anesthesia. The choice of anesthesia technique in conditions that may increase intracranial pressure, such as cerebral edema, may vary based on balancing risks and benefits. Neuraxial analgesia and anesthesia are the first choice in healthy pregnancies, but may be contraindicated in cases with intracranial lesions or increased bleeding risk (9). The presence of focal neurological deficits may favor general anesthesia for cesarean delivery (10). General anesthesia in these patients may result in an increased hemodynamic response to laryngoscopy. Agents used in induction and maintenance can also affect cerebral autoregulation (11). Anesthesia induction and maintenance for these patients should be planned to minimize the increase in intracranial pressure. The optic nerve, a part of the central nervous system, is surrounded by a dural sheath and a subarachnoid space containing cerebrospinal fluid. Three millimeters behind the ocular globe, the optic nerve is solely surrounded by fat, and the dural sheath can retract within its fatty environment, particularly in conditions of increased pressure in the cerebrospinal fluid (2). Recent clinical studies have reported that ultrasonographic measurements of the optic nerve sheath diameter (ONSD) are correlated with increased intracranial pressure symptoms and may serve as a non-invasive reliable indicator of ICP (12,13). Studies have reported high inter-observer reliability for ONSD measurements (14,15). ONSD measurement is easy, repeatable at the bedside, rapid, inexpensive, and does not involve radiation. Compared to healthy pregnant women, preeclamptic women are considered to have higher intracranial pressure during the childbirth process. Anesthetic management for delivery in these women can be complex and controversial. The aim of this study is to evaluate ultrasonographic measurements of optic nerve sheath diameter during the perioperative period, independent of anesthesia management, in healthy and preeclamptic pregnant women undergoing cesarean section. We believe that these assessments will contribute to more reliable anesthesia planning for preeclamptic pregnancies.