Increase In Increased Intracranial Pressure Research Articles

Feasibility of Fluid Responsiveness Assessment in Patients at Risk for Increased Intracranial Pressure.

Background: Effective fluid management is important for patients at risk of increased intracranial pressure (ICP). Maintaining constant cerebral perfusion represents a challenge, as both hypovolemia and fluid overload can severely impact patient outcomes. Fluid responsiveness tests, commonly used in critical care settings, are often deemed potentially hazardous for these patients due to the risk of disrupting cerebral perfusion. Methods: This single-center, prospective, clinical observational study enrolled 40 patients at risk for increased ICP, including those with acute brain injury. Informed consent was obtained from each participant or their legal guardians before inclusion. The study focused on the dynamics of ICP and cerebral perfusion pressure (CPP) changes during the Passive Leg Raise Test (PLRT) and the End-Expiratory Occlusion Test (EEOT). Results: The results demonstrated that PLRT and EEOT caused minor and transient increases in ICP, while consistently maintaining stable CPP. EEOT induced significantly lower ICP elevations, making it particularly suitable for use in high-risk situations. Conclusions: PLRT and EEOT can be considered feasible and safe for assessing fluid responsiveness in patients at risk for increased ICP. Notably, EEOT stands out as a preferred method for high-risk patients, offering a dependable strategy for fluid management without compromising cerebral hemodynamics.

Characteristics Of Ocular Fundus In Brain Infections At Cipto Mangunkusumo Hospital Jakarta

Background: Brain infections (BI) may cause optic nerve abnormalities. Awareness on optic nerve abnormalities will be useful in assisting further management. The characteristics of the ocular fundus (fundus) in BI have not been widely studied in Indonesia. This study aims to apprehend the depiction of the fundus in BI in Cipto Mangunkusumo Hospital Jakarta (RSCM). Methods: Cross-sectional study conducted on October-December 2021 at RSCM. Images from 20D-lens fundoscopy were captured with a digital camera. Results are analyzed if there are similarities between at least two examiners. Results: There were 49 subjects whose fundoscopy results could be analyzed. A total of 25 subjects has normal fundus. Abnormalities were seen in 8 subjects, which comprised of 4 (12.1%) papilledema, 3 (9.1%) papillatrophy and 1 (3%) retinal haemorrhage. The highest mean aperture pressure was found in the papillatrophy group (37cmH2O), followed by papilledema (27cmH2O). Discussion: BI can increase intracranial pressure (ICP). Nonetheless, we found only 12.1% had papilledema. The highest mean aperture pressure was found in the papillatrophy group which showed an increase in ICP over a long period of time. The highest mortality was found in the normal fundus group so that papilledema cannot be directly associated with a worse prognosis considering the uncontrolled confounding factors such as other BI complications. Conclusion: Although BI causes an increase in ICP, papilledema is not always found. High aperture pressure was found in the papillatrophy group, but the highest mortality was found in the normal fundus group.

Effects of intubation technique on intracranial pressure: a cadaveric study.

Patients are at risk of increased intracranial pressure (ICP) during manipulation for endotracheal intubation. The aim of this cadaveric study was to quantify this relationship. Five fresh frozen adult cadaveric heads were used. The internal carotid artery (ICA) and internal jugular vein (IJV) were dissected bilaterally. All vessels were occluded on the right side. To mimic central venous pressures, the left IJV was cannulated and filled with water to maintain a pressure of approximately 7 cm H2O. The ICA cannula was attached to an oscillating water pump. Next, an ICP monitor was placed. Normophysiological volumes of water were infused to maintain normal ICP. Baseline ICP and IJV pressures were recorded. The heads were then placed in the sniffing position and in neutral position for nasal intubation, and finally an oral endotracheal tube was placed using standard head/neck maneuvers. The ICP was recorded. Mean baseline ICP was 13 mmHg (range 4-18 mmHg) and mean IJV pressure was 6 cm H2O. In the sniffing position, ICP increased in all specimens by a mean of 5 mmHg. In the neutral position, after intubation, the ICP increased in all specimens by a mean of 3 mmHg. Nasal intubation resulted in an increase in four of the five specimens. The mean increase in ICP with this maneuver was 2 mmHg. We present a cadaveric model of ICP measurement during neck manipulation using intracranial fluid dynamics. The ICP increased consistently. Following clinical studies, physicians involved in intubating patients with concern for raised ICP should change the technique to avoid complications.

Evaluation of the relationship between NIRS (near-infrared spectroscopy) and optic nerve sheath diameter measurement in children with increased intracranial pressure: a pilot study

BackgroundThe increased intracranial pressure (ICP) syndrome may emerge depending on many different neurological factors and the early diagnosis and treatment are important for the prevention of neurologic damage and related mortality. In recent years, the follow-up of increased ICP with non-invasive methods has been rising. In this study, our objective was to determine the significance and any possible correlation between Optic Nerve Sheath Diameter (ONSD) and Near Infrared Spectroscopy (NIRS) in children with increased ICP.MethodsPatients who were hospitalized in our pediatric ICU at Çukurova University Medical Faculty between June 2018 and June 2019 due to the suspicion of increased ICP were included in this study. The demographic characteristics of patients, diagnosis at admission, results of the cranial CT and MRI examinations, and results of the simultaneous ONSD and NIRS measurements were recorded.ResultsA total of 36 patients were included in our study. With respect to the diagnosis, non-traumatic causes were at the forefront in 30 patients (83.3%), and the most common causes were meningoencephalitis (n = 9; 25%) and non-traumatic bleeding (n = 7; 19.4%). Six of the patients were under the age of one year (16.7%), and the mean values of ONSD and NIRS were 4.8 ± 0.7 mm and 71.1 ± 12.4% respectively in this group. Fourteen patients were in the one to ten year age group and the mean values of ONSD and NIRS were 6.1 ± 0.6 mm and 72.7 ± 9.3% respectively. Sixteen patients were over ten years of age (44.4%), and the mean values of ONSD and NIRS were 5.6 ± 0.7 mm and 74.2 ± 16% respectively. There was no correlation between the ONSD and NIRS values (r:0.307; p = 0.068).ConclusionOur study showed that ONSD measurements were helpful in children with increased ICP and reflected the increase in ICP. However, our study also demonstrated that ONSD was not in correlation with the NIRS monitoring. We believe that there is a need for further studies focused on the use of ONSD and NIRS in the monitoring of increased ICP.

Role of ultrasound as diagnostic tool in evaluation of optic nerve thickness in cases of raised intracranial pressure

Head trauma and intracranial pathologies can result in the increased Intra Cranial Pressure (ICP). Early diagnosis is important in the clinical outcome. As the optic nerve has a dural continuation, any increase in ICP will increase the thickness of Optic nerve Sheath Diameter (ONSD). Ultrasound plays a vital role, as it is a non-invasive, portable, reliable, and an economical tool to measure the ONSD. We aim to assess the role of ultrasound as a diagnostic tool in the measurement of ONSD in subjects with raised ICP All patients with CT signs of raised intracranial pressure were taken as cases. Normal CT brain patients were considered as the control group. It was a prospective study that included data of 60 patients (30 Test, 30 Control) for 1 year. Linear probe of high resolution 10MHz on Philips HD 15 ultrasound machine was employed in the evaluation of ONSD in both groups. From the entry point of optic nerve to globe 3mm distance was considered standard in measurement of ONSD. In the control group 14(46.6%) were females, 16(53.3%) were males and in the test group 11(36.6%) females, 19(63.3%) were males. In the control group upper limit of ONSD was 4.8 mm, lower limit 4.3mm, and mean was 4.49 mm. In the test group, the upper limit of ONSD was5.7mm, lower limit 4.8mm, and mean 5.14mm. There is an obvious raise in the thickness of ONSD in the individuals with positive signs of raised ICP in comparison with normal individuals. Being a non-invasive, and economical, portable ultrasound has a pivot role in the diagnosis of the thickness of ONSD thickness earlier than the onset of papilledema.

Pentobarbital Coma With Therapeutic Hypothermia for Treatment of Refractory Intracranial Hypertension in Traumatic Brain Injury Patients: A Single Institution Experience.

IntroductionTraumatic brain injury (TBI) results in primary and secondary brain injuries. Secondary brain injury can lead to cerebral edema resulting in increased intracranial pressure (ICP) secondary to the rigid encasement of the skull. Increased ICP leads to decreased cerebral perfusion pressure which leads to cerebral ischemia. Refractory intracranial hypertension (RICH) occurs when ICP remains elevated despite first-tier therapies such as head elevation, straightening of the neck, analgesia, sedation, paralytics, cerebrospinal fluid (CSF) drainage, mannitol and/or hypertonic saline administration. If unresponsive to these measures, second-tier therapies such as hypothermia, barbiturate infusion, and/or surgery are employed.MethodsThis was a retrospective review of patients admitted at Arrowhead Regional Medical Center from 2008 to 2019 for severe TBI who developed RICH requiring placement into a pentobarbital-induced coma with therapeutic hypothermia. Primary endpoints included mortality, good recovery which was designated at Glasgow outcome scale (GOS) of 4 or 5, and improvement in ICP (goal is <20 mmHg). Secondary endpoints included complications, length of intensive care unit (ICU) stay, length of hospital stay, length of pentobarbital coma, length of hypothermia, need for vasopressors, and decompressive surgery versus no decompressive surgery.ResultsOur study included 18 patients placed in pentobarbital coma with hypothermia for RICH. The overall mortality rate in our study was 50%; with 60% mortality in pentobarbital/hypothermia only group, and 46% mortality in surgery plus pentobarbital/hypothermia group. Maximum ICP prior to pentobarbital/hypothermia was significantly lower in patients who had a prior decompressive craniectomy than in patients who were placed into pentobarbital/hypothermia protocol first (28.3 vs 35.4, p<0.0238). ICP was significantly reduced at 4 hours, 8 hours, 12 hours, 24 hours, and 48 hours after pentobarbital and hypothermia treatment. Initial ICP and maximum ICP prior to pentobarbital/hypothermia was significantly correlated with mortality (p=0.022 and p=0.026). Patients with an ICP>25 mmHg prior to pentobarbital/hypothermia initiation had an increased risk of mortality (p=0.0455). There was no statistically significant difference in mean ICP after 24 hours after pentobarbital/hypothermia protocol in survivors vs non-survivors. Increased time to reach 33°C was associated with increased mortality (r=0.47, p=0.047); with a 10.5-fold increase in mortality for >7 hours (OR 10.5, p=0.039).ConclusionProlonged cooling time >7 hours was associated with a 10.5-fold increase in mortality and ICP>25 mmHg prior to initiation of pentobarbital and hypothermia is suggestive of a poor response to treatment. We recommend patients with severe TBI who develop RICH should first undergo a 12 x 15 cm decompressive hemicraniectomy because they have better survival and are more likely to have ICP <25 mmHg as the highest elevation of ICP if the ICP were to become and stay elevated again. Pentobarbital and hypothermia should be initiated if the ICP becomes elevated and sustained above 20 mmHg with a prior decompressive hemicraniectomy and refractory to other medical therapies. However, our data suggests that patients are unlikely to survive if there ICP does not decrease to less than 15mmHg at 8 and 12 hours after pentobarbital/hypothermia and remain less than 20 mmHg within first 48 hours.

Visual changes after space flight: is it really caused by increased intracranial tension? A systematic review

Spaceflight-Associated Neuro-ocular Syndrome (SANS) was linked to increased intracranial pressure (ICP) attributable to the combined effects of microgravity and environmental conditions encountered during spaceflight. Microgravity countermeasures as lower body negative pressure (LBNP) are potential interventions for SANS. Our aim is to provide a comprehensive qualitative analysis of literature contrasting simulation and spaceflight studies, focusing on the pathophysiology of SANS, and highlighting gaps in current knowledge. We systematically searched PubMed electronic database for English primary research published until February 2019 discussing intracranial changes in spaceflight or simulated microgravity, excluding animal and experimental studies. Two authors screened all the abstracts with a third author resolving disagreements. The full-text manuscripts were analyzed in pilot-tested tables. Nineteen studies were reviewed; 13 simulation, and two out of six spaceflight studies were prospective. ICP changes were investigated in 11 simulation studies, where eight demonstrated a significant increase in ICP after variable periods of head-down tilt. three showed a significant increase in intraocular pressure (IOP) in conjunction with ICP elevation. With increasing ambient CO<inf>2</inf>: one showed an increase in IOP without further increase in ICP, while another showed a slight further decrease in ICP. LBNP demonstrated no significant effect on ICP in one and a decrease thereof in another study. After spaceflight, increased ICP on lumbar puncture was demonstrated in five studies. Exposure to microgravity increases ICP possibly precipitating ocular changes. Whether other factors come into play is the subject of investigation. Further randomized studies and methods of direct ICP measurement during spaceflight are needed.

Propofol Affects Optic Nerve Sheath Diameter less than Sevoflurane during Robotic Surgery in the Steep Trendelenburg Position.

Background Robot-assisted laparoscopic radical prostatectomy (RLRP) can increase intracranial pressure (ICP) related to a change in position. Increasing ICP may result in various ocular complications, which are rare but serious, such as a corneal abrasion and ischemic optic neuropathy. We performed a prospective observational trial using ultrasonographic measurements to compare optic nerve sheath diameter (ONSD) related to ICP between patients who received either propofol or sevoflurane and underwent RLRP. Methods Thirty-two male patients scheduled to undergo RLRP were assigned into groups according to the anesthetic agent used (group P: propofol, n = 16; group S: sevoflurane, n = 16). ONSD, end-tidal partial pressure of CO2, and blood pressure were measured 10 min after induction of anesthesia (T0), 30 min (T1), 60 min (T2), and 90 min after changing to the steep Trendelenburg position and introducing a pneumoperitoneum (T3) and 10 min after returning the patient's position to supine (T4) during surgery. Results No significant differences were observed in the demographic data of the patients, surgery time, or intraoperative variables, including hemodynamic and respiratory variables, at any of the time points. The mean right ONSDs in the propofol and sevoflurane groups were 37.3 and 40.1 mm at 30 min (p=0.003), respectively. The mean left ONSDs were 38.4 and 40.8 mm at 30 min (p=0.021) after changing to the Trendelenburg position. The ONSDs between the two groups were significantly different during surgery. Conclusions ONSD increased more in the sevoflurane group than in the propofol group during RLRP. Intravenous anesthetics could alleviate the increase in ICP during RLRP.

Automated Optic Nerve Sheath Diameter Measurement Using Super-pixel Analysis.

The optic nerve is a part of the central nervous system surrounded by cerebrospinal fluid and is encased in a sheath. Changes to the cerebrospinal fluid due to injury, tumor rupture and so on can increase intracranial pressure (ICP) and can result in changes in the sheath diameter. Measuring the changes in the sheath can be done through ultrasound imaging with which the optic nerve sheath diameter can be measured. Since this approach is non-invasive, it would reduce the cost for patients and healthcare if sheath diameter could be used as a predictor of increase in ICP. However, the manual measurement of the nerve sheath diameter is very time consuming and could be affected by human errors. In this paper we propose an image processing approach in which the optic nerve sheath diameter is measured automatically. In our proposed method, we first denoise images and then detect the region of interest using a simple line integral method. After that by analyzing super-pixels we measure the diameter. We compared the results of the proposed method with manual measurements from two experts. The average percentage of error between the proposed method and the experts' measurements did not substantially differ from the error between the two experts.

A Novel Step-Down Infusion Therapy: Its Safety and Effectiveness in Intracranial Pressure Control Using Barbiturate Therapy

Background: Barbiturate therapy has been widely used to suppress increased intracranial pressure (ICP); however, classical barbiturate therapy has disadvantages such as cardiac function depression. This is due to lack of detailed pharmacological dynamics of barbiturate and an established safety infusion method. Methods: Two healthy male beagles intubated and anesthetized using thiamylal (4·0 mg/kg/h) and propofol (4·0 mg/kg/h) were maintained for 36 h; one dog was maintained under normothermia and the other, hypothermia. A 1·0 mL blood sample was collected at 0, 12, 24, 36, 42, 48 h and drug concentration measured using liquid chromatography-mass spectrometry. Barbiturate therapy was performed at the earliest convenience using the ‘Step-Down Infusion’ method for severe traumatic brain injury patients or sever cerebrovascular disease patients having a Glasgow coma scale 8, and ICP was measured for at least 7 days. Findings: In the animals, thiamylal concentration increased with time and was influenced by body temperature; the dog with hypothermia had a higher concentration than normothermic dog. Stable values were noted with propofol. In the clinical study, step-down infusion of thiamylal under normothermia resulted in stable concentrations with no abnormal accumulation or threatening changes in serum potassium. Blood pressure was also stable under 25·0 g/mL and no hemodynamic instability was found. ICP increase was inhibited by the increase in thiamylal concentration and cerebral perfusion pressure (CPP) was maintained over 65 mmHg during the time course. Interpretation: Fixed long-term infusion of barbiturate induced marked drug accumulation, which was enhanced by hypothermia. Our novel “Step-down infusion” method under normothermia can maintain stable, safe thiamylal concentration to achieve both ICP reduction and CPP maintenance without serious side effects such as hypotension or hypokalemia. As the safe maximum concentration of barbiturate remains unclear, further clinical investigation is warranted. Funding Statement: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Declaration of Interests: All authors declare that no support, financial or otherwise, has been received from any organization that may have an interest in the submitted work, and there are no other relationships or activities that could appear to have influenced the submitted work. Ethics Approval Statement: All procedures in this study were carried out in strict accordance with the guidelines for animal experimentation at the Animal Research Center of Kurume University. All the animal experiments were reviewed and approved by the Institutional Animal care and use committee (No. P150516). Induction was performed under anesthesia and all efforts made to minimize suffering. The clinical study was reviewed and approved by the Institutional ethical committee of Kurume University (No. 12268).

Trigonocephaly: Long-term results after surgical correction of metopic suture synostosis.

Premature closure and ossification of the metopic suture results in a triangular head shape called trigonocephaly and is characterized by a wedge-shaped forehead and frontotemporal narrowing. Untreated craniosynostosis may lead to increased intracranial pressure (ICP) and, thereby, impaired neurodevelopment. Over the last decades, its incidence has been increasing, currently making it the 2nd most common type of isolated craniosynostosis. Treatment consist of cranioplasty, which should be performed before the age of 1 year. The aim of this study was to evaluate the long-term surgical outcomes in children operated on for trigonocephaly. The authors reviewed 30 consecutive cases of metopic synostosis treated over a 14-year period in the Plastic Surgery Department in Polanica-Zdrój, Poland. The data was evaluated using the patients' clinical records, and preoperative and postoperative photographs. The patients showed up on a follow-up visit at a median age of 9 years and were examined by an ophthalmologist and a neurologist. The surgical outcomes were evaluated according to the Whitaker classification. In 23 patients, remodeling and the advancement of fronto-orbital skull segments was performed at a median age of 18 months and in 7 milder cases, simple suturectomy or burring of the metopic ridge was sufficient. According to the Whitaker classification, results were considered good to excellent (category I and II). Only 1 patient was included into category III. None of the examined cases were included into category IV, which would require a major craniofacial procedure, duplicating or exceeding the original operation. Neurological abnormalities were found in 12 cases and vision defects in 15 cases. Trigonocephaly is currently the 2nd most common type of isolated synostosis. Surgical treatment based on Tessier's and Marchac's modified methods provides good results in patients at the age of about 12 months and prevents the consequences of ICP increase. Primary neurological and behavioral disorders may occur, despite corrective surgery.

Ultrasonic Assessment of Optic Nerve Sheath to Detect Increased Intracranial Pressure.

Purpose:Increased intracranial pressure (ICP) is one of the prevalent symptoms of trauma, especially traumatic headache, which requires quick action for the diagnosis and treatment. The optic nerve sheath diameter (ONSD) is a newly proposed technique for the detection of an increase in ICP. The aim of this study was to assess the efficacy of this new diagnostic method in patients with increased ICP induced by trauma.Methods:This prospective study was conducted between December 2016 and February 2017. The patients with traumatic headache and who had been diagnosed with increased ICP using clinical signs and computed tomography scan were compared to the voluntary healthy group. In each patient, measurements were performed employing ultrasound three times on each eye in an axial region, and the mean of these sizes was obtained as the ONSD.Results:A total of 112 participants were examined. The mean ONSD measurement of the patients and the voluntary healthy group was 6.01 ± 0.76 and 3.41 ± 0.56 mm in the right eye, 6.11 ± 0.75 and 3.39 ± 0.54 mm in the left eye, and 6.06 ± 0.75 and 4.02 ± 1.07 mm in both sides, respectively. The ONSD in the right and left sides had high and significant correlation in the patients (r = 0.929, P < 0.000) and voluntary healthy (r = 0.630, P < 0.000) group. The mean ONSD of one of the patients was 6.24 ± 0.56 mm, and in another patient with no clinical sign of increased ICP, the mean ONSD was 4.61 ± 0.09 mm.Conclusions:Ultrasound performed on the diaphragm of the optic nerve with acceptable sensitivity can detect patients with an increase in ICP and can be efficacious in expediting the action needed to reduce ICP. Due to the sensitivity and specificity of the ultrasound and high accuracy of the diameter of optic nerve sheath in detecting increase in ICP, as well as considering the fact that ultrasound is a noninvasive and available technique; it can be performed at the patient's bedside.

Acetazolamide Mitigates Intracranial Pressure Spikes Without Affecting Functional Outcome After Experimental Hemorrhagic Stroke

Increased intracranial pressure (ICP) after stroke can lead to poor outcome and death. Novel treatments to combat ICP rises are needed. The carbonic anhydrase inhibitor acetazolamide diminishes cerebrospinal fluid (CSF) production, reduces ICP in healthy animals, and is beneficial for idiopathic intracranial hypertension patients. We tested whether acetazolamide mitigates ICP elevations by presumably decreasing CSF volume after collagenase-induced striatal hemorrhage in rats. We confirmed that acetazolamide did not adversely affect hematoma formation in this model or physiological variables, such as temperature. Then, we assessed the effects of acetazolamide on ICP. Lastly, we tested the effects of acetazolamide on behavioral and histological outcome. Acetazolamide reduced the magnitude and occurrence of short-timescale ICP spikes, assessed as disproportionate increases in ICP (sudden ICP increases > 10 mmHg), 1-min peak ICP, and the magnitude of spikes > 20 mmHg. However, mean ICP was unaffected. In addition, acetazolamide reduced ICP variability, reflecting improved intracranial compliance. Compliance measures were strongly correlated with high peak and mean ICP, whereas ipsilateral hemisphere water content was not correlated with ICP. Despite effects on ICP, acetazolamide did not improve behavioral function or affect lesion size. In summary, we show that intracerebral hemorrhage creates an impaired compliance state within the cranial space that can result in large, transient ICP spikes. Acetazolamide ameliorates intracranial compliance and mitigates ICP spikes, but does not improve functional outcome, at least for moderate-severity ICH in rats.

Increased ICP and Its Cerebral Haemodynamic Sequelae.

Increased intracranial pressure (ICP) is a pathological feature of many neurological diseases; however, the local and systemic sequelae of raised ICP are incompletely understood. Using an experimental paradigm, we aimed to describe the cerebrovascular consequences of acute increases in ICP. We assessed cerebral haemodynamics [mean arterial blood pressure (MAP), ICP, laser Doppler flowmetry (LDF), basilar artery Doppler flow velocity (Fv) and estimated vascular wall tension (WT)] in 27 basilar artery-dependent rabbits during experimental (artificial lumbar CSF infusion) intracranial hypertension. WT was estimated as the difference between critical closing pressure and ICP. From baseline (~9 mmHg) to moderate increases in ICP (~41 mmHg), cortical LDF decreased (from 100 to 39.1%, p < 0.001), while mean global Fv was unchanged (from 47 to 45 cm/s, p = 0.38). In addition, MAP increased (from 88.8 to 94.2 mmHg, p < 0.01 and WT decreased (from 19.3 to 9.8 mmHg, p < 0.001). From moderate to high ICP (~75 mmHg), both global Fv and cortical LDF decreased (Fv, from 45 to 31.3 cm/s, p < 0.001; LDF, from 39.1 to 13.3%, p < 0.001) while MAP increased further (94.2 to 114.5 mmHg, p < 0.001) and estimated WT was unchanged (from 9.7 to 9.6 mmHg, p = 0.35). In this analysis, we demonstrate a cortical vulnerability to increases in ICP and two ICP-dependent cerebro-protective mechanisms: with moderate increases in ICP, WT decreases and MAP increases to buffer cerebral perfusion, while with severe increases of ICP, an increased MAP predominates.

Transorbital ultrasound of optic nerve sheath diameter in children with raised intracranial pressure

Background : Increased intracranial pressure (ICP), also known as intracranial hypertension is defined as cerebrospinal fluid (CSF) pressure = 20 mm Hg. It is a common neurological emergency seen in children with a wide variety of underlying etiologies such as brain tumors, obstructive hydrocephalus, posttraumatic intracranial hemorrhage, meningoencephalitis, and toxic encephalitis [1,2]. If left untreated, it can produce adverse and often irreversible neurological consequences and damage the brain through compression of its structures or restriction of its blood flow. Hence, early identification of elevated ICP is critical to ensuring timely and appropriate management [3].Evaluation in critically ill patients requires complicated procedures, creating a need for rapid diagnosis and treatment of these patients along with frequent re-evaluation of raised ICP [1,4-6]. The current standard of care for diagnosing raised ICP is invasive which involves intracranial placement of a monitoring device. The ideal ICP monitor would therefore be non-invasive, portable, easy to use, cost effective and allow for continuous monitoring.There has been a longstanding quest for a reliable, non-invasive technique to assess ICP.The opportunity to make the diagnosis of raised ICP earlier using an appropriate non-invasive technique, makes the applicability of such a method broader than just neurocritical care patients. The accessible, natural bony windows in the human skull, i.e. orbit, auditory canal and AF (neonates), can potentially allow access to important information about the brain and ICP, making transorbital ultrasound measurement of the optic nerve sheath diameter (ONSD) as a surrogate marker of raised ICP [11-22]. The direct cerebrospinal fluid (CSF) connection between the peri-optic and intracranial subarachnoid spaces, makes this technique a particularly appealing option for assessing ICP [23]. The favourable acoustic properties and superficial anatomical location of the eye, make transorbital sonographic assessment of the optic nerve sheath (ONS) very suitable, futher enhancing its use. The region of the ONS located 3mm posterior to the lamina cribrosa of the retina is considered the most distensible and is recommended as the most consistent region to acquire the ONSD measurement [24]. Changes in the ONSD can be visualized using images from ultrasound, MRI and CT scans. Several studies have demonstrated a strong association between distension of the ONSD and an increase in ICP [13,14,25,26-28]. It should also be noted that, with RICP, the optic nerve diameter increases initially, later leading to papilledema, so transorbital sonography is able to show the increased ICP earlier than ophthalmoscopy. Methods : The optic nerve diameter was measured by transorbital sonography in transverse view, 3 mm posterior to the papilla in both eyes, and the mean was calculated. Two groups were examined: a control group (children with normal ICP) and a case group (increased ICP as clinically suspected and later confirmed by an alternative method). Results : In a sample of 100 children, 50 (50%) belonged to case group and 50 (50%) to control group. 68 subjects (68%) were male, and 32(32%) were female. The mean ± SD ages were 8.82 ± 4.23 years in the case group and 9.16 ± 3.86 years in the control group. The mean optic nerve diameters were 4.40 ± 0.97 mm in the case group and 2.35 ± 0.27 mm in the control group. The difference in the means was significant (P <0.05) Conclusion : Optic nerve diameter, measured by transorbital sonography, was significantly greater in patients with increased ICP compared with control group. The evaluation of the optic nerve sheath diameter is a simple non-invasive procedure, which is potentially useful in the assessment and monitoring of children suspected of having raised intracranial pressure.

Choroid plexus aquaporin 1 and intracranial pressure are increased in obese rats: towards an idiopathic intracranial hypertension model?

Idiopathic intracranial hypertension (IIH) is a condition of increased intracranial pressure (ICP) without identifiable cause. The majority of IIH patients are obese, which suggests a connection between ICP and obesity. The aim of the study was to compare ICP in lean and obese rats. We also aimed to clarify if any ICP difference could be attributed to changes in some well-known ICP modulators; retinol and arterial partial pressure of CO2 (pCO2). Another potential explanation could be differences in water transport across the choroid plexus (CP) epithelia, and thus we furthermore investigated expression profiles of aquaporin 1 (AQP1) and Na/K ATPase. ICP was measured in obese and lean Zucker rats over a period of 28 days. Arterial pCO2 and serum retinol were measured in serum samples. The CPs were isolated, and target messenger RNA (mRNA) and protein were analyzed by quantitative PCR and western blot, respectively. Obese rats had elevated ICP compared to lean controls on all recording days except day 0 (P<0.001). Serum retinol (P=0.35) and arterial pCO2 (P=0.16) did not differ between the two groups. Both AQP1 mRNA and protein levels were increased in the CP of the obese rats compared to lean rats (P=0.0422 and P=0.0281). There was no difference in Na/K ATPase mRNA or protein levels (P=0.2688 and P=0.1304). Obese Zucker rats display intracranial hypertension and increased AQP1 expression in CP compared to lean controls. The mechanisms behind these changes are still unknown, but appear to be unrelated to altered pCO2 levels or retinol metabolism. This indicates that the increase in ICP might be related to increased AQP1 levels in CP. Although further studies are warranted, obese Zucker rats could potentially model some aspects of the IIH pathophysiology.

Does Size and Site Matter in Therapeutic Decompressive Craniectomy? A Laboratory-Based Experimental Study

Therapeutic decompressive craniectomy (TDC) controls increased intracranial pressure (ICP). Its role was controversial until its successful introduction to treat malignant middle cerebral artery ischemia. However, standardization of size and site of TDC remains controversial. This study was designed to evaluate whether size and site matter in TDC. A replica skull of a patient with refractory increased ICP and successful TDC was used. ICP was increased using an intracranial balloon modified to monitor ICP and permit progressive incremental increases in ICP. When a desired increased ICP was reached, segments of TDC were removed sequentially to increase its size until the ICP normalized. We also measured the volume of air required to raise the ICP back to the increased ICP value. The most effective TDC size to lower increased ICP was 8.3 cm in diameter (P < 0.001). However, a 7.5-cm TDC was sufficient to control increased ICP of 25-30 mm Hg (P < 0.01). There was strong correlation between TDC size and potential volume created to accommodate brain swelling postoperatively (Pearson correlation coefficient= 0.95928). The location of TDC did not matter when size was ≤3.5 cm or ≥7.5 cm; location mattered when size was 4.5 cm or 5.5 cm, where anteriorly located flaps were more effective in lowering increased ICP and increasing cranial volume (P < 0.05). The size of a TDC is very important in reducing increased ICP. The size should be tailored to the level of increased ICP and the likelihood of further brain swelling postoperatively. A smaller TDC should be located more anteriorly to control increased ICP. Although location is not as important when increased ICP is >30 mm Hg and TDC size ≥8.3 cm is required.

Intracranial Hypertension Is Painless!

Headache is usually considered a key symptom of intracranial hypertension (ICHT). However, there are no published experimental data to support the concept that increased intracranial pressure (ICP) is painful in humans. This prospective study was performed in 16 patients with suspected normal-pressure hydrocephalus, necessitating a lumbar infusion test with measurement of cerebrospinal fluid (CSF) hydrodynamics. During the test, ICP was increased from baseline to a plateau. Headache was scored on a visual analog scale (VAS) (0 = no pain, 10 = very severe pain) at baseline ICP and when ICP plateaued. At baseline, mean ICP was 11 ± 3.6 mmHg and VAS was 0. At plateau, mean ICP was 28 ± 9.5 mmHg and VAS was 0. There was a significant increase in ICP (p <0.001), but no increase in headache intensity (VAS). An acute (20-min) moderate increase in ICP was not accompanied by a headache. We demonstrate that an acute, isolated increase in CSF pressure does not produce a headache. To occur, a headache needs activation of the pain-sensitive structures (dura and venous sinuses) or central activation of the cerebral nociceptive structures. This peripheral or central activation does not occur with an isolated increase in CSF pressure.

Noninvasive intracranial pressure monitoring via optic nerve sheath diameter for robotic surgery in steep Trendelenburg position.

Background:Recent reports of increased intracranial pressure (ICP) due to steep Trendelenburg (ST) position causing neurological deterioration, decreased regional cerebral oxygen saturation and postoperative visual loss after robotic urological and gynecological surgeries led us to consider a simple technique of ICP monitoring. Ours is one of the first instances reported of quantitative noninvasive measurement of increase in ICP with ST position by serial measurement of binocular optic nerve sheath diameter (ONSD) in patients undergoing robot assisted urological and gynecological oncosurgery. We tested whether ONSD values rose to above the upper limits of normal and for what length of time they remained elevated.Materials and Methods:Prospective, randomized, interventional, parallel group, active control study conducted on 252 American Society of Anesthesiologists I and II patients. ONSD was measured using 7.5 MHz linear ultrasound probe in supine and Trendelenburg positions.Statistics:Student's t-test to compare the inter-group mean ONSD and the repetitive t-test for intra-group analysis.Result:Comparison of the mean ONSD values of both groups yielded a 2-tailed significance P <0.01 at all compared time points intra- and post-operatively. In Group-O (open surgery; supine position), the baseline mean bilateral ONSD was 4.36 mm, which did not show any statistically significant change throughout open surgery and postoperative period. On de-docking the robot, 6.2 mm was the mean ONSD value in Group-R (robotic group) while 4.3 mm was the corresponding value in control Group-O.Conclusion:ONSD evaluation is a simple, quick, safe, readily available, reliable, cost effective, noninvasive, potential standard of care for screening and monitoring of patients undergoing robotic surgery in ST position.

Considerações sobre o modelo experimental de hipertensão intracraniana e avaliação do sistema de microchip para monitoração de pressão epidural

Resumo Objetivo: Neste trabalho temos o objetivo de avaliar a acurácia do sistema de aferição da pressão intracraniana (PIC) epidural com microchip. Métodos: Foram estudados 27 suínos sob anestesia geraI, devidamente assistidos com monitoração ventilatória e hemodinâmica. Durante o experimento foi reproduzido um processo expansivo intracerebral programado no lobo frontal direito. O experimento constou de três grupos (A, B e C) com hipertensão intracraniana gerada com balão reproduzindo um hematoma intracerebral. Em todos os grupos foram calibrados os parâmetros normais: os dois sistemas de PIC foram comparados e estudados quanto à correlação dos valores aferidos. Resultados: O comportamento médio da PIC ao longo dos momentos de avaliação foi estatisticamente diferente entre os grupos (p &lt; 0,001). A reprodução de ressangramento resultou em elevação significativa da PIC (p &lt; 0,001). Avaliando-se a acurácia comparativa geral, verificou-se um coeficiente de correlação intraclasse de 0,8. Conclusão: O modelo de hipertensão intracraniana por balão em suínos é factível e confiável na geração de hipertensão intracraniana. O sistema de aferição de pressão intracraniana epidural apresenta elevado coeficiente de correlação com o sistema de aferição parenquimatoso na avaliação global.