Principles and Management of Increased Intracranial Pressure

Intracranial pressure (ICP) is a reflection of the total volume inside the skull. Normal ICP is 5 to 15 mm Hg. Intracranial hypertension is defined as sustained ICP of more than 20 mm Hg. Increased ICP may lead to a reduction of cerebral perfusion pressure, a shift of brain tissue, and, as a result, secondary brainstem injury. Early recognition and treatment of elevated ICP are needed to prevent irreversible damage.

Effects of Positive End-Expiratory Pressure on Lung Recruitment, Respiratory Mechanics, and Intracranial Pressure in Mechanically Ventilated Brain-Injured Patients

Background: The pathophysiological effects of positive end-expiratory pressure (PEEP) on respiratory mechanics, lung recruitment, and intracranial pressure (ICP) in acute brain-injured patients have not been completely elucidated. The primary aim of this study was to assess the effects of PEEP augmentation on respiratory mechanics, quantitative computed lung tomography (qCT) findings, and its relationship with ICP modifications. Secondary aims included the assessment of the correlations between different factors (respiratory mechanics and qCT features) with the changes of ICP and how these factors at baseline may predict ICP response after greater PEEP levels.Methods: A prospective, observational study included mechanically ventilated patients with acute brain injury requiring invasive ICP and who underwent two-PEEP levels lung CT scan. Respiratory system compliance (Crs), arterial partial pressure of carbon dioxide (PaCO2), mean arterial pressure (MAP), data from qCT and ICP were obtained at PEEP 5 and 15 cmH2O.Results: Sixteen examinations (double PEEP lung CT and neuromonitoring) in 15 patients were analyzed. The median age of the patients was 54 years (interquartile range, IQR = 39–65) and 53% were men. The median Glasgow Coma Scale (GCS) at intensive care unit (ICU) admission was 8 (IQR = 3–12). Median alveolar recruitment was 2.5% of total lung weight (−1.5 to 4.7). PEEP from 5 to 15 cmH2O increased ICP [median values from 14.0 (11.2–17.5) to 23.5 (19.5–26.8) mmHg, p < 0.001, respectively]. The amount of recruited lung tissue on CT was inversely correlated with the change (Δ) in ICP (rho = −0.78; p = 0.0006). Additionally, ΔCrs (rho = −0.77, p = 0.008), ΔPaCO2 (rho = 0.81, p = 0.0003), and ΔMAP (rho = −0.64, p = 0.009) were correlated with ΔICP. Baseline Crs was not predictive of ICP response to PEEP.Conclusions: The main factors associated with increased ICP after PEEP augmentation included reduced Crs, lower MAP and lung recruitment, and increased PaCO2, but none of these factors was able to predict, at baseline, ICP response to PEEP. To assess the potential benefits of increased PEEP in patients with acute brain injury, hemodynamic status, respiratory mechanics, and lung morphology should be taken into account.

Clinical and Radiological Characteristics of Non-Benign Pineal Cyst Lesions in Children

Background: With the increasing availability and advances in brain imaging, pineal cyst lesions (PCL) are becoming a common finding in the pediatric population. In the absence of evidence-based guidelines, optimal diagnostic and therapeutic approaches have not been established, and there is a risk of under- or overtreatment of these patients.Objectives: The aim of our study was to evaluate the clinical presentation and radiological features of PCL in a cohort of pediatric patients and to identify clinical parameters more commonly associated with neoplasms in the pineal region. In addition, the prevalence of PCL in the pediatric population of Slovenia was estimated.Methods: In this observational, cohort study, children treated at University Children's Hospital, Ljubljana, Slovenia in the period 1997–2016 were included if PCL was found on brain imaging. We analyzed indications for referral to a neurologist, clinical signs and symptoms, radiological features, treatment and outcome.Results: The cohort consisted of 143 children with PCL. Pineocytoma was suspected in 31 children (21.7%). Six children underwent surgery – pineocytoma was confirmed in two cases and germinoma in one (2/3 of these children had signs of increased intracranial pressure (ICP), while PCL was benign in the remaining 4 cases. Only 2 PCL enlarged during the study period, both <2mm, none of these children developed neoplasm. Two children had PCL >20mm in diameter; both showed signs of increased ICP, one patient was found to have a germinoma of the pineal region, while the other had no neoplasm.Conclusions: Most PCL do not change their features during radiological follow-up and even atypical PCL are very rarely associated with a malignant neoplasm of the pineal region. A PCL larger than 20 mm and signs of increased ICP were identified as potential markers for selecting patients at risk.

Eye-Neck Integrated Ultrasound in Idiopathic Intracranial Hypertension and Cerebral Venous Sinus Thrombosis

Background: The clinical presentation of cerebral venous sinus thrombosis (CVST) overlaps with that of idiopathic intracranial hypertension (IIH), but no screening tool exists. We investigated the role of eye-neck integrated ultrasound in the diagnosis and differentiation of IIH and CVST.Methods: Twenty IIH patients, 30 CVST patients, and 40 healthy controls were retrospectively analyzed. The ultrasonographic optic nerve sheath diameter (ONSD) and hemodynamic characteristics of the internal jugular veins (IJVs) were recorded. The cerebrospinal fluid opening pressure was measured after ultrasonic examination.Results: The ONSD was significantly larger in IIH patients than in controls (4.71 ± 0.41 vs. 3.93 ± 0.24 mm, p < 0.001). The ONSD cut-off for IIH diagnosis was 4.25 mm (AUC = 0.978; 95% CI: 0.95–1.0, p < 0.001, sensitivity: 90%, specificity: 93%). In the CVST group, 22 (73.3%) patients had elevated intracranial pressure (ICP); the mean ONSD was significantly higher in patients with increased ICP than in those without (4.43 ± 0.33 vs. 3.95 ± 0.17 mm, p < 0.001). The mean blood flow volume (BFV) was significantly reduced in CVST patients (425.17 ± 349.83 mL/min) compared to that in controls (680.37 ± 233.03 mL/min, p < 0.001) and IIH patients (617.67 ± 282.96 mL/min, p = 0.008). The optimal BFV cut-off for predicting CVST was 527.28 mL/min (AUC = 0.804, 95% CI: 0.68–0.93, p < 0.001, sensitivity: 80%, specificity: 78%). The velocity of the unilateral IJVs-J3 segment decreased or remained constant during deep inspiration (abnormal respiratory modulate blood flow test, ARMT) in 32.5% of controls, with no bilateral ARMT. The prevalence of bilateral ARMT was 25% in IIH patients (χ2 = 12.9, p = 0.005) and 27% in CVST patients (χ2 = 17.6, p = 0.001).Conclusion: Eye-neck integrated ultrasound is an easily available bedside technique to assess ICP and hemodynamic characteristics of IJVs. ONSD measurement can identify patients with increased ICP, and reduced IJV BFV may aid the differentiation of CVST and IIH.

Severe and persistent coronavirus disease 2019 cough resulting in bone flap displacement and pseudomeningocele

Background: Cough is one of the most common symptoms of coronavirus disease 2019 (COVID-19) infection. This relatively benign symptom may lead to serious sequelae, especially in postoperative neurosurgical patients. Case Description: Here, we report a case of bone flap displacement, pseudomeningocele formation, and consequent cerebrospinal fluid leak in a patient with COVID-19 infection who recently underwent craniotomy for excision of cerebral metastasis. We highlight the pathophysiologic mechanisms of cough that may cause increased intracranial pressure (ICP), leading to the postoperative morbidity. Conclusion: Aside from additional risks to the patient’s health and increased treatment costs, these complications also lead to subsequent delays in the management of the underlying disease. Symptomatic treatment of cough is advised to prevent complications resulting from increased ICP.

Clinical and Radiological Predictors of Ventriculoperitoneal Shunt Insertion in Myelomeningocele Patients

BACKGROUND: Myelomeningocele (MMC) is one of the most common developmental anomalies of the CNS. Many of these patients develop hydrocephalus (HCP). The rate of cerebrospinal fluid diversion in these patients varies significantly in literature, from 52% to 92%. MMC repair conventionally occurs in the post-natal period. With the technological advances in surgical practice and fetal surgeries, intra uterine MMC repair IUMR is adopted in some centers. Cerebrospinal fluid shunting has numerous complications, most notably shunt failure and shunt infection. Studies have suggested that patients with greater numbers of shunt revisions have poorer performance on neuropsychological testing. There is also good evidence to suggest that the IQs of patients with MMC who do not undergo shunt placement are higher than that of their shunt treated counterparts. AIM: In this study, we are trying to identify strong clinical and radiological predictors for the need of ventriculoperitoneal (VP) shunt insertion in patients with MMC who underwent surgical repair and closure of the defect initially. This will decrease the overall rate of shunt placement in this group of patients through applying a strict policy adopting only shunt insertion for the desperately needing patient. METHODS: Prospective clinical study conducted on 96 patients with MMC presented to Aboul Reish Pediatric Specialized Hospital, Cairo University. After confirming the diagnosis through clinical and radiological aids, patients are carefully examined, if HCP is evident clinically and radiologically a shunt is inserted together with MMC repair at the same session after excluding sepsis or cerebrospinal fluid (CSF) infection, (GROUP A). If there are no signs of increased ICP, MMC repair shall be done alone (GROUP B). Those patients shall be monitored carefully postoperatively and after discharge and shall be followed up regularly to early detect and promptly manage latent HCP. Multiple clinical and radiological indices were used throughout the follow-up period and statistical significance of each was measured. RESULTS: Shunt placement was required in 45 (46.88%) of the 96 patients. Eighteen patients (18.75%) needed the shunt as soon as they presented to us (GROUP A), because they were having clinically active HCP. Twenty-seven (28.13%) patients were operated on by MMC repair initially without shunt placement because they did not have signs of increased ICP at the time of presentation. Yet, they developed latent HCP requiring shunt placement during the follow-up period (GROUP B2). Fifty-one patients of the study population (53.13%) underwent surgical repair of the MMC without the need of further VP insertion and they were followed up for 6 months period after the repair without developing latent HCP (GROUP B1). Patients of GROUP B were the study population susceptible for the development of latent HCP. Out of 78 patients in GROUP B, only 27 patients (34.62%) needed a VP shunt. CONCLUSION: In our study, we found that the rate of shunt insertion in patients with MMC is lower than the previously reported rate in the literature. A more thorough evaluation of the patient’s post-operative need for a shunt is mandatory. We suggest that we could accept postoperative (after MMC repair) ventriculomegaly provided it does not mean any deterioration in the patient’s clinical or developmental state. We assume that reduction of shunt insertion rate will eventually reduce what has previously been an enormous burden for a significant proportion of children with MMC.

Mean value of B-mode optic nerve sheath diameter as an indicator of increased intracranial pressure: a systematic review and meta-analysis

Objectives Timely diagnosis and treatment of increased intracranial pressure can decrease morbidity and prevent mortality. The present meta-analysis aims to determine the mean value of the ONSD measured in patients with various elevated ICP etiologies under different clinical settings, as well as comparing the value of ONSD between patients with and without elevated ICP. Methods This meta-analysis complied with the Preferred Reporting Items for Systematic Reviews and Meta-analysis Statement8. PubMed, Embase, and Cochrane Library were searched to identify ONSD measured by US for patients with increased ICP from establishment to October 2020. Results A total of 779 patients with elevated ICP among 22 studies were included in the present meta-analysis. Studies were published between 2003 and 2020. Eighteen were comparative (18/22, 81.8%), and four were single-armed study (4/22, 18.2%). Twenty were prospective studies (20/22, 90.9%). There was moderate-to-high heterogeneity based on the prediction ellipse area and variance logit of sensitivity and specificity. Conclusions The mean value of the ONSD among patients diagnosed with increased ICP was 5.82 mm (95% CI 5.58–6.06 mm). Variations were observed based on etiology of intracranial hypertension, clinical settings where ONSD was measured, and standards for diagnosing intracranial hypertension. The US-ONSD among patient with elevated ICP was significantly higher than the normal control. Although a cut-off value is not clearly determined, these mean values can be implemented to evaluate the sensitivity and specificity of US-ONSD in diagnosing intracranial hypertension in future studies.

Comparison of transorbital ultrasound measurements to predict intracranial pressure in brain-injured patients requiring external ventricular drainage

OBJECTIVE The optic nerve sheath diameter (ONSD) excluding the dura mater (ONSDE; i.e., the subarachnoid diameter) and the ONSD including the dura mater (ONSDI) have been used differently in studies, but the predictive ability of these two different measurements of the ONSD as measured by invasive intracranial pressure (ICP) monitoring has never been compared. Additionally, studies on the prediction of ICP using central retinal artery (CRA) Doppler ultrasonography are scarce. The authors aimed to determine how the two different ONSD measurements, the ONSD/eyeball transverse diameter (ETD) ratio, and transorbital Doppler ultrasonography parameters are associated with ICP via external ventricular drainage (EVD). METHODS This prospective observational study included 50 patients with brain injury who underwent EVD between August 2019 and September 2020. The mean of three repeated measurements of the ONSDI and ONSDE was calculated to reduce artifact and off-axis measurements. ETD, an immutable value, was measured from the initial brain CT with a clear outline of the eyeball. Simultaneously, flow velocities in the CRA and posterior ciliary artery (PCA) were compared with the ICP. RESULTS The ONSDE, ONSDI, and ONSD/ETD ratio were significantly associated with ICP (p = 0.005, p < 0.001, and p < 0.001, respectively). The ONSD/ETD ratio showed the highest predictive power of increased ICP (area under the curve [AUC] 0.897). The ONSDI was correlated more with the ICP than was the ONSDE (AUC 0.855 vs 0.783). None of the Doppler ultrasonography parameters in the CRA and PCA were associated with ICP. CONCLUSIONS The ONSD/ETD ratio is a better predictor of increased ICP compared with the ONSDI or ONSDE in brain-injured patients with nonsevere ICP. The ONSDI may be more available for predicting the ICP than the ONSDE.

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

Background The 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. Methods Patients 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. Results A 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). Conclusion Our 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.

Intracranial baroreflex is attenuated in an ovine model of renovascular hypertension

We have previously shown that elevations in intracranial pressure (ICP) within physiological ranges in normotensive animals increase arterial pressure; termed the intracranial baroreflex. Hypertension is associated with alterations in reflexes which maintain arterial pressure however, whether the intracranial baroreflex is altered is not known. Hence, in the present study, we tested the hypothesis that in hypertension, physiological increases in ICP would not be accompanied with an increase in arterial pressure. Renovascular hypertension was associated with no change in heart rate, renal blood flow or ICP levels compared to the normotensive group. ICV infusion of saline produced a ramped increase in ICP of 20 ± 1 mmHg. This was accompanied by an increase in arterial pressure (16 ± 2 mmHg) and a significant decrease in renal vascular conductance. ICV infusion of saline in the hypertensive group also increased ICP (19 ± 2 mmHg). However, the increase in arterial pressure was significantly attenuated in the hypertensive group (5 ± 2 mmHg). Ganglionic blockade abolished the increase in arterial pressure in both groups to increased ICP. Our data indicates that physiological increases in ICP lead to increases in arterial pressure in normotensive animals but this is severely attenuated in renovascular hypertension.