Change in optic nerve sheath diameter as a radiological marker of outcome from endoscopic third ventriculostomy in children

Clinical and radiologic criteria to predict endoscopic third ventriculostomy success in non-communicating pediatric hydrocephalus

OBJECTIVE

Endoscopic third ventriculocisternostomy (ETV) became the relevant treatment option for non-communicating pediatric hydrocephalus. ETV success was predicted in relation to age, diagnosis, and previous shunt implantation. Radiological factors are usually taken for indication decision-making. The aim of this study is to investigate radiological signs of non-communicating hydrocephalus for ETV success in a single-center retrospective analysis.

PATIENTS AND METHODS

ETV interventions were collected from a 10-year period (2010-2019) from our institution. Clinical patient characteristics such as prematurity, age, diagnosis, and previous shunt treatment and follow-up in terms of possible shunt implantation or revision surgeries were investigated. Radiological data was retrieved from the in-house PACS system to analyze preoperative signs for non-communicating hydrocephalus such as ventricular size, pressure gradients at the third ventricle, and any signs of obstruction from internal towards external cerebral spinal fluid communication. Fisher's test was used to demonstrate the significance of each individual predictor. A multivariable model was built using the backward elimination method with multiple logistic regression.

RESULTS

From 136 ETV interventions, 95 met the inclusion criteria (age < 18 years; > 6-month follow-up; MR image data availability, treatment goal for shunt independence). In chi-square statistical evaluation of single parameters age > 6 months (OR 32.5; 95% CI 4.8-364), ventricular width (FOHR < 0.56; OR 6.1; 95% CI 2.2-16.3) and non-post-hemorrhagic hydrocephalus as underlying diagnosis (OR 13.1; 95% CI 1.9-163) showed significant increased odds ratio for shunt independence during follow-up. Logistic regression analysis for multiple parameters showed age > 6 months (OR 29.3; 95% CI 4.1-606) together with outward bulged lamina terminalis (OR 4.6; 95% CI 1.2-19.6), smaller FOHR (continuous parameter; OR 2.83 × 10-5; 95% CI 4.7 × 10-9-0.045), and non-4th-ventricular-outlet obstruction (4thVOO; OR 0.31; 95% CI 0.09-1.02) as significant factors for ETV success.

CONCLUSION

ETV has become a relevant treatment for non-communicating hydrocephalus, with typical MR image characteristics. Analyzing radiological markers as predictors for success smaller ventricular width and outward displaced lamina terminalis was relevant in combination with age > 6 months. Since the analysis is based on single-center experience, a larger cohort of patients with a multi-center approach should further investigate the combined clinical and radiological criteria.

The Predictive Role of Early Postoperative Magnetic Resonance Imaging After Endoscopic Third Ventriculostomy

OBJECTIVE

Endoscopic third ventriculostomy (ETV) is a treatment option for obstructive hydrocephalus; reported success rates vary. We investigated immediate postoperative magnetic resonance imaging to evaluate the role of imaging parameters associated with outcomes.

METHODS

Retrospective chart review was performed on patients undergoing initial ETV between 2005 and 2019. Patients with preoperative and postoperative magnetic resonance imaging with follow-up>one year were included. The following were noted: changes in subarachnoid cerebrospinal fluid, third ventricle diameter, bowing of the third ventricle floor, and postoperative flow void. Kaplan-Meier survival methods were used to assess ETV success and univariable and multivariable Cox proportional-hazards models were fitted to assess factors contributing to ETV success.

RESULTS

Fifty-eight subjects were included. Nineteen (32.8%) experienced failure within one year; individually, no single imaging parameter predicted success. However, all cases of failure had no identifiable flow void. Any postoperative radiological change was not consistently associated with decreased odds of failure. Obstructive hydrocephalus treated with ETV demonstrated significantly better ETV success than patients treated with nonobstructive hydrocephalus. Interobserver reliability was moderate for 2 of the radiological variables and substantial for 1 of the radiological variables.

CONCLUSIONS

Individually, none of the qualitative radiologic parameters measured in our study predicted ETV success. Absence of a flow void predicted ETV failure, but additional studies are needed to determine its true negative predictive value. Inability to clarify which specific parameter predicts success reflects the limited role of immediate postoperative imaging in influencing clinical management.

G, Gunasekaran A, Chandar V. Comparison of Optic Nerve Sheath Diameter (ONSD) Measurements Obtained from USG Before and After Placement of Ventriculoperitoneal Shunt in Obstructive Hydrocephalus as a Surrogate Marker for Adequacy of Shunt Function: A Prospective Observational Study

Introduction  Optic nerve sheath diameter (ONSD) measured using ultrasonography has been widely used as a surrogate marker of elevated intracranial pressure. However, literature is sparse on the correlation between ONSD and ventriculoperitoneal (VP) shunt function, especially in adults with hydrocephalus. Our study was designed to assess the correlation between ONSD measured using ultrasonography before and 12 hours after VP shunt placement and the success of VP shunt placement assessed using computed tomography (CT) of the brain. Materials and Methods  Fifty-one patients between 16 and 60 years of age, with obstructive hydrocephalus scheduled for VP shunt surgery were included in this prospective, observational study. ONSD measurements were obtained from both eyes prior to induction of anesthesia, immediately after the surgery, and at 6, 12, and 24 hours after the surgery. An average of three readings was obtained from each eye. Cerebrospinal fluid (CSF) opening pressure was noted after entry into the lateral ventricle. Noncontrast CT (NCCT) brain was obtained 12 hours after the surgery and was interpreted by the same neurosurgeon for signs of successful VP shunt placement. Results  There was a significant reduction in ONSD in the postoperative period compared to ONSD measured preoperatively. The average ONSD (mean ± standard deviation) measured prior to induction of anesthesia, immediately after the surgery, and at 6, 12, and 24 hours after the surgery was 5.71 ± 0.95, 5.20 ± 0.84, 5.06 ± 0.79, 4.90 ± 0.79, and 4.76 ± 0.75 mm, respectively. The mean CSF opening pressure was 19.6 ± 6.9 mm Hg. Postoperative NCCT brain revealed misplacement of the shunt tip in only one patient. Conclusion  ONSD measured using ultrasonography may be used as a reliable indicator of VP shunt function in adults with obstructive hydrocephalus.

Optic nerve sheath diameter correlates with both success and failure of hydrocephalus treatment in pediatric patients with pineal region lesions

BACKGROUND

Pineal region lesions in children are heterogenous pathologies often symptomatic due to occlusive hydrocephalus and thus elevated intracranial pressure (ICP). MRI-derived parameters to assess hydrocephalus are the optic nerve sheath diameter (ONSD) as a surrogate for ICP and the frontal occipital horn ratio (FOHR), representing ventricle volume. As elevated ICP may not always be associated with clinical signs, the adjunct of ONSD could help decision making in patients undergoing treatment. The goal of this study is to assess the available magnetic resonance imaging (MRI) of patients with pineal region lesions undergoing surgical treatment with respect to pre- and postoperative ONSD and FOHR as an indicator for hydrocephalus.

METHODS

Retrospective data analysis was performed in all patients operated for pineal region lesions at a tertiary care center between 2010 and 2023. Only patients with pre- and postoperative MRI were selected for inclusion. Clinical data and ONSD at multiple time points, as well as FOHR were analyzed. Imaging parameter changes were correlated with clinical signs of hydrocephalus before and after surgical treatment.

RESULTS

Thirty-three patients with forty operative cases met the inclusion criteria. Age at diagnosis was 10.9 ± 4.6 years (1-17 years). Hydrocephalus was seen in 80% of operative cases preoperatively (n = 32/40). Presence of hydrocephalus was associated with significantly elevated preoperative ONSD (p = 0.006). There was a significant decrease in ONSD immediately (p < 0.001) and at 3 months (p < 0.001) postoperatively. FOHR showed a slightly less pronounced decrease (immediately p = 0.006, 3 months p = 0.003). In patients without hydrocephalus, no significant changes in ONSD were observed (p = 0.369). In 6/6 patients with clinical hydrocephalus treatment failure, ONSD increased, but in 3/6 ONSD was the only discernible MRI change with unchanged FOHR.

CONCLUSIONS

ONSD measurements may have utility in evaluating intracranial hypertension due to hydrocephalus in patients with pineal region tumors. ONSD changes appear to have value in assessing hydrocephalus treatment failure.

Transorbital point-of-care ultrasound versus fundoscopic papilledema to support treatment indication for potentially elevated intracranial pressure in children

PURPOSE

To compare transorbital point-of-care ultrasound techniques -optic nerve sheath diameter (US-ONSD) and optic disc elevation (US-ODE)- with fundoscopic papilledema to detect potentially raised intracranial pressure (ICP) with treatment indication in children.

METHODS

In a prospective study, 72 symptomatic children were included, 50 with later proven disease associated with raised ICP (e.g. pseudotumour cerebri, brain tumour, hydrocephalus) and 22 with pathology excluded. Bilateral US-ONSD and US-ODE were quantified by US using a 12-MHz-linear-array transducer. This was compared to fundoscopic optic disc findings (existence of papilledema) and, in 28 cases, invasively measured ICP values.

RESULTS

The sensitivity and specificity of a cut-off value of US-ONSD (5.73 mm) to detect treatment indication for diseases associated with increased ICP was 92% and 86.4%, respectively, compared to US-ODE (0.43 mm) with sensitivity: 72%, specificity: 77.3%. Fundoscopic papilledema had a sensitivity of 46% and a specificity of 100% in this context. Repeatability and observer-reliability of US-ODE examination was eminent (Cronbach's α = 0.978-0.989). Papilledema was detected fundoscopically only when US-ODE was > 0.67 mm; a US-ODE > 0.43 mm had a positive predictive value of 90% for potentially increased ICP.

CONCLUSION

In our cohort, transorbital point-of-care US-ONSD and US-ODE detected potentially elevated ICP requiring treatment in children more reliably than fundoscopy. US-ONSD and US-ODE indicated the decrease in ICP after treatment earlier and more reliably than fundoscopy. The established cut-off values for US-ONSD and US-ODE and a newly developed US-based grading of ODE can be used as an ideal first-line screening tool to detect or exclude conditions with potentially elevated ICP in children.

Interesting negative correlation between transorbital optic nerve sheath diameter and Evans' index values; can it be predictive for failure of endoscopic third ventriculostomy?

Background: Currently, Endoscopic third ventriculostomy (ETV) is one of the commonly used surgical options for the treatment of non-communicating hydrocephalus but reported success rates from ETV vary considerably, and a reliable noninvasive means to detect the efficacy of ETV is still lacking. In this study, the changes in Evans's Index and the transorbital optic nerve sheath (ONSD) diameter measurement after endoscopic third ventriculostomy were compared. Methods: Preoperative and early postoperative ultrasonographic ONSD measurement and preoperative and postoperative 3 months Evans' index of patients with hydrocephalus on whom ETVs were performed between 1 February 2018 and 23 May 2022 and analyzed. Results: The chart of 8 male and 2 female patients was analyzed. Their median age at presentation was 5.3 years (range 1 - 14 years). Mean ONSD values were 5.66 mms in the preoperative period, which was decreased to a mean of 4.17 mms in the early postoperative period. The Evans' index was 0.5320 in the preoperative period; however, it decreased to 0.4460 in the postoperative 3rd months. The preoperative and early postoperative mean ONSD values and Evans' Index of patients were significantly different. Interestingly, a negative correlation was also observed between ONSD values and Evans' index. Conclusions: ONSD measurement and Evans' index have been commonly used after ETV procedures İn pediatric patients with hydrocephalus. Still, there is an unexplained negative correlation between ONSD and Evans' index values. This study indicates that the two measures (Evans's index and ONSD) should be considered when performing follow-up examinations in patients after ETV.

Evaluation of third ventriculostomy outcome by measuring optic nerve sheath diameter in adult hdyrocephalus

OBJECTIVE

It is difficult to demonstrate the success of the procedure in patients with third ventriculostomy. We evaluated that optic nerve sheath diameter (ONSD) measurement, which can reflect intracranial pressure, may be a criterion for decision of endoscopic third ventriculostomy (ETV) success.

METHODS

28 adult patients suffering long overt standing ventriculomegaly (LOVA) who performed ETV were included in this retrospective study. The patients were divided into two groups as successful (group A) and failed ETV group (group B) according to their postoperative evaluation. ONSD was measured on pre- and post-operative computed tomography (CT) and Evan's index (EI), diameter of third ventricule (V3), the patency of ETV stoma and periventricular edema were evaluated by magnetic resonance imaging (MRI).

RESULTS

The mean ONSD was measured as 6.39±0.92mm for the right eye, 6.50±0.91mm for the left eye on preoperative CT. The mean ONSD by CT (after surgery) was 4.89±0.87mm for the right eye, 5.02±0.1mm for the left eye (p<0.05). Postoperative group A and group B were compared according to ONSD measurement; mean ONSD in group A was 4.52±0.69mm for the right and 4.59±0.9mm for the left, mean ONSD in group B was 5.82±0.51mm for the right and 6.1±0.32mm for the left (p<0.05). The best ONSD value for detecting failed ETV was 5.40mm (sensitivity 90%, specifity 75%, AUROC 0.938) for right and 5.91mm (sensitivity 90%, specifity 75%, AUROC 0.950) for left. EE was measured as 0.39±0.12mm on preoperative MRI and 0.39±0.12mm on postoperative MRI (p=0.3). V3 was measured as 14.7±2.47mm on preoperative MRI and 10.47±1.99mm on postoperative MRI (p<0.05).

CONCLUSION

The statistical values obtained from study show that the ONSD measurement can help in the postoperative evaluation of patients, who had a ETV surgery.

Quantitative Evans index estimation using ultrasonographic measurement of the optic nerve sheath diameter in supine and upright position

OBJECTIVES

We aimed to quantitatively assess Evans index (EI) using ultrasonographic optic nerve sheath diameter (ONSD) measurements in supine and upright position in normal pressure hydrocephalus (NPH) patients.

METHODS

Ultrasonographically ONSD was measured in a supine and upright position before and 4-5 days after the ventriculoperitoneal shunt surgery. The changes of the ONSD between supine and upright positions were calculated as ∆ONSD = sONSD-uONSD and as the variation ONSD_V = 100% × [(sONSD - uONSD)/sONSD]. Multiple linear regression analyses were conducted to assess associations between EI and the variation of ONSD. We derived the mathematical function to predict EI. Bland-Altman analysis was applied to evaluate the accuracy and precision of the EI prediction.

RESULTS

Thirteen adult patients (mean age 61.8 ± 11.1 (SD) years; 6 (46%) female) undergone VP shunt implantation for NPH. The mean EI was 0.432 (95% CI, 0.393-0.471) preoperatively and 0.419 (95% CI, 0.373-0.466) postoperatively (p = 0.066). There is a decrease of the ONSD during positional changes from supine to upright position and pre- and postoperative EI correlated with preoperative variation ONSD_V1 (r =  - 0.610 and - 0.648, p < 0.05). The mathematical function for preoperative EI estimation was EI_preop = 0.504 - 0.022 × ONSD_V1 + 0.101 × gender (M = 0; W = 1), (Durbin-Watson value = 1.94), and for postoperative was EI_postop = 0.487 - 0.022 × ONSD_V1 + 0.117 × gender; (Durbin-Watson value 2.23).

CONCLUSIONS

Ultrasonographic ONSD measurements in supine and upright position provide a potential method to quantify EI that can be conducted at the bedside.

Comparison of B-Scan Ultrasound and MRI-Based Optic Nerve Sheath Diameter (ONSD) Measurements in Children

BACKGROUND

Qualitative, noninvasive assessment of intracranial pressure is of eminent importance in pediatric patients in many clinical situations and can reliably be performed using transorbital ultrasonographic measurement of the optic nerve sheath diameter (ONSD). MRI-based determination of ONSD can serve as an alternative if ultrasound (US) is not possible or available for various reasons, for example, in small, incompliant children. This study investigates repeatability and observer reliability of US ONSD and correlation and bias of US- versus MRI-based ONSD assessment in pediatric patients.

METHODS

One hundred fifty children diagnosed with tumor (n = 40), hydrocephalus (n = 42), and other cranial pathologies (n = 68) were included. Bilateral ONSD was quantified by US using a 12-MHz linear array transducer. This was compared with ONSD measured in simultaneously acquired (≤24 h) T2-weighted MRI scans of the orbit.

RESULTS

Repeatability of individual US values and intraobserver ONSD was outstanding (Cronbach's α = 0.984 and 0.996, respectively). Overall mean values for ONSD were 5.8 ± 0.88 mm and 5.7 ± 0.89 mm for US and MRI, respectively. Correlation between US and MRI-based ONSD was strong (r = 0.976, P < 0.01). Bland and Altman analysis showed a mean bias of 0.078 mm. A repeated-measures correlation (r_rm) in 9 patients showed an excellent value (r_rm = 0.94, P < 0.01).

CONCLUSIONS

Repeatability and reliability of US ONSD determination is excellent. In case US ONSD assessment is not possible or available, MRI scans can serve as an excellent alternative. The difference of US and MRI ONSD is minimal and insignificant, and thus, both techniques can complement each other.

Surgical treatment of post-infectious hydrocephalus in infants

The management of post-infective hydrocephalus in infants remains a challenging task for the pediatric neurosurgeon. The decision-making curve is often complex in that appropriate temporizing measures need to be implemented to properly clear any infection within the CSF before any decision can be made regarding a permanent solution. The etiology differs at varying stages of neonatal development, and the weight of the child, skin fragility, and relevant surgical treatment options are often important limiting factors. Deciding on the optimal treatment option involves assessing the etiology, age, and clinical and radiological features of the individual case and selecting the most appropriate surgical option.

Utility of Serial Optic Nerve Sheath Diameter Measurements in Patients Undergoing Cerebral Spinal Fluid Diversion Procedures for Hydrocephalus

BACKGROUND

Functional status of cerebrospinal fluid (CSF) diversion procedure for hydrocephalus is difficult to assess on several occasions. We report the use of serial ultrasonographic measurement of optic nerve sheath diameter (ONSD) to assess the functional status of CSF diversion procedures in patients with hydrocephalus.

METHODS

In this prospective observational study, ultrasonographic ONSD measurement was performed preoperatively, on postoperative days 1, 3, and 7 (n = 51 at each time point) and at follow-up (n = 31) in patients undergoing ventriculoperitoneal shunt or endoscopic third ventriculostomy for hydrocephalus. Change in ONSD values during first week after CSF diversion procedure and at follow-up were correlated with ventriculoperitoneal shunt/ETV function.

RESULTS

ONSD ≥5.5 mm strongly correlated with clinical and imaging features of raised ICP (P < 0.001). Mean ONSD progressively decreased in the postoperative period and was the lowest on postoperative day 7 (P < 0.001) with >95% of patients having ONSD <5.5 mm at that time point. At follow-up (median, 12 months; n = 31), ONSD had further reduced in 78.6% of patients. All 3 patients with shunt dysfunction had an increase in the ONSD value compared with that on postoperative day 7.

CONCLUSIONS

ONSD measurement on postoperative day 7 after CSF diversion correlates well with early surgical outcome but decreases further in many patients at a follow-up of 12 months. Rise in postoperative day 7 ONSD at follow-up correlates with failure of the CSF diversion procedure.

Evaluation of third ventriculostomy outcome by measuring optic nerve sheath diameter in adult hdyrocephalus

OBJECTIVE

It is difficult to demonstrate the success of the procedure in patients with third ventriculostomy. We evaluated that optic nerve sheath diameter (ONSD) measurement, which can reflect intracranial pressure, may be a criterion for decision of endoscopic third ventriculostomy (ETV) success.

METHODS

28 adult patients suffering long overt standing ventriculomegaly (LOVA) who performed ETV were included in this retrospective study. The patients were divided into two groups as successful (group A) and failed ETV group (group B) according to their postoperative evaluation. ONSD was measured on pre- and post-operative computed tomography (CT) and Evan's index (EI), diameter of third ventricule (V3), the patency of ETV stoma and periventricular edema were evaluated by magnetic resonance imaging (MRI).

RESULTS

The mean ONSD was measured as 6.39±0.92mm for the right eye, 6.50±0.91mm for the left eye on preoperative CT. The mean ONSD by CT (after surgery) was 4.89±0.87mm for the right eye, 5.02±0.1mm for the left eye (p<0.05). Postoperative group A and group B were compared according to ONSD measurement; mean ONSD in group A was 4.52±0.69mm for the right and 4.59±0.9mm for the left, mean ONSD in group B was 5.82±0.51mm for the right and 6.1±0.32mm for the left (p<0.05). The best ONSD value for detecting failed ETV was 5.40mm (sensitivity 90%, specifity 75%, AUROC 0.938) for right and 5.91mm (sensitivity 90%, specifity 75%, AUROC 0.950) for left. EE was measured as 0.39±0.12mm on preoperative MRI and 0.39±0.12mm on postoperative MRI (p=0.3). V3 was measured as 14.7±2.47mm on preoperative MRI and 10.47±1.99mm on postoperative MRI (p<0.05).

CONCLUSION

The statistical values obtained from study show that the ONSD measurement can help in the postoperative evaluation of patients, who had a ETV surgery.

Multimodality Monitoring in Neurocritical Care: Decision-Making Utilizing Direct And Indirect Surrogate Markers

Substantial progress has been made to create innovative technology that can monitor the different physiological characteristics that precede the onset of secondary brain injury, with the ultimate goal of intervening prior to the onset of irreversible neurological damage. One of the goals of neurocritical care is to recognize and preemptively manage secondary neurological injury by analyzing physiologic markers of ischemia and brain injury prior to the development of irreversible damage. This is helpful in a multitude of neurological conditions, whereby secondary neurological injury could present including but not limited to traumatic intracranial hemorrhage and, specifically, subarachnoid hemorrhage, which has the potential of progressing to delayed cerebral ischemia and monitoring postneurosurgical interventions. In this study, we examine the utilization of direct and indirect surrogate physiologic markers of ongoing neurologic injury, including intracranial pressure, cerebral blood flow, and brain metabolism.

Use of neuroimaging measurements of optic nerve sheath diameter to assess intracranial pressure in craniosynostosis

PURPOSE

This study aims to evaluate accuracy of optic nerve sheath diameter (ONSD) measurements obtained by magnetic resonance imaging (MRI) in patients with craniosynostosis (CS) for detection of high intracranial pressure (ICP) and to correlate MRI-derived ONSD measurements with those obtained by computed tomography (CT) scans in CS patients.

METHODS

A retrospective review was conducted on CS patients who had MRI- and age-matched controls with normal MRI. Diagnosis of intracranial hypertension was based on presence of papilledema, direct ICP monitoring, and/or lumbar puncture. The search also included patients with MRI and CT done within 30 days apart. ONSDs were measured 3 mm behind the globe on both modalities.

RESULTS

The study identified 56 CS patients (mean age 3.8 ± 3.47 years) and 49 controls (mean age 3.7 ± 3.62 years). Mean ONSD in patients with high ICP was significantly higher than in patients without high ICP (P = 0.0001) and in controls (P < 0.0001). The optimal ONSD threshold for predicting raised ICP in patients >1 year old was 6 mm (71.4% sensitivity, 89.7% specificity). Nineteen patients with 38 single-eye MRI/CT pairs were identified. Substantial agreement between both modalities resulted (r = 0.959, 95% CI 0.923-0.978), and Bland and Altman Plot analysis showed that 95% of measurements fell within limits of agreement (1.96 SD; ± 0.6 mm).

CONCLUSION

In CS patients, ONSD measured by MRI represent indirect non-invasive means of ICP assessment. Both MRI and CT measurements of ONSD gave comparable results, and the use of CT-derived ONSD measurements may give some idea about ICP in CS patients.

Precision Medicine With Point-of-Care Ultrasound: The Future of Personalized Pediatric Emergency Care

The Precision Medicine Initiative spearheaded by the National Institute of Health has pioneered a new model of health care focused on health care delivery that is tailored to an individual. Medical advances have already provided clinicians with the tools to better predict treatment outcomes based on the individual needs of each patient's disease process. Three-dimensional printing allows medical devices and implants to be custom made-to-order. Technological advances in preoperative imaging have augmented the ability for surgeons to plan a specific surgical approach for each patient. In a similar vein, point-of-care ultrasound offers the emergency care provider an opportunity to move beyond protocols and provide precise medical care tailored to the acute needs of each ill or injured emergent patient. In this article, we explore several cutting-edge applications of point-of-care ultrasound that can help providers develop a personalized approach to resuscitation and emergent procedures in pediatrics.

Diagnostic value of neuro-ophthalmological signs in cases of Chiari I malformation

INTRODUCTION

Our purpose was to evaluate the diagnostic value of measuring diameters of optic nerve sheath (ONSD), presence/absence of papilledema, tortuosity of the optic nerve, flattening of the posterior sclera, and intraocular protrusion of the prelaminar optic nerve for intracranial pressure assessment in cases of Chiari I malformation.

METHODS

In a retrospective study, MRI data of 37 consecutive pediatric patients with Chiari malformation and data of 400 patients without intracranial pathology were compared and analyzed. ONSDs were measured at the point where the ophthalmic artery crosses the optic nerve (anatomical landmark). The correlation analysis was performed with clinical findings, gender, age, papilledema, and other neuro-ophthalmological findings.

RESULTS

ONSD was enlarged in 38 % of cases of Chiari malformation. The enlargement was bilateral, no correlation with age or gender was found (p = 0.67 and p = 0.76, respectively). The presence of papilledema was detected in 19 % of cases presenting less valuable diagnostic sign if compared with ONSD. The tortuosity of the optic nerve was found in 22 % of cases, but in three patients, it was unilateral. All patients with enlarged ONSD and other neuro-ophthalmological signs present were treated surgically, while most of the patients without these signs (20/23) were treated conservatively.

CONCLUSION

In majority of pediatric cases of Chiari malformation, the ONSD is not enlarged and other neuro-ophthalmological signs are not present. Detecting the enlarged ONSD and other neuro-ophthalmological signs in cases of Chiari malformation may indicate the elevated intracranial pressure and necessity for urgent surgical intervention.

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.

Non-invasive intracranial pressure assessment

Assessing intracranial pressure (ICP) remains a cornerstone in neurosurgical care. Invasive techniques for monitoring ICP remain the gold standard. The need for a reliable, safe and reproducible technique to non-invasively assess ICP in the context of early screening and in the neurocritical care environment is obvious. Numerous techniques have been described with several novel advances. While none of the currently available techniques appear independently accurate enough to quantify raised ICP, there is some promising work being undertaken.

Non-invasive assessment of intracranial pressure

Monitoring of intracranial pressure (ICP) is invaluable in the management of neurosurgical and neurological critically ill patients. Invasive measurement of ventricular or parenchymal pressure is considered the gold standard for accurate measurement of ICP but is not always possible due to certain risks. Therefore, the availability of accurate methods to non-invasively estimate ICP has the potential to improve the management of these vulnerable patients. This review provides a comparative description of different methods for non-invasive ICP measurement. Current methods are based on changes associated with increased ICP, both morphological (assessed with magnetic resonance, computed tomography, ultrasound, and fundoscopy) and physiological (assessed with transcranial and ophthalmic Doppler, tympanometry, near-infrared spectroscopy, electroencephalography, visual-evoked potentials, and otoacoustic emissions assessment). At present, none of the non-invasive techniques alone seem suitable as a substitute for invasive monitoring. However, following the present analysis and considerations upon each technique, we propose a possible flowchart based on the combination of non-invasive techniques including those characterizing morphologic changes (e.g., repetitive US measurements of ONSD) and those characterizing physiological changes (e.g., continuous TCD). Such an integrated approach, which still needs to be validated in clinical practice, could aid in deciding whether to place an invasive monitor, or how to titrate therapy when invasive ICP measurement is contraindicated or unavailable.

High resolution transbulbar sonography in children with suspicion of increased intracranial pressure

PURPOSE

To evaluate the accuracy of high resolution transbulbar sonography for the estimation of intracranial pressure (ICP) in children.

METHODS

In children and adolescents with acute neurologic symptoms of various origin, transbulbar sonography was performed. Besides measurement of the optic nerve sheath diameter (ONSD), the ultrastructure of the subarachnoid space of the optic nerve sheath was evaluated. The results of transbulbar sonography were correlated with clinical data based on cross-sectional imaging, ICP measurement, and ophthalmologic examination.

RESULTS

Eighty-one patients (age 3-17.8 years, mean 11.7 years) were included. In 25 children, cross-sectional imaging and ICP measurement revealed increased intracranial pressure. The mean ONSD was 6.85 ± 0.81 mm. Twenty patients (20/25, 80 %) had a microcystic appearance of the subarachnoid space of the optic nerve. In 56 children without evidence of increased intracranial pressure, the mean ONSD was 5.77 ± 0.48 mm. Forty-nine patients (49/56, 87.5 %) had a normal homogenous appearance of the subarachnoid space. The ONSD in children with increased intracranial pressure was significantly higher than in patients without (p < 0.001).

CONCLUSION

High resolution transbulbar sonography of the optic nerve is a useful technique for the rapid and non-invasive estimation of intracranial pressure in children. Besides measurement of the optic nerve sheath diameter, evaluation of the ultrastructure of the subarachnoid space of the optic nerve is a helpful parameter.