Does optic nerve sheath diameter on MRI decrease with clinically improved pediatric hydrocephalus?

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.

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.

Optic nerve ultrasonography in the evaluation of the relationship between arachnoid cyst and headache

AIM

This study is aimed to show the difference between optic nerve sheath diameter (ONSD) values in migraine patients with and without arachnoid cysts from migraine patients and control groups, and to evaluate the relationship with the arachnoid cyst size on magnetic resonance imaging (MRI) and their clinical severity.

METHODS

This cross-sectional study included pediatric patients who were previously diagnosed with migraine and the control group. The patients consist of 3 groups. The first group was 24 patients with arachnoid cysts on brain magnetic resonance imaging (MRI) who met the diagnostic criteria for migraine (group 1); the second group was 20 patients with only headache without arachnoid cysts or other findings on brain magnetic resonance imaging (MRI) (group 2); the third group was completely healthy 20 control group. Demographic data of the patients, the onset of headache time, clinical severity, electroencephalography (EEG) findings, optic nerve sheath diameter (ONSD) measurements by ultrasonography, and the volume of arachnoid cyst on brain MRI were determined and compared.

RESULTS

The optic nerve sheath diameter (ONSD) value was the highest in group 1 and the lowest in the control group (p: 0.001). The clinical severity was statistically different between the groups (p: 0.038). Accordingly, the majority of the clinical severity of group 1 was determined in grades 3 and 4. A weak positive correlation was found between the arachnoid cyst size on MRI and the ONSD measurement (r = 0.410, p = 0.047). The ONSD value statistically significantly increased with clinical severity in group 1 (p: 0.003).

CONCLUSION

The reliability of the optic nerve sheath diameter (ONSD) measurements in determining the increase of the intracranial pressure was shown in previous studies. This is the first study in the literature presenting that the intracranial pressure effects of arachnoid cysts can be demonstrated by ONSD. We have considered that arachnoid cysts detected in headaches can create a compression effect and cause the pain to intensify.

Clinical Relevance of Transorbital Ultrasonographic Measurement of Optic Nerve Sheath Diameter (ONSD) for Estimation of Intracranial Pressure Following Cerebrospinal Fluid Diversion Surgery

Background and aim

Raised intracranial pressure (ICP) can be estimated by various invasive as well as non-invasive techniques. Optic nerve sheath diameter (ONSD ) is a bedside non-invasive technique for assessment of ICP as a regular follow-up tool and has added advantage over CT scan/MRI, which require patient transfer to the suite. Cerebrospinal fluid (CSF) diversion procedures such as a ventriculoperitoneal shunt or external ventricular drainage are commonly done to relieve symptoms of patients with raised ICP. Change in ICP measured through ONSD after CSF diversion procedures may guide the proper functioning of the shunt and immediate post-operative management. The present study was conducted to compare ONSD before and after CSF diversion procedures and correlate the ONSD with ICP. Our secondary objective was to determine the ONSD cutoff for the prediction of ICP >20mm Hg.

Setting, design, and methods

This prospective, comparative, and observational study was carried out at Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, India. The present study was conducted on 40 adult patients undergoing CSF diversion surgery under general anaesthesia. Ultrasonographic measurement of the ONSD was performed before induction, after induction, after endotracheal intubation, after completion of shunt surgery, and then every two hours for 12 hours. The direct ICP was measured by the neurosurgeon at the time of the initial ventricular puncture.

Statistical analysis

The Wilcoxon signed-rank test was used to compare pre and post variables. Qualitative variables were compared using the Chi-Square test/Fisher’s exact test as appropriate. Spearman's rho statistical measure of linear association was applied to measure the strength of linear association between parameters to show how close the points lie to a straight line. A p-value of <0.05 was considered statistically significant.

Results

The mean value of ONSD before induction and after induction was 6.36 ± 0.61 mm and 6.29 ±0.64 mm, respectively. After endotracheal intubation, ONSD slightly increased to 6.34 ±0.62mm, followed by a consistent decrease in ONSD values. The mean direct ICP recorded was 30.93±6.22 mmHg. Comparison of mean ONSD before induction, after induction, and after intubation with ONSD after surgery was statistically significant (p <0.001). We found a strong positive correlation between direct ICP and ONSD after intubation with a correlation coefficient of 0.969 (P <0.001). Receiver operating characteristic (ROC) curve analysis showed an ONSD cutoff of >5.85, predicted ICP>20 mmHg with a sensitivity of 92.3%, and specificity of 85.7%.

Conclusion

Measurement of ONSD by ultrasonography is an important and reliable tool in the assessment of normalization of ICP post CSF diversion procedure.

Assessment of Optic Nerve Sheath Diameter and Its Postoperative Regression among Patients Undergoing Brain Tumor Resection in a Tertiary Care Center

Introduction  Bedside measurement of optic nerve sheath diameter (ONSD) using ultrasonography (USG) is a useful method for detecting raised intracranial pressure (ICP). The primary and main objective of this study is to estimate ONSD among patients with brain tumor and its regression post tumor resection to assess the correlation as well as diagnostic accuracy of the same.

Materials and Methods  This prospective observational study was performed in a tertiary health care center over a span of 3 months on 68 adults of either sex, out of which 30 were nonneurosurgical patients, taken as control group. Rest 38 were neurosurgical patients posted for brain tumor resection. Normal ONSD in our population was determined by calculating average ONSD using transorbital USG in individuals of control group. ONSD in neurosurgical patients taken as case group was recorded before surgery, intraoperatively immediately post tumor resection, as well as 12 and 24 hours post surgery. These values were analyzed to see the correlation of ONSD with tumor resection.

Results  The mean (±standard deviation) binocular ONSD in our population was 4.28 ± 0.28 mm. The mean preoperative binocular ONSD in cases using transorbital USG came out to be 5.43 ± 0.37 mm with 88.23% sensitivity and 100% specificity. Postoperatively, transorbital ONSD showed significant regression at 12 and 24 hours as compared with preoperative values ( p -value < 0.05).

Conclusion  Transorbital ultrasonographic measurement of ONSD could be considered as an indirect indicator of ICP in neurosurgical patients perioperatively. The technique is quick to perform at bedside, feasible in critical patients, and without any harmful effects.

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.

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.

The Use of Ultrasound-Measured Optic Nerve Sheath Diameter to Predict Ventriculoperitoneal Shunt Failure in Children

OBJECTIVE

The goal of this study was to assess the accuracy of ultrasound-measured optic nerve sheath diameter (ONSD) as a screen for ventriculoperitoneal shunt failure.

METHODS

We prospectively enrolled a convenience sample of children presenting to the ED with suspected shunt failure. The ONSD was measured by ultrasound and compared with computed tomography/magnetic resonance imaging (CT/MRI) and neurosurgical impression. We defined shunt failure on ultrasound as an ONSD greater than 4.0 mm in infants 12 months and younger or greater than 4.5 mm in children older than 12 months. A single emergency radiologist at our institution read all CTs and MRIs for categorical determination of shunt failure. We defined shunt failure based on neurosurgical impression as a decision to admit and perform shunt revision. We report test characteristics and 95% confidence intervals of ONSD as a predictor for shunt failure.

RESULTS

We enrolled 32 subjects. The sensitivities of ONSD compared with CT/MRI and neurosurgical impression, 60.0% and 75.0%, respectively, were low. However, the negative predictive values of ONSD compared with CT/MRI and neurosurgical impression were 90.0% and 95.0%, respectively.

CONCLUSIONS

Optic nerve sonography may be a useful tool to identify children presenting with suspected ventriculoperitoneal shunt failure who do not require further imaging. This would reduce the use of CT scan and exposure to ionizing radiation in children with suspected shunt malfunction who do not require neurosurgical intervention. Consideration of additional risk factors and a larger sample size may yield stronger results.

Measurement of changes in optic nerve sheath diameter using ultrasound and computed tomography scan before and after the ventriculoperitoneal shunt surgery in patients with hydrocephalus - A prospective observational trial

BACKGROUND

The standard methods for measuring intracranial pressure (ICP) are invasive in nature. Non invasive methods such as ONSD may help circumvent these complications and may serve as a surrogate marker for increased ICP. The primary aim of this study was to assess the ONSD (optic nerve sheath diameter) changes using ultrasonography (USG) and computed tomography (CT) scan in hydrocephalus patients before and after the insertion of VP shunt.

MATERIALS AND METHODS

A prospective observational study was conducted among 69 patients undergoing VP shunt surgery between the ages of 2 to 60 years. ONSD variation was measured by USG and CT scan both before and after the surgery. The difference in the pre-operative and post-operative ONSD measurement was analyzed using a paired t-test. Whereas, the measurements of ONSD were compared for agreement between two modalities (USG and CT) using Interclass correlation (ICC) and Bland Altman graph plot.

RESULTS

Among 69 patients 38 were males, 31 were females and 12 were under the age of 10 years. In the adult group, average preoperative and postoperative ONSD measurement by USG was 5.80 ± 0.63 mm and 4.52 ± 0.72 (p < 0.001) and by CT was 5.77 ± 0.83 mm and 4.49 ± 0.76 mm (p < 0.001) respectively. Similarly, in the pediatric population, average preoperative and postoperative ONSD measurement by USG was found to be 4.76 ± 1.14 mm and 3.90 ± 1.08 mm and by CT was found to be 4.75+/-1.11 mm and 3.85 ± 1.09 mm respectively (p <0.001).

CONCLUSION

In patients with hydrocephalus undergoing VP shunt surgery, we found a significant reduction in ONSD after the shunt insertion in both pediatric and adult population. We also found a good correlation between the USG and CT scan measurements of ONSD.

Contemporary management and surveillance strategy after shunt or endoscopic third ventriculostomy procedures for hydrocephalus

The management of hydrocephalus can be challenging even in expert hands. Due to acute presentation, recurrence, accompanying complications, the need for urgent diagnosis; a robust management plan is an absolute necessity. We devised a novel time efficient surveillance strategy during emergency, and clinic follow up settings which has never been described in the literature. We searched all articles embracing management/surveillance protocol on pediatric hydrocephalus utilizing the terms "hydrocephalus follow up" or "surveillance protocol after hydrocephalus treatment". The authors present their own strategy based on vast experience in the hydrocephalus management at a single institution. The need for the diagnostic laboratory testing, age and presentation based radiological imaging, significance of neuro-opthalmological exam, and when to consider the emergent exploration have been discussed in detail. Moreover, a definitive triaging strategy has been described with the help of flow chart diagrams for clinicians, and the neurosurgeons in practice. The triage starts from detail history, physical exam, necessary labs, radiological imaging depending on the presentation, and the age of the child. A quick head CT scan helps after shunt surgery while, a FAST sequence MRI scan (fsMRI) is important in post ETV patients. The need for neuro-opthalmological exam, and the shunt series stays vital in asymptomatic patients during regular follow up.

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 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.

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

PURPOSE

The purpose of this study was to investigate the value of the change in optic nerve sheath diameter (ONSD) as a radiological marker of endoscopic third ventriculostomy (ETV) outcome in children.

METHODS

Magnetic resonance imaging (MRI) scans of patients on whom ETVs were performed between the periods of January 2009 and June 2013 were reviewed. ONSD measurements on pre- and post-operative images were performed by two blinded observers, and the relationship between the change in these measurements and outcome from ETV were investigated. These findings were then also compared to conventional imaging features associated with ETV outcome.

RESULTS

MRI scans of 24 patients were adequate to measure the ONSD pre- and post-operatively. In patients with successful ETV (n = 19), the mean change in ONSD was 0.73 mm and in patients with a failed ETV (n = 5), the mean change in ONSD was 0.18 mm (p = 0.0007). A change in ONSD of 7.5 % of the initial measurement demonstrated a sensitivity of 92.9 % and a sensitivity of 85.7 % for ETV outcome (area under the receiver operating characteristic curve (AUROC) = 0.96).

CONCLUSION

Change in ONSD is a useful radiological marker of ETV outcome and may be used in combination with conventional radiological parameters to aid decision-making in this difficult group of patients.

Resolution of papilledema after endoscopic third ventriculostomy versus cerebrospinal fluid shunting in hydrocephalus: a comparative study

Object

In this study the authors compare the efficacy of endoscopic third ventriculostomy (ETV) versus CSF shunting for resolution of papilledema in hydrocephalus.

Methods

This comparative case series study recruited 12 patients (24 eyes) with hydrocephalus who underwent either an ETV (Group 1, 6 patients [12 eyes]) or CSF shunt treatment (Group 2, 6 patients [12 eyes]). A complete ophthalmological examination including retinal nerve fiber layer (RNFL) evaluation by optical coherence tomography was provided for all patients before surgery and in the 1st week, 1st month, and 3rd month postoperatively. The 2 groups were compared for quantitative changes in RNFL thickness and, thereby, resolution of papilledema. Statistical evaluation was performed using the Mann-Whitney U-test with the aid of SPSS version 16.0.

Results

The mean preoperative RNFL thickness was 259.7 ± 35.8 μm in Group 1 and 244.5 ± 53.4 μm in Group 2 (p = 0.798). The mean decrease in RNFL thickness was 101.3 ± 38.8 μm, 141.2 ± 34.6 μm, and 162.0 ± 35.9 μm in Group 1 versus 97.0 ± 44.6 μm, 143 ± 45.6 μm, and 130.0 ± 59.8 μm in Group 2 for the postoperative 1st week, 1st month, and 3rd month, respectively. There was no significant difference between the two groups with respect to decrease in RNFL thickness during the 1st week, 1st month, and 3rd month (p = 0.563, p = 0.753, and p = 0.528, respectively).

Conclusions

This is the first study to quantitatively evaluate papilledema in assessing the success of ETV and CSF shunting. The authors' results indicated that ETV is as effective as CSF shunting with respect to decreasing intracranial pressure and resolution of papilledema.