Optic Nerve Sheath Diameter and Retinal Artery Resistive Index Measurements with Bedside Ophthalmic Ultrasound in Pediatric Patients with Pseudotumor Cerebri Syndrome

Optic nerve sheath diameter as a non-invasive tool to detect clinically relevant raised intracranial pressure in children: an observational analytical study

BACKGROUND

Raised intracranial pressure (ICP) contributes to approximately 20% of the admissions in the paediatric intensive care unit (PICU) in our setting. Timely identification and treatment of raised ICP is important to prevent brain herniation and death in such cases. The objective of this study was to examine the role of optic nerve sheath diameter (ONSD) in detecting clinically relevant raised ICP in children.

METHODS

A hospital-based observational analytical study in a PICU of a tertiary care institute in India on children aged 2-14 years. ONSD was measured in all children on three time points that is, day 1, day 2 and between day 4 and 7 of admission. ONSD values were compared between children with and without clinical signs of raised ICP.

RESULTS

Out of 137 paediatric patients recruited, 34 had signs of raised ICP. Mean ONSD on day 1 was higher in children with signs of raised ICP (4.99±0.57 vs 4.06±0.40; p<0.01). Mean ONSD on day 2 also was higher in raised ICP patients (4.94±0.55 vs 4.04±0.40; p<0.01). The third reading between days 4 and 7 of admission was less than the first 2 values but still higher in raised ICP patients (4.48±1.26 vs 3.99±0.57; p<0.001). The cut-off ONSD value for detecting raised ICP was 4.46 mm on the ROC curve with an area under curve 0.906 (95% CI 0.844 to 0.968), 85.3% sensitivity and 86.4% specificity. There was no difference in ONSD between the right and the left eyes at any time point irrespective of signs of raised ICP.

CONCLUSION

We found that measurement of ONSD by transorbital ultrasound was able to detect clinically relevant raised ICP with an excellent discriminatory performance at the cut-off value of 4.46 mm.

Ultrasound-guided initial diagnosis and follow-up of pediatric idiopathic intracranial hypertension

BACKGROUND

Idiopathic intracranial hypertension in children often presents with non-specific symptoms found in conditions such as hydrocephalus. For definite diagnosis, invasive intracranial pressure measurement is usually required. Ultrasound (US) of the optic nerve sheath diameter provides a non-invasive method to assess intracranial pressure. Transtemporal US allows imaging of the third ventricle and thus assessment for hydrocephalus.

OBJECTIVE

To investigate whether the combination of US optic nerve sheath and third ventricle diameter can be used as a screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure and exclude hydrocephalus as an underlying pathology. Further, to analyze whether both parameters can be used to monitor treatment outcome.

MATERIALS AND METHODS

We prospectively included 36 children with idiopathic intracranial hypertension and 32 controls. Using a 12-Mhz linear transducer and a 1-4-Mhz phased-array transducer, respectively, optic nerve sheath and third ventricle diameters were determined initially and during the course of treatment.

RESULTS

In patients, the mean optic nerve sheath diameter was significantly larger (6.45±0.65 mm, controls: 4.96±0.32 mm) and the mean third ventricle diameter (1.69±0.65 mm, controls: 2.99±1.31 mm) was significantly smaller compared to the control group, P<0.001. Optimal cut-off values were 5.55 mm for the optic nerve sheath and 1.83 mm for the third ventricle diameter.

CONCLUSIONS

The combined use of US optic nerve sheath and third ventricle diameter is an ideal non-invasive screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure while ruling out hydrocephalus. Treatment can effectively be monitored by repeated US, which also reliably indicates relapse.

Characterization of Ocular Sonography Findings and their Relationship to Clinical Features from a South Indian Cohort of Idiopathic Intracranial Hypertension

Background

Idiopathic intracranial hypertension (IIH) typically manifests with headache, accompanied by papilledema and visual loss, and has a higher prevalence in females. In recent years, ocular sonography, particularly, measurement of optic nerve sheath diameter (ONSD), is being investigated for diagnosis of IIH.

Methods

A total of 35 patients over the age of 18 years, fulfilling the modified Dandy's criteria for diagnosis of IIH were included. Patients underwent assessment with magnetic resonance imaging, lumbar puncture, and ocular sonography to measure ONSD and ocular arterial indices.

Results

The mean ONSD values (in centimeters) in the right eye of patients with IIH was 0.57 ± 0.13, while it was 0.48 ± 0.03 in controls. In the left eye, the mean ONSD value (cm) was 0.59 ± 0.13 in patients with IIH and 0.48 ± 0.03 in controls. ONSD was significantly higher in cases compared to controls (P < 0.001, Welch test). Pulsatility index of the central retinal artery was significantly higher in cases compared to controls (P < 0.001, Welch test). Resistance index of the ophthalmic artery was statistically significant (P < 0.005, Welch test). Receiver operating characteristic curve analysis revealed a cutoff value of 5.1 mm on the right side and 5 mm on the left side had a sensitivity and specificity of more than 80% for IIH diagnosis.

Conclusion

Our study provides insights into the utility of optic nerve sheath measurements and arterial indices in the diagnosis of IIH in a South Indian cohort. Further research is needed to fully understand the longitudinal relationship of these parameters and treatment outcomes in IIH.

Non-Invasive Quantitative Approximation of Intracranial Pressure in Pediatric Idiopathic Intracranial Hypertension Based on Point-of-Care Ultrasound of the Optic Nerve Sheath Diameter

BACKGROUND

To investigate whether ultrasound-based optic nerve sheath diameter (US-ONSD) is a reliable measure to follow up children with idiopathic intracranial hypertension (IIH). In addition, to analyze the inter- and intra-individual relationships between US-ONSD and intracranial pressure (ICP), and to investigate whether an individualized mathematical regression equation obtained from two paired US-ONSD/ICP values can be used to approximate ICP from US-ONSD values.

METHODS

159 US examinations and 53 invasive ICP measures via lumbar puncture (LP) were performed in 28 children with IIH. US-ONSD was measured using a 12 Mhz linear transducer and compared to ICP values. In 15 children, a minimum of 2 paired US-ONSD/ICP determinations were performed, and repeated-measures correlation (rmcorr) and intra-individual correlations were analyzed.

RESULTS

The cohort correlation between US-ONSD and ICP was moderate (r = 0.504, p < 0.01). Rmcorr (r = 0.91, p < 0.01) and intra-individual correlations (r = 0.956-1) of US-ONSD and ICP were excellent. A mathematical regression equation can be calculated from two paired US-ONSD/ICP values and applied to the individual patient to approximate ICP from US-ONSD.

CONCLUSIONS

Related to excellent intra-individual correlations between US-ONSD and ICP, an individualized regression formula, created from two pairs of US-ONSD/ICP values, may be used to directly approximate ICP based on US-ONSD values. Hence, US-ONSD may become a non-invasive and reliable measure to control treatment efficacy in pediatric IIH.

Optic Nerve Ultrasound Evaluation in Children: A Review

Managing patients with neurocritical illness requires monitoring and treating elevated intracranial pressure (ICP), especially in cases in children. In terms of precise and real-time measurements, invasive ICP measurements are presently the gold standard for the initial diagnosis and follow-up ICP assessments. As a rapid and non-invasive way to detect elevated ICP, point-of-care ultrasonography (POCUS) of optic nerve sheath diameter (ONSD) has been proposed. The utility of bedside POCUS of ONSD to detect elevated ICP with excellent diagnostic test accuracy in adults has already been demonstrated. Nonetheless, data on the relationship between POCUS of ONSD and ICP in children are scarce. Therefore, the purpose of this review is to point out the most recent findings from the pediatric published literature and briefly discuss what was assessed with ONSD ultrasound examination, and also to describe and discuss the diagnostic procedures available for optic nerve ultrasound appraisal. A search of the medical databases PubMed and Scopus was carried out. The terms such as "ocular ultrasonography", "ICP assessment", "children", "point-of-care ultrasound", and "POCUS" were searched. In conclusion, the use of the standardized A-scan technique coupled with the B-scan technique should be suggested to provide data that are as accurate, precise, repeatable, and objective as possible.

Optic Nerve Sheath Diameter Ultrasound: A Non-Invasive Approach to Evaluate Increased Intracranial Pressure in Critically Ill Pediatric Patients

Early diagnosis of increased intracranial pressure (ICP) is crucial for prompt diagnosis and treatment of intracranial hypertension in critically ill pediatric patients, preventing secondary brain damage and mortality. Although the placement of an external ventricular drain coupled to an external fluid-filled transducer remains the gold standard for continuous ICP monitoring, other non-invasive approaches are constantly being improved and can provide reliable estimates. The use of point-of-care ultrasound (POCUS) for the assessment of ICP has recently become widespread in pediatric emergency and critical care settings, representing a valuable extension of the physical examination. The aim of this manuscript is to review and discuss the basic principles of ultra-sound measurement of the optic nerve sheath diameter (ONSD) and summarize current evidence on its diagnostic value in pediatric patients with ICP. There is increasing evidence that POCUS measurement of the ONSD correlates with ICP, thus appearing as a useful extension of the physical examination in pediatrics, especially in emergency medicine and critical care settings for the initial non-invasive assessment of patients with suspected raised ICP. Its role could be of value even to assess the response to therapy and in the follow-up of patients with diagnosed intracranial hypertension if invasive ICP monitoring is not available. Further studies on more homogeneous and extensive study populations should be performed to establish ONSD reference ranges in the different pediatric ages and to define cut-off values in predicting elevated ICP compared to invasive ICP measurement.

Is Ocular Sonography a Reliable Method for the Assessment of Elevated Intracranial Pressure in Children?

Point-of-care ultrasound has been widely used by clinicians at the bedside in recent years. Various types of point-of-care ultrasound practices are employed, especially in pediatric emergency rooms and intensive care units. Pediatric intensive care specialists perform point-of-care ultrasound virtually as a part of physical examination since it provides just-in-time vital clinical information, which could assist in acute management strategies in critically ill patients. Measurement of optic nerve sheath diameter using point-of-care ultrasound is a noninvasive and radiation-free technique to determine raised intracranial pressure. Ophthalmic artery and central retinal artery Doppler indices can be used as transcranial Doppler to assess raised intracranial pressure. The aim of this review was to provide detailed information on ultrasonographic measurements of optic nerve sheath diameter and central retinal artery Doppler indices as techniques of interest for predicting increased intracranial pressure in pediatric patients in view of the literature.