Ultrasonographic measurement of the optic nerve sheath diameter to detect intracranial hypertension: an observational study

Lumbar Puncture and Brain Herniation in Acute Bacterial Meningitis: An Updated Narrative Review

The risk of lumbar puncture (LP) to precipitate brain herniation in acute bacterial meningitis (ABM) was reviewed in this journal in 2007. We report the case of an infant with ABM who had acute apnea requiring intubation and tonic posturing (mistaken for seizure), and then had brain herniation within four hours of an LP. The case prompted this updated narrative review, from 2007 to 2024, focused on the twelve points made in 2007. The review included 14 case reports of brain herniation shortly after LP in ABM, 23 observational studies or systematic reviews, 28 narrative reviews, and 9 guidelines, each with evidence, advice, or recommendations important for the decision to perform LP in ABM. We found evidence to support, and did not find convincing evidence to refute, the twelve points. We found five additional claims made that were meant to refute some of the original points; however, these were based upon data that did not support the claims made. Limitation of the evidence reviewed was the absence of randomized trials to prove whether those patients who herniated may have been destined to herniate regardless of whether they had an LP. Reasons why ABM may be a unique circumstance where normal CT scan cannot determine the risk of herniation after an LP were discussed. We argue that the preponderance of evidence supported the conclusion that, in a patient with strongly suspected ABM who is clinically considered at high risk for herniation, interventions to control ICP and antibiotics administration should be the priority, followed secondarily by an urgent CT scan and, even with a normal CT, not an LP. The case report emphasized that respiratory arrest or suspected tonic seizure can be due to early herniation, and indicate CT scan, and prolonged LP deferral (for 3-4 days) even with a normal CT.

Sonographically measured optic nerve sheath diameter as a predictor of stroke severity and outcome among Ghanaian acute stroke patients

BACKGROUND

Elevated intracranial pressure (ICP) is a veritable and potentially modifiable predictor of adverse stroke outcome. Sonographically measured optic nerve sheath diameter (ONSD), a non-invasive proxy for ICP, could potentially be utilized as an objective measure of severity and outcome among acute stroke patients.

OBJECTIVE

To evaluate the relationship between admission ONSD, stroke severity, and functional outcomes among patients with acute stroke.

METHODS

A prospective cohort study was conducted among patients with neuroimaging-confirmed acute strokes admitted to a tertiary hospital in Ghana. The ONSD of each patient was measured within 24 h of admission. Multivariable linear regression was conducted to determine the relationship between admission ONSDs, Glasgow Coma score (GCS), and modified Rankin Score (mRS) at days 30, 60, and 90.

RESULTS

We enrolled 116 patients comprising 69 ischaemic strokes, mean (SD) age 62.6 years ± 12.8 versus 47 hemorrhagic strokes, aged 50.9 years ± 12.2 years (p = 0.000). Presence of neuroimaging features of raised ICP was associated with elevated admission ONSD (β 1.253 (95 % CI: 0.229-2.277), p = 0.017). A higheradmission ONSD was an independent predictor of lowerGlasgow Coma scorein individuals with ischemic strokes (adjusted β -8.602 (95 % CI -16.077- -1.127), p = 0.025) but not hemorrhagic strokes. For individuals with hemorrhagic strokes, higher admission ONSD was an independent predictor of month 1 mRS (β 5.363 (95 % CI 0.804-9.922), p = 0.022) and month 2 mRS (β 10.546 (95 % CI 0.595-20.498), p = 0.039). However, for ischemic strokes, elevatedadmissionONSD was an independent predictor of mRS at month 2 (β 16.501 (95 % CI 5.202-27.800), p = 0.005) and month 3(β 16.643 (95 % CI 3.666-29.620), p = 0.014).

CONCLUSION

Sonographically determined ONSD is an independent predictor of stroke severity and functional outcomes in this Ghanaian cohort. Randomized control trials exploring the potential role of ONSD in guiding clinical decisions during acute stroke management are warranted, especially in resource-limited settings.

Effect on the size of optic nerve sheath diameter in patients undergoing surgeries under spinal anaesthesia versus peripheral nerve blocks - A randomised controlled study

Background and Aims

Post-dural puncture headache is a complication of spinal anaesthesia, theorised to be triggered by a lowering in intracranial pressure due to the cerebrospinal fluid leak through the dural puncture. Our objective was to evaluate whether there is a decrease in optic nerve sheath diameter (ONSD) with a reduction in intracranial pressure after spinal anaesthesia.

Methods

Patients were randomised by a computer-generated randomisation table to receive spinal anaesthesia (Group S) or peripheral nerve block (Group P) after assessing their eligibility for the anaesthesia procedure as per the protocol. The ONSD was measured in the preoperative period and again at 4 h and 24 h after the anaesthetic, both in the supine and sitting positions, along with haemodynamic parameters. Continuous variables such as age, height, weight, mean arterial pressures, and ONSD were expressed as mean [standard deviation (SD)] [95% confidence interval (CI)] and compared using the student's t-test. Repeated measure ANOVA and Bonferroni were used to compare intra-group parameters.

Results

The mean decrease in the ONSD from a baseline mean of 3.95 (SD: 0.17) (95%CI: 3.87, 4.02) to 3.89 (SD: 0.26) (95%CI: 3.78, 4.007) mm at 4 h and 3.94 (SD: 0.12) (95%CI: 3.89, 4.0) mm at 24 h after spinal anaesthesia was statistically significant. The changes in the ONSD measurements in Group P were not statistically significant. Headache was not reported at 24 h or in the follow-up at postoperative day 5.

Conclusion

Measurement of ONSD is an easy, economical method for identifying decreased intracranial pressure after spinal anaesthesia. Further research could identify cut-off values to prognosticate PDPH in high-risk individuals.

From Cadavers to Soundwaves: The Evolution of Autopsy in Medical Diagnosis and the Rise of Point-of-Care Ultrasound

This article aims to explore how closely point-of-care ultrasound (POCUS) aligns with final diagnoses and whether it could serve as a modern macroscopic alternative to autopsy. To address this question, a comprehensive literature review was conducted, examining the historical decline of autopsy, the influence of evidence-based medicine on diagnostic confidence, and the potential of POCUS to enhance clinical decision-making. POCUS has demonstrated high accuracy in detecting major pathological conditions, particularly in critical care and emergency settings, and its use has now extended to primary care. However, its role as a "bedside autopsy" remains debated. While POCUS provides real-time, macroscopic assessment, it does not allow for histopathological analysis, limiting its ability to determine the definitive cause of death. Despite these limitations, integrating POCUS into clinical workflows may help reduce diagnostic discrepancies and serve as a practical alternative in settings where traditional autopsy is unavailable or underutilized. Although POCUS cannot fully replace traditional autopsy, it offers a valuable tool for macroscopic postmortem assessment and may help bridge some of the diagnostic gaps created by declining autopsy rates. Incorporating POCUS findings into clinicopathological conferences and medical education could enhance diagnostic accuracy and reinforce evidence-based clinical practice. Further research is needed to refine its applications in postmortem diagnostics and establish its optimal role in forensic and hospital-based settings.

The Brussels consensus for non-invasive ICP monitoring when invasive systems are not available in the care of TBI patients (the B-ICONIC consensus, recommendations, and management algorithm)

BACKGROUND

Invasive systems are commonly used for monitoring intracranial pressure (ICP) in traumatic brain injury (TBI) and are considered the gold standard. The availability of invasive ICP monitoring is heterogeneous, and in low- and middle-income settings, these systems are not routinely employed due to high cost or limited accessibility. The aim of this consensus was to develop recommendations to guide monitoring and ICP-driven therapies in TBI using non-invasive ICP (nICP) systems.

METHODS

A panel of 41 experts, that regularly use nICP systems for guiding TBI care, was established. Three scoping and four systematic reviews with meta-analysis were performed summarizing the current global-literature evidence. A modified Delphi method was applied for the development of recommendations. An in-person meeting with group discussions and voting was conducted. Strong recommendations were defined for an agreement of at least 85%. Weak recommendations were defined for an agreement of 75-85%.

RESULTS

A total of 34 recommendations were provided (32 Strong, 2 Weak) divided into three domains: general consideration for nICP use, management of ICP using nICP methods and thresholds of nICP tools for escalating/de-escalating treatment. We developed four clinical algorithms for escalating treatment and heatmaps for de-escalating treatment.

CONCLUSIONS

Using a mixed-method approach involving literature review and an in-person consensus by experts, a set of recommendations designed to assist clinicians managing TBI patients using nICP systems plus clinical assessment, in the presence or absence of brain imaging, were built. Further clinical studies are required to validate the potential use of these recommendations in the daily clinical practice.

Optic Nerve Sheath Measurement on Ultrasound: A Novel Diagnostic Test for Giant Cell Arteritis

OBJECTIVE

Optic nerve sheath enhancement on magnetic resonance imaging has been reported in patients with giant cell arteritis (GCA), with or without visual manifestations. Whether similar findings can be documented on ultrasound is unknown. Optic nerve ultrasound is a point-of-care, easy to learn, rapid, and noninvasive technique. This study aims to investigate whether optic nerve sheath diameter (ONSD) measured on ultrasound is useful in the diagnosis of active, new-onset GCA.

METHODS

A single-center, diagnostic accuracy study was performed from June to November 2022 on consecutive eligible patients referred for suspected GCA. Optic nerve ultrasound was performed on both eyes. The ONSD (includes the optic nerve and its sheath) and optic nerve diameter (OND) were measured 3 mm behind the ocular globe. The presence or absence of GCA was confirmed clinically 6 months later. Multivariable linear regression, adjusting for age and sex, was used to determine the association between optic nerve ultrasound measures and final GCA diagnosis.

RESULTS

Thirty participants were enrolled, including nine participants with a final diagnosis of GCA. Mean ± SD ONSD was 5.98 ± 1.17 mm in patients with GCA and 4.02 ± 0.99 mm in patients without GCA. Mean ONSD was greater by 1.26 mm in patients with GCA (95% confidence interval 0.30-2.21 mm, P = 0.01) compared with those without GCA, adjusting for age and sex. Mean ± SD OND was 2.97 ± 0.46 mm in patients with GCA and 2.47 ± 0.58 mm in patients without GCA. There was no evidence of an association between GCA diagnosis and OND.

CONCLUSION

Patients with GCA had a significantly greater ONSD on ultrasound than patients without GCA. Optic nerve ultrasound may represent a novel, rapid, bedside diagnostic test for GCA. A large prospective study is required to confirm these findings and evaluate whether ONSD can be used as a disease activity biomarker in GCA.

Effect of Neck Rotation With Flexion on Ultrasonographic Optic Nerve Sheath Diameter in Patients Undergoing Elective Craniotomy

Background Extreme neck positioning to facilitate craniotomy can result in impaired venous drainage from the brain and a subsequent rise in increased intracranial pressure (ICP). The effects of varied neck positioning intraoperatively on ultrasonographic optic nerve sheath diameter (USG-ONSD) are still unexplored. This study aims to quantify the angle of neck rotation and flexion that can cause a significant increase in USG-ONSD in patients undergoing elective craniotomy. Methods A total of 100 patients were recruited in this non-randomized study and equally divided into two groups. In one group, patients with neck rotation ≤30 degrees and in another group, patients with neck rotation >30 degrees with varying degrees of neck flexion were included. The average of three USG-ONSD measurements in both eyes was obtained and compared in both groups at baseline, after positioning, and at the end of the surgery after making the neck neutral. Results The results of 100 recruited patients were analyzed. All the patients had neck flexion in the range of 40° to 45°, whereas the neck rotation ranged from 10° to 45°. The USG-ONSD of both eyes changed significantly from baseline to post-positioning time point in patients with neck rotation >30° (right eye p=0.038, left eye p=0.04) when compared to neck rotation ≤30°. There was no significant change in USG-ONSD from baseline to the postoperative time point after making the neck neutral (right eye p=0.245, left eye p=0.850) in both groups. Conclusions This study demonstrates that USG-ONSD, a surrogate measure of ICP, increased significantly after neck flexion with rotation >30° in neurosurgical patients. However, USG-ONSD becomes comparable to baseline after putting the patient's neck in a neutral position after surgery.

A Novel Method for Prediction of Raised Intracranial Pressure Through Automated ONSD and ETD Ratio Measurement From Ocular Ultrasound

The paper presents a novel framework for the prediction of the raised Intracranial Pressure (ICP) from ocular ultrasound images of traumatic patients through automated measurement of Optic Nerve Sheath Diameter (ONSD) and Eyeball Transverse Diameter (ETD). The measurement of ONSD using an ocular ultrasound scan is non-invasive and correlates with the raised ICP. However, the existing studies suggested that the ONSD value alone is insufficient to indicate the ICP condition. Since the ONSD and ETD values may vary among patients belonging to different ethnicity/origins, there is a need for developing an independent global biomarker for predicting raised ICP condition. The proposed work develops an automated framework for the prediction of raised ICP by developing algorithms for the automated measurement of ONSD and ETD values. It is established that the ONSD and ETD ratio (OER) is a potential biomarker for ICP prediction independent of ethnicity and origin. The OER threshold value is determined by performing statistical analysis on the data of 57 trauma patients obtained from the AIIMS, New Delhi. The automated OER is computed and compared with the conventionally measured ICP by determining suitable correlation coefficients. It is found that there is a significant correlation of OER with ICP (r = .81, p ≤ .01), whereas the correlation of ONSD alone with ICP is relatively less (r = .69, p = .004). These correlation values indicate that OER is a better parameter for the prediction of ICP. Further, the threshold value of OER is found to be 0.21 for predicting raised ICP conditions in this study. Scatter plot and Heat map analysis of OER and corresponding ICP reveal that patients with OER ≥ 0.21, have ICP in the range of 17 to 35 mm Hg. In the data available for this research work, OER ranges from 0.17 to 0.35.