Effect of different positive end expiratory pressure levels on optic nerve sheath diameter in patients with or without midline shift who are undergoing supratentorial craniotomy.

PURPOSE: In general, high levels of PEEP application is avoided in patients undergoing craniotomy to prevent a rise in ICP. But that approach would increase the risk of secondary brain injury especially in hypoxemic patients. Because the optic nerve sheath is distensible, a rise in ICP is associated with an increase in the optic nerve sheath diameter (ONSD). The cutoff value for elevated ICP assessed by ONSD is between 5.6 and 6.3 mm. We aimed to evaluate the effect of different PEEP levels on ONSD and compare the effect of different PEEP levels in patients with and without intracranial midline shift. METHODS: This prospective observational study was performed in aged 18-70 years, ASA I-III, 80 patients who were undergoing supratentorial craniotomy. After the induction of general anesthesia, the ONSD's were measured by the linear transducer from 3 mm below the globe at PEEP values of 0-5-10 cmH2O. The ONSD were compered between patients with (n = 7) and without midline shift (n = 73) at different PEEP values. RESULTS: The increases in ONSD due to increase in PEEP level were determined (p < 0.001). No difference was found in the comparison of ONSD between patients with and without midline shift in different PEEP values (p = 0.329, 0.535, 0.410 respectively). But application of 10 cmH2O PEEP in patients with a midline shift increased the mean ONSD value to 5.73 mm. This value is roughly 0.1 mm higher than the lower limit of the ONSD cutoff value. CONCLUSIONS: The ONSD in adults undergoing supratentorial tumor craniotomy, PEEP values up to 5 cmH2O, appears not to be associated with an ICP increase; however, the ONSD exceeded the cutoff for increased ICP when a PEEP of 10 cmH2O was applied in patients with midline shift.

Longitudinal imaging of vitreal hyperreflective foci in mice with acute optic nerve damage using visible-light optical coherence tomography.

Hyperreflective foci (HRFs) appear in optical coherence tomography (OCT) images of the retina and vitreous of patients with various ocular diseases. HRFs are hypothesized to be immune cells that appear in response to ischemia or tissue damage. To accurately identify HRFs and establish their clinical significance, it is necessary to replicate the detection of similar patterns in vivo in a small animal model. We combined visible-light OCT with temporal speckle averaging (TSA) to visualize and track vitreal HRFs (VHRFs) densities for three days after an optic nerve crush (ONC) injury. Resulting vis-OCT images revealed that VHRF density significantly increased approximately 10-fold at 12 h after ONC and returned to baseline three days after ONC. Additional immunohistochemistry results confirmed these VHRFs as inflammatory cells induced from optic nerve damage.

Improved optic nerve visualization and treatment planning through a dedicated optic nerve MRI protocol.

OBJECTIVE: This study describes an innovative optic nerve MRI protocol for better delineating optic nerve anatomy from neighboring pathology. METHODS: Twenty-two patients undergoing MRI examination of the optic nerve with the dedicated protocol were identified and included for analysis of imaging, surgical strategy, and outcomes. T2-weighted and fat-suppressed T1-weighted gadolinium-enhanced images were acquired perpendicular and parallel to the long axis of the optic nerve to achieve en face and in-line views along the course of the nerve. RESULTS: Dedicated optic nerve MRI sequences provided enhanced visualization of the nerve, CSF within the nerve sheath, and local pathology. Optic nerve sequences leveraged the "CSF ring" within the optic nerve sheath to create contrast between pathology and normal tissue, highlighting areas of compression. Tumor was readily tracked along the longitudinal axis of the nerve by images obtained parallel to the nerve. The findings augmented treatment planning. CONCLUSIONS: The authors present a dedicated optic nerve MRI protocol that is simple to use and affords improved cross-sectional and longitudinal visualization of the nerve, surrounding CSF, and pathology. This improved visualization enhances radiological evaluation and treatment planning for optic nerve lesions.

Endoscopic endonasal decompression of the optic nerve in the setting of compressive lesions: how I do it.

BACKGROUND: Many lesions in the anterior skull base may compress the optic nerve (ON), leading to vision loss, and even irreversible blindness. Although decompression of the optic nerve has traditionally been achieved transcranially, the endoscopic endonasal approach (EEA) is gaining traction as a minimally invasive approach recently. METHOD: We describe the key steps of an EEA ON decompression. The relevant surgical anatomy with illustration is described. Additionally, a video detailing our technique and instruments on an illustrative case is provided. CONCLUSION: Endoscopic endonasal approach ON decompression with a straight feather blade is a feasible, minimally invasive procedure to decompress the ON in the setting of anterior skull base mass lesions.

Optic nerve sheath diameter measurements to predict delayed neurological sequelae after carbon monoxide poisoning.

OBJECTIVES: Delayed neurological sequelae are a major complication of carbon monoxide poisoning. However, today there is still no objective screening tool for predicting delayed neurological sequelae in patients with carbon monoxide poisoning. The present study aimed to assess the usefulness of optic nerve sheath diameter measurements in predicting delayed neurological sequelae after carbon monoxide poisoning. METHODS: In this retrospective study, patients with a diagnosis of carbon monoxide poisoning in the emergency department from 2010 to 2021 were included in the study. Right and left optic nerve sheath diameters were calculated based on cranial computed tomography scans, and the presence of delayed neurological sequelae was evaluated. RESULTS: The mean (± standard deviation) optic nerve sheath diameter in patients who developed delayed neurological sequelae was statistically significantly greater on both the right and left compared to patients who did not develop delayed neurological sequelae (right; 5.02 ± 0.06 mm versus 4.89 ± 0.07 mm, P < 0.001; left; 5.03 ± 0.09 mm versus 4.85 ± 0.10 mm, P < 0.001). A multivariate linear regression analysis revealed that carboxyhemoglobin and both right and left optic nerve sheath diameter were the factors associated with the delayed neurological sequelae. DISCUSSION: The present study revealed that optic nerve sheath diameter measurements may be a useful screening tool to predict delayed neurological sequelae after carbon monoxide poisoning. The ability to predict a poor neurological prognosis in carbon monoxide poisoning is important for initiating early rehabilitation interventions and make help future trials. Limitations of this study include that normal optic nerve sheath diameters are not well established, and that not every patient underwent computed tomography. CONCLUSIONS: Optic nerve sheath diameters measurements may be a helpful screening tool for predicting delayed neurological sequelae after carbon monoxide poisoning.

Partial regression of peripapillary myelinated nerve fibers after non-arteritic anterior ischemic optic neuropathy.

A 71-year-old woman presented a non-arteritic anterior ischemic optic neuropathy in an optic nerve with previously registered superonasal peripapillary myelinated nerve fibers. Her past medical history was significant for controlled systemic hypertension, hyperlipidemia, and diabetes mellitus. The physiologic cup was absent in both optic discs. Non-arteritic anterior ischemic optic neuropathy mainly affected the temporal and inferior sectors of the peripapillary retinal nerve fiber layer, as could be demonstrated by retinal nerve fiber layer optical coherence tomography and optic disc optical coherence tomography angiography. Unlike other published reports, just a slight regression of the myelinated nerve fibers was observed after 1 year of follow-up. This occurred because ischemia mainly affected the temporal and inferior peripapillary sectors, whereas myelinated nerve fibers were superonasal to the optic disc.

Clinical and paraclinical characteristics of optic neuritis in the context of the McDonald criteria 2017.

Optic neuritis is often an initial symptom in multiple sclerosis (MS) or clinically isolated syndrome (CIS), yet comprehensive studies using the 2017 McDonald criteria for MS are scarce. Patient records from our academic centre (2010-2018) were reviewed. Using the 2017 McDonald criteria, three groups were formed: MS optic neuritis (optic neuritis with confirmed MS), CIS optic neuritis (optic neuritis without confirmed MS) and suspected optic neuritis (sON). We compared clinical and paraclinical findings among the groups to identify predictors for CIS- or MS-optic neuritis. The study included 129 MS, 108 CIS, and 44 sON cases. The combination of visual impairment, dyschromatopsia, and retrobulbar pain was observed in 47% of MS patients, 42% of CIS patients, and 30% of sON patients. Dyschromatopsia was the strongest indicator of MS or CIS diagnosis in the backward regression model. 56% of MS patients had relative afferent pupillary defect, 61% optic nerve anomalies within magnetic resonance imaging, and 81% abnormal visual evoked potentials. Our results emphasize the challenges in diagnosing optic neuritis, as not all patients with objectively diagnosed MS exhibit the triad of typical symptoms. To address potentially missing clinical features, incorporating additional paraclinical findings is proposed.

Investigation of optic nerve function in Behçet's patients with optic disc hyperfluorescence in fundus fluorescein angiography.

PURPOSE: The aim was to investigate the changes in optic nerve function that may help in the diagnosis of subclinical optic nerve involvement in patients with Behçet's disease (BD) and isolated optic disc (OD) hyperfluorescence in fluorescein angiography (FA). MATERIALS AND METHODS: Three groups were formed; BD patients with isolated OD hyperfluorescence in FA, BD patients without ocular involvement (normal FA) and control group. A total of 88 eyes of 45 patients were included. The groups were compared in terms of OCT-RNFL, contrast sensitivity and VEP latency. RESULTS: When the OCT-RNFL values were compared, there was a significant difference between the control group and Behçet's patients with normal FA. Contrast sensitivity values differed significantly among the groups, and the lowest mean contrast sensitivity was observed in the group with OD hyperfluorescence (p < 0.05). CONCLUSION: As far as we know, this is the first publication that investigates optic nerve function in BD patients with isolated OD hyperfluorescence in FA. Assessment with FA of asymptomatic BD patients with visual complaints and low contrast sensitivity may be helpful at early detection of inflammatory optic neuropathy by close follow-up in patients with OD hyperfluorescence.

Assessment of Optic Nerve Sheath Diameter in Patients Undergoing Endoscopic Retrograde Cholangiopancreatography: A Prospective, Randomized, Controlled Double-Blinded Comparison of Propofol and Ketofol Anesthesia.

BACKGROUND: ERCP is an endoscopic procedure for the diagnosis and treatment of biliopancreatic system diseases. An increase in intra-abdominal pressure due to the insufflation of air to the intestinal lumen may be transmitted to ICP through the course of ERCP. In this prospective, randomized, controlled double-blinded study, we aimed to assess the ICP change using ultrasonography measurement of ONSD in patients undergoing ERCP comparing the effects of propofol and ketofol anesthesia. MATERIAL/METHODS: One hundred and nine patients undergoing ERCP under propofol or ketofol anesthesia were enrolled in the study. Ultrasonography measurement of ONSD was performed before (T0) and immediately after induction of anesthesia (T1), during sphincterotomy (T2), at the end of procedure (T3), and after the patient is fully awake (T4). RESULTS: Comparison of ONSD values and ONSD alteration between groups showed no statistically significant difference (P > 0.05). Both groups showed significantly greater changes from T0 to T2 compared with values from T0 to T1, T3, and T4, respectively (P = 0,000). T0 to T3 alteration was also significantly greater than T0 to T1 and T4 change in both groups (P = 0,000). CONCLUSIONS: ERCP procedure increases intracranial pressure most prominently during sphincterotomy both under propofol or ketofol anesthesia. Further studies are needed to investigate the impact of this phenomenon on adverse clinical outcomes.

Measurement of optic nerve sheath diameter on computed tomography for the differentiation of transient ischemic attacks.

OBJECTIVE: The objective of this study was to investigate whether the measurement of mean optic nerve sheath diameter in patients with transient ischemic attack could be used to distinguish between control groups, the acute ischemic stroke group, and subgroups within the acute ischemic stroke category. METHODS: Retrospectively, the mean optic nerve sheath diameters of patients aged 18 years and older belonging to control, transient ischemic attack, acute ischemic stroke, and subgroups within the acute ischemic stroke category were measured with initial computed tomography conducted in the emergency department. RESULTS: Out of the 773 patients included in the study, 318 (41.1%) were in the control group, 77 (10%) had transient ischemic attack, and 378 (49%) were categorized as stroke patients. The average mean optic nerve sheath diameter was significantly higher in both the stroke and transient ischemic attack groups compared with the control group (p<0.001 for both comparisons). Furthermore, the mean optic nerve sheath diameter in the stroke subgroups was significantly higher than in both the transient ischemic attack and control groups (p<0.001 for all comparisons). In transient ischemic attack patients, the mean optic nerve sheath diameter showed a significant ability to predict transient ischemic attack (AUC=0.913, p<0.001), with a calculated optimal cutoff value of 4.72, sensitivity of 94.8%, and specificity of 73.9%. CONCLUSION: The mean optic nerve sheath diameter of patients in the transient ischemic attack group was lower compared with those in the stroke subgroups but higher compared with the control group.

Uncommon optic nerve arteriovenous malformation: A case report and literature review.

BACKGROUND: The rapid progress in imaging techniques has led to an upsurge in the incidence of optic nerve arteriovenous malformations (AVMs) diagnoses. Nevertheless, a comprehensive integration addressing their diagnostic and therapeutic attributes remains elusive. CASE DESCRIPTION AND THE LITERATURE REVIEW: In this report, we present a case of optic nerve AVM in a patient who initially presented with progressive visual deterioration in the right eye. An orbital magnetic resonance imaging (MRI) scan revealed an abnormal signal intensity within the optic nerve region of the affected eye, and Computed Tomography Angiography (CTA) demonstrated the presence of a vascular malformation involving the optic nerve in the right eye. The diagnosis of optic nerve AVMs relies on Digital Subtraction Angiography (DSA). Given the challenging nature of surgical intervention, the patient opted for conservative management. Upon subsequent evaluation, no significant changes were observed in the patient's right visual acuity and visual field. Furthermore, a comprehensive literature review was conducted. CONCLUSIONS: In summary, the principal clinical presentations associated with optic nerve AVMs include a deterioration in both visual acuity and visual field. Angiography serves as the preferred diagnostic modality to confirm optic nerve AVMs. Microsurgical intervention or interventional embolization techniques may offer effective management approaches to address this complex condition.

Visualization of Optic Nerve Structural Patterns in Papilledema Using Deep Learning Variational Autoencoders.

Purpose: To visualize and quantify structural patterns of optic nerve edema encountered in papilledema during treatment. Methods: A novel bi-channel deep-learning variational autoencoder (biVAE) model was trained using 1498 optical coherence tomography (OCT) scans of 125 subjects over time from the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) and 791 OCT scans of 96 control subjects from the University of Iowa. An independent test dataset of 70 eyes from 70 papilledema subjects was used to evaluate the ability of the biVAE model to quantify and reconstruct the papilledema spatial patterns from input OCT scans using only two variables. Results: The montage color maps of the retinal nerve fiber layer (RNFL) and total retinal thickness (TRT) produced by the biVAE model provided an organized visualization of the variety of morphological patterns of optic disc edema (including differing patterns at similar thickness levels). Treatment effects of acetazolamide versus placebo in the IIHTT were also demonstrated in the latent space. In image reconstruction, the mean signed peripapillary retinal nerve fiber layer thickness (pRNFLT) difference ± SD was -0.12 ± 17.34 µm, the absolute pRNFLT difference was 13.68 ± 10.65 µm, and the RNFL structural similarity index reached 0.91 ± 0.05. Conclusions: A wide array of structural patterns of papilledema, integrating the magnitude of disc edema with underlying disc and retinal morphology, can be quantified by just two latent variables. Translational Relevance: A biVAE model encodes structural patterns, as well as the correlation between channels, and may be applied to visualize individuals or populations with papilledema throughout treatment.

Optic nerve topography in multiple sclerosis diagnostic criteria: Existing knowledge and future directions.

Current diagnostic criteria for multiple sclerosis (MS) do not consider the optic nerve as a typical topography for establishing the diagnosis. Recent studies have proved the utility of optic nerve magnetic resonance imaging, optical coherence tomography and visual evoked potentials in detecting optic nerve lesions during the early stages of MS. In addition, emerging evidence supports the inclusion of optic nerve topography as a fifth region to fulfil the dissemination in space criteria. Anticipating a modification in the McDonald criteria, it is crucial for neurologists to familiarize with the diagnostic properties of each test in detecting optic nerve lesions and understand how to incorporate them into the MS diagnostic process. Therefore, the objective of this article is to review the existing evidence supporting the use of these tests in the diagnostic process of MS and provide a practical algorithm that can serve as a valuable guide for clinical practice.

Ultrasonic optic nerve sheath diameter can be used as a diagnostic measure after accidental dural puncture during cesarean section: a case report.

BACKGROUND: Parturients are prone to postdural puncture headache (PDPH) after epidural puncture. Cerebral venous sinus thrombosis (CVST) is a fatal complication of PDPH. The main symptom of both is headache, however, the mechanism is not similar. For persistent PDPH, early differential diagnosis from CVST is essential. Optic nerve sheath diameter (ONSD) measurements can be used to identify changes in intracranial pressure as an auxiliary tool to distinguish the cause of headache. CASE PRESENTATION: The dura of a 32-year-old woman undergoing cesarean section was accidentally penetrated while administering epidural anesthesia, and the patient developed PDPH the subsequent day. The patient refused epidural blood patch (EBP) treatment and was discharged after conservative treatment. Fourteen days post-discharge, she was readmitted for a seizure. Magnetic resonance imaging (MRI) and Magnetic resonance angiography (MRA) indicated low cranial pressure syndrome and superior sagittal sinus thrombosis with acute infarction. The next morning, the EBP was performed with 15 ml autologous blood. Subsequently, the headache symptoms decreased during the day and worsened at night. ONSD measurement suggested dilation of the optic nerve sheath, and subsequently, the patient showed intracranial hypertension with papilledema. After dehydration and anticoagulant treatment, the patient's symptoms were relieved and she was discharged from the hospital 49 days later. CONCLUSIONS: Headache is the main symptom of PDPH and cerebral venous thrombosis, which are difficult to distinguish. ONSD measurement may help to estimate the intracranial pressure, and early measurement may be helpful for women with PDPH to avoid serious complications, such as CVST.

Adding the Optic Nerve in Multiple Sclerosis Diagnostic Criteria: A Longitudinal, Prospective, Multicenter Study

BACKGROUND AND OBJECTIVES: The optic nerve is not one of the areas of the CNS that can be used to demonstrate dissemination in space (DIS) within the 2017 McDonald criteria for the diagnosis of multiple sclerosis (MS). Objectives were (1) to assess whether optic nerve-MRI (ON-MRI), optical coherence tomography (OCT), and visual evoked potentials (VEP) detect optic nerve involvement in clinically isolated syndrome (CIS) and (2) to evaluate the contribution of the optic nerve topography to the current diagnostic criteria in a prospective, multicenter cohort. METHODS: MAGNIMS centers were invited to provide prospective data on patients with CIS who underwent a visual assessment with at least 2 of 3 investigations (ON-MRI, OCT, or VEP) within 6 months of onset. Modified DIS criteria were constructed by adding the optic nerve topography, defined by each investigation separately and any combination of them, as the fifth area of the CNS. A risk assessment analysis and the performance of the different DIS criteria were analyzed using the diagnosis of MS according to the 2017 McDonald criteria as the primary outcome and new T2 lesions and/or a second relapse as the secondary outcome. RESULTS: We included 157 patients with CIS from 5 MAGNIMS centers; 60/157 (38.2%) patients presented with optic neuritis. Optic nerve involvement on ON-MRI was found in 40.2% patients at study entry and in 72.5% of those with optic neuritis.At follow-up (mean 27.9 months, SD 14.5), 111/157 patients (70.7%) were diagnosed with MS according to the 2017 McDonald criteria. Fulfilling either 2017 DIS or any modified DIS criteria conferred a similar high risk for reaching primary and secondary outcomes. The modified DIS criteria had higher sensitivity (92.5% [with ON-MRI] vs 88.2%), but slightly lower specificity (80.0% [with GCIPL IEA ≥4 µm] vs 82.2%), with overall similar accuracy (86.6% [with ON-MRI] vs 86.5%) than 2017 DIS criteria. Consistent results were found for secondary outcomes. DISCUSSION: In patients with CIS, the presence of an optic nerve lesion defined by MRI, OCT, or VEP is frequently detected, especially when presenting with optic neuritis. Our study supports the addition of the optic nerve as a fifth topography to fulfill DIS criteria.