Asymmetric papilledema in idiopathic intracranial hypertension

Imaging the brain: diagnosis aided by structural features on neuroimaging studies

The use of neuroimaging allows the ophthalmologist to identify structural lesions in the orbit or along the neuroaxis that allow for more accurate diagnosis and treatment of patients with neuro-ophthalmic diseases. The primary imaging tools include computed tomography (CT) and magnetic resonance imaging (MRI), both of which can be used to evaluate the brain, spinal cord and canal, and orbits. Neurovascular structures, both arterial and venous, also can be imaged in high resolution with modern CT and MR angiography and CT and MR venography. In many cases, invasive procedures such as catheter angiography can be avoided with these studies, and angiography is often reserved for confirmation of vascular lesions combined with endovascular treatment. In this article, we illustrate how the evaluation of patients presenting with neuro-ophthalmic diseases involving the afferent and efferent visual pathways can be optimized with the use of appropriate diagnostic imaging studies. The complementary value of ophthalmic imaging is also demonstrated, and the advantages and disadvantages of both CT and MRI as well as their use in longitudinal patient follow up is demonstrated.

Application of novel non-invasive ophthalmic imaging to visualize peripapillary wrinkles, retinal folds and peripapillary hyperreflective ovoid mass-like structures associated with elevated intracranial pressure

Background

Elevated intracranial pressure (ICP) is a serious and potentially life-threatening condition, for which clinically useful non-invasive measures have been elusive, in some cases due to their inadequate sensitivity and specificity. Our aim was to evaluate novel non-invasive ophthalmic imaging of selected pathological features seen in elevated ICP, namely peripapillary hyperreflective ovoid mass-like structures (PHOMS), peripapillary wrinkles (PPW) and retinal folds (RF) as potential biomarkers of elevated ICP.

Methods

This single-center pilot study included subjects with untreated or incompletely treated high ICP. The retinas of these subjects were evaluated with averaged en-face optical coherence tomography (OCT), OCT retinal cross-sections (OCT B-scans), adaptive optics scanning light ophthalmoscopy (AOSLO), and fundus photos.

Results

Seven subjects were included in the study. 6 subjects with high ICP (5 idiopathic intracranial hypertension, 1 medication induced, 30.8 ± 8.6 years, 75% female, 5 with papilledema) and 1 control (20-25 years) were included. PHOMS, PPW and RF were present in all subjects with papilledema, but neither in the high ICP subject without papilledema nor in the control subject. Averaged en-face OCT scans and AOSLO were more sensitive for PPW and RF than OCT B-scans and commercial fundus photos.

Conclusion

PPW, RF and PHOMS volume have potential as non-invasive biomarkers of ICP. Novel imaging modalities may improve sensitivity. However, lack of automated image acquisition and processing limits current widespread adoption in clinical settings. Further research is needed to validate these structures as biomarkers for elevated ICP and improve clinical utility.

Case report: Unilateral papilledema in a dog with a large suprasellar mass and suspected intracranial hypertension: insights from funduscopy, optical coherence tomography, and magnetic resonance imaging

A spayed, 8-year-old female Poodle, weighing 5.7 kg, was presented with the chief complaint of vision impairment. Vision assessment, including pupillary light reflexes, menace response, dazzle reflex, and maze navigation in photopic and scotopic circumstances, revealed a negative response in both eyes except for positive direct pupillary light reflex in the right eye and positive consensual pupillary light reflex from the right eye to the left eye. Systemic evaluation, including neurologic status, blood profile, and thoracic radiographs, did not reveal any abnormalities. Complete ophthalmic examinations, ocular ultrasonography, and electroretinography did not identify a cause of blindness. Upon funduscopy, the left eye exhibited an increased optic disk diameter, blurred optic disk borders, and loss of the physiologic pit, as well as an increase in vascular tortuosity. In the right eye, there were multifocal depigmented areas in the non-tapetal fundus and several pigmented spots surrounded by a region of dull tapetal reflection in the tapetal fundus. The optical coherence tomography revealed severe anterior deformation of the optic nerve head and Bruch's membrane in the peripapillary region of the left eye. Magnetic resonance imaging revealed an irregular, broad-based suprasellar mass, with features suggestive of intracranial hypertension, including dorsal displacement of third ventricles, a rightward shift of the falx cerebri, trans-tentorial herniation, perilesional edema, flattening/protrusion of the posterior sclera, and lager optic nerve sheath diameter in left side than right side. This is the first comprehensive report that describes unilateral papilledema in a dog with a brain tumor, using advanced ophthalmic and neuro-imaging modalities.

Idiopathic intracranial hypertension in Omani adults: A tertiary center experience

BACKGROUND

To evaluate the clinical profile, risk factors, and ophthalmic diagnostic and monitoring tools in Omani patients with idiopathic intracranial hypertension (IIH) using optical coherence tomography (OCT).

METHODS

A retrospective single institutional cohort study on Omani patients with a fulfilled diagnosis of IIH from January 1, 2014, to January 1, 2020, was conducted. The data obtained from the neuro-ophthalmic clinic contained age of onset of the disease, gender of patients, body mass index (BMI), presence of other associated conditions, and medication use.

RESULTS

Our study group comprised 21 patients with IIH with an annual incidence rate of 2.8 per 100,000 population. Female-to-male ratio was 9.5:1 with a mean age of 27.24 ± 7.1. Headaches appeared to be the most prevalent symptom in 21 (100%) patients, followed by transient obscuration of vision in 9 (42.9%) patients and diplopia in 3 (14.3%) patients, and the least common symptom was pulsatile tinnitus in 2 (9.5%) patients. Increased BMI was seen in 19 (90.5%) patients and noted to be the most prevalent predisposing factor among our study group. The use of oral contraceptive pills was documented in 4 (19%) patients and 1 (4.8%) patient was noted to have polycystic ovary syndrome. All patients (100%) had a best-corrected visual acuity of 1.0 in both eyes pre- and postrecovery and 7 (33.3%) patients had an enlarged blind spot on visual field testing. All patients had papilledema on presentation and an average of 14.1 months to resolve to normal clinically and on OCT monitoring. All patients were treated with medications and only 1 (4.8%) continued to have intractable headaches that did not respond to maximum medical therapy and required surgery.

CONCLUSION

The incidence of IIH in the Omani population was found to be less than neighboring countries but comparable worldwide. OCT is considered a useful tool to confirm and document papilledema and more importantly monitor recovery.

Risk factors associated with progression from papilloedema to optic atrophy: results from a cohort of 113 patients

BACKGROUND

The aim of this study was to assess the risk factors for atrophic progression of patients with papilloedema secondary to intracranial hypertension, using optical coherence tomography parameters.

METHODS

A retrospective study was conducted at Marseille University Hospitals' Ophthalmology departments between December 2015 and December 2021. All patients with papilloedema resulting from elevated intracranial hypertension at the initial presentation were included. Ophthalmological evaluations included analysing retinal nerve fibre layer (RNFL), ganglion cell layer (GCL) and total peripapillary retinal thickness (RT).

RESULTS

The study included 222 eyes from 113 patients. The main aetiologies of intracranial hypertension were idiopathic intracranial hypertension (49/113), intracranial tumours (33/113) and cerebral venous thrombosis (15/113). The initial RNFL and RT showed significant correlations with optic atrophy. The mean RNFL was 199.63 µm in the 'no atrophy' group and 365.28 µm in the 'atrophy' group (p<0.001). Similarly, the mean RT was 483.72 µm in the 'non-atrophy' group and 796.69 µm in the 'atrophy' group (p<0.001). The presence of peripapillary haemorrhages showed a strong correlated with optic atrophy with an OR=19.12 (p<0.001). Impaired initial visual acuity was also associated with final optic atrophy with an OR=7.76 (p=0.020). Furthermore, impaired initial GCL was a major predictor of optic atrophy (OR=18.25 (p=0.021)).

CONCLUSION

Our study highlights the risk factors for optic atrophy in papilloedema, aiming to facilitate the early detection of patients at a high risk of vision loss and enable more aggressive medical or surgical management.

Pediatric myelin oligodendrocyte glycoprotein antibody associated disease-Asymmetric papilledema and elevated ICP are two of the chameleons: A case report

BACKGROUND

Myelin oligodendrocyte glycoprotein antibody (MOGA) associated diseases are inflammatory immune-mediated demyelinating disorders with relapse potential involving the central nervous system. Multiple unusual clinical manifestations of those disorders were reported, making treatment decisions difficult.

CASE PRESENTATION

A healthy 12-year-old obese boy presented with headache and bilateral asymmetric papilledema. The patient had a negative medical history. His neurological and general examinations were unremarkable, his initial magnetic resonance imaging showed elevated intracranial pressure (ICP) only. A lumbar puncture revealed increased opening pressure and pleocytosis. The MOGA titer was 1:320. He needed acetazolamide and steroid therapy. After 2 months of medication, weight loss, exercise, the patient symptoms significantly improved, papilledema resolved, and visual function improved.

CONCLUSION

MOGA-associated disorders have a variety of clinical features, so a high index of suspicion is required for their diagnosis. Papilledema and an elevated ICP are 2 of the chameleons of MOGA-associated disorders. MOGA test may be useful in patients with elevated ICP and inflammatory cerebrospinal fluid profiles. An investigation of the possible association between those disorders and high ICP is warranted.

Diagnosis of Optic Disc Oedema: Fundus Features, Ocular Imaging Findings, and Artificial Intelligence

Optic disc swelling is a manifestation of a broad range of processes affecting the optic nerve head and/or the anterior segment of the optic nerve. Accurately diagnosing optic disc oedema, grading its severity, and recognising its cause, is crucial in order to treat patients in a timely manner and limit vision loss. Some ocular fundus features, in light of a patient's history and visual symptoms, may suggest a specific mechanism or aetiology of the visible disc oedema, but current criteria can at most enable an educated guess as to the most likely cause. In many cases only the clinical evolution and ancillary testing can inform the exact diagnosis. The development of ocular fundus imaging, including colour fundus photography, fluorescein angiography, optical coherence tomography, and multimodal imaging, has provided assistance in quantifying swelling, distinguishing true optic disc oedema from pseudo-optic disc oedema, and differentiating among the numerous causes of acute optic disc oedema. However, the diagnosis of disc oedema is often delayed or not made in busy emergency departments and outpatient neurology clinics. Indeed, most non-eye care providers are not able to accurately perform ocular fundus examination, increasing the risk of diagnostic errors in acute neurological settings. The implementation of non-mydriatic fundus photography and artificial intelligence technology in the diagnostic process addresses these important gaps in clinical practice.

Expanding the clinical spectrum of idiopathic intracranial hypertension

PURPOSE OF REVIEW

Idiopathic intracranial hypertension (IIH) is a disorder of raised intracranial pressure (ICP). Although the majority of patients with IIH present classically with headache and papilledema, some patients may have unusual presentations or manifestations. Recent advancements in neuroimaging have facilitated the identification of other presentations associated with IIH. This review provides an overview of the expanding clinical spectrum of IIH.

RECENT FINDINGS

Presentations of IIH that are considered unusual include highly asymmetric or unilateral papilledema, IIH without papilledema, and IIH associated with cranial nerve involvement. These presentations likely reflect differences in the way cerebrospinal fluid (CSF) pressure is transmitted intracranially. Radiological signs of intracranial hypertension are increasingly recognized in patients with IIH and provide further insights into the effects of raised ICP on intracranial structures. Osseous changes in the skull base leading to formation of meningoceles and encephaloceles have been identified in patients with IIH, spontaneous skull base CSF leak, and drug-resistant temporal lobe epilepsy, suggesting a possible association.

SUMMARY

Clinicians should be familiar with the expanding clinical spectrum of IIH and the implications for the management of these presentations.

Visual outcomes of idiopathic intracranial hypertension in a neuro-ophthalmology clinic in Jeddah, Saudi Arabia

PURPOSE

Idiopathic intracranial hypertension (IIH) is a disorder with elevated intracranial pressure more than 250 mm H2O, without evidence of meningeal inflammation, space-occupying lesion, or venous thrombosis. In this study, we aim to study the clinical profile, evaluation, management, and visual outcome in a hospital-based population of IIH cases in Jeddah.

METHODS

This is a retrospective observational cohort study that included the medical records of all patients referred to neuro-ophthalmology service for evaluation of papilledema. The medical records have been reviewed from October 2018 to February 2020 at Jeddah Eye Hospital, Saudi Arabia. A total of 51 patients presented with papilledema in the studied period. Forty-seven patients met our inclusion criteria and were included in the study.

RESULTS

The study found that the incidence rate of IIH is 16:100 of the referred cases to the neuro-ophthalmology clinic. Most of the patients were females (41, 91.2%), with a mean age of presentation of 32 ± 11 years. The most common presenting symptom was headache (40 patients, 88.8%), followed by transient visual obscuration (TVO) (20 patients, 44.4%), and reduced visual acuity (15 patients, 33.3%). All 45 patients were started on medical treatment with oral acetazolamide with four patients (8.8%) shifted to topiramate because of the lack of response or intolerance to acetazolamide while four patients (8.8%) underwent lumbar-peritoneal shunt because of inadequate control of the disease despite the treatment with medical therapy. For both eyes, the change in visual acuity across all assessment points was statistically significant. Nevertheless, there were no significant changes in the visual field findings among all of the compared assessment points.

CONCLUSION

The present study has shown that IIH-related papilledema is common in young female patients with headaches, TVOs, and reduced visual acuity. Those are the most common symptoms in our IIH population. Medical treatment and monitoring of IIH is efficient and should be considered to enhance the prognosis of IIH-related complications. In addition, the visual acuity and the visual field should be frequently monitored for these patients.

Telltale Signs of Idiopathic Intracranial Hypertension With Normal Opening Cerebrospinal Fluid Pressure

Introduction

Idiopathic Intracranial Hypertension (IIH) with normal opening cerebrospinal fluid (CSF) pressure comprises a rare IIH variant.

Case Report

We report the case of a non-obese Caucasian woman, who presented with asymmetrical papilledema, typical IIH-findings on optic nerve sonography and brain magnetic resonance imaging (MRI), and was diagnosed with IIH despite normal opening CSF pressure. Following treatment with acetazolamide, a complete remission of her symptoms was achieved, accompanied by significant improvement of the fundoscopy findings.

Conclusion

Although normal opening CSF pressure in IIH patients is rare, clinicians should be aware of this IIH variant and promptly indicate IIH treatment in patients presenting with typical clinical symptoms and neuroimaging findings suggestive of IIH.

Different Characteristics of Pre-Pubertal and Post-Pubertal Idiopathic Intracranial Hypertension: A Narrative Review

Idiopathic intracranial hypertension (IIH) affects both children and adults. There are currently no clinical trials in IIH for those who are adolescents or children. The aims of this narrative review were to characterise the differences between pre- and post-pubertal IIH and to highlight the need to be more inclusive in clinical trial planning and recruitment. A detailed search of the scientific literature was performed using the PubMed database, from inception until 30 May 2022 using keywords. This included English language papers only. The abstracts and full texts were reviewed by two independent assessors. The literature revealed that the pre-pubertal group had a more variable presentation. The presenting features in the post-pubertal paediatric group were more akin to adults with headache as the dominant feature. They were also more likely to be female and have an increased body mass index. A clear limitation of the literature was that a number of paediatric studies had variable inclusion criteria, including secondary causes of raised intracranial pressure. Pre-pubertal children do not display the same predilection towards the female sex and obesity as post-pubertal children, who have a similar phenotype to the adult cohort. Inclusion of adolescents in clinical trials should be considered given the similar phenotype to adults. There is a lack of consistency in the definition of puberty, making the IIH literature difficult to compare. Inclusion of secondary causes of raised intracranial pressure has the potential to confound the accuracy of analysis and interpretation of the results.

Idiopathic Intracranial Hypertension and Endoscopic Optic Nerve Sheath Fenestration

Idiopathic intracranial hypertension (IIH), also called as benign intracranial hypertension is a disorder, which is  considered benign in its course except its' ill effects on vision. Ocular findings in IIH such as papilledema, macular changes, retinal micro haemorrhages, cotton wool spots and tortuosity of vessels are the prominent features in funduscopy examination in these patients. Papilledema is a hallmark feature for evaluation of response to treatment. Ophthalmological rescue is a primary goal of management of idiopathic intracranial hypertension. Among the treatment options described in literature, optic nerve sheath fenestration is a minimally invasive endoscopic technique for the rescue of vision. We present this case-report, which will help ophthalmologists and the surgeons to determine the significance of the funduscopy changes after optic nerve sheath fenestration and help in decision making.

Idiopathic Intracranial Hypertension: Incidental Discovery Versus Symptomatic Presentation

BACKGROUND

We aim to compare the clinical characteristics, disease course and visual outcomes between Canadian patients with idiopathic intracranial hypertension (IIH) who were incidentally discovered and those who sought care due to symptoms of IIH.

METHODS

Retrospective chart review of consecutive IIH patients conducted at tertiary neuro-ophthalmology clinics. Patients were divided into Group 1 (incidentally discovered disease) and Group 2 (patients seeking medical care due to symptoms of intracranial hypertension).

RESULTS

One hundred eighty-six patients were included in the study; of which, 75 (40.3%; Group-1) were incidentally discovered and 111 presented due to symptoms of IIH (Group-2). There were no differences in proportion of females (P = 0.101), age (P = 0.450), body mass index (P = 0.386), MRI findings of empty or partially empty sella (P = 0.41), and sella grade (P = 0.704). Group-1 patients were less likely to have experienced headache (P = 0.001), transient visual obscurations (P < 0.001), and diplopia (P = 0.026) at presentation. Group-1 patients were less likely to receive medical (P < 0.001) and surgical (P = 0.004) treatment. There was no difference in proportion of patients who lost weight between the groups (P = 0.848). At baseline, Group-1 patients exhibited better visual acuity (P = 0.001), Humphrey mean deviation (P < 0.001) and retinal nerve fiber layer thickness (P < 0.001). Group-1 patients continued to have better visual acuity (P = 0.002) and Humphrey mean deviation (P < 0.001) at final follow-up.

CONCLUSIONS

A significant portion of IIH patients were incidentally discovered. This group exhibited a favorable prognosis and only a minority of these patients required treatment. The way in which patients enter the medical system may be a valuable way to risk stratify IIH patients.

Subarachnoid space of the optic nerve sheath and intracranial hypertension: a macroscopic, light and electron microscopic study

PURPOSE

The optic nerve (ON) is an extension of the central nervous system via the optic canal to the orbital cavity. It is accompanied by meninges whose arachnoid layer is in continuity with that of the chiasmatic cistern. This arachnoid layer is extended along the ON, delimiting a subarachnoid space (SAS) around the ON. Not all forms of chronic intracranial hypertension (ICH) present papilledema. The latter is sometimes asymmetric, unilateral, or absent. The radiological signs of optic nerve sheath (ONS) dilation, in magnetic resonance imaging, are inconsistent or difficult to interpret. The objective of this study was to analyze the anatomy, the constitution, and the variability of the SAS around the ON in its intraorbital segment to improve the understanding of the pathophysiologic mechanism of asymmetric or unilateral or absent papilledema in certain ICH.

METHODS

The study was carried out on nine cadaveric specimens. In four embalmed specimens, macroscopic analysis of the SAS of the ONS were performed, with description about density of the arachnoid trabecular meshwork in three distinct areas (bulbar segment, mid-orbital segment and the precanal segment). In three other embalmed specimens, after staining of SAS by methylene blue (MB), we performed macroscopic analysis of MB progression in the SAS of the ONS. Then, in two non-embalmed specimens, light and electron microscopy (EM) analysis were also done.

RESULTS

On the macroscopic level, after staining of SAS, we found in all cases that MB progressed on 16 mm average throughout the SAS of the ONS without reaching the papilla. In four embalmed specimens, in the SAS of the ONS, the density of the arachnoid trabecular meshwork showed inter-individual variability (100%) and intra-individual variability with bilateral variability (50%) and/or variability within the same ONS (88%). On the microscopic level, the arachnoid trabeculae of the ONS are composed of dense connective tissue. The EM perfectly depicted its composition which is mainly of collagen fibers of parallel orientation.

CONCLUSION

The variability of the SAS around the ONS probably impacts the symmetrical or asymmetrical nature of papilledema in ICH.

The odyssey of the ocular and cerebrospinal fluids during a mission to Mars: the "ocular glymphatic system" under pressure

A significant proportion of the astronauts who spend extended periods in microgravity develop ophthalmic abnormalities including optic disc edema, globe flattening, chorioretinal folds, and hyperopic refractive error shifts. A constellation of these neuro-ophthalmic findings has been termed "spaceflight-associated neuro-ocular syndrome". Understanding this syndrome is currently a top priority for NASA, especially in view of future long-duration missions (e.g., Mars missions). The recent discovery of an "ocular glymphatic system" can potentially help to unlock mechanisms underlying microgravity-induced optic disc edema. Indeed, a major paradigm shift is currently occurring in our understanding of transport of fluids and solutes through the optic nerve following the recent discovery of an optic nerve glymphatic pathway for influx of cerebrospinal fluid. In addition, the recent identification of an entirely new glymphatic pathway for efflux of ocular fluid may have profound implications for fluid dynamics in the eye. Observations pertaining to this ocular glymphatic pathway provide critical new insights into how intracranial pressure can alter basic fluid transport in the eye. We believe that these novel findings have the potential to be game changers in our understanding of the pathogenesis of optic disc edema in astronauts. In the present review, we integrate these new insights with findings on the intracranial and neuro-ophthalmologic effects of microgravity in one coherent conceptual framework. Further studies in this area of investigation could not only provide exciting new insights into the mechanisms underlying microgravity-induced optic disc edema but also offer opportunities to develop countermeasure strategies.

Cerebrospinal fluid and ophthalmic disease

PURPOSE OF REVIEW

The purpose of this review is to discuss the contemporary body of literature examining the relationship between cerebrospinal fluid (CSF) and ophthalmic disease. This review focuses on diseases that have a pathogenesis related to the translaminar pressure difference, defined as the pressure difference between the orbital subarachnoid space (OSAS) and the intraocular pressure. The diseases discussed include glaucoma, idiopathic intracranial hypertension, and spaceflight associated neuro-ocular syndrome.

RECENT FINDINGS

The relationship between cerebrospinal and ophthalmic disease has been investigated for over 100 years. Recent research provides insight into the mechanisms that dictate CSF circulation in the OSAS and how alterations in these mechanism lead to disease. This review discusses these recent findings and their relationship to major ophthalmic diseases.

SUMMARY

The recent findings provide insight into diseases that have pathogenic mechanisms that are not fully understood. This information will help physicians gain a clearer understanding of the relationship between CSF and ophthalmic disease and guide future research.

The Effects of Space Radiation and Microgravity on Ocular Structures

Long-term exposure to microgravity and space radiation leads to physiological and pathological changes in human biology. Pathological neuro-ocular changes are collected under the name spaceflight-associated neuro-ocular syndrome. This review examines studies on the effects of microgravity and space radiation on the ocular structures and their results. In addition, we discuss treatment methods and hypotheses to reduce the effects of microgravity and space radiation on biological structures.

Papilledema: A Review of the Pathophysiology, Imaging Findings, and Mimics

Increased intracranial pressure is the most common cause of papilledema. Multiple etiologies such as cerebral edema, hydrocephalus, space occupying lesions, infection, and idiopathic intracranial hypertension among others should be considered. Imaging plays a critical role in the detection of pathologies that can cause papilledema. MRI with contrast and CE-MRV, in particular, are key for the diagnosis of idiopathic intracranial hypertension. This review will focus in common and infrequent causes of papilledema, the role of imaging in patients with papilledema as well as its potential mimickers.

The use of OCT to detect signs of intracranial hypertension in patients with sagittal suture synostosis: Reference values and correlations

PURPOSE

To obtain pediatric normative reference values and determine whether optical coherence tomography (OCT) corresponds better with clinical signs of intracranial hypertension (ICH) compared to the traditional screening method fundoscopy in a large cohort of one type of single suture craniosynostosis.

METHODS

Control subjects without optic nerve diseases and isolated sagittal synostosis patients aged 3-10 years who underwent fundoscopy and OCT were included in this prospective cohort study. Normative reference values were obtained through bootstrap analysis. Main outcome was the association between peripapillary total retinal thickness (TRT) and total retinal volume (TRV) and appearance on fundoscopy. Signs and symptoms suggestive of ICH, including skull growth arrest, fingerprinting, and headache, were scored.

RESULTS

Sixty-four healthy controls and 93 isolated sagittal synostosis patients were included. Normative cut-off values for mean TRT are < 256 μm and > 504 μm and for mean TRV < 0.21 mm³ and > 0.39 mm³. TRT was increased in 16 (17%) and TRV in 15 (16%) of 93 patients, compared to only 4 patients with papilledema on fundoscopy (4%). Both parameters were associated with papilledema on fundoscopy (OR = 16.7, p = 0.02, and OR = 18.2, p = 0.01). Skull growth arrest was significantly associated with abnormal OCT parameters (OR = 13.65, p < 0.01).

CONCLUSIONS

The established cut-off points can be applied to screen for ICH in pediatrics. The present study detected abnormalities with OCT more frequent than with fundoscopy, which were associated with skull growth arrest. Therefore, a combination of OCT, fundoscopy, and skull growth arrest can improve clinical decision-making in craniosynostosis.

Unilateral Isolated Paucisymptomatic Optic Disc Edema

BACKGROUND

Unilateral isolated optic disc edema (UIODE) represents a challenging clinical presentation that frequently precipitates an extensive diagnostic work-up. Patients without an apparent diagnosis despite appropriate investigations are often categorized as having "papillophlebitis," an entity that is poorly defined in the existing literature. Our aim was to describe the characteristics of a series of patients with paucisymptomatic UIODE, determine the optimal diagnostic approach to such cases, and clarify the clinical features of presumed papillophlebitis.

METHODS

We retrospectively identified 29 patients with UIODE who were seen by neuro-ophthalmologists at a single center between 2005 and 2019. Each patient presented with isolated, unilateral disc edema that was either entirely asymptomatic or associated with minimal visual symptoms. Patients underwent a comprehensive neuro-ophthalmic evaluation and several ophthalmic and systemic investigations. Data from the initial visit and all subsequent clinical visits were collected, including patient demographics, examination findings, and details of the diagnostic work-up.

RESULTS

Our 29 patients with UIODE were found to have a variety of underlying diagnoses including unilateral papilledema due to idiopathic intracranial hypertension (10 patients), optic nerve sheath meningioma (5), incipient nonarteritic anterior ischemic neuropathy (4), vitreopapillary traction (3), orbital masses (2), a peripapillary choroidal neovascular membrane (1), and presumed papillophlebitis (4). The duration of disc edema varied considerably based on the etiology, but most patients had favorable visual outcomes.

CONCLUSIONS

A systematic approach to the evaluation of UIODE, combined with long-term follow-up, led to a definite diagnosis in a majority of patients, with only 4 patients presumed to have papillophlebitis, a diagnosis the actual existence of which remains controversial.

Clinical profile, diagnostic challenges, and outcomes in subacute/chronic cerebral sinus venous thrombosis

Purpose:

To report clinical profile, diagnostic challenges, and outcomes in cases of subacute/chronic cerebral sinus venous thrombosis (CSVT) presenting to neuro-ophthalmologists/neurologists.

Methods:

This was a multicentric, retrospective, observational study. Records of patients with neuroimaging proven subacute/chronic CSVT seen the from January 1, 2016 to March 31, 2020 were analyzed. Data collected included duration of symptoms, diagnosing physician, ophthalmological vs. focal/generalized neurological symptoms, optic disc examination, perimetry, and neuroimaging findings. Statistical analysis was performed using STATA software.

Results:

Forty-three patients with subacute (30)/chronic (13) CSVT were identified (32 males, 11 females). Median age was 37 (IQR 27–47) years. The presenting complaints were blurred vision 34 (79%), headaches in 25 (58%), vomiting 12 (28%), and diplopia 11 (26%). Eleven patients had associated sixth cranial nerve palsy. All but two patients had either disc edema/optic atrophy; four had unilateral disc edema at presentation. Ophthalmologists and neurologists diagnosed/suspected CSVT correctly in 13/29 (45%) and 11/14 (78.5%) patients, respectively. Most common initial alternate diagnosis was idiopathic intracranial hypertension in 12 (28%). Female gender, age ≤36, unilateral papilledema, not obtaining venogram at initial workup increased chances of initial alternate diagnosis. Median follow-up duration was 21 days. Average visual function remained stable in majority of patients at last follow-up. In total, 47.6% of patients had best-corrected visual acuity ≥20/30 at the final follow-up.

Conclusion:

In our series, subacute or chronic CSVT presented presented primarily with symptoms of intracranial hypertension. Unilateral papilledema, middle-aged patients, female gender, lack of focal/generalized neurological symptoms created diagnostic dilemma. Visual function remained stable in majority of patients.

Papilledema: A review of etiology, pathophysiology, diagnosis, and management

Papilledema is optic nerve head edema secondary to raised intracranial pressure (ICP). It is distinct from other causes of optic disk edema in that visual function is usually normal in the acute phase. Papilledema is caused by transmission of elevated ICP to the subarachnoid space surrounding the optic nerve that hinders axoplasmic transport within ganglion cell axons. There is ongoing controversy as to whether axoplasmic flow stasis is produced by physical compression of axons or microvascular ischemia. The most common cause of papilledema, especially in patients under the age of 50, is idiopathic intracranial hypertension (IIH); however, conditions that decrease cerebrospinal fluid (CSF) outflow by either causing CSF derangements or mechanically blocking CSF outflow channels, and rarely conditions that increase CSF production, can be the culprit. When papilledema is suspected clinically, blood pressure should be measured, and pseudopapilledema should be ruled out. Magnetic resonance imaging of the brain and orbits with venography sequences is the preferred neuroimaging modality that should be performed next to look for indirect imaging signs of increased ICP and to rule out nonidiopathic causes. Lumbar puncture with measurement of opening pressure and evaluation of CSF composition should then be performed. In patients not in a typical demographic group for IIH, further investigations should be conducted to assess for underlying causes of increased ICP. Magnetic resonance imaging of the neck and spine, magnetic resonance angiography of the brain, computed tomography of the chest, complete blood count, and creatinine testing should be able to identify most secondary causes of intracranial hypertension. Treatment for patients with papilledema should be targeted toward the underlying etiology. Most patients with IIH respond to weight loss and oral acetazolamide. For patients with decreased central acuity and constricted visual fields at presentation, as well as patients who do not respond to treatment with acetazolamide, surgical treatments should be considered, with ventriculoperitoneal shunting being the typical procedure of choice.

Three-Layered Optic Disc Hemorrhages in Idiopathic Intracranial Hypertension

Papilledema related to idiopathic intracranial hypertension (IIH) may present with optic disc hemorrhaging. The significance and characteristics of these hemorrhages still remains to be clarified. Here, we present 2 unique cases with severe unilateral optic disc hemorrhaging in all 3 retinal layers (preretinal, intraretinal, and subretinal) and a good visual outcome. A 42- and a 44-year-old woman presented with signs and symptoms of raised intracranial pressure. Visual acuity was normal and Humphrey visual field testing showed only mild vision loss with enlarged blind spots. Dilated fundus examination revealed moderate papilledema in both eyes with severe optic disc hemorrhaging in the left eye in the first patient and the right eye in the second patient. The optic disc hemorrhaging occurred in all 3 retinal layers (preretinal, intraretinal, and subretinal), and the fellow eyes had only minimal hemorrhage. All patients had normal magnetic resonance imaging/magnetic resonance venography, and lumbar punctures revealed elevated opening pressures and normal cerebrospinal fluid contents. The papilledema resolved after 4 months in both cases with medical therapy. Optic disc hemorrhaging may be severe in patients with IIH, but this does not necessarily confer a poor visual outcome. The differential diagnosis of hemorrhages in all 3 retinal layers may be expanded to include IIH.

Extent of transverse sinus stenosis does not predict visual outcomes in idiopathic intracranial hypertension

BACKGROUND

We aimed to investigate whether the degree of transverse sinus stenosis (TSS) on magnetic resonance venography (MRV) can predict visual outcomes in patients with idiopathic intracranial hypertension (IIH).

METHODS

A chart review identified IIH patients followed for at least 6 months. Mean deviation (MD) on visual field (VF) testing at initial and last follow-up visits, best corrected visual acuity (BCVA), patients' age, body mass index, and lumbar puncture opening pressure were recorded. MRV was used to grade TSS on a scale of 0-8 using the grading scheme proposed by Farb et al., whereby a lower score indicates a greater degree of stenosis. Linear regression analysis was used to test for association between above variables and MD on VF, including change in MD over time.

RESULTS

44 female patients were followed for a median of 26 months. All patients had unilateral or bilateral TSS on MRV. The median TSS score was 3/8. The median BCVA was 0.06 logMAR at baseline. The median VF MD was -3.02 dB at baseline and -1.96 dB at final follow-up. There was no significant association between the degree of TSS and either baseline MD (P-value = 0.34) or the change in MD on VF over the course of follow-up (P-value = 0.54). Baseline BCVA (P = 0.045) and baseline MD (P < 0.001) were the only significant predictors of changes in MD on VF over follow-up.

CONCLUSIONS

Baseline BCVA and MD on VF were the only significant predictors of visual outcome in IIH patients. While all patients demonstrated TSS on MRV, the degree of TSS did not correlate with visual prognosis.

Current Perspectives on Idiopathic Intracranial Hypertension without Papilloedema

The pseudotumor cerebri syndrome embraces disorders characterised by raised intracranial pressure, where the commonest symptom is headache (90%). Idiopathic intracranial hypertension without papilloedema (IIHWOP) is increasingly recognised as a source of refractory headache symptoms and resultant neurological disability. Although the majority of patients with IIHWOP are phenotypically similar to those with idiopathic intracranial hypertension (IIH), it remains uncertain as to whether IIHWOP is nosologically distinct from IIH. The incidence, prevalence, and the degree of association with the world-wide obesity epidemic is unknown. Establishing a diagnosis of IIHWOP can be challenging, as often lumbar puncture is not routinely part of the work-up for refractory headaches. There are published diagnostic criteria for IIHWOP; however, some report uncertainty regarding a pathologically acceptable cut off for a raised lumbar puncture opening pressure, which is a key criterion. The literature provides little information to help guide clinicians in managing patients with IIHWOP. Further research is therefore needed to better understand the mechanisms that drive the development of chronic daily headaches and a relationship to intracranial pressure; and indeed, whether such patients would benefit from therapies to lower intracranial pressure. The aim of this narrative review was to perform a detailed search of the scientific literature and provide a summary of historic and current opinion regarding IIHWOP.

Unilateral Papilledema in Idiopathic Intracranial Hypertension: A Case Series

Idiopathic intracranial hypertension (IIH) typically presents with bilateral papilledema; however, highly asymmetric and rare unilateral cases have been reported. We report three cases of IIH meeting modified Dandy criteria presenting with unilateral papilledema. Magnetic resonance imaging (MRI) demonstrated bilateral distention of the optic nerve sheaths and computed tomography (CT) of the orbits demonstrated a smaller diameter of the optic canal in the unaffected eye in two cases. Papilledema fully resolved in all with acetazolamide. Of postulated mechanisms, we suspect that differences in bony optic canal diameter, compliance of the lamina cribrosa, and optic nerve sheath anatomy may contribute to asymmetry.

Transverse sinus stenting for treatment of papilloedema secondary to a large brain herniation into a dural venous sinus with associated tectal plate lesion: Case report and literature review

Brain herniation into a dural venous sinus is a rare entity of unknown clinical significance without a clear relationship to raised intracranial pressure. There are yet to be detailed reports of interventional neuroradiology procedures involving sinus stenting across brain herniations. The authors of this paper present the first case of a stent placed across a large brain herniation into the transverse sinus in a patient with a tectal plate lesion and features of chronically raised intracranial pressure. This case demonstrates objective resolution of papilloedema and venous sinus pressure gradient at six months without complication.

Etiology, pathogenesis and management of idiopathic intracranial hypertension, and role of optic canal size in asymmetric papilledema: A review

Idiopathic intracranial hypertension (IIH) is characterized by raised intracranial pressure of unknown origin that primarily afflicts obese women of childbearing age. There are several treatment options, but currently there are none that are effective for the entire affected population. The lack of a universally effective treatment is related to an incomplete understanding of the etiology of the condition and the lack of a well-defined pathophysiological mechanism for the disease process. Classically, IIH has been thought of as a diagnosis of exclusion once radiographical imaging has ruled out all other causes of elevated intracranial pressure. Today, we know that imaging does capture subtle changes, and might provide keys to finally understand the pathogenesis of IIH so that a definitive treatment can be discovered or developed. Recently, advancements in radiography, optical coherence tomography, and electroretinography have shown promise for the future of IIH evaluation. A topic within IIH imaging that has recently sparked interest is the possibility that the severity of papilledema may have an association with the size of the optic canal. In this article, we also discuss the recent studies on the relationship between asymmetric papilledema and optic canal size.

Approach to patient with unilateral optic disc edema and normal visual function

In patients with swollen optic nerve head and normal visual function, optic disc drusen (ODD) is the most common diagnosis. The best tests for detecting ODD are funds autofluorescence and enhanced-depth imaging ocular coherence tomography (EDIOCT). After ODD has been ruled out, asymmetric papilledema should be assumed to be the cause and MRI of the brain and orbits with contrast and venography should be performed in all patients. It allows one to look for indirect signs of increased inctracranial pressure (ICP), optic perineuritis, and other inflammatory or compressive processes affecting optic nerve or its sheath such as optic nerve sheath meningioma. If imaging signs of raised ICP are present, lumbar puncture should be performed with measurement of opening pressure and analysis of cerebrospinal fluid (CSF) contents in all patients with fever, meningismus or neurologic deficits as well as patients who are not in the typical demographic group for idiopathic intracranial hypertension (IIH). Optic nerve sheath enhancement on MRI should prompt work-up for causes of optic perineuritis. When the appropriate neuroimaging is normal, the differential diagnosis is limited and ophthalmological consultation is necessary to determine whether other subtle ocular abnormalities are present on biomicroscopic and dilated fundus examination.

Spaceflight associated neuro-ocular syndrome

PURPOSE OF REVIEW

Several decades of long duration space flight missions by the National Aeronautics and Space Administration has revealed an interesting and unique constellation of neuro-ophthalmic findings now called spaceflight associated neuro-ocular syndrome (SANS). The unique space environment of microgravity produces novel physiological changes and derangements that present a challenge to astronauts in current and future long duration space missions. Although the precise mechanism of SANS is not fully understood, in this review, we examine recent developments that may to help explain possible causes and potential countermeasures.

RECENT FINDINGS

The cause of SANS is still largely unknown. A growing body of evidence implicates multiple factors that contribute to the development of SANS including cephalad fluid shifts, increased intracranial pressure, venous/lymphatic stasis, inflammation, metabolism, axoplasmic stasis and radiation exposure.

SUMMARY

The pathologic mechanism behind SANS may be multifactorial and may be amenable to different countermeasures for prevention and management of SANS.

Atypical presentations of idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is a disorder of unknown etiology that results in isolated raised intracranial pressure. Classic symptoms and signs of IIH include headache, papilledema, diplopia from sixth nerve palsy and divergence insufficiency, and pulsatile tinnitus. Atypical presentations include: (1) highly asymmetric or even unilateral papilledema, and IIH without papilledema; (2) ocular motor disturbances from third nerve palsy, fourth nerve palsy, internuclear ophthalmoplegia, diffuse ophthalmoplegia, and skew deviation; (3) olfactory dysfunction; (4) trigeminal nerve dysfunction; (5) facial nerve dysfunction; (6) hearing loss and vestibular dysfunction; (7) lower cranial nerve dysfunction including deviated uvula, torticollis, and tongue weakness; (8) spontaneous skull base cerebrospinal fluid leak; and (9) seizures. Although atypical findings should raise a red flag and prompt further investigation for an alternative etiology, clinicians should be familiar with these unusual presentations.

Unilateral persistent disc oedema due to cerebral sinus venous thrombosis (CSVT): diagnostic and management challenge

A 50-year-old woman was incidentally diagnosed to have unilateral disc oedema during comprehensive ophthalmological evaluation. She had a prior history of ulcerative colitis. She had normal visual function and was initially diagnosed to have incipient non-arteritic anterior ischaemic optic neuropahty. Risk factor evaluation revealed hyperhomocysteinaemia. She was asked to come for a follow-up in 2 months. However, she was lost to follow-up and returned to the clinic for the evaluation for headaches, 23 months later. Her ocular examination was stable and she had persistent unilateral disc oedema unchanged from the prior visit. Repeat MRI brain and MR venogram brain with contrast-established diagnosis of cerebral sinus venous thrombosis (CSVT). She denied any neurological symptoms. Later on, she was diagnosed to have hyperhomocysteinaemia with methyl tetrahydrofolate reductase gene mutation. This case highlights the importance of recognising although rare, unilateral disc oedema secondary to elevated intracranial pressure from CSVT.

Unilateral papilledema in idiopathic intracranial hypertension: A rare entity

Idiopathic Intracranial Hypertension (IIH), also known as pseudotumor cerebri is a clinical syndrome of unknown etiology, which typically affects young, obese women of childbearing age and is characterized by increased intracranial pressure and bilateral papilledema. Unilateral and highly asymmetrical papilledema is a rare presentation in IIH occurring in less than 4% of patients with definite IIH and can poses a diagnostic challenge for the treating physician as it usually raises the suspicion of localized ocular pathology. As per current consensus, papilledema results in stasis of axoplasmic transport due to mechanical compression, leading to secondary vascular changes of venous dilation and hemorrhage. Given this mechanism, the underlying reasons for unilateral and asymmetrical papilledema remain unclear.

Demographics, Clinical Characteristics, and Management of Idiopathic Intracranial Hypertension in Kuwait: A Single-Center Experience

Background: Idiopathic intracranial hypertension (IIH) affects predominantly obese females during their reproductive age period. The demographics of this condition has not been studied in Kuwait before. Objectives: To determine the demographics, clinical features, risk factors, and treatment modalities of IIH in the main neurology tertiary referral hospital in Kuwait and to compare our data with literature. Methods: A retrospective study was conducted to identify cases of IIH seen between January 1, 2018, and December 31, 2018. Patients were diagnosed in and referred from the neurology and neuro-ophthalmology clinics. Results: Our cohort consisted of 139 patients. We estimated a crude annual incidence rate of IIH of 3.28 per 100,000 population. Female-to-male ratio was 9.6:1. Mean age was 32.1 ± 10.8 years. Mean age of males was 31.46 ± 12.63 and that of females was 32.11 ± 10.67. The median of the duration from the first symptoms till diagnosis was 6 weeks (2-10 weeks). Headache was the most common symptom in 134 (96.4%) patients, followed by visual disturbances in 85 (61.2%) patients, transient visual obscurations (TVOs) in 84 (60.4%) patients, pulsatile tinnitus in 72 (51.8%) patients, diplopia in 22 (15.8%) patients, other symptoms (e.g., nausea, vomiting, radicular neck, and back pain) in 19 (13.7%) patients, and 1 (0.7%) patient had facial weakness. High body mass index (BMI) was seen in 89.9% of patients, either overweight or obese, and it was the most common risk factors in both males (46.2%) and females (61.1%). Anemia was found in 38.1%; 21.6% of patients used OCPs and 7.9% used vitamin A. Bilateral transverse sinus stenosis (BTSS) was detected in 47 (33.8%) patients. Only 2 (1.4%) patients developed "fulminant IIH" characterized by rapidly progressive disease. All the patients received medical treatment and only 12 (8.6%) needed surgical management. Conclusion: Incidence of IIH in Kuwait is similar to other regional studies but higher than Western studies. Demographics and clinical features of IIH in our study are comparable to international and regional figures. Most of our patients had a benign course. IIH is more prevalent in females and strongly associated with obesity.

A clinical and radiological study in patients with idiopathic intracranial hypertension

Abstract

Idiopathic intracranial hypertension (IIH) is one of the chronic causes of elevated intracranial pressure with no evident cause in neuroimaging and normal CSF analysis. It primarily affects overweight women of childbearing age.

Aim of work

To describe the clinical picture of IIH, neuroimaging and response to treatment after 3 months follow up in a sample of Egyptian patients.

Patients and methods

This was a prospective study carried out on 25 patients presented at Alexandria University Hospital with symptomatology of IIH. All the patients were subjected to complete history taking, neurological examination, fundus examination, lumbar puncture, and MRI brain and MR cerebral venography. The patients were followed-up for 3 months for assessment of treatment response.

Results

Patients’ ages ranged from 1 0to 50 years, with a mean BMI 32.32 ± 5.28 kg m2. Headache was the presenting manifestation in 100% of the patients. About 60% of the sample were either misdiagnosed or had a delayed diagnosis. There was a significant positive correlation between CSF opening pressure (r = 0.504, p = 0.010), severity of headache (r = 0.472, p = 0.017) and grade of papilledema. Optic hydropes and empty sellaturcica were the most common MRI abnormalities occurring in 95.8% and 70.8%, respectively. Only 30% of the cases had normal MRV. Stenosis at genu junction and focal stenosis at transverse sinus occurred in 24% and 20% of the cases, respectively. Combined medical and serial lumbar puncture were the most effective line of therapy in the recruited patients.

Conclusion

Headache is the most common presentation of IIH, and its severity is positively correlated with papilledema grade. CSF pressure is also positively correlated with papilledema grade.

Pathogenesis and Evaluation of the Effects of Idiopathic Intracranial Hypertension on the Optic Nerves

Idiopathic intracranial hypertension (IIH) is a clinical syndrome of raised intracranial pressure of unknown aetiology. Although papilloedema and visual alterations are among the most important manifestations of the disease, their pathophysiological mechanisms are not fully understood. We aim to review the up-to-date evidence regarding how the optic nerves are affected, the possible pathophysiology and the methods of their assessment.

Idiopathic Intracranial Hypertension

PURPOSE OF REVIEW

Idiopathic intracranial hypertension is a syndrome of increased intracranial pressure of unclear etiology that most often occurs in obese women of childbearing age but can also occur in men, children, and older adults. This article reviews the diagnostic criteria, clinical features, neuroimaging findings, differential diagnosis, and management options for this condition.

RECENT FINDINGS

Recent population studies have found that the annual incidence of idiopathic intracranial hypertension is increasing in association with obesity rates, whereas recent scientific studies indicate a possible role for androgen sex hormones and adipose tissue in the pathogenesis of the disease. Prospective clinical trials have demonstrated a role for weight loss, acetazolamide, and topiramate in the management of mild disease. A recently begun randomized multicenter trial of surgical interventions will provide insight into the indications for surgical intervention, optimal timing and choice of intervention, and long-term outcomes.

SUMMARY

Idiopathic intracranial hypertension is a disorder producing symptoms and signs of increased intracranial pressure in the absence of an alternative cause. The main goals of treatment are to preserve visual function and alleviate symptoms, which can usually be achieved with a combination of weight loss, medical therapies, and surgical interventions depending on the severity of symptoms and vision loss, response to treatment, and subsequent clinical course.

Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update

Prolonged microgravity exposure during long-duration spaceflight (LDSF) produces unusual physiologic and pathologic neuro-ophthalmic findings in astronauts. These microgravity associated findings collectively define the “Spaceflight Associated Neuro-ocular Syndrome” (SANS). We compare and contrast prior published work on SANS by the National Aeronautics and Space Administration’s (NASA) Space Medicine Operations Division with retrospective and prospective studies from other research groups. In this manuscript, we update and review the clinical manifestations of SANS including: unilateral and bilateral optic disc edema, globe flattening, choroidal and retinal folds, hyperopic refractive error shifts, and focal areas of ischemic retina (i.e., cotton wool spots). We also discuss the knowledge gaps for in-flight and terrestrial human research including potential countermeasures for future study. We recommend that NASA and its research partners continue to study SANS in preparation for future longer duration manned space missions.

Visual evoked potentials follow-up in idiopathic intracranial hypertension

OBJECTIVE

To demonstrate the importance of visual evoked potential (VEP) in determining the severity and prognosis of the disease and in monitoring the clinical course in patients with idiopathic intracranial hypertension (IIH).

METHODS

This is a prospective cross-sectional study conducted covering the period between March 2014 and January 2015. The study included 32 patients recently diagnosed with IIH and 30 healthy volunteers. The initial VEP values of the IIH patients were compared to the VEP values of the healthy control group. Furthermore, the initial VEP values of the IIH patients were compared with their VEP values after one month of treatme RESULTS: The mean age of the IIH patients was 37.8+/-12.02 years. Of the IIH patients, 27 (84%) were females and 5 (16%) were males. There was a statistically significant association of the initial VEP values with the visual field findings (p=0.011) and visual acuity (p=0.040). Moreover, a statistically significant difference was found between the control group and IIH patients in terms of right (p less than 0.001) and left P100 values (p less than 0.001). While 18 (56%) of the initial VEPs of IIH patients were pathological, 14 (44%) of the second VEPs were pathological, and this difference was not statistically significant (p=0.125).

CONCLUSION

A relationship between the VEP P100 values and the severity of the disease was detected, while the importance of monitoring VEP values in the follow-up of IIH patients was not demonstrated.

Unilateral high myopia leading to asymmetric disc edema in idiopathic intracranial hypertension

Asymmetrical disc edema in idiopathic intracranial hypertension (IIH) is an uncommon finding, with an unclear understanding. This report reinforces the importance of recognizing this entity in IIH diagnosis, and not misdiagnose the condition as unilateral disc edema. In this unique report, the causative association of asymmetric optic disc edema, with optic nerve kink, due to unilateral high myopia, is documented.

The role of intracranial pressure in glaucoma and therapeutic implications

Despite glaucoma being the second leading cause of blindness globally, its pathogenesis remains incompletely understood. Although intraocular pressure (IOP) contributes to glaucoma, and reducing IOP slows progress of the disease, some patients progress despite normal IOP (NTG). Glaucomatous damage causes characteristic cupping of the optic nerve where it passes through the lamina cribrosa. There is evidence that cerebrospinal fluid (CSF) within the optic nerve sheath has a different composition from CSF surrounding the brain. Furthermore, fluctuations in CSF flow into the optic nerve sheath may be reduced by trabeculae within the sheath, and on standing intracranial pressure (ICP) within the sheath is stabilised at around 3 mmHg due to orbital pressure. Blood pressure has been linked both to glaucoma and ICP. These facts have led some to conclude that ICP does not play a role in glaucoma. However, according to stress formulae and Laplace's Law, stress within the lamina cribrosa is dependent on the forces on either side of it, (IOP and ICP), and its thickness. On lying flat at night, ICP between the brain and optic nerve sheath should equalise. Most evidence suggests ICP is lower in glaucoma than in control groups, and that the lamina cribrosa is thinner and more posteriorly displaced in glaucoma. Subjects who have had ICP reduced have developed signs of glaucoma. This review finds most evidence supports a role for low ICP in the pathogenesis of glaucoma. Caffeine, theophylline and vitamin A may increase ICP, and could be new candidates for an oral treatment.

Optic nerve sheath diameter asymmetry in healthy subjects and patients with intracranial hypertension

BACKGROUND

Ultrasonography of the optic nerve sheath diameter (ONSD) is used for the non-invasive assessment of increased intracranial pressure (ICP). ONSD values are usually obtained by averaging the measurements of the two eyes, but asymmetric ONSD dilation is possible, leading to potentially inaccurate ICP estimation when using binocular averaging. In addition, few data are available about the asymmetry of the ONSD and the use of the maximum ONSD value between eyes for raised ICP detection. The aim of the study was to evaluate the interocular ONSD asymmetry in healthy subjects and patients with intracranial hypertension (IH) by ultrasonography and to investigate whether the maximum ONSD could be as useful as the binocular assessment.

METHODS

Forty healthy subjects and 40 patients with IH (20 with idiopathic intracranial hypertension and 20 with intracerebral hemorrhage) who underwent transorbital sonography were retrospectively enrolled. The prevalence and degree of ONSD asymmetry were compared among groups; ONSD median binocular and maximum values were compared.

RESULTS

Forty-two out of 80 subjects (52.5%) showed significant ONSD asymmetry, without significant differences in prevalence among groups (p = 0.28). The median asymmetry was higher in patients than in healthy subjects (0.45 mm vs 0.23 mm; p = 0.007), without significant differences between the two pathologies (p = 0.58). Both binocular and maximum ONSD measurements were significantly higher in patients with IH than in controls (p < 0.001).

CONCLUSIONS

Interocular ONSD asymmetry occurs both in healthy subjects and, more consistently, in patients with IH. Both binocular and maximum ONSD may be useful markers for increased ICP detection.