Current Perspectives on Idiopathic Intracranial Hypertension without Papilloedema

Risk factors and disease associations in people living with idiopathic intracranial hypertension

INTRODUCTION

Idiopathic intracranial hypertension is a neurological condition characterized by a raised intracranial pressure and papilledema, leading to chronic headaches and visual disturbances. By recognizing modifiable risk factors and deploying evidence-based interventions, healthcare providers have the potential to mitigate the burden of the disease and improve patient outcomes.

AREAS COVERED

It is well known that the condition occurs in predominantly pre-menopausal females who live with obesity particularly in the context of recent weight gain. This review discusses what risk factors may contribute to the metabolic underpinnings of cerebrospinal fluid dysregulation. There are a number of disease associations that are important to screen for as they can alter management.

EXPERT OPINION

There is emerging evidence to suggest that idiopathic intracranial hypertension is a systemic metabolic disease and it is unknown what are all the risk factors are that precipitate the condition. Targeting certain hardwired risk factors is unachievable. However, as recent weight gain has been identified as a predominant risk factor for the development of the disease and relapse, modification of body weight should be the primary aim of management. Insightful research into the involvement of the neuroendocrine axis driving cerebrospinal fluid dysregulation now has the potential for the development of therapeutic targets.

Managing idiopathic intracranial hypertension in the eye clinic

Idiopathic intracranial hypertension (IIH) is a neuro-ophthalmological condition characterised by a raised intracranial pressure and papilloedema that causes disabling headaches. The main risk factors of female sex and living with obesity have been known for some time, however the knowledge of the underlying pathophysiology is evolving. Papilloedema can impact the visual function, and the majority of people are offered acetazolamide. Those with sight threatening disease need urgent management, though there is little high quality evidence to recommend any particular surgical intervention. Headache treatment is an unmet clinical need and simple medication overuse advice has the potential to reduce the chronification of migraine-like headaches. IIH is emerging as a systemic metabolic disease distinct from people living with obesity alone. While weight loss is the main stay of disease modifying therapy this is challenging to access and many healthcare professionals that manage the condition have no formal training or accessible pathways for weight management. The aim of this "how to do it" article is to present the latest advances in knowledge of IIH that we pragmatically included in routine clinical care for people living with the condition.

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.

Optic Nerve Head and Retinal Changes in Idiopathic Intracranial Hypertension: Correlation with Short-Term Cerebrospinal Fluid Pressure Monitoring

BACKGROUND

We aimed to assess the status of the optic nerve and retina by optical coherence tomography (OCT) in a group of patients with idiopathic intracranial hypertension (IIH) on the basis of dynamic changes in intracranial pressure.

METHODS

This observational and cross-sectional study included patients affected by idiopathic intracranial hypertension with papilledema (IIHWP) and patients with idiopathic intracranial hypertension without papilledema (IIHWOP). All participants underwent an OCT examination of the macula and optic nerve head. Parameters related to intracranial pressure, including cerebrospinal fluid (CSF) opening pressure (oCSFp), CSF mean pressure (mCSFp), and pulse wave amplitude (PWA), were included in the analysis.

RESULTS

Out of the 22 subjects enlisted for the study, a total of 16 patients suggestive of IIH were finally enrolled. Papilledema was detected in nine subjects (56.2%) and seven patients were affected by IIHWOP (43.7%). The OCT examination showed a higher mean RNFL thickness in IIHWP patients in comparison to IIHWOP in both eyes (p < 0.05 and p < 0.01, respectively). Intracranial pressure (ICP) measurements showed that IIHWP had higher values of oCSFp, mCSFp, and PWA compared to IIHWOP (p = 0.0001, p = 0.0001, and p = 0.0001, respectively). In addition, ICP parameters significantly correlated with RNFL.

CONCLUSIONS

Clinical parameters suggestive of idiopathic intracranial hypertension are associated with retina and optic nerve OCT parameters. OCT is a useful tool to detect these alterations in a non-invasive fashion.

Idiopathic intracranial hypertension: a step change in understanding the disease mechanisms

The understanding of idiopathic intracranial hypertension (IIH) has evolved over the past few years. Previously, IIH was considered a disease exclusively affecting the neuro-ophthalmic axis, characterized by raised intracranial pressure, headache and papilloedema, and resulting in the risk of severe and permanent visual loss and life-changing disabling headaches. Recent advances have begun to redefine IIH as a probable metabolic disease involving a range of systemic manifestations. More than 95% of individuals affected by the disease are women of reproductive age with obesity. The incidence is rapidly rising and parallels the escalating worldwide obesity rates. Contemporary insights identify associations with insulin resistance, type 2 diabetes and a twofold increased risk of cardiovascular disease in excess of that driven by obesity alone. Adipose distribution in people with IIH, like that in other metabolic diseases, is preferentially centripetal and is associated with changes in intracranial pressure. Evidence now demonstrates adipose tissue dysfunction in people with IIH, involving transcriptional and metabolic priming for lipogenesis and weight gain. Hormonal perturbations are also observed, including a unique phenotype of androgen excess that promotes cerebrospinal fluid secretion. Knowledge of these additional disease features is driving research into novel therapeutic targets and altering the approach to multidisciplinary care.

Overlap and Differences in Migraine and Idiopathic Intracranial Hypertension

PURPOSE OF REVIEW

Migraine and idiopathic intracranial hypertension (IIH) are increasingly encountered but remain enigmatic. This review compares the similarities and differences of the diagnostic criteria, pathophysiology, and risk factors for chronic migraine and IIH.

RECENT FINDINGS

While migraine and IIH are distinct diseases, both conditions are frequently found concurrently and may share a link. Increased intracranial pressure (ICP) in those with or without pre-existing migraine may present with migraine-like headaches and contribute to migraine chronification. Increased intracranial pressure may be a coincidental occurrence in patients with migraine and normalization of pressure does not always translate to headache improvement. Limited information is available regarding the standard of treatment for patients with chronic migraine and IIH without papilledema. There continues to be controversy over the normal range of cerebral spinal fluid (CSF) values. Recognizing the concurrence of both conditions advances our understanding of headache pathology and demonstrates a striking need for more research.

Inaccuracy of idiopathic intracranial hypertension diagnosis in case reports

BACKGROUND

We reviewed the medical case report literature to determine the proportion of cases of idiopathic intracranial hypertension (IIH) that were either inappropriately labelled as IIH or prematurely given this diagnosis.

METHODS

We searched OVID MEDLINE from 2012 to 2022 to identify case reports that diagnosed patients with IIH. Case reports were assessed for diagnostic accuracy using Friedman et al.'s revised diagnostic criteria for primary pseudotumor cerebri syndrome. Our primary outcome was the crude prevalence of inappropriate or premature IIH diagnoses. Our secondary outcome was determining if inaccurate IIH diagnoses were associated with variables such as journal subscription model and impact factor, author affiliation, country of origin, and year of publication.

RESULTS

A total of 33/185 case reports (17.8%) either incorrectly labelled a patient as having IIH or did not perform all of the investigations necessary to make a diagnosis of IIH. Some of these studies (4.8%) were believed to still represent 'probable' IIH given the clinical presentation, whereas 13.0% of studies were determined to have mislabelled their patients as having IIH. The most common reason that case reports did not meet diagnostic criteria included: a lack of MRV in atypical patient cases (42.4%, n = 14), no papilledema in addition to a lack of characteristic neuroimaging features (33.3%, n = 11), intracranial hypertension being secondary to another documented cause (12.1%, n = 4), normal LP opening pressure in addition to other factors (12.1%,n = 4), no description of neuroimaging (6.1%, n = 2), and abnormal CSF composition (6.1%, n = 2). Case reports that used the term 'IIH' incorrectly had a significantly lower journal impact factor (2.0 vs. 2.6, p = 0.01).

CONCLUSIONS

There is a high prevalence of premature or inappropriate diagnoses of IIH in the peer-reviewed case report literature. Adherence to published diagnostic criteria is needed when publishing IIH case reports, and authors are expected to report all relevant data in their report to ensure that an accurate diagnosis is made.

A Neuro-Ophthalmologist's Guide to Advances in Intracranial Pressure Measurements

Cerebrospinal fluid disorders have a wide-ranging impact on vision, headache, cognition and a person's quality of life. Due to advances in technology and accessibility, intracranial pressure measurement and monitoring, usually managed by neurosurgeons, are being employed more widely in clinical practice. These developments are of direct importance for Ophthalmologists and Neurologists because the ability to readily measure intracranial pressure can aide management decisions. The aim of this review is to present the emerging evidence for intracranial pressure measurement methods and interpretation that is relevant to Neuro-ophthalmologists.

Experimental drugs for the treatment of idiopathic intracranial hypertension (IIH): shedding light on phase I and II trials

INTRODUCTION

Idiopathic intracranial hypertension is a neurological condition characterized by a raised intracranial pressure and papilledema that causes debilitating headaches. While the extent of the pathophysiology is being discovered, the condition is emerging as a systemic metabolic disease distinct to people living with obesity alone. Idiopathic intracranial hypertension is becoming more common and therefore establishing licensed therapeutics is a key priority.

AREA COVERED

The translation of preclinical work in idiopathic intracranial hypertension is evident by the two early phase trials evaluating 11-β-hydroxysteroid dehydrogenase inhibitor, AZD4017, and a glucagon like peptide-1 receptor agonist, Exenatide. This review summarizes these two early phase trials evaluating targeted medicines for the treatment of intracranial pressure. The modulation of these two distinct mechanisms have potential for therapeutic intervention in people living with idiopathic intracranial hypertension.

EXPERT OPINION

The clinical trial landscape in idiopathic intracranial hypertension is a challenge due to the rarity of the disease and the lack of agreed meaningful trial outcomes. Further preclinical work to fully understand the pathogenesis is required to enable personalized targeted drug treatment.