Idiopathic intracranial hypertension is associated with lower body adiposity

Understanding the pathophysiology of idiopathic intracranial hypertension (IIH): a review of recent developments

Idiopathic intracranial hypertension (IIH) is a condition of significant morbidity and rising prevalence. It typically affects young people living with obesity, mostly women of reproductive age, and can present with headaches, visual abnormalities, tinnitus and cognitive dysfunction. Raised intracranial pressure without a secondary identified cause remains a key diagnostic feature of this condition, however, the underlying pathophysiological mechanisms that drive this increase are poorly understood. Previous theories have focused on cerebrospinal fluid (CSF) hypersecretion or impaired reabsorption, however, the recent characterisation of the glymphatic system in many other neurological conditions necessitates a re-evaluation of these hypotheses. Further, the impact of metabolic dysfunction and hormonal dysregulation in this population group must also be considered. Given the emerging evidence, it is likely that IIH is triggered by the interaction of multiple aetiological factors that ultimately results in the disruption of CSF dynamics. This review aims to provide a comprehensive update on the current theories regarding the pathogenesis of IIH.

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.

Headaches and obesity

Obesity and headache disorders are two very common conditions in the general population that have been increasing in incidence over the last decades. Recent studies have shown a significant relationship between obesity and headaches, particularly migraine, with an important role in whether the disease is chronic. On the other hand, no such association was found with tension-type headaches. Studies showing an overlapping of hunger-control pathways and those involved in the pathophysiology of migraine may justify the close association between obesity and migraine. Moreover, a secondary headache for which obesity is a strong risk factor is idiopathic Intracranial Hypertension (pseudotumor cerebri), with several studies showing the impact of weight reduction/bariatric surgery in the treatment of the disease. In conclusion, since obesity is a modifiable risk factor, it is important for physicians treating patients with headaches, and particularly migraine, to be aware of the association between these two disorders.

"More Guts Than Brains?"-The Role of Gut Microbiota in Idiopathic Intracranial Hypertension

BACKGROUND

Idiopathic intracranial hypertension syndrome (IIH) is most common among obese women. Weight loss is an important factor in improving papilledema. Over the last decade, growing evidence has identified gut microbiota as a potential factor in the pathophysiology of obesity. Accordingly, we investigated whether the gut microbiome is modified in IIH patients compared with healthy controls, and provide possible new treatment venues.

METHODS

Shotgun metagenomic sequencing of the gut microbiome of 25 cases of IIH patients (according to the modified Dandy criteria) and 20 healthy controls. Participants were further stratified according to their body mass index. The total DNA from each sample was extracted using the PureLink Microbiome DNA Purification Kit A29789 (Invitrogen, Thermo Fisher Scientific, US). Library preparation was performed using the Nextera DNA Flex Library Prep Kit. Samples were sequenced on the Illumina Novaseq 6000 device. A list of bacterial species that significantly differed between the IIH patients and healthy controls was produced in addition to species diversity. In addition, patients' cohort alone was analyzed, (excluding the healthy controls), and the effect of acetazolamide treatment on their gut microbiota was analyzed.

RESULTS

IIH patients have a lower diversity of bacterial species compared with healthy individuals. These bacteria, that is, Lactobacillus ruminis (L. ruminis) (p<6.95E-08), Atopobium parvulum (p<3.9E-03), Megamonas hypermegale (p<5.61E-03), Ruminococcus gnavus (p<1.29E-02), MEL.A1 (p<3.04E-02), and Streptococcus sp. I-G2 (p<3.04E-02), were previously characterized with beneficial health effects. Moreover, we found that Lactobacillus brevis, a beneficial bacterium as well, is more abundant in acetazolamide treated patients (p<7.07E-06).

CONCLUSIONS

Gut microbiota plays a potential role in IIH etiology and therefore, can provide a promising new treatment approach for this disease.

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.

Elevated Intracranial Pressure Associated With Exogenous Hormonal Therapy Used for Gender Affirmation

BACKGROUND

Addison disease, corticosteroid withdrawal, and taking synthetic growth hormone have been linked with development of intracranial hypertension, but there is still debate on whether administration of other exogenous hormones plays a role in precipitating elevated pressure. The growing use of hormonal therapy for gender affirmation provides an opportunity to explore this possibility.

METHODS

All transgender patients taking exogenous hormones for female-to-male (FTM) and male-to-female (MTF) transitions who were diagnosed with intracranial hypertension at Massachusetts Eye and Ear Infirmary, Massachusetts General Hospital and Beth Israel Deaconess Medical Center between August 2014 and November 2018 were included in a retrospective review. Visual acuity, type, and dose of exogenous hormone, visual field testing, clinical exam, results of neuroimaging and lumbar puncture, and treatment modalities were catalogued and analyzed.

RESULTS

Six transgender individuals were identified. Five were FTM, with an average hormone treatment time of 18.4 months, and one was MTF who had been treated with hormones for 4 years. The average age of all patients was 23.5 years. The average time between onset of symptoms and presentation was 5 months. Fifty percent of the patients reported pulse-synchronous tinnitus, 83% reported positional headache, 33% reported transient visual obscurations, and 16% reported diplopia. Lumbar punctures performed on 4 of the patients revealed elevated opening pressures and normal cerebrospinal fluid constituents. MRI findings consistent with elevated intracranial pressure (ICP) were present in the other 2 patients in whom lumbar puncture was unsuccessful. Four patients were treated with acetazolamide and one was treated with topiramate, with an average follow-up time of 15.7 months. All patients demonstrated bilateral optic disc swelling, and all maintained normal acuity and color vision. Performance on visual field testing was not significantly affected in any patient.

CONCLUSIONS

This is the largest reported series to date of gender-transitioning patients with intracranial hypertension, including one novel MTF conversion. These observations warrant further investigation into the possible link of exogenous hormonal therapy and elevated ICP and any mechanisms or confounders underlying this potential association.

Statins in Neuro-ophthalmology

Statins are effective and well-tolerated hypolipidaemic agents which have been increasingly studied for their pleiotropic immunomodulatory and anti-inflammatory effects. Statins have potential therapeutic benefit in a range of neuro-ophthalmological conditions but may also induce or exacerbate certain neurological disorders. This literature review examines evidence from clinical and in vitro studies assessing the effects of statins in myasthenia gravis, myopathy, multiple sclerosis, neuromyelitis optica, idiopathic intracranial hypertension (pseudotumour cerebri), migraine, giant cell arteritis, Bell's palsy, ocular ischaemia, stroke, Alzheimer's disease and Parkinson's disease.

An update on idiopathic intracranial hypertension in adults: a look at pathophysiology, diagnostic approach and management

Idiopathic intracranial hypertension is a neurological syndrome determined by a rise in intracranial pressure without a detectable cause. Course and prognosis may be changeable, requiring a multidisciplinary approach for its diagnosis and management. Although its precise pathogenesis is still unknown, many studies have been carried out to define the possible causal and associated factors, such as retinoids, steroid hormones, body mass index and recent weight gains, cytokines and adipokines levels. The clinical presentation can be variable including chronic headache, disturbance of vision, diplopia and tinnitus. Even if papilloedema is considered the most specific sign, it could not be observed in more than 5% of patients during the evaluation of the fundus oculi. Neuroradiological signs acquire greater importance in patients who do not present papilloedema and may suggest the diagnosis of idiopathic intracranial hypertension. Other assessments can be useful in the diagnostic process, such as optical coherence tomography, visual evoked potentials, ocular ultrasonography and fundus fluorescein angiography and autofluorescence. Nonetheless, cerebrospinal fluid pressure measurement is required to establish a definite diagnosis. Management may be different, since surgical procedures or lumbar punctures are often required when symptoms develop rapidly leading to a loss of visual function. Apart from these cases, patients can be treated with a pharmacological approach and low-calorie diet, but they also need to be monitored over time since relapses years later are not uncommon.

Metabolic Concepts in Idiopathic Intracranial Hypertension and Their Potential for Therapeutic Intervention

BACKGROUND

Traditional risk factors associated with idiopathic intracranial hypertension (IIH) include obesity, weight gain, and female sex. The incidence of IIH is increasing and yet the underlying trigger and the fueling pathological mechanisms are still poorly understood.

EVIDENCE ACQUISITION

Review of ophthalmology, neurology, general surgery, obesity, endocrinology, nutrition, and neurosurgery literature was made.

RESULTS

The facts that implicate sex and obesity in IIH and headache are examined. The role of fat distribution in IIH is questioned, and the concept of adipose tissue functioning as an endocrine organ driving IIH is discussed. The impact of androgen metabolism in IIH is reviewed as is the emerging role of glucagon-like-peptide-1 analogues in modulating intracranial pressure. This introduces the concept of developing targeted disease-modifying therapeutic strategies for IIH.

CONCLUSIONS

This review will discuss the possible role of the adipose/gut/brain metabolism axis in IIH and speculate how this may impact the pathogenesis of IIH and therapeutic opportunities.

Preclinical update on regulation of intracranial pressure in relation to idiopathic intracranial hypertension

Background

Elevated intracranial pressure (ICP) is observed in association with a range of brain disorders. One of these challenging disorders is idiopathic intracranial hypertension (IIH), characterized by raised ICP of unknown cause with significant morbidity and limited therapeutic options. In this review, special focus is put on the preclinical research performed in order to understand the pathophysiology behind ICP regulation and IIH. This includes cerebrospinal fluid dynamics, molecular mechanisms underlying disturbances in brain fluids leading to elevated ICP, role of obesity in IIH, development of an IIH model and ICP measurements in rodents. The review also discusses existing and new drug targets for IIH that have been evaluated in vivo.

Conclusions

ICP monitoring in rodents is challenging and different methods have been applied. Some of these methods are invasive, depend on use of anesthesia and only allow short-term monitoring. Long-term ICP recordings are needed to study IIH but existing methods are hampered by several limitations. As obesity is one of the most common risk factors for IIH, a rodent obese model has been developed that mimics some key aspects of IIH. The most commonly used drugs for IIH have been evaluated in vivo for their efficacy at lowering ICP in the existing animal models. These studies suggest these drugs, including acetazolamide, might have limited or no reducing effect on ICP. Two drug targets that can impact ICP in healthy rodents are topiramate and a glucagon-like peptide-1 receptor (GLP-1R) agonist. However, it remains to evaluate their effect in an IIH model with more precise and valid ICP monitoring system. Therefore, continued evaluation in the preclinical research with refined tools is of great importance to further understand the pathophysiology behind disorders with raised ICP and to explore new drug targets.

Evaluating the Fat Distribution in Idiopathic Intracranial Hypertension Using Dual-Energy X-ray Absorptiometry Scanning

Idiopathic intracranial hypertension (IIH) is strongly associated with obesity. We aimed to utilise dual-energy X-ray absorptiometry (DEXA) to characterise fat distribution, and to evaluate change in fat mass and distribution following weight loss. IIH patients (n = 24) had a similar fat distribution to body mass index (BMI)- and gender-matched obese controls (n = 47). In the IIH cohort, truncal fat mass correlated with lumbar puncture pressure. Weight loss in IIH patients resulted in a significant reduction in disease activity and fat mass, predominantly from the truncal region (-4.40 ± 1.6%; p = 0.008) compared with the limbs (+0.79 ± 6.5%; p = 0.71). These results indicate that, contrary to previous studies using waist-hip ratios, IIH adiposity is centripetal, similar to simple obesity. Future studies should establish the risk of the metabolic syndrome and the role of adipose tissue depot-specific function in IIH.

Obesity and Weight Loss in Idiopathic Intracranial Hypertension: A Narrative Review

BACKGROUND

Most patients with idiopathic intracranial hypertension (IIH) are obese. Weight loss is felt to be an important factor in improving IIH. The mechanism by which weight loss leads to a reduction in elevated intracranial pressure is unclear. Evidence from prospective studies evaluating the role of weight loss in IIH is lacking.

EVIDENCE ACQUISITION

We performed a detailed review of the published literature regarding the association of IIH and obesity, including proposed pathogenetic mechanisms, and the effect of weight loss and weight-loss interventions in IIH. References were identified by searching PubMed with the terms idiopathic intracranial hypertension and weight loss. Additional citations were found in the identified references.

RESULTS

Over 90% of IIH patients are obese or overweight. The risk of IIH increases as a function of body mass index (BMI) and weight gain over the preceding year. The risk of IIH-induced vision loss also increases with increasing BMI, especially with BMI >40 kg/m. Several mechanisms have been proposed linking obesity to the development of IIH but the pathophysiology remains unknown. Published studies and clinical observations strongly support weight loss as an effective treatment, although there are no prospective controlled trials. Weight loss in the range of 6%-10% often leads to IIH remission. Weight loss of ≥5% at 1 year is achieved in roughly 50%-70% of patients if they are enrolled in a high-intensity lifestyle modification program and in 20%-35% of patients if they direct their own weight loss. Weight is typically regained over 1-3 years but about a third of patients maintain ≥5% weight loss over the long term. Patients treated initially with lifestyle modification therapy show a modest persisting benefit over self-directed patients. Selected commercial weight loss programs also may improve long-term maintenance of weight loss. New antiobesity drugs significantly improve the proportion of obese patients who have ≥5% loss of weight at 1 year.

CONCLUSIONS

Obesity is an important contributing factor for the development of IIH, although the pathophysiological mechanism linking obesity to IIH is unknown. The risk of developing IIH and associated visual loss increases with increasing BMI. Weight loss is an effective treatment for IIH. Long-term maintenance of initial weight loss is helped modestly by lifestyle modification programs and possibly by selected commercial weight loss programs. New antiobesity drugs may provide further options for IIH therapy in the future.

Evolving evidence in adult idiopathic intracranial hypertension: pathophysiology and management

Idiopathic intracranial hypertension (IIH) is a rare but important disease associated with significant morbidity. There is an expected rise in prevalence in line with the escalating global burden of obesity. Modern revisions in the terminology and diagnostic criteria for IIH help guide clinicians in investigations and researchers in standardising recruitment criteria for clinical trials. The pathophysiology of IIH is incompletely characterised; suggested underpinning mechanisms include the role of cerebrospinal fluid regulation as well as metabolic and endocrinological perspectives. Recent treatment trials are providing insights into the management but debate still surrounds key areas in treatment. This review will provide an up-to-date discussion on the potential pathogenic mechanisms and management of IIH.

Idiopathic intracranial hypertension, hormones, and 11β-hydroxysteroid dehydrogenases

Idiopathic intracranial hypertension (IIH) results in raised intracranial pressure (ICP) leading to papilledema, visual dysfunction, and headaches. Obese females of reproductive age are predominantly affected, but the underlying pathological mechanisms behind IIH remain unknown. This review provides an overview of pathogenic factors that could result in IIH with particular focus on hormones and the impact of obesity, including its role in neuroendocrine signaling and driving inflammation. Despite occurring almost exclusively in obese women, there have been a few studies evaluating the mechanisms by which hormones and adipokines exert their effects on ICP regulation in IIH. Research involving 11β-hydroxysteroid dehydrogenase type 1, a modulator of glucocorticoids, suggests a potential role in IIH. Improved understanding of the complex interplay between adipose signaling factors such as adipokines, steroid hormones, and ICP regulation may be key to the understanding and future management of IIH.

Idiopathic intracranial hypertension and obesity

Idiopathic intracranial hypertension (IIH), also known as primary pseudotumor cerebri syndrome (PTCS), is a condition of unknown etiology which affects primarily overweight, reproductive-aged women and causes increased intracranial pressure (ICP). This review discusses the recently revised diagnostic criteria for PTCS for adults and children. Additionally, the role of obesity in the epidemiology, etiology, and management of IIH as well as the current knowledge of obesity profiles and markers in IIH are reviewed. We also highlight the emerging, unifying theory of the neuroendocrine effects on the mineralocorticoid receptor to explain a possible mechanism for the increased cerebrospinal fluid production and ICP in secondary PTCS.

Obesity and headache: part I--a systematic review of the epidemiology of obesity and headache

Individually, both obesity and headache are conditions associated with a substantial personal and societal impact. Recent data support that obesity is comorbid with headache in general and migraine specifically, as well as with certain secondary headache conditions such as idiopathic intracranial hypertension. In the current manuscript, we first briefly review the epidemiology of obesity and common primary and secondary headache disorders individually. This is followed by a systematic review of the general population data evaluating the association between obesity and headache in general, and then obesity and migraine and tension-type headache disorders. Finally, we briefly discuss the data on the association between obesity and a common secondary headache disorder that is associated with obesity, idiopathic intracranial hypertension. Taken together, these data suggest that it is important for clinicians and patients to be aware of the headache/migraine-obesity association, given that it is potentially modifiable. Hypotheses for mechanisms of the obesity-migraine association and treatment considerations for overweight and obese headache sufferers are discussed in the companion manuscript, as part II of this topic.

Idiopathic intracranial hypertension

Background

Idiopathic intracranial hypertension or pseudotumour cerebri is primarily a disorder of young obese women characterised by symptoms and signs associated with raised intracranial pressure in the absence of a space-occupying lesion or other identifiable cause.

Summary

The overall incidence of idiopathic intracranial hypertension is approximately two per 100,000, but is considerably higher among obese individuals and, given the global obesity epidemic, is likely to rise further. The pathophysiology of this condition is poorly understood, but most theories focus on the presence of intracranial venous hypertension and/or increased cerebrospinal fluid outflow resistance and how this relates to obesity. A lack of randomised clinical trials has resulted in unsatisfactory treatment guidelines and although weight loss is important, especially when used in conjunction with drugs that reduce cerebrospinal fluid production, resistant cases remain difficult to manage and patients invariably undergo neurosurgical shunting procedures. The use of transverse cerebral sinus stenting remains contentious and long-term benefits are yet to be determined.

Conclusion

An understanding of the clinical features, diagnostic work-up and therapeutic options available for patients with idiopathic intracranial hypertension is important both for neurologists and ophthalmologists as visual loss maybe permanent if untreated.

Update on intracranial hypertension and hypotension

PURPOSE OF REVIEW

The aim of this article is to review recent findings on the pathophysiology of idiopathic changes in intracranial pressure. The review will focus on idiopathic intracranial hypertension (IIH) and spontaneous intracranial hypotension (SIH).

RECENT FINDINGS

Substantial evidence indicates that IIH is associated with delayed absorption of cerebrospinal fluid (CSF). Stenoses of the transverse sinus are common in IIH, but their clinical significance has not been entirely clarified. Despite the observed efficacy of endovascular treatment in some IIH patients, a correlation between the extent of observed stenoses and the clinical course of the disease could not be demonstrated. The underlying cause of SIH is a spontaneous CSF leakage into the epidural space. Conservative treatment and the epidural blood patch remain the treatment of choice for this rare syndrome.

SUMMARY

Recent clinical evidence indicates that IIH is probably a result of CSF outflow abnormality rather than of CSF production. Further research is needed to elucidate the causes of elevated intracranial pressure and the mechanism leading to visual loss. Prospective randomized clinical trials are needed to clarify a possible therapeutic potential of endovascular treatment. Research efforts on SIH should focus further on associated connective tissue disorders predisposing to CSF leaks.

Idiopathic intracranial hypertension; research progress and emerging themes

Idiopathic intracranial hypertension (IIH) is a condition characterised by increased intracranial pressure of unknown cause predominantly seen in obese women of childbearing age and associated with a history of recent weight gain. The aetiology is poorly understood and there are no evidence-based guidelines on the management of the disease. We aim to provide a review of the recent literature outlining the latest advances in this field over the past few years. Areas of emerging interest related to the pathophysiology of IIH will be discussed, such as the role of obesity, adipose tissue and 11β-hydroxysteroid dehydrogenase type 1. We consider the latest research on the role of venous sinus stenosis in IIH and ex vivo advances into cerebrospinal fluid drainage via the arachnoid granulation tissue. The latest techniques for optic nerve head evaluation and the role of optical coherence tomography will be summarised. Finally, we will discuss recent advances in the management of IIH, including weight loss, and medical and surgical treatment strategies.

Volumetric assessment of optic nerve sheath and hypophysis in idiopathic intracranial hypertension

BACKGROUND AND PURPOSE

Idiopathic intracranial hypertension is a headache syndrome characterized by increased CSF pressure. Compression of the hypophysis and distension of the optic nerve sheath are reliable imaging signs. The purpose of the study was to validate, in patients with idiopathic intracranial hypertension, MR imaging-based volumetric measurements of the optic nerve sheath and hypophysis as an objective observation method for more accurate diagnosis and posttreatment follow-up.

MATERIALS AND METHODS

Twenty-three patients with idiopathic intracranial hypertension as well as age-, sex-, and body mass index-matched controls underwent volumetric measurements of the optic nerve, optic nerve sheath, and hypophysis on high-resolution T2-weighted MR images by using a 7-cm surface coil, followed by correlation with CSF opening pressures and clinical symptom scores of visual disturbances and headache.

RESULTS

Mean values of optic nerve sheath (341.86 ± 163.69 mm(3) versus 127.56 ± 53.17 mm(3), P < .001) and hypophysis volumes (554.59 ± 142.82 mm(3) versus 686.60 ± 137.84 mm(3), P < .05) differed significantly between healthy and diseased subjects. No significant differences between mean optic nerve volumes were observed. Receiver operating characteristic analysis showed optic nerve sheath volumes of >201.30 mm(3) (sensitivity, 86.96%; specificity, 91.30%) and hypophysis volumes of <611.21 mm(3) (sensitivity, 78.26%; specificity, 69.57%) to be indicative of idiopathic intracranial hypertension diagnosis. In patients with idiopathic intracranial hypertension, no correlations were found between optic nerve sheath and hypophysis volumes and CSF opening pressures or clinical scores of visual disturbances and headache.

CONCLUSIONS

Semiautomated volumetric measurement of optic nerve sheath and hypophysis has the potential to more accurately diagnose and follow patients with idiopathic intracranial hypertension.

The obesity pattern of idiopathic intracranial hypertension in men

BACKGROUND

Idiopathic intracranial hypertension (IIH), also known as pseudotumor cerebri, is a disorder of unknown etiology, predominantly affecting obese women of childbearing age. IIH is uncommon in men, with a reported female-to-male ratio of 8:1. The pathogenesis of IIH is poorly understood. Several mechanisms have been suggested, but no one mechanism has been able to account for all manifestations of the disease. This research aims to characterize the obesity phenotype(s) of men with IIH in order to find potential inducers for this disease.

METHODS

This is a cross-sectional study based on subjects' medical records. It compared anthropometric parameters between 22 men with IIH, 60 healthy men, and 44 females with IIH. One-way analysis with age and body mass index included as covariates was applied for the assessment of the difference in fat distribution among the three groups.

RESULTS

No significant differences were observed between the male IIH cohort and healthy males for age, BMI, and waist measurements, whereas hip circumference was significantly larger in the IIH cohort (114 ± 13 vs. 104 ± 16 cm; respectively, p < 0.001). Consequently, waist-to-hip ratio (WHR) was significantly lower in the male IIH cohort (0.88 ± 0.08 vs. 0.95 ± 0.12; p < 0.001). While no significant differences were observed for age and hip measurements between male IIH and female IIH cohorts, waist circumference and waist-to-hip ratio (WHR) were significantly larger in the male cohort (102 ± 19 cm vs. 95 ± 13 cm, p < 0.001; 0.88 ± 0.08 vs. 0.78 ± 0.06, p < 0.001, respectively). All these results maintained after adjustment for age and BMI.

CONCLUSIONS

This is the first report of body fat distribution patterns in men with IIH. Whereas male IIH have larger central fat deposition than female IIH patients, abdominal fatness is less accentuated in IIH men compared to normal obese men. The later observation is in agreement with similar results regarding female IIH patients. We believe that these findings justify further investigation into the involvement of various fat depots in the pathogenesis of IIH in men and women alike.

Hyperandrogenism is associated with earlier age of onset of idiopathic intracranial hypertension in women

PURPOSE

Previous reports have connected between Idiopathic intracranial hypertension (IIH), obesity and different hormonal states. The aim of this study was to characterize the endocrine profile in women with IIH.

METHODS

This is a data-based study of 51 IIH patients. We measured anthropometric parameters and assessed hormonal profile including cortisol, testosterone, bioavailable testosterone (BT), prolactin, dehydroepiandrosterone sulfate (DHEA-S), androstenedione, insulin, aldosterone, estradiol, follicle stimulating hormone (FSH) and luteinizing hormone (LH). Pearson or Spearman rank correlation for non-normally distributed variables were calculated to evaluate the relation among the anthropometric measurements: age, body mass index (BMI), waist and hip circumference and waist to hip ratio (WHR) with hormones levels.

RESULTS

Seventy-eight percent of the cohort had WHR < 0.85 and 21.6% had a WHR > 0.85. Increased levels of testosterone, BT and androstenedione were all positively related to younger age of diagnosis in patient who are diagnosed after the age of 25 (R = -1.066, -0.845, -0.735, p < 0.001, =0.024, 0.019, respectively). No correlation was found between any of the analyzed hormones and the duration of the disease, WHR or BMI, except insulin, which was positively related to BMI (R = 0.461, p = 0.001).

CONCLUSIONS

Increased levels of circulating androgens are associated with earlier age of onset of IIH in women.

Morphometric and volumetric MRI changes in idiopathic intracranial hypertension

Objective

We aimed at validating established imaging features of idiopathic intracranial hypertension (IIH) by using state-of-the-art MR imaging together with advanced post-processing techniques and correlated imaging findings to clinical scores.

Methods

Twenty-five IIH patients as well as age-, sex- and body mass index (BMI)-matched controls underwent high-resolution T1w and T2w MR imaging in a 1.5 T scanner, followed by assessment of optic nerve sheaths, pituitary gland, ventricles and Meckel's cave. Imaging findings were correlated with cerebrospinal fluid (CSF) opening pressures and clinical symptom scores of visual disturbances (visual field defects or enlarged blind spot), headache, tinnitus (pulsatile and non-pulsatile) and vertigo. CSF as well as ventricle volumes were determined by using an automated MRI volumetry algorithm.

Results

So-called ‘empty sella’ and optic nerve sheath distension were identified as reliable imaging signs in IIH. Posterior globe flattening turned out as a highly specific but not very sensitive sign. No abnormalities of the lateral ventricles were observed. These morphometric results could be confirmed using MR volumetry (VBM). Clinical symptoms did not correlate with an increase in lumbar opening pressure.

Conclusions

Our study results indicate that lateral ventricle size is not affected in IIH. In contrast, abnormalities of the pituitary gland and optic nerve sheath were reliable diagnostic signs for IIH.

Pediatric idiopathic intracranial hypertension and extreme childhood obesity

OBJECTIVE

To estimate the magnitude of the association between overweight, moderate, and extreme childhood obesity and the risk of idiopathic intracranial hypertension (IIH).

STUDY DESIGN

Risk estimates were obtained from the Kaiser Permanente Southern California Children's Health Study (n = 913 178). Weight classes were assigned by body mass index specific for age and sex. A combination of electronic database searches followed by complete medical records review was used to identify all children diagnosed with IIH between 2006 and 2009.

RESULTS

We identified 78 children with IIH, the majority of whom were girls (n = 66, 84.5%), age 11-19 (n = 66, 84.5%), non-Hispanic Whites (n = 37, 47.4%), and overweight or obese (n = 57, 73.1%). The adjusted ORs and 95% CIs of IIH with increasing weight class were 1.00, 3.56 (1.72-7.39), 6.45 (3.10-13.44), and 16.14 (8.18-31.85) for underweight/normal weight (reference category), overweight, moderately obese and extremely obese 11-19 year olds, respectively (P for trend < .001). Other independent IIH risk factors included White non-Hispanic race/ethnicity for all age groups and female sex, but only in older children. Overweight/obese children also had more IIH symptoms at onset than normal weight children.

CONCLUSIONS

We found that childhood obesity is strongly associated with an increased risk of pediatric IIH in adolescents. Our findings suggest that the childhood obesity epidemic is likely to lead to increased morbidity from IIH particularly among extremely obese, White non-Hispanic teenage girls. Our findings also suggest careful screening of these at risk individuals may lead to earlier detection and opportunity for treatment of IIH.

Update on the pathophysiology and management of idiopathic intracranial hypertension

Idiopathic intracranial hypertension is a disease of unknown aetiology, typically affecting young obese women, producing a syndrome of increased intracranial pressure without identifiable cause. Despite a large number of hypotheses and publications over the past decade, the aetiology is still unknown. Vitamin A metabolism, adipose tissue as an actively secreting endocrine tissue and cerebral venous abnormalities are areas of active study regarding the pathophysiology of idiopathic intracranial hypertension. There continues to be no evidence based consensus or formal guidelines regarding management and treatment of the disease. Treatment studies show that the diagnostic lumbar puncture is a valuable intervention beyond its diagnostic importance, and that weight management is critical. However, many questions remain regarding the efficacy of acetazolamide, CSF shunting procedures and cerebral transverse venous sinus stenting.

Update on idiopathic intracranial hypertension

PURPOSE

To provide an update on various features of idiopathic intracranial hypertension.

DESIGN

Perspective.

METHODS

Selected articles on the epidemiology, clinical and imaging features, natural history, pathophysiology, and treatment of idiopathic intracranial hypertension were reviewed and interpreted in the context of the authors' clinical and research experience.

RESULTS

Idiopathic intracranial hypertension primarily is a disease of obese women of childbearing age, but it can affect patients of any weight, sex, and age. Although a relatively rare disorder, idiopathic intracranial hypertension's associated costs in the United States entail hundreds of millions of dollars. Even after treatment, headaches frequently are persistent and may require the continued involvement of a neurologist. Quality-of-life reductions and depression are common among idiopathic intracranial hypertension patients. However, visual dysfunction, especially visual field abnormalities, represents the major morbidity of this disorder, and serial automated perimetry remains the primary method of patient monitoring. Patients who are men, black, very obese, or anemic are at higher risk of visual loss. Vitamin A metabolism, adipose tissue as an actively secreting endocrine tissue, and cerebral venous abnormalities are areas of active study regarding the pathophysiology of idiopathic intracranial hypertension. Treatment studies show that lumbar puncture is a valuable treatment (in addition to its crucial diagnostic role), and that weight management is critical. However, open questions remain regarding the efficacy of acetazolamide, cerebrospinal fluid diversion procedures, and cerebral venous stenting.

CONCLUSIONS

Many questions remain unanswered about idiopathic intracranial hypertension. Ongoing studies, especially an ongoing National Institutes of Health-funded clinical trial of acetazolamide, should provide more insight into this important, yet poorly understood, syndrome of isolated intracranial hypertension.

Pseudotumor cerebri: brief review of clinical syndrome and imaging findings

PTC is a clinical entity of uncertain etiology characterized by intracranial hypertension. The syndrome classically manifests with headaches and visual changes in women with obesity. Traditionally, imaging ruled out secondary causes of elevated CSF pressure but now may reveal findings frequently seen in patients with PTC, including the following: flattening of the globe, an empty sella, an enlarged ONS, protrusion and enhancement of the optic nerve head, and increased tortuosity of the optic nerve. Novel imaging methods, including MR venography, have additionally identified sinovenous stenosis as a potential indicator of PTC.

The syndrome of pseudotumour cerebri and idiopathic intracranial hypertension

PURPOSE OF REVIEW

Idiopathic intracranial hypertension (IIH) is a condition in which raised intracranial pressure is associated with a high body mass index, and in those societies in which the prevalence of obesity is increasing the disorder is of increasing importance. It is one cause of the syndrome of pseudotumour cerebri but the cause and the link with a rise in body weight are not understood. Furthermore the treatment of the more severe, sight-threatening cases is controversial.

RECENT FINDINGS

A major theme in recent years has been an attempt to identify the underlying mechanism of IIH. Some theories - such as the dural sinus stenosis theory - seem to ignore the relationship with weight gain; others have proposed a direct link between obesity and raised intracranial pressure through a specific fat distribution in the body; others through the production of lipokines; and yet others have suggested a converse causation with raised intracranial pressure giving rise to obesity. Uncontrolled case series continue to demonstrate the success of interventions such as cerebrospinal fluid diversion procedures, venous sinus stenting and bariatric surgery but there are no level 1 clinical trials.

SUMMARY

Interest in IIH is increasing and currently generating numerous studies but there is no consensus view on either cause or management.