Idiopathic intracranial hypertension in the USA: the role of obesity in establishing prevalence and healthcare costs

Exploring the utility of retinal optical coherence tomography as a biomarker for idiopathic intracranial hypertension: a systematic review

This study aimed to examine the existing literature that investigated the effectiveness of optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A) as a biomarker for idiopathic intracranial hypertension (IIH). Our search was conducted on January 17th, 2024, and included the databases, Medline, Scopus, Embase, Cochrane, Latin American and Caribbean Health Sciences Literature (LILACS), International Standard Randomized Controlled Trial Number (ISRCTN) registry, and the International Clinical Trials Registry Platform (ICTRP). Our final review included 84 articles. In 74 studies, OCT was utilized as the primary ocular imaging method, while OCT-A was employed in two studies including eight studies that utilized both modalities. Overall, the results indicated that IIH patients exhibited significant increases in retinal nerve fiber layer (RNFL) thickness, total retinal and macular thickness, optic nerve head volume, and height, optic disc diameter and area, rim area, and thickness compared to controls. A significant correlation was observed between cerebrospinal fluid (CSF) pressure and OCT parameters including RNFL thickness, total retinal thickness, macular thickness, optic nerve head volume, and optic nerve head height. Interventions aimed at lowering CSF pressure were associated with a substantial improvement in these parameters. Nevertheless, studies comparing peripapillary vessel density using OCT-A between IIH patients and controls yielded conflicting results. Our systematic review supports OCT as a powerful tool to accurately monitor retinal axonal and optic nerve head changes in patients with IIH. Future research is required to determine the utility of OCT-A in IIH.

An interdisciplinary integrated specialized one-stop outpatient clinic for idiopathic intracranial hypertension - an assessment of sick leave, presenteeism, and health care utilization

BACKGROUND

Management of idiopathic intracranial hypertension (IIH) is complex requiring contributions from multiple specialized disciplines. In practice, this creates considerable organizational and communicational challenges. To meet those challenges, we established an interdisciplinary integrated outpatient clinic for IIH with a central coordination and a one-stop- concept. Here, we aimed to evaluate effects of this concept on sick leave, presenteeism, and health care utilization.

METHODS

In a retrospective cohort study, we compared the one-stop era with integrated care (IC, 1-JUL-2021 to 31-DEC-2022) to a reference group receiving standard care (SC, 1-JUL-2018 to 31-DEC-2019) regarding economic outcome parameters assessed over 6 months. Multivariate binary logistic regression models were used to adjust for confounders.

RESULTS

Baseline characteristics of the IC group (n = 85) and SC group (n = 81) were comparable (female: 90.6% vs. 90.1%; mean age: 33.6 vs. 32.8 years, educational level: ≥9 years of education 60.0% vs. 59.3%; located in Vienna 75.3% vs. 76.5%). Compared to SC, the IC group showed significantly fewer days with sick leave or presenteeism (-5 days/month), fewer unscheduled contacts for IIH-specific problems (-2.3/month), and fewer physician or hospital contacts in general (-4.1 contacts/month). Subgroup analyses of patients with migration background and language barrier consistently indicated stronger effects of the IC concept in these groups.

CONCLUSIONS

Interdisciplinary integrated management significantly improves the burden of IIH in terms of sick leave, presenteeism and healthcare consultations - particularly in socioeconomically underprivileged patient groups.

National trends in the endovascular and surgical treatment of idiopathic intracranial hypertension

BACKGROUND

The pattern of surgical treatments for Idiopathic Intracranial Hypertension (IIH) in the United States is not well-studied, specifically the trend of utilizing endovascular venous stenting (EVS) as an emerging technique.

METHODS

In this cross-sectional study, we aimed to explore the national trend of utilizing different procedures for the treatment of IIH including EVS, Optic Nerve Sheath Fenestration (ONSF), and CSF Shunting, with a focus on novel endovascular procedures. Moreover, we explored rates of 90-day readmission and length of hospital stay following different procedures, besides the effects of sociodemographic and clinical parameters on procedure choice.

RESULTS

36,437 IIH patients were identified from records between 2010 and 2018. Those in the EVS group were 29 years old on average, and 93.4 % were female. Large academic hospital setting was independently associated with higher EVS utilization, while other factors were not predictive of procedure choice. The proportion of EVS use in IIH hospitalizations increased significantly from 2010 to 2018 (P < 0.001), while there was a relative decline in the frequency of shunting procedures (P = 0.001), with ONSF utilization remaining stable (P = 0.39). The rate of 90-day readmission and length of hospital stay were considerably lower following EVS compared to other procedures (Ps < 0.001).

CONCLUSION

This study presents novel population-level data on national trends in the frequency and outcome of EVS for IIH therapy. EVS was associated with shorter length of hospital stays and fewer readmission rates. In addition, a continuous increase in venous stenting compared to other procedures suggests an increasing role for endovascular therapies in IIH.

Changes in Prevalence of Idiopathic Intracranial Hypertension in the United States Between 2015 and 2022, Stratified by Sex, Race, and Ethnicity

BACKGROUND AND OBJECTIVES

With the obesity epidemic within the United States, the prevalence of idiopathic intracranial hypertension (IIH) is predicted to rise. IIH prevalence and racial disparities have rarely been reported in the United States. The purpose of this study was to evaluate the prevalence of IIH in a large national database while stratifying by sex, age, race, and ethnicity.

METHODS

This was a cross-sectional epidemiologic evaluation conducted in the TriNetX US Collaborative network using data from 2015 to 2022. Patients with an International Classification of Diseases code of IIH and papilledema or unspecified papilledema were included in the study. Any secondary cause of intracranial hypertension including cerebral neoplasms and hydrocephalus were excluded from the study. IIH trends were later compared with TriNetX cohort obesity trends. Prevalence and prevalence odds ratios (ORs) were calculated in Microsoft Excel and R Studio.

RESULTS

Among 85 million patients in this database, a 1.35 times increase in the prevalence of IIH occurred between 2015 and 2022 from 7.3 (95% CI 6.9-7.7) individuals per 100,000 to 9.9 (95% CI 9.5-10.3) individuals per 100,000 in 2022. In 2022, Black female individuals had the highest prevalence of IIH with 22.7 individuals per 100,000 compared with the 13.7 White female individuals per 100,000. Patients aged 11-17 years showed the largest growth of IIH prevalence with female individuals increasing by 10 individuals per 100,000 by 2022. Overall, Black and Hispanic patients had the largest prevalence OR of IIH at 1.66 (95% CI 1.49-1.85) and 1.33 (95% CI 1.14-1.56), respectively, compared with White female patients.

DISCUSSION

IIH is a rapidly increasing health care concern for the US population, particularly among adolescent patients. Black and Hispanic female individuals are most predominately affected by this incapacitating disorder.

CSF hyperdynamics in rats mimicking the obesity and androgen excess characteristic of patients with idiopathic intracranial hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a syndrome exhibiting elevated intracranial pressure (ICP), visual disturbances, and severe headache. IIH primarily affects young obese women, though it can occur in individuals of any age, BMI, and sex. IIH is characterized by systemic metabolic dysregulation with a profile of increased androgen hormones. However, the contribution of obesity/hormonal perturbations to cerebrospinal fluid (CSF) dynamics remains unresolved.

METHODS

We employed obese female Zucker rats and adjuvant testosterone to reveal IIH causal drivers. ICP and CSF dynamics were determined with in vivo experimentation and magnetic resonance imaging, testosterone levels assessed with mass spectrometry, and choroid plexus function revealed with transcriptomics.

RESULTS

Obese rats had undisturbed CSF testosterone levels and no changes in ICP or CSF dynamics. Adjuvant testosterone treatment of obese rats elevated the CSF secretion rate, although with no effect on the ICP, due to elevated CSF drainage capacity of these rats.

CONCLUSIONS

Obesity in itself therefore does not suffice to recapitulate the IIH symptoms in rats, but modulation of CSF dynamics appears with adjuvant testosterone treatment, which mimics the androgen excess observed in female IIH patients. Obesity-induced androgen dysregulation may thus contribute to the disease mechanism of IIH and could potentially serve as a future therapeutic target.

The Vienna idiopathic intracranial hypertension database-An Austrian registry

BACKGROUND

Idiopathic intracranial hypertension (IIH) is becoming increasingly more prevalent bearing the risk of visual impairment and affecting the quality of life. Clinical presentation and outcome are heterogeneous. Large, well-characterized cohorts are scarce.

OBJECTIVE

To characterize the clinical spectrum, diagnostic findings, therapeutic management, and outcome of IIH.

METHODS

We identified patients with IIH according to modified Friedman criteria treated at our center between 2014 and 2021. The Vienna IIH database is described in detail.

RESULTS

Of 113 patients 89% were female (mean age 32.3 years). Median body mass index (BMI) was 31.8, with 85% overweight (BMI > 25) and 5% were classified as IIH without papilledema. Headache was present in 84% and showed migraine features in 43%. Median opening pressure in lumbar puncture was 31 cmH2O. Pharmacotherapy (predominantly acetazolamide) was established in 99%, 56% required at least 1 therapeutic lumbar puncture and 13% a surgical intervention. After a median 3.7 years follow-up, 57% had achieved significant weight loss, papilledema was present in 59% and headache in 76% (58% improved). Comparing initial presentation to follow-up, perimetry was abnormal in 67% vs. 50% (8% worsened, 24% improved) and transorbital sonography in 87% vs. 65% with a median optic nerve sheath diameter of 5.4 mm vs. 4.9 mm. Median peripapillary retinal nerve fiber layer thickness decreased from 199 µm to 99 µm and ganglion cell layer volume from 1.13 mm3 to 1.05 mm3.

CONCLUSION

The large representative Vienna IIH cohort characterizes IIH-related symptoms, diagnostic findings, treatment, and outcome emphasizing substantial long-term sequelae of IIH. Future analyses will aim to refine phenotyping and identify factors predicting outcome.

Weight management communications in idiopathic intracranial hypertension: challenges and recommendations from the patients' perspective

Background

Idiopathic intracranial hypertension (IIH) is a neurometabolic condition severely impacting the quality of life of people living with IIH (PwIIH). Most PwIIH are overweight or live with obesity, and weight loss is recommended by healthcare professionals (HCPs) as it is central to disease management. There is currently no research evaluating patient-clinician interactions when discussing weight management in IIH. The aim of this study was to evaluate the patient experience of communication with HCPs regarding weight management from the perspective of PwIIH.

Methods

A cross-sectional online survey was developed and distributed by the IIH UK charity via their mailing list and social media network. Eligible participants were adults with IIH who have been recommended to lose weight by their HCP. Descriptive statistics were used to summarise quantitative responses and content analysis was used to inductively draw out themes from open-ended free-text responses.

Results

There were 625 respondents. One-fifth of PwIIH (n=127/603, 21%) felt that HCPs were supportive and empathetic about weight management. Five themes were identified on how experiences regarding weight management for IIH can be improved, with PwIIH recommending for HCPs to: (1) detail the relationship between IIH and weight, (2) individualise care, (3) give advice, (4) provide support and (5) adapt communication.

Conclusion

The majority of PwIIH recalled a poor experience and negative emotions when engaged in discussions regarding weight management with their HCPs. Further research should explore the HCPs perspective and evaluate interventions aiming to improve the quality of patient-HCPs communication in IIH.

Modelling idiopathic intracranial hypertension in rats: contributions of high fat diet and testosterone to intracranial pressure and cerebrospinal fluid production

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a condition characterized by increased intracranial pressure (ICP), impaired vision, and headache. Most cases of IIH occur in obese women of childbearing age, though age, BMI, and female sex do not encompass all aspects of IIH pathophysiology. Systemic metabolic dysregulation has been identified in IIH with a profile of androgen excess. However, the mechanistic coupling between obesity/hormonal perturbations and cerebrospinal fluid dynamics remains unresolved.

METHODS

Female Wistar rats were either fed a high fat diet (HFD) for 21 weeks or exposed to adjuvant testosterone treatment for 28 days to recapitulate IIH causal drivers. Cerebrospinal fluid (CSF) and blood testosterone levels were determined with mass spectrometry, ICP and CSF dynamics with in vivo experimentation, and the choroid plexus function revealed with transcriptomics and ex vivo isotope-based flux assays.

RESULTS

HFD-fed rats presented with increased ICP (65%), which was accompanied by increased CSF outflow resistance (50%) without altered CSF secretion rate or choroid plexus gene expression. Chronic adjuvant testosterone treatment of lean rats caused elevated ICP (55%) and CSF secretion rate (85%), in association with increased activity of the choroid plexus Na⁺,K⁺,2Cl^- cotransporter, NKCC1.

CONCLUSIONS

HFD-induced ICP elevation in experimental rats occurred with decreased CSF drainage capacity. Adjuvant testosterone, mimicking the androgen excess observed in female IIH patients, elevated the CSF secretion rate and thus ICP. Obesity-induced androgen dysregulation may thus contribute to the disease mechanism of IIH.

Long-Term Outcomes of Bariatric Surgery in Idiopathic Intracranial Hypertension Patients

BACKGROUND

Idiopathic intracranial hypertension (IIH), a rare neurological disorder, has limited effective long-term treatments. Bariatric surgery has shown short-term promise as a management strategy, but long-term efficacy has not been evaluated. We investigated IIH-related outcomes 4 to 16 years postsurgery.

MATERIALS AND METHODS

This cross-sectional retrospective cohort study included Intracranial Hypertension Registry (IHR) participants with existing medical records that completed a bariatric surgery questionnaire at least 4 years postsurgery. Two physicians independently evaluated the IIH disease course at bariatric surgery and at the time of the questionnaire using detailed medical records. Determinations of improvements were based on within-participant comparisons between the 2 time points. IIH-related outcomes were then combined with bariatric surgery information and outcomes to assess the relationship between weight loss and alterations in IIH.

RESULTS

Among participants that underwent bariatric surgery and met study criteria (n=30) the median body mass index (BMI) at the time of surgery was 45.0 [interquartile range (IQR): 39.8-47.0], dropped to a postsurgical nadir of 27.3 (IQR: 22.8-33.1), and rose to 33.4 (IQR: 29.9-41.7) at the time of the questionnaire. Improvements in the IIH disease course at time of the questionnaire occurred in 37% of participants. However, there was a notable association between durable weight loss and IIH improvement as 90% (9 of 10) of participants that attained and maintained a BMI of 30 or below displayed improvement.

CONCLUSIONS

Attaining and maintaining a BMI of 30 or below was associated with long-term improvement in the IIH disease course, including improved disease management and amelioration of signs and symptoms of participants of the IHR.

Increased Intracranial Pressure Due to Transverse Sinus Compression by a Meningioma En Plaque

Idiopathic intracranial hypertension (IIH) is defined as raised intracranial pressure of unknown etiology. Looking for underlying causes needs to be undertaken before the diagnosis is confirmed and managed accordingly. We are reporting a rare and unique case of a patient with the clinical diagnosis of idiopathic intracranial hypertension or pseudotumor cerebri. She is not obese and not taking any predisposing medication. Her first magnetic resonance imaging (MRI) and magnetic resonance venogram (MRV) were reported as showing left transverse sinus thrombosis. She was treated with anticoagulation. Her final diagnosis of left transverse sinus compression by a meningioma en plaque (MEP) was finally made with a repeat MRI. A high index of suspicion of unusual causes is important when IIH presents in an atypical patient or with an atypical presentation. The prognosis and management of real IIH and raised intracranial pressure due to other causes are different.

Stereotactic-Guided Transcerebellar Cisternoperitoneal Shunt Placement for Idiopathic Intracranial Hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) can cause debilitating symptoms and optic nerve ischemia if untreated. Cerebrospinal fluid diversion is often necessary to reduce intracranial pressure; however, current ventriculoperitoneal and lumboperitoneal shunting techniques have high failure rates in patients with IIH.

OBJECTIVE

To describe our experience treating IIH with a novel stereotactic-guided transcerebellar cisternoperitoneal shunt (SGTC-CPS) technique that places the proximal shunt catheter in the posterior cisterna magnum.

METHODS

Retrospective perioperative and postoperative data from all patients who underwent SGTC-CPS placement for IIH from March 1, 2015, to December 31, 2020, were analyzed. Patients were positioned as for ventriculoperitoneal shunt placement but with the head turned farther laterally to adequately expose the retrosigmoid space. Using neuronavigation, an opening was made near the transverse-sigmoid junction, and the proximal catheter was inserted transcerebellarly into the posterior foramen magnum.

RESULTS

Thirty-two patients underwent SGTC-CPS placement (29 female; mean body mass index, 36.0 ± 7.5; 14 with prior shunt failures). The mean procedure time for shunt placement was 145 minutes. No intraoperative complications occurred, and all patients were discharged uneventfully. At the 6-month follow-up, 81% of patients (21 of 26) had relief of their presenting symptoms. Shunt survival without revision was 86% (25 of 29) at 1 year and 67% (10 of 15) at 3 years, with no infections.

CONCLUSION

The SGTC-CPS offers an alternative solution for cerebrospinal fluid diversion in patients with IIH and demonstrates a lower failure rate and more durable symptom relief compared with ventriculoperitoneal or lumboperitoneal shunt placement. Using proper techniques and equipment promotes safe and facile placement of the proximal catheter.

Micronutrient Deficiencies Presenting with Optic Disc Swelling Associated with or without Intracranial Hypertension: A Systematic Review

Idiopathic intracranial hypertension (IIH) is a neurological disorder characterised by optic disc swelling secondary to raised intracranial pressure (ICP) of unknown cause. Obesity is the most established and prevalent risk factor in developed countries. As obesogenic diets are high in calories and nutrient-poor, there may be associated nutritional deficiencies that contribute to the clinical presentation of IIH. Yet none, aside from iron deficiency, are currently included in the inclusion or exclusion criteria for the diagnosis of IIH. Our primary aim was to determine which micronutrient deficiencies, aside from iron deficiency, could present with optic disc swelling associated with or without intracranial hypertension that could potentially meet current IIH diagnostic criteria. To this end, we conducted a systematic search of articles published between 1 January 1980 and 18 December 2020 reporting cases of optic disc swelling associated with micronutrient deficiencies. In total, 65 cases met the eligibility criteria from initial searches: all were case reports and case series with a high risk of bias. Our findings suggest that patients with IIH or unexplained optic disc swelling ought to be screened, investigated, and treated for associated micronutrient deficiencies in vitamin A, B1 and B12; and weight loss interventions in IIH patients ought to promote better nutrition in addition to overall calorie restriction.

A New Perspective on the Pathophysiology of Idiopathic Intracranial Hypertension: Role of the Glia-Neuro-Vascular Interface

Idiopathic intracranial hypertension (IIH) is a neurological disease characterized by symptoms and signs of increased intracranial pressure (ICP) of unknown cause. Most attention has been given to the role of cerebrospinal fluid (CSF) disturbance and intracranial venous hypertension caused by sinus vein stenosis. We previously proposed that key pathophysiological processes take place within the brain at the glia-neuro-vascular interface. However, the relative importance of the proposed mechanisms in IIH disease remains unknown. Modern treatment regimens aim to reduce intracranial CSF and venous pressures, but a substantial proportion of patients experience lasting complaints. In 2010, the first author established a database for the prospective collection of information from individuals being assessed for IIH. The database incorporates clinical, imaging, physiological, and biological data, and information about treatment/outcome. This study retrieved information from the database, asking the following research questions: In IIH subjects responding to shunt surgery, what is the occurrence of signs of CSF disturbance, sinus vein stenosis, intracranial hypertension, and microscopic evidence of structural abnormalities at the glia-neuro-vascular interface? Secondarily, do semi-quantitative measures of abnormal ultrastructure at the glia-neurovascular differ between subjects with definite IIH and non-IIH (reference) subjects? The study included 13 patients with IIH who fulfilled the diagnostic criteria and who improved following shunt surgery, i.e., patients with definite IIH. Comparisons were done regarding magnetic resonance imaging (MRI) findings, pulsatile and static ICP scores, and immune-histochemistry microscopy. Among these 13 IIH subjects, 6/13 (46%) of patients presented with magnetic resonance imaging (MRI) signs of CSF disturbance (empty sella and/or distended perioptic subarachnoid spaces), 0/13 (0%) of patients with IIH had MRI signs of sinus vein stenosis, 13/13 (100%) of patients with IIH presented with abnormal preoperative pulsatile ICP [overnight mean ICP wave amplitude (MWA) above thresholds], 3/13 (23%) patients showed abnormal static ICP (overnight mean ICP above threshold), and 12/13 (92%) of patients with IIH showed abnormal structural changes at the glia-neuro-vascular interface. Comparisons of semi-quantitative structural variables between IIH and aged- and gender-matched reference (REF) subjects showed IIH abnormalities in glial cells, neurons, and capillaries. The present data suggest a key role of disease processes affecting the glia-neuro-vascular interface.

Psychiatric Comorbidities in Patients With Idiopathic Intracranial Hypertension: A Prospective Cohort Study

BACKGROUND AND OBJECTIVES

Psychiatric disease is a frequent comorbidity in idiopathic intracranial hypertension (IIH) and has been associated with a poor subjective outcome. No prospective studies have investigated psychiatric comorbidities in new-onset IIH. Our primary aim was to investigate disease severity in IIH depending on comorbid psychiatric disease. Important secondary outcomes were disease severity after 6 months and prevalence of psychiatric diseases in IIH.

METHODS

This prospective, observational cohort study consecutively included patients with clinically suspected, new-onset IIH from 2 headache centers. A standardized diagnostic workup was completed to confirm or exclude IIH according to the revised Friedman criteria: semi-structured interview, neurologic and neuro-ophthalmologic examination, lumbar puncture with opening pressure (OP), and neuroimaging. Exclusion criteria were known IIH, secondary intracranial hypertension, missing data, and pregnancy. Disease severity was evaluated based on papilledema, visual fields, OP, and headache in patients with IIH without psychiatric disease (IIH-P) compared with patients with IIH with psychiatric disease (IIH+P). A blinded neuro-ophthalmologist assessed visual outcomes. Age- and sex-matched prevalence rates of psychiatric diseases in the general population were found in national reports.

RESULTS

A total of 258 patients were screened; 69 were excluded. A total of 189 patients with clinically suspected IIH were then evaluated with the diagnostic workup and IIH was confirmed in 111 patients (58.7%). A total of 45% of patients with IIH had a psychiatric comorbidity. Visual fields were worse in patients with IIH+P at baseline (-8.0 vs -6.0 dB; p = 0.04) and after 6 months (-5.5 vs -4.0 dB; p < 0.01) compared with IIH-P. Highly prevalent psychiatric disorders were major depressive disorder (24.3%; n = 27), anxiety or stress-related disorders (24.3%; n = 27), and emotionally unstable personality disorder (6.3%; n = 7). Substance abuse (1.8%), schizophrenia (0.9%), and bipolar disorder (0.9%) were rare. In the general population, prevalence estimates of major depressive disorder and emotionally unstable personality disorder were 1.8%-3.3% and 2%, respectively.

DISCUSSION

Visual fields were significantly worse at baseline and 6 months in IIH+P compared with IIH-P. Psychiatric comorbidities, particularly depression and emotionally unstable personality disorder, were highly prevalent in IIH. Increased awareness of psychiatric disease as a marker for worse visual status may improve patient care.

Developing a "Fast-Track" Strategy for Interventional Management of Patients With Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH) has an increasing incidence worldwide over the past decade, with a high economic burden on patients and society. Up to 10% of patients with IIH have progressive visual decline requiring an invasive intervention (including cerebrospinal fluid shunting, cerebral dural sinus stenting, or optic nerve sheath fenestration [ONSF]). IIH patients with visual decline usually undergo evaluation and initial management through the emergency department (ED) and commonly have a long hospital stay due to the lack of a dedicated methodology for evaluation and management, particularly in patients who present with visual loss (i.e., fulminant IIH). An innovative practice approach is needed to improve the means of multidisciplinary communication in care and evaluation of IIH patients. This paper aims to discuss the need for the development and implementation of a multidisciplinary "fast-track" strategy for the evaluation and management of patients with fulminant IIH or those with a suboptimal response to maximum tolerated medical treatment at risk for visual loss. We suggest that such a program could reduce hospital stay and ED visits and therefore reduce healthcare costs and improve patient outcomes by accelerating the management process.

Thinning of the Skull Base and Calvarial Thickness in Patients With Idiopathic Intracranial Hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a disorder characterized by elevated intracranial pressure without secondary causes on neuroimaging. IIH typically occurs in young, obese female patients and, when severe, can cause permanent and irreversible vision loss. The association between skull base thinning in patients with intracranial hypertension and obesity has been previously reported; however, no study has reported these findings in IIH. The goal of our study is to determine whether IIH is independently associated with skull base and calvarial thinning.

METHODS

A retrospective, matched case-control study was performed. Each patient diagnosed with IIH (case) was matched with a patient diagnosed with headache (control) by age, gender, and race. Patients were included if they underwent computed tomographic imaging of the head, maxillofacial, or orbits within 3 months of their diagnosis. Exclusion criteria were history of skull base or frontal bone pathology because of surgery or skull trauma, central nervous system infections, or incomplete radiologic data. Patient demographics, medical history, clinical examination, and skull base, calvarial, and zygoma thickness were recorded. Skull base thickness was measured by the height of the auditory canal in the coronal plane. Calvarial thickness was measured just anterior to the foramen rotundum in the coronal plane. Extracranial zygoma thickness was measured and used as an internal imaging control because the zygoma is not subject to intracranial forces.

RESULTS

One hundred twenty-six patients were included in the study, 63 cases and 63 controls. Each group comprised 61 female patients (97%), 24 (38%) Caucasian, 23 (37%) black, 1 (2%) Asian, and 15 (24%) others. The average age was 31.5 ± 8.7 years. Patients with IIH were more likely to be obese (n = 60, 95%) compared with the control patients (n = 23, 37%, P < 0.001). All patients with IIH underwent lumbar puncture (LP) with an average opening pressure (OP) of 40.5 ± 15.6 cm H2O, whereas only 13 (20%) controls underwent an LP with a mean OP of 19.5 ± 8.5 cm H2O. There was no statistical difference in mean visual acuity between the IIH and control groups (logMar 0.22 [20/30] ± 0.45 vs logMar 0.09 [20/25] ± 0.30, P = 0.093, respectively). Compared with the controls, patients with IIH were more likely to have headache (97% vs 74%, P = 0.001), pulsatile tinnitus (48% vs 7%, P < 0.001), horizontal binocular diplopia (24% vs 4%, P = 0.006), confrontational visual field deficit (23% vs 2%, P = 0.003), and papilledema (74% vs 0%, P < 0.001). Patients with IIH had thinner skull base and calvarium width compared with the controls (mean skull base thickness 4.17 ± 0.94 mm vs 5.05 ± 1.12 mm, P < 0.001 and mean calvarial width 1.50 ± 0.50 mm vs 1.71 ± 0.61 mm, P = 0.024). Zygoma thickness was similar in both groups (mean zygoma thickness 1.18 ± 0.30 mm in the IIH group vs 1.26 ± 0.35 mm in the control group, P = 0.105). In a subgroup analysis controlling for obesity (body mass index >30 kg/m2), there was no statistically significant difference in skull base, calvarial, or zygoma thickness between obese and nonobese patients.

CONCLUSIONS

Patients with IIH have thinner mean skull base and calvarial thickness compared with the controls. There was no difference in the mean extracranial zygoma thickness, which was the internal imaging control. Contrary to previous reports, we did not find an association between obesity and skull base or calvarial thinning. These findings suggest that IIH is associated with skull base and calvarial thinning.

Detecting Cognitive Impairment in Idiopathic Intracranial Hypertension Using Ocular Motor and Neuropsychological Testing

Objective: To determine whether cognitive impairments in patients with Idiopathic Intracranial Hypertension (IIH) are correlated with changes in visual processing, weight, waist circumference, mood or headache, and whether they change over time.

Methods: Twenty-two newly diagnosed IIH patients participated, with a subset assessed longitudinally at 3 and 6 months. Both conventional and novel ocular motor tests of cognition were included: Symbol Digit Modalities Test (SDMT), Stroop Colour and Word Test (SCWT), Digit Span, California Verbal Learning Test (CVLT), prosaccade (PS) task, antisaccade (AS) task, interleaved antisaccade-prosaccade (AS-PS) task. Patients also completed headache, mood, and visual functioning questionnaires.

Results: IIH patients performed more poorly than controls on the SDMT (p< 0.001), SCWT (p = 0.021), Digit Span test (p< 0.001) and CVLT (p = 0.004) at baseline, and generated a higher proportion of AS errors in both the AS (p< 0.001) and AS-PS tasks (p = 0.007). Further, IIH patients exhibited prolonged latencies on the cognitively complex AS-PS task (p = 0.034). While weight, waist circumference, headache and mood did not predict performance on any experimental measure, increased retinal nerve fibre layer (RNFL) was associated with AS error rate on both the block [F_{(3, 19)}=3.22, B = 0.30, p = 0.022] and AS-PS task [F_{(3, 20)} = 2.65, B = 0.363, p = 0.013]. Unlike ocular motor changes, impairments revealed on conventional tests of cognition persisted up to 6 months.

Conclusion: We found multi-domain cognitive impairments in IIH patients that were unrelated to clinical characteristics. Marked ocular motor inhibitory control deficits were predicted by RNFL thickness but remained distinct from other cognitive changes, underscoring the significance of visual processing changes in IIH.

Awareness, Diagnosis and Management of Idiopathic Intracranial Hypertension

The diagnosis and management of idiopathic intracranial hypertension (IIH) can be difficult and multiple medical subspecialities are often involved. Several national and international guidelines regarding the investigations and management of IIH have been published in recent years but still there is no consensus about the optimal organization of IIH-care. The objective of this review was to propose and describe a referral pathway and an organization scheme for diagnosis and management of IIH. An extensive search of existing literature was conducted and summarized. In total, 237 IIH-articles were identified and hereof 43 included. The clinical practice in our specialized IIH-clinic is characterized and described. We conclude that an educational campaign involving medical care providers and patients with chronic headaches is necessary. A detailed organizational proposal for a referral pathway and management of IIH patients based on the literature search and our clinical experience from a highly specialized IIH outpatient clinic is suggested and discussed.

Cost-effectiveness of bariatric surgery versus community weight management to treat obesity-related idiopathic intracranial hypertension: evidence from a single-payer healthcare system

BACKGROUND

Idiopathic intracranial hypertension (IIH) is associated with significant morbidity, predominantly affecting women of childbearing age living with obesity. Weight loss has demonstrated successful disease-modifying effects; however, the long-term cost-effectiveness of weight loss interventions for the treatment of IIH has not yet been established.

OBJECTIVES

To estimate the cost-effectiveness of weight-loss treatments for IIH.

SETTING

Single-payer healthcare system (National Health Service, England).

METHODS

A Markov model was developed comparing bariatric surgery with a community weight management intervention over 5-, 10-, and 20-year time horizons. Transition probabilities, utilities, and resource use were informed by the IIH Weight Trial (IIH:WT), alongside the published literature. A probabilistic sensitivity analysis was conducted to characterize uncertainty within the model.

RESULTS

In the base case analysis, over a 20-year time horizon, bariatric surgery was "dominant," led to cost savings of £49,500, and generated an additional 1.16 quality-adjusted life years in comparison to the community weight management intervention. The probabilistic sensitivity analysis indicated a probability of 98% that bariatric surgery is the dominant option in terms of cost-effectiveness.

CONCLUSION

This economic modeling study has shown that when compared to community weight management, bariatric surgery is a highly cost-effective treatment option for IIH in women living with obesity. The model shows that surgery leads to long-term cost savings and health benefits, but that these do not occur until after 5 years post surgery, and then gradually increase over time.

Abnormal Intracranial Pulse Pressure Amplitude Despite Normalized Static Intracranial Pressure in Idiopathic Intracranial Hypertension Refractory to Conservative Medical Therapy

Idiopathic intracranial hypertension (IIH) incorporates symptoms and signs of increased intracranial pressure (ICP) and is diagnosed by increased lumbar cerebrospinal fluid pressure. However, our knowledge about the characteristics of ICP abnormality, e.g., changes in pulsatile versus static ICP, remains scarce. This study questioned how overnight pulsatile ICP (mean ICP wave amplitude, MWA) associates with static ICP (mean ICP) in IIH patients who were refractory to conservative medical treatment. The material included 80 consecutive IIH patients undergoing ICP monitoring prior to shunt, as part of work-up for failed conservative medical therapy. In this group, the overnight mean ICP was normalized in 52/80 patients, but with abnormal overnight MWA in 45 of the 52 patients. Even though there was a positive correlation between MWA and mean ICP at group level and within individual ICP recordings, the levels of MWA were abnormal in a high proportion of patients despite normalized mean ICP. Taken together, the present results disclosed lasting abnormal pulsatile ICP despite normalized static ICP in IIH patients refractory to conservative medical therapy, which may reflect the underlying pathophysiology. It is tentatively suggested that abnormal pulsatile ICP in IIH may reflect alterations at the glia-neurovascular interface, resulting in impaired astrocytic pulsation absorber mechanisms.

Accuracy of a Deep Learning System for Classification of Papilledema Severity on Ocular Fundus Photographs

OBJECTIVE

To evaluate the performance of a deep learning system (DLS) in classifying the severity of papilledema associated with increased intracranial pressure on standard retinal fundus photographs.

METHODS

A DLS was trained to automatically classify papilledema severity in 965 patients (2,103 mydriatic fundus photographs), representing a multiethnic cohort of patients with confirmed elevated intracranial pressure. Training was performed on 1,052 photographs with mild/moderate papilledema (MP) and 1,051 photographs with severe papilledema (SP) classified by a panel of experts. The performance of the DLS and that of 3 independent neuro-ophthalmologists were tested in 111 patients (214 photographs, 92 with MP and 122 with SP) by calculating the area under the receiver operating characteristics curve (AUC), accuracy, sensitivity, and specificity. Kappa agreement scores between the DLS and each of the 3 graders and among the 3 graders were calculated.

RESULTS

The DLS successfully discriminated between photographs of MP and SP, with an AUC of 0.93 (95% confidence interval [CI] 0.89-0.96) and an accuracy, sensitivity, and specificity of 87.9%, 91.8%, and 86.2%, respectively. This performance was comparable with that of the 3 neuro-ophthalmologists (84.1%, 91.8%, and 73.9%, p = 0.19, p = 1, p = 0.09, respectively). Misclassification by the DLS was mainly observed for moderate papilledema (Frisén grade 3). Agreement scores between the DLS and the neuro-ophthalmologists' evaluation was 0.62 (95% CI 0.57-0.68), whereas the intergrader agreement among the 3 neuro-ophthalmologists was 0.54 (95% CI 0.47-0.62).

CONCLUSIONS

Our DLS accurately classified the severity of papilledema on an independent set of mydriatic fundus photographs, achieving a comparable performance with that of independent neuro-ophthalmologists.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that a DLS using mydriatic retinal fundus photographs accurately classified the severity of papilledema associated in patients with a diagnosis of increased intracranial pressure.

The Effective Management of Idiopathic Intracranial Hypertension Delivered by In-person and Virtual Group Consultations: Results and Reflections from a Phase One Service Delivery

The increasing incidence of idiopathic intracranial hypertension (IIH) with the obesity epidemic is leading to increased pressures on service capacity. Evidence shows that group consultations (GCs) deliver effective, person-centred healthcare, but the feasibility for IIH is unknown. We set out to develop and test a safe and effective GC service for IIH. Through an interactive approach, we co-designed a bespoke in-person and virtual GC model, where patients are reviewed in a group setting. Improvements were made following each session following patient input and team reflections. Outcomes measured included patient satisfaction, self-perceived health literacy, and successful implementation of the GCs. During the pilot, eight in-person GCs were delivered: once-monthly (Oct-Dec 2019), then twice-monthly (Jan-Feb 2020). Feedback was received from 49/53 patients. 100% felt more satisfied and heard, 100% felt more involved in decision-making, 98% had a better understanding of their condition, 96% felt more able to cope with their condition and keep themselves healthy, 94% rated this as a positive experience, and 90% reported improved access and more time with their clinician compared with existing 1:1 appointments. Since September 2020, in response to the COVID-19 pandemic, we transitioned to weekly virtual GCs, receiving overwhelmingly positive feedback (median scores: patient satisfaction 9.5/10; being listened to by clinician 10/10; involved by clinician in treatment decisions 10/10; clinician explanation of treatment 10/10; and opportunity to discuss condition or treatment 10/10). GCs are safe and effective for IIH, and preferred in our patient cohort. This allowed ongoing high-quality, person-centred care despite challenges from the COVID-19 pandemic.

The Health Economic Evaluation of Bariatric Surgery Versus a Community Weight Management Intervention Analysis from the Idiopathic Intracranial Hypertension Weight Trial (IIH:WT)

BACKGROUND

The Idiopathic Intracranial Hypertension Weight Trial (IIH:WT) established the efficacy of bariatric surgery as compared to a community weight management intervention in reducing intracranial pressure in active IIH. The aim of this cost-effectiveness analysis was to evaluate the economic impact of these weight loss treatments for IIH.

METHODS

IIH:WT was a five-year randomised, controlled, parallel group, multicentre trial in the United Kingdom, where participants with active IIH and a body mass index ≥35 kg/m2 were randomly assigned (1:1) to receive access to bariatric surgery or a community weight management intervention. All clinical and quality of life data was recorded at baseline, 12 and 24 months. Economic evaluation was performed to assess health-care costs and cost-effectiveness. Evaluations were established on an intention to treat principle, followed by a sensitivity analysis using a per protocol analysis.

RESULTS

The mean total health care costs were GBP 1353 for the community weight management arm and GBP 5400 for the bariatric surgery arm over 24 months. The majority of costs for the bariatric surgery arm relate to the surgical procedure itself. The 85% who underwent bariatric surgery achieved a 12.5% reduction in intracranial pressure at 24 months as compared to 39% in the community weight management arm; a mean difference of 45% in favour of bariatric surgery. The cost effectiveness of bariatric surgery improved over time.

CONCLUSIONS

The IIH:WT was the first to compare the efficacy and cost-effectiveness of bariatric surgery with community weight management interventions in the setting of a randomised control trial. The cost-effectiveness of bariatric surgery improved over time and therefore the incremental cost of surgery when offset against the incremental reduction of intracranial pressure improved after 24 months, as compared with 12 months follow up.

Impaired glymphatic function in idiopathic intracranial hypertension

Idiopathic intracranial hypertension is a brain disease incorporating cerebrospinal fluid disturbance, increased intracranial pressure and visual failure, but with unknown cause. This study examined a hypothesis that glymphatic function is impaired in idiopathic intracranial hypertension patients. The MRI contrast agent gadobutrol was utilized as a cerebrospinal fluid tracer following intrathecal administration. Consecutive standardized T1 MRI acquisitions over 48 h were done to assess tracer distribution within brain of 15 idiopathic intracranial hypertension patients and 15 reference individuals who were comparable in age and gender distribution. Using FreeSurfer software, we semi-quantified tracer level in multiple brain regions as T1 MRI signal change. The tracer enriched the entire brain of idiopathic intracranial hypertension and reference subjects. In idiopathic intracranial hypertension, tracer enrichment was increased and clearance of tracer delayed from a wide range of brain regions, including both grey and white matter. Differences were most evident in frontal and temporal regions. The pulsatile intracranial pressure was measured overnight and tracer propagation in brain compared between individuals with pathological and normal pulsatile intracranial pressure. In individuals with pathological pulsatile intracranial pressure, tracer enrichment was stronger and clearance from brain delayed, particularly in regions nearby large artery trunks at the brain surface. The present in vivo observations provide evidence for impaired glymphatic function in several brain regions of idiopathic intracranial hypertension patients. Glymphatic failure may imply altered clearance of metabolic byproducts, which may precede neurodegeneration. Further studies are needed to characterize glymphatic failure in idiopathic intracranial hypertension.

An institutional review of hospital resource utilization and patient radiation exposure in shunted idiopathic intracranial hypertension

Patients with idiopathic intracranial hypertension (IIH) frequently utilize healthcare services and undergo radiological studies to assess refractory headache symptoms despite cerebrospinal fluid diversion. To delineate the clinical utility of different imaging modalities and to estimate cumulative patient radiation exposure in shunted patients with IIH, we retrospectively reviewed 100 randomly selected patients with IIH and a prior cerebrospinal fluid diversion procedure treated at our institution between July 2010 and August 2018. Patients had an average of 16.3 office (SD ± 13.8), 12.4 emergency department (± 21.0), and 4.6 inpatient (± 5.1) encounters over an average 4.8 years of follow-up. Patients underwent an average of 9.0 head CTs (± 8.1), 10.3 shunt series x-rays (± 11.2), and 4.3 MRIs (± 3.7). Approximated radiation exposure per patient was 21.4 mSv (± 18.7). Radiological studies performed for acute symptoms usually demonstrated no actionable findings (82.5% CTs, 97.5% shunt series x-rays, and 79.6% MRIs). Shunted IIH patients undergo numerous radiological studies and are subject to considerable levels of radiation, yet imaging shows actionable findings in less than 10% percent of radiographic studies. IIH patients may benefit from radiation-reducing protocols and the use of alternative imaging to assess symptoms.

Increased occurrence of pathological mitochondria in astrocytic perivascular endfoot processes and neurons of idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) primarily affects fertile, overweight women, and presents with the symptoms of raised intracranial pressure. The etiology is unknown but has been thought to relate to cerebrospinal fluid disturbance or cerebral venous stenosis. We have previously found evidence that IIH is also a disease of the brain parenchyma, evidenced by alterations at the neurogliovascular interface, including astrogliosis, pathological changes in the basement membrane and pericytes, and alterations of perivascular aquaporin‐4. The aim of this present electron microscopic study was to examine whether mitochondria phenotype was changed in IIH, particularly focusing on perivascular astrocytic endfeet and neurons (soma and pre‐ and postsynaptic terminals). Cortical brain biopsies of nine reference individuals and eight IIH patients were analyzed for subcellular distribution and phenotypical features of mitochondria using transmission electron microscopy. We found significantly increased prevalence of pathological mitochondria and reduced number of normal mitochondria in astrocytic endfeet of IIH patients. The degree of astrogliosis correlated negatively with the number of normal mitochondria in astrocytic endfoot processes. Moreover, we found significantly increased number of pathological mitochondria in pre‐ and postsynaptic neuronal terminals, as well as significantly shortened distance between mitochondria and endoplasmic reticulum contacts. Finally, the length of postsynaptic density, a marker of synaptic strength, was on average reduced in IIH. The present data provide evidence of pathological mitochondria in perivascular astrocytes endfeet and neurons of IIH patients, highlighting that impaired metabolism at the neurogliovascular interface may be a facet of IIH.

Guide to preclinical models used to study the pathophysiology of idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is characterised by raised intracranial pressure (ICP) and papilloedema in the absence of an identifiable secondary cause typically occurring in young women with obesity. The impact is considerable with the potential for blindness, chronic disabling headaches, future risk of cardiovascular disease and marked healthcare utilisation. There have been marked advances in our understanding the pathophysiology of IIH including the role of androgen excess. Insight into pathophysiological underpinnings has arisen from astute clinical observations, studies, and an array of preclinical models. This article summarises the current literature pertaining to the pathophysiology of IIH. The current preclinical models relevant to gaining mechanistic insights into IIH are then discussed. In vitro and in vivo models which study CSF secretion and the effect of potentially pathogenic molecules have started to glean important mechanistic insights. These models are also useful to evaluate novel therapeutic targets to abrogate CSF secretion. Importantly, in vitro CSF secretion assays translate into relevant changes in ICP in vivo. Models of CSF absorption pertinent to IIH, are less well established but highly relevant and of future interest. There is no fully developed in vivo model of IIH but this remains an area of importance. Progress is being made to improve our understanding of the underlying aetiology in IIH including the characterisation of disease biomarkers and their mechanistic role in driving disease pathology. Preclinical models, used to evaluate IIH mechanisms are yielding important mechanistic insights. Further work to refine these techniques will provide translatable insights into disease aetiology.

Emerging themes in idiopathic intracranial hypertension

Purpose

Idiopathic intracranial hypertension (IIH) is a rare disorder characterised by raised intracranial pressure. The underlying pathophysiology is mostly unknown and effective treatment is an unmet clinical need in this disease. This review evaluates key emerging themes regarding disease characteristics, mechanisms contributing to raised intracranial pressure and advances in potential therapeutic targets.

Findings

IIH is becoming more common, with the incidence rising in parallel with the global obesity epidemic. Current medical management remains centred around weight management, which is challenging. Metabolic investigations of patients have identified specific androgen profiles in cerebrospinal fluid (CSF), which suggest an endocrine dysfunction impacting CSF secretion in IIH. Glucagon-like peptide-1 (GLP-1) and 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) have been found to play a role in CSF dynamics in IIH and have formed the basis of the first clinical trials looking at new treatments.

Conclusions

Identification of novel molecular targets thought to underlie IIH pathology is now being translated to clinical trials.

Transverse venous sinus stenosis in idiopathic intracranial hypertension: a prospective pilot study

OBJECTIVE

Whether transverse venous sinus stenosis (TVSS) causes idiopathic intracranial hypertension (IIH) or is an effect of the increased intracranial pressures is controversial. The purpose of this study was to assess the feasibility of serial imaging in patients with IIH on medical management.

DESIGN AND PARTICIPANTS

Patients found to have IIH and TVSS on contrast-enhanced magnetic resonance venography (CEMRV) were recruited in a prospective cohort study. Patients were medically managed and followed with a CEMRV immediately after lumbar puncture, 3-6 months after diagnosis with resolution of IIH symptoms, and 1 year after diagnosis. Ophthalmological data were collected at the time of diagnosis, 3-6 months after diagnosis, and 1 year after diagnosis. Feasibility data, including patient recruitment rate, barriers, and logistical issues, were recorded.

RESULTS

Twenty patients with suspected IIH were screened, and 5 of 7 (71.4%; 95% confidence interval: 36.21-100) eligible patients were enrolled in 1 year, at completion. All recruited patients had clinical resolution of their IIH on medical therapy, and none of them had any obvious change in their TVSS.

CONCLUSIONS

Prospective examination of TVSS with serial magnetic resonance imaging in patients with IIH is feasible. TVSS in patients with IIH did not show any change, despite clinical improvement on medical management in all participants.

Blood-Brain Barrier Dysfunction in Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH) is traditionally considered benign and characterized by symptoms related to increased intracranial pressure, including headache and impaired vision. We have previously demonstrated that brains of IIH patients exhibit patchy astrogliosis, increased perivascular expression of the water channel aquaporin-4 (AQP4) as well as degenerating pericyte processes and capillary basement membranes. Given the established association between pericyte degeneration and blood-brain barrier (BBB) dysfunction, we investigated blood protein leakage by light microscopic immunohistochemistry. We also assessed perivascular AQP4 expression by immunogold transmission electron microscopy. The study included 14 IIH patients and 14 reference (REF) subjects undergoing neurosurgery for epilepsy, aneurysm, or tumor. Evidence of BBB dysfunction, measured as area extravasated fibrinogen/fibrin, was significantly more pronounced in IIH than REF individuals. The extent of extravasated fibrinogen was positively correlated with increasing degree of astrogliosis and vascular AQP4 immunoreactivity, determined by light microscopy. Immunogold transmission electron microscopy revealed no overall changes in AQP4 expression at astrocytic vascular endfeet in IIH (n = 8) compared to REF (n = 11) individuals. Our results provide evidence of BBB leakage in IIH, signifying that IIH is a more serious neurodegenerative disease than previously considered.

Lumbo-peritoneal shunt as treatment modality for visual symptoms in idiopathic intracranial hypertension: A single institution experience

OBJECTIVES

To evaluate the efficacy of lumbo-peritoneal shunt (LPS) in patients of idiopathic intracranial hypertension presenting with visual symptoms.

METHODS

Between Apr. 2014 and Mar. 2018, 70 patients of Idiopathic Intracranial Hypertension (IIH) underwent treatment at our institution. Patients were evaluated for neurological and ophthalmological status and were subjected to LPS depending on their symptoms.

RESULTS

Mean opening pressure was 29.97±5.33cm of water and mean Body-Mass Index (BMI) was 26.51±3 and the two were significantly correlated (p-value 0.006). All patients with visual symptoms (23) underwent LPS and others (47) were managed medically. All patients with LPS and 25 of medically managed patients improved, while 22 medically-managed patients required LPS due to deterioration in visual symptomatology. The proportion of patients showing complete resolution of features of IIH was significantly different between the three groups. Of the 7 patients with shunt extrusion/migration, only 2 required revision.

CONCLUSION

LPS is an equally effective and more technically familiar modality for treatment of IIH for neurosurgeons and should be offered to asymptomatic patients with objective visual signs. Shunt extrusion/migration may not always warrant revision due to "mini-shunt" that drains Cerebro-Spinal Fluid (CSF) through shunt tract even after extrusion.

The role of opening CSF pressure in response to treatment for idiopathic intracranial hypertension (IIH)

The aim of the current study was to assess the risk factors, clinical symptoms and Cerebrospinal fluid (CSF) pressure of idiopathic intracranial hypertension (IIH) with emphasis on determining the risk factors which involved in poor response to treatment. We retrospectively included 202 patients who were diagnosed with IIH. Disease severity was classified according to prescribed therapeutic option into 4 groups: acetazolamide (group 1), Acetazolamide plus topiramate or Lasix (group 2), repeated LP (group 3) and surgical intervention (group 4). Being in the higher group was considered as a higher severity of disease and poor response to treatment. Among the evaluated features of IIH, the strongest association were observed between opening CSF pressure and disease severity. So that, the highest CSF pressure was observed in patients who underwent surgery, which represent the highest severity of disease (group 4) and poor response to therapy (mean ± SD: 43.9 ± 21.1 cm H₂O). Headache was the most prevalent symptom of IIH in our series which was significantly higher among acetazolamide group. Blurred vision was the second most common symptoms which, unlike the headache was more reported in surgery group. Our results suggested that higher CSF pressure could be the risk factors of poor response to therapy, which may raise need for more intensive treatment. Furthermore, suffering of headache without blurred vision can consider as a prognostic factor for mild severity and good response to treatment.

Mortality among patients with idiopathic intracranial hypertension enrolled in the IH Registry

OBJECTIVE

To determine (1) if mortality among patients with idiopathic intracranial hypertension (IIH) enrolled in the Intracranial Hypertension Registry (IHR) is different from that of the general population of the United States and (2) what the leading underlying causes of death are among this cohort.

METHODS

Mortality and underlying causes of death were ascertained from the National Death Index. Indirect standardization using age- and sex-specific nationwide all-cause and cause-specific mortality data extracted from the Centers for Disease Control and Prevention Wonder Online Database allowed for calculation of standardized mortality ratios (SMR).

RESULTS

There were 47 deaths (96% female) among 1437 IHR participants that met inclusion criteria. The average age at death was 46 years (range, 20-95 years). Participants of the IHR experienced higher all-cause mortality than the general population (SMR, 1.5; 95% confidence interval [CI], 1.2-2.1). Suicide, accidents, and deaths from medical/surgical complications were the most common underlying causes, accounting for 43% of all deaths. When compared to the general population, the risk of suicide was over 6 times greater (SMR, 6.1; 95% CI, 2.9-12.7) and the risk of death from accidental overdose was over 3 times greater (SMR, 3.5; 95% CI, 1.6-7.7). The risk of suicide by overdose was over 15 times greater among the IHR cohort than in the general population (SMR, 15.3; 95% CI, 6.4-36.7).

CONCLUSIONS

Patients with IIH in the IHR possess significantly increased risks of death from suicide and accidental overdose compared to the general population. Complications of medical/surgical treatments were also major contributors to mortality. Depression and disability were common among decedents. These findings should be interpreted with caution as the IHR database is likely subject to selection bias.

Eye Conditions in Women

Changes in vision can have significant impact on health and quality of life. Differences between women and men have been identified in the incidence of several eye conditions. Some of these differences are a result of the greater longevity of women. However, the eye, like other organs, is susceptible to the impacts of inflammation and sex steroids. Conditions, such as thyroid eye disease, optic neuritis, and dry eye disease are related to autoimmune or inflammatory conditions and are, thus, more common among women. Idiopathic intracranial hypertension occurs disproportionately in women of childbearing age; the etiology of this condition appears to be related to both inflammatory and sex hormone fluctuations.

Spontaneous cerebrospinal fluid leak and idiopathic intracranial hypertension

PURPOSE OF REVIEW

To review the most recent literature on the relationship of spontaneous cerebrospinal fluid (CSF) leak with idiopathic intracranial hypertension (IIH) and considerations in management of these conditions.

RECENT FINDINGS

A link has been proposed between spontaneous CSF leak and IIH based on similar demographics, radiologic, and clinical findings in these patients, and on a plausible mechanism of skull base erosion in the setting of high CSF pressure over time. IIH patients with CSF leak may not present with classic IIH signs and symptoms as the leak can alleviate excess pressure; however, they may develop these after a leak is repaired. There may also be a higher risk of leak recurrence if intracranial hypertension is not treated postoperatively.

SUMMARY

A growing body of evidence supports an association between IIH and spontaneous CSF leak. However, this relationship is still not fully elucidated, and there is no current agreement on how to incorporate screening, management, or counseling guidelines for CSF leak into the care of IIH patients. There are also no specific guidelines for evaluation/management of IIH in patients with spontaneous CSF leak. Further interdisciplinary research is needed to explore this connection and to establish screening, evaluation, and management guidelines.

Long-Term Follow-up of Pseudotumor Cerebri Syndrome in Prepubertal Children, Adolescents, and Adults

PURPOSE

Pseudotumor cerebri syndrome can have a recurrent course. We compared the long-term disease course, recurrences, and final visual outcomes in prepubertal children, adolescents, and adults.

METHODS

In this retrospective observational study, patients were divided into prepubertal children (group A) adolescents (group B), and adults (group C).

RESULTS

Sixty-five patients (56 females, nine males) were included, 26.2% in group A, 24.6% in group B, and 49.2% in group C. Age at diagnosis was 8.6 ± 2.0 years, 14.3 ± 1.5 years, and 31.9 ± 9.7 years for the prepubertal children, adolescents, and adults, respectively. Medical treatment duration was similar (2.4 to 3.3 years, P > 0.05). Recurrences were observed in 23.5% of prepubertal children, 50% of adolescents, and 28.1% of adults. Recurrences occurred within 1.3 ± 0.6 years from treatment cessation in the prepubertal group compared with 3.8 ± 5.1 years in adolescents and 2.7 ± 2.0 years in adults (P = 0.267). Optic neuropathy was evident in 41% of group A, 31% of group B, and 87.5% of group C (P < 0.001). Obesity and cerebrospinal fluid opening pressures were unassociated with either relapsing rates or final visual outcomes in all groups.

CONCLUSIONS

Pseudotumor cerebri syndrome exhibits a relapsing course in a third of cases. Recurrences tend to occur within one year after treatment cessation in prepubertal children, and within three years in older patients, revealing the importance of longer follow-up, especially in adults. Optic neuropathy was more common in adults along with a tendency for visual decline. Longer treatment times were associated with fewer recurrences.

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.

The effect of CSF drain on the optic nerve in idiopathic intracranial hypertension

Background

Elevation of intracranial pressure in idiopathic intracranial hypertension induces an edema of the prelaminar section of the optic nerve (papilledema). Beside the commonly observed optic nerve sheath distention, information on a potential pathology of the retrolaminar section of the optic nerve and the short-term effect of normalization of intracranial pressure on these abnormalities remains scarce.

Methods

In this exploratory study 8 patients diagnosed with idiopathic intracranial hypertension underwent a MRI scan (T2 mapping) as well as a diffusion tensor imaging analysis (fractional anisotropy and mean diffusivity). In addition, the clinical presentation of headache and its accompanying symptoms were assessed. Intracranial pressure was then normalized by lumbar puncture and the initial parameters (MRI and clinical features) were re-assessed within 26 h.

Results

After normalization of CSF pressure, the morphometric MRI scans of the optic nerve and optic nerve sheath remained unchanged. In the diffusion tensor imaging, the fractional anisotropy value was reduced suggesting a tissue decompression of the optic nerve after lumbar puncture. In line with these finding, headache and most of the accompanying symptoms also improved or remitted within that short time frame.

Conclusion

The findings support the hypothesis that the elevation of intracranial pressure induces a microstructural compression of the optic nerve impairing axoplasmic flow and thereby causing the prelaminar papilledema. The microstructural compression of the optic nerve as well as the clinical symptoms improve within hours of normalization of intracranial pressure.

What are the research priorities for idiopathic intracranial hypertension? A priority setting partnership between patients and healthcare professionals

OBJECTIVE

Idiopathic intracranial hypertension (IIH) is under-researched and the aim was to determine the top 10 research priorities for this disease.

DESIGN

A modified nominal group technique was used to engage participants who had experience of IIH.

SETTING

This James Lind Alliance Priority Setting Partnership was commissioned by IIH UK, a charity.

PARTICIPANTS

People with IIH, carers, family and friends, and healthcare professionals participated in two rounds of surveys to identify unique research questions unanswered by current evidence. The most popular 26 uncertainties were presented to stakeholders who then agreed the top 10 topics.

RESULTS

The top 10 research priorities for IIH included aetiology of IIH, the pathological mechanisms of headache in IIH, new treatments in IIH, the difference between acute and gradual visual loss, the best ways to monitor visual function, biomarkers of the disease, hormonal causes of IIH, drug therapies for the treatment of headache, weight loss and its role in IIH and finally, the best intervention to treat IIH and when should surgery be performed.

CONCLUSIONS

This priority setting encouraged people with direct experience of IIH to collectively identify critical gaps in the existing evidence. The overarching research aspiration was to understand the aetiology and management of IIH.

Idiopathic Intracranial Hypertension: Review of Clinical Syndrome, Imaging Findings, and Treatment

Idiopathic intracranial hypertension (IIH) is a syndrome of unknown cause that is increasing in frequency. Patients who are typically women of childbearing age and obese present with headaches and may also present with visual changes that may become chronic. The purpose of this review is to describe the possible mechanisms for this disease and also to illustrate the ever increasing role of imaging in the diagnosis of this disorder. In addition, the various methods of treatment including medical and surgical will be reviewed. The fact that idiopathic intracranial hypertension has undergone many name changes over the years serves as a reminder that the underlying mechanism is still not well understood. Although there are only several possible mechanisms that can cause increased intracranial pressure, it is still not certain which of these mechanisms is involved. The role of imaging has significantly changed in the evaluation of patients with possible IIH. First, it is involved in ruling out secondary causes of increased intracranial pressure. In addition, there is now ample evidence that the previously held belief that imaging of patients with IIH should be normal is incorrect but rather that there are several subtle findings that radiologists need to look for. These findings include a partially empty sella, flattening of the posterior globe, cupping of optic disks and distension of the optic nerve sheaths. In addition, the role of intracranial venography is playing an ever increasing role due to the finding that a very high percentage of patients have dural venous sinus stenoses. It is becoming clear that there is potentially true morbidity associated with idiopathic intracranial hypertension. The earlier the disease can be diagnosed, the earlier treatment can be started to minimalize permanent visual changes including blindness. Treatment varies from institution to institution due to the fact that multiple specialists with different perspectives treat these patients. Knowledge of subtle imaging features associated with idiopathic intracranial hypertension can help radiologists establish the diagnosis earlier and potentially prevent complications of this disorder. However imaging has not as of yet been shown to be beneficial in managing patients with idiopathic intracranial hypertension.

Differing presenting features of idiopathic intracranial hypertension in the UK and US

AIM

Demographic factors potentially influencing the presentation and severity of idiopathic intracranial hypertension (IIH) in the US vs. UK populations include obesity and ethnicity. We aimed to compare the presenting features of IIH between populations in the UK and US tertiary referral centres, to assess what population differences exist and whether these cause different presentations and impact on visual function.

METHODS

Clinical data were collected on 243 consecutive UK IIH patients and 469 consecutive US IIH patients seen after 2012 in two tertiary centres. Visual function was defined as severe visual loss when Humphrey visual field mean deviation was <-15 dB, when Goldmann visual fields showed constriction or when visual acuity was <20/200.

RESULTS

US patients were more commonly of self-reported black race (58.9% vs. 7.1%) than UK patients, but had a similar mean body mass index (38.3 ± 0.63kg/m² UK vs. 37.7 ± 0.42kg/m² US; p = 0.626). The UK cohort had lower presenting Frisén grade (median 1 vs. 2; p < 0.001) and severe visual loss less frequently (15.4% vs. 5%; p = 0.014), but there was no difference in mean cerebrospinal fluid-opening pressure (CSF-OP) (35.8 ± 0.88cmH₂O UK vs. 36.3 ± 0.52cmH₂O US; p = 0.582). African Americans had poorer visual outcomes compared with US whites (19.4% vs. 10% severe visual loss; p = 0.011). Visual function was weakly associated with CSF-OP (R² = 0.059; p = 0.001), which was similar between UK and US patients.

CONCLUSIONS

The UK and the US cohorts had a similar average presenting BMI. However, the worse presenting visual function in the US IIH cohort was partially attributable to differences in the black populations in the two countries.

Emergency department utilization among individuals with idiopathic intracranial hypertension

PURPOSE

Idiopathic intracranial hypertension (IIH) can be a debilitating disorder that is difficult to identify and treat. Failure to adequately manage IIH symptoms may force patients to present at emergency departments (EDs) seeking symptom relief. The purpose of this paper is to empirically characterize ED use by previously diagnosed IIH patients.

DESIGN/METHODOLOGY/APPROACH

Patients diagnosed with IIH, and who registered with the Intracranial Hypertension Registry by 2014, were solicited for study inclusion. A survey was designed to elicit ED use during the period 2010-2012. Information on demographic and socioeconomic characteristics, IIH signs and symptoms, time since diagnosis, perspectives of ED use and quality of life was collected. Quality of life was assessed using an adaptation of the Migraine-Specific Quality of Life Questionnaire. Data were analyzed using descriptive statistics and nonparametric hypothesis tests.

FINDINGS

In total, 39 percent of IIH patients used emergency services over the study period; those that did used the services intensely. These patients were more likely to be non-white, live in households making less than $25,000 annually, have public insurance and have received a diversional shunt procedure. Patients who used the ED were less likely to live in households making $100,000, or more, annually and have private insurance. Participants who used the ED had significantly lower quality-of-life scores, were younger and had been diagnosed with IIH for less time.

ORIGINALITY/VALUE

ED staff and outside physicians can utilize the information contained in this study to more effectively recognize the unique circumstances of IIH patients who present at EDs.

Intracranial Venous Sinus Stenting: A Review of Idiopathic Intracranial Hypertension and Expanding Indications

Idiopathic intracranial hypertension (IIH) is a functionally limiting disorder secondary to increased intracranial pressures (ICPs) with a prevalence of one per 100,000 persons. It is estimated to cost >$400 million per year in productively. Symptoms classically consist of chronic headaches, papilledema, and visual loss. The pathophysiology is unknown but postulated to involve increased resistance to cerebrospinal fluid (CSF) absorption. Traditional treatments involve weight loss, acetazolamide, CSF diversion, or optic nerve fenestration. More recent technology has allowed exploration of venous sinus stenosis. Through venous sinus stenting (VSS), the ICPs and venous sinus pressures decrease. After treatment, >75% exhibit an improvement in headaches, ~50% improvement in tinnitus, and ~50 % improvement in ophthalmologic testing. Complications are rare but involve stent stenosis, femoral pseudoaneurysm, and hemorrhages. Future studies will look into controlled studies for VSS as well as expansion to other venous structures of the intracranial circulation.

The link between idiopathic intracranial hypertension, fibromyalgia, and chronic fatigue syndrome: exploration of a shared pathophysiology

PURPOSE

Idiopathic intracranial hypertension (IICH) is a condition characterized by raised intracranial pressure (ICP), and its diagnosis is established when the opening pressure measured during a lumbar puncture is elevated >20 cm H2O in nonobese patients or >25 cm H2O in obese patients. Papilledema is caused by forced filling of the optic nerve sheath with cerebrospinal fluid (CSF). Other common but underappreciated symptoms of IICH are neck pain, back pain, and radicular pain in the arms and legs resulting from associated increased spinal pressure and forced filling of the spinal nerves with CSF. Widespread pain and also several other characteristics of IICH share notable similarities with characteristics of fibromyalgia (FM) and chronic fatigue syndrome (CFS), two overlapping chronic pain conditions. The aim of this review was to compare literature data regarding the characteristics of IICH, FM, and CFS and to link the shared data to an apparent underlying physiopathology, that is, increased ICP.

METHODS

Data in the literature regarding these three conditions were compared and linked to the hypothesis of the shared underlying physiopathology of increased cerebrospinal pressure.

RESULTS

The shared characteristics of IICH, FM, and CFS that can be caused by increased ICP include headaches, fatigue, cognitive impairment, loss of gray matter, involvement of cranial nerves, and overload of the lymphatic olfactory pathway. Increased pressure in the spinal canal and in peripheral nerve root sheaths causes widespread pain, weakness in the arms and legs, walking difficulties (ataxia), and bladder, bowel, and sphincter symptoms. Additionally, IICH, FM, and CFS are frequently associated with sympathetic overactivity symptoms and obesity. These conditions share a strong female predominance and are frequently associated with Ehlers-Danlos syndrome.

CONCLUSION

IICH, FM, and CFS share a large variety of symptoms that might all be explained by the same pathophysiology of increased cerebrospinal pressure.

The expanding burden of idiopathic intracranial hypertension

Objective

To quantify the hospital burden and health economic impact of idiopathic intracranial hypertension.

Methods

Hospital Episode Statistics (HES) national data was extracted between 1st January 2002 and 31st December 2016. All those within England with a diagnosis of idiopathic intracranial hypertension were included. Those with secondary causes of raised intracranial pressure such as tumours, hydrocephalus and cerebral venous sinus thrombosis were excluded.

Results

A total of 23,182 new IIH cases were diagnosed. Fifty-two percent resided in the most socially deprived areas (quintiles 1 and 2). Incidence rose between 2002 and 2016 from 2.3 to 4.7 per 100,000 in the general population. Peak incidence occurred in females aged 25 (15.2 per 100,000). 91.6% were treated medically, 7.6% had a cerebrospinal fluid diversion procedure, 0.7% underwent bariatric surgery and 0.1% had optic nerve sheath fenestration. Elective caesarean sections rates were significantly higher in IIH (16%) compared to the general population (9%), p < 0.005. Admission rates rose by 442% between 2002 and 2014, with 38% having repeated admissions in the year following diagnosis. Duration of hospital admission was 2.7 days (8.8 days for those having CSF diversion procedures). Costs rose from £9.2 to £50 million per annum over the study period with costs forecasts of £462 million per annum by 2030.

Conclusions

IIH incidence is rising (by greater than 100% over the study), highest in areas of social deprivation and mirroring obesity trends. Re-admissions rates are high and growing yearly. The escalating population and financial burden of IIH has wide reaching implications for the health care system.

Idiopathic intracranial hypertension: consensus guidelines on management

The aim was to capture interdisciplinary expertise from a large group of clinicians, reflecting practice from across the UK and further, to inform subsequent development of a national consensus guidance for optimal management of idiopathic intracranial hypertension (IIH).

METHODS

Between September 2015 and October 2017, a specialist interest group including neurology, neurosurgery, neuroradiology, ophthalmology, nursing, primary care doctors and patient representatives met. An initial UK survey of attitudes and practice in IIH was sent to a wide group of physicians and surgeons who investigate and manage IIH regularly. A comprehensive systematic literature review was performed to assemble the foundations of the statements. An international panel along with four national professional bodies, namely the Association of British Neurologists, British Association for the Study of Headache, the Society of British Neurological Surgeons and the Royal College of Ophthalmologists critically reviewed the statements.

RESULTS

Over 20 questions were constructed: one based on the diagnostic principles for optimal investigation of papilloedema and 21 for the management of IIH. Three main principles were identified: (1) to treat the underlying disease; (2) to protect the vision; and (3) to minimise the headache morbidity. Statements presented provide insight to uncertainties in IIH where research opportunities exist.

CONCLUSIONS

In collaboration with many different specialists, professions and patient representatives, we have developed guidance statements for the investigation and management of adult IIH.

Meta-analysis and systematic review of population-based epidemiological studies in idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is positively associated with obesity, mostly in young women. The global increase in obesity may influence the burden of IIH. Using the PubMed, Embase, MEDLINE and Web of Science databases, a meta-analysis and systematic review of epidemiological studies of IIH were performed up to June 2017. Temporal changes in IIH incidence were measured, and incidence rates of IIH were correlated with country-specific World Health Organization obesity rates. Prevalence data and shunting rates of IIH were recorded. The quality of epidemiological studies was assessed using the Standards of Reporting of Neurological Disorders (STROND) criteria. In 15 identified studies, there were 889 patients (87% women), mean age 29.8 years. The incidence of IIH ranged from 0.03 to 2.36 per 100 000 per year. The pooled incidence of IIH was 1.20 per 100 000 per year although there was very high heterogeneity (I² 98%). The incidence rates of IIH were correlated with country-specific prevalence of obesity (Spearman's correlation 0.82, P < 0.01). The prevalence of IIH was rarely recorded. A shunting procedure was reported in 8% of patients. STROND criteria were variably reported, median of 26.5 of 43 (range 16-35). IIH is a public health concern as increased obesity prevalence is associated with increased incidence of IIH. A better quality of epidemiological studies is required to improve understanding of IIH and inform health policy for IIH management.