Evidence for potential involvement of pro-inflammatory adipokines in the pathogenesis of idiopathic intracranial hypertension

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.

Cerebrospinal fluid proteins in idiopathic intracranial hypertension: An exploratory SWATH proteomics analysis

PURPOSE

The pathogenesis of idiopathic intracranial hypertension (IIH) is currently poorly understood. This exploratory study aimed to identify potential cerebrospinal fluid (CSF) biomarkers in IIH cases compared to controls using SWATH-MS proteomics approach.

EXPERIMENTAL DESIGN

CSF samples were collected prospectively from IIH cases and control subjects which were subjected to SWATH-MS based untargeted proteomics. Proteins with fold change > 1.5 or < 0.67 and p-value < 0.05 were considered significantly differentially expressed. Data are available via ProteomeXchange with identifier PXD027751. Statistical analysis was conducted in R version 3.6.2.

RESULTS

We included CSF samples from 33 subjects, consisting of 13 IIH cases and 20 controls. A total of 262 proteins were identified in Proteinpilot search. Through SWATH analysis, we quantified 232 proteins. We observed 37 differentially expressed proteins between the two groups with 24 upregulated and 13 downregulated proteins. There were two differential proteins among overweight versus non-overweight IIH cases. Network for 23 proteins was highly connected in the interaction analysis.

CONCLUSIONS AND CLINICAL RELEVANCE

Neurosecretory, neuroendocrine, and inflammatory proteins were predominantly involved in causing IIH. This exploratory study served as a platform to identify 37 differentially expressed proteins in IIH and also showed significant differences between overweight and non-overweight IIH patients.

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.

Cerebrospinal fluid (CSF) and idiopatic intracranial hypertension (IIH): a critical review

Pseudotumor cerebri is a syndrome that results from increased intracranial pressure. The main symptoms are headache, vision disturbances, and pulsatile tinnitus. Definitive diagnosis requires the presence of clinical and/or radiological signs of intracranial hypertension, high opening pressure on lumbar puncture (LP), and normal CSF constitution. Several studies have evaluated new contributions of CSF in the clinical evaluation and the in understanding of the pathophysiology of pseudotumor cerebri. Such studies have included the analysis of inflammatory biomarkers, adipokines, proteomic analysis, and CSF flow studies. In this review, we present the main results obtained so far and critically discuss the present status and the potential role of research involving the CSF in this condition. Based on current knowledge, it is possible to conclude that CSF research with new biomarkers has not yet provided information that can be employed in clinical practice at this moment. However, a better understanding of the constitution and dynamics of CSF circulation in patients with pseudotumor cerebri has brought some information about this condition and can potentially improve our knowledge about this condition in the future.

Increased systemic and adipose 11β-HSD1 activity in idiopathic intracranial hypertension

Context

Idiopathic intracranial hypertension (IIH) is a disease of raised intracranial pressure (ICP) of unknown etiology. Reductions in glucocorticoid metabolism are associated with improvements in IIH disease activity. The basal IIH glucocorticoid metabolism is yet to be assessed.

Objective

The objective of this study was to determine the basal glucocorticoid phenotype in IIH and assess the effects of weight loss on the IIH glucocorticoid phenotype.

Design

A retrospective case-control study and a separate exploratory analysis of a prospective randomized intervention study were carried out.

Methods

The case-control study compared female IIH patients to BMI, age, and sex-matched controls. In the randomized intervention study, different IIH patients were randomized to either a community weight management intervention or bariatric surgery, with patients assessed at baseline and 12 months. Glucocorticoid levels were determined utilizing 24-h urinary steroid profiles alongside the measurement of adipose tissue 11β-HSD1 activity.

Results

Compared to control subjects, patients with active IIH had increased systemic 11β-hydroxysteroid dehydrogenase (11β-HSD1) and 5α-reductase activity. The intervention study demonstrated that weight loss following bariatric surgery reduced systemic 11β-HSD1 and 5α-reductase activity. Reductions in these were associated with reduced ICP. Subcutaneous adipose tissue explants demonstrated elevated 11β-HSD1 activity compared to samples from matched controls.

Conclusion

The study demonstrates that in IIH, there is a phenotype of elevated systemic and adipose 11β-HSD1 activity in excess to that mediated by obesity. Bariatric surgery to induce weight loss was associated with reductions in 11β-HSD1 activity and decreased ICP. These data reflect new insights into the IIH phenotype and further point toward metabolic dysregulation as a feature of IIH.

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.

Cerebral Venous Outflow Implications in Idiopathic Intracranial Hypertension-From Physiopathology to Treatment

In this review, we provide an update on the pathogenesis, diagnosis, and management of adults with idiopathic intracranial hypertension (IIH) and implications of the cerebral venous system, highlighting the progress made during the past decade with regard to mechanisms of the venous outflow pathway and its connection with the cerebral glymphatic and lymphatic network in genesis of IIH. Early diagnosis and treatment are crucial for favorable visual outcomes and to avoid vision loss, but there is also a risk of overdiagnosis and misdiagnosis in many patients with IIH. We also present details about treatment of intracranial hypertension, which is possible in most cases with a combination of weight loss and drug treatments, but also in selected cases with surgical interventions such as optic nerve sheath fenestration, cerebral spinal fluid (CSF) diversion, or dural venous sinus stenting for some patients with cerebral venous sinus stenosis, after careful analysis of mechanisms of intracranial hypertension, patient clinical profile, and method risks.

Idiopathic intracranial hypertension: Do we diagnose and manage it appropriately in the light of current data?

BACKGROUND AND OBJECTIVE

Idiopathic intracranial hypertension (IIH) is an increase of intracranial pressure without a known cause, which usually presented with headache. This study aimed to evaluate the changing diagnosis and management approaches of neurologists for IIH in light of recent data.

METHODS

An online questionnaire about IIH was developed covering 28 questions, and five sections: demographic data, diagnosis, examination, treatment, and follow-up. We compared the approach of neurologists with 1-9 years of experience (group-A) with that of neurologists with more than 10 years' experience (group-B).

RESULTS

A total of 517 neurologists (group A: n = 252, group B: n = 265) participated in the study. Responder rate of questionarre is 18.3%. The approach to IIH in diagnosis, examination, treatment, and follow-up processes was similar in both groups. The younger group (group A) recognized all neuro-radiologic findings, especially flattening of the posterior aspect of the globe (p = 0.001) and tortuosity of the optic nerve (p < 0.001) at higher rates compared with group B. The most commonly used medical treatment was acetazolamide (99%); corticosteroids were used more frequently by group B (p < 0.001). Optic nerve sheath fenestration (88.3%) was the first-line and ventriculo-peritoneal shunt (70.5%) was the second preferred surgical approach. It was observed that serial lumbar puncture applications (57.0%) were preferred more frequently than venous sinus stenting (19.0%) and bariatric surgery (10.0%).

CONCLUSIONS

The changing information in the last decade about IIH was more closely followed by younger neurologists despite their lesser experience, but classic methods were preferred in surgical approaches in both groups. Our findings indicated that post-graduate education and guidelines should be disseminated for IIH.

Neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios as inflammation markers in patients with papilledema due to idiopathic intracranial hypertension

Purpose:

The aim of this study was to investigate the role of inflammation in the pathogenesis of idiopathic intracranial hypertension (IIH) using the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) as inflammation markers.

Methods:

The files of 33 IIH patients and 33 controls were screened for this retrospective study. For each patient, the NLR and PLR values were calculated using a single fasting blood sample. For both eyes, papilledema (PE) grades, best-corrected visual acuity (BCVA), retinal nerve fiber layer thickness (RNFLT), and ganglion cell layer thickness (GCLT) measurements were recorded along with the demographic data, including body mass index (BMI), and complete neurological and ophthalmological findings. Comparisons between the two groups and between the IIH patients with and without PE were made. The associations of NLR and PLR with all other parameters were analyzed independently from age, gender, and BMI.

Results:

NLR and PLR were higher in patients with IIH than controls (P < 0.05). They were also higher in patients with PE (P < 0.05) in the IIH group. NLR and PLR were found to be associated with BCVA (P < 0.001 and P = 0.023, respectively), global RNFLT (P = 0.004 and 0.012, respectively), RNFLT of the temporal quadrant (P < 0.001 and P = 0.042, respectively) and PE grade (P < 0.001 and P = 0.035, respectively).

Conclusion:

The NLR and PLR values and their associations with BCVA, RNFLT, and PE support the hypothesis that inflammation is a very important component of the pathogenesis of IIH.

Systemic and adipocyte transcriptional and metabolic dysregulation in idiopathic intracranial hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a condition predominantly affecting obese women of reproductive age. Recent evidence suggests that IIH is a disease of metabolic dysregulation, androgen excess, and an increased risk of cardiovascular morbidity. Here we evaluate systemic and adipose specific metabolic determinants of the IIH phenotype.

METHODS

In fasted, matched IIH (n = 97) and control (n = 43) patients, we assessed glucose and insulin homeostasis and leptin levels. Body composition was assessed along with an interrogation of adipose tissue function via nuclear magnetic resonance metabolomics and RNA sequencing in paired omental and subcutaneous biopsies in a case-control study.

RESULTS

We demonstrate an insulin- and leptin-resistant phenotype in IIH in excess of that driven by obesity. Adiposity in IIH is preferentially centripetal and is associated with increased disease activity and insulin resistance. IIH adipocytes appear transcriptionally and metabolically primed toward depot-specific lipogenesis.

CONCLUSION

These data show that IIH is a metabolic disorder in which adipose tissue dysfunction is a feature of the disease. Managing IIH as a metabolic disease could reduce disease morbidity and improve cardiovascular outcomes.

FUNDING

This study was supported by the UK NIHR (NIHR-CS-011-028), the UK Medical Research Council (MR/K015184/1), Diabetes UK, Wellcome Trust (104612/Z/14/Z), the Sir Jules Thorn Award, and the Midlands Neuroscience Teaching and Research Fund.

Increased IL-8 concentrations in the cerebrospinal fluid of patients with unipolar depression

INTRODUCTION

Unipolar depression is a common and debilitating disorder. Immunological explanatory approaches have become increasingly important in recent years and can be studied particularly well in the cerebrospinal fluid (CSF). Previous studies discerned alterations in interleukin (IL)-6 and IL-8 levels; however, findings regarding IL-8 were partly contradictory. The aim of the present study was to investigate the concentrations of different cytokines and chemokines, focusing on IL-8, in the CSF of patients with unipolar depression.

MATERIALS AND METHODS

Participants included 40 patients with unipolar depression and 39 mentally healthy controls with idiopathic intracranial hypertension. CSF cytokine levels were measured using a magnetic bead multiplexing immunoassay.

RESULTS

IL-8 levels in the CSF of the patient group with depression were significantly higher than those in the control group (Mean ± SD: 38.44 ± 6.26 pg/ml versus 21.40 ± 7.96 pg/ml; p < .001).

LIMITATIONS

The significance of the results is limited by the retrospective design and methodological aspects.

DISCUSSION

The main findings of this study were significantly higher concentrations of IL-8 in the CSF of patients with unipolar depression than in the control group. The detection of high CSF IL-8 levels in this study supports the idea that inflammatory processes might play a role in the pathophysiology of a subgroup of patients with depression.

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.

Neurofilament light chain as biomarker in idiopathic intracranial hypertension

BACKGROUND

Damage of the optic nerve is the major complication of idiopathic intracranial hypertension. A biomarker indicative for optic nerve damage would help identifying high-risk patients requiring surgical procedures. Here, we studied the potential of cerebrospinal fluid neurofilament to predict idiopathic intracranial hypertension-induced optic nerve damage.

METHODS

In two centers, serum and cerebrospinal fluid of 61 patients with clinically suspected idiopathic intracranial hypertension were prospectively collected. Neurofilament concentrations were measured and related to ophthalmological assessment.

RESULTS

The average cerebrospinal fluid neurofilament concentration in patients with moderate and severe papilledema was increased compared to patients with minor and no papilledema (1755 ± 3507 pg/ml vs. 244 ± 102 pg/ml; p < 0.001). Cerebrospinal fluid neurofilament concentrations correlated with the maximal lumbar puncture opening pressure (r = 0.67, p < 0.001). In patients fulfilling the Friedman criteria for idiopathic intracranial hypertension with or without papilledema (n = 35), development of bilateral visual field defects and bilateral atrophy of the optic nerve were associated with increased average age-adjusted cerebrospinal fluid neurofilament concentrations. At last follow-up (n = 30), 8/13 of patients with increased, but only 3/17 with normal, cerebrospinal fluid neurofilament had developed bilateral visual field defects and/or bilateral optic nerve atrophy resulting in a sensitivity of 72.7% and a specificity of 73.7% of cerebrospinal fluid neurofilament to detect permanent optic nerve damage.

CONCLUSIONS

Cerebrospinal fluid neurofilament is a putative biomarker for optical nerve damage in idiopathic intracranial hypertension.

Infectious and inflammatory disorders might increase the risk of developing idiopathic intracranial hypertension - a national case-control study

Objective

To investigate whether conditions causing inflammatory activation are associated with increased risk of idiopathic intracranial hypertension.

Methods

All newly diagnosed idiopathic intracranial hypertension patients (cases) in Sweden between 2000–2016 were identified using pre-determined algorithms (n = 902) and matched with five controls from the general population and five individuals with an obesity diagnosis (n = 4510) for age, sex, region, and vital status. National health registers provided information on infections, inflammatory disorders and dispensed medications. Conditional logistic regression was used to estimate odds ratios and 95% confidence intervals.

Results

Compared to general population controls, the cases had fourfold increased odds of having an infection (odds ratio = 4.3, 95% confidence interval 3.3–5.6), and threefold increased odds of an inflammatory disorder the year prior to idiopathic intracranial hypertension diagnosis (odds ratio = 3.2, 95% confidence interval 2.4–4.3). Organ specific analyses showed that odds were increased for the study diseases in the respiratory organ, kidney organ and gastrointestinal tract, but not for female genital infections. Similar results were found when comparing idiopathic intracranial hypertension with obese controls though the odds ratios were of lower magnitude. Sub-analyses on exposure to anti-infectious and anti-inflammatory drugs confirmed the increased odds ratios for idiopathic intracranial hypertension patients.

Conclusions

These findings suggest that major inflammatory activation may be a risk factor in idiopathic intracranial hypertension development.

Serum glial fibrillary acidic protein (GFAP)-antibody in idiopathic intracranial hypertension

AIM

Idiopathic intracranial hypertension (IIH), a disease of obscure origin, is characterized by headache and visual disturbances due to increased intracranial pressure. Recent line of evidence has suggested involvement of inflammation in IIH pathogenesis thus bringing forward anti-glial autoimmunity as a potential contributor of IIH. Glial fibrillary acidic protein (GFAP) is a major astrocytic autoantigen associated with a specific form of meningoencephalitis.

MATERIALS AND METHODS

In this study, we investigated the presence of GFAP-antibody in 65 sera (49 obtained during active disease and 16 during remission) and in 15 cerebrospinal fluid (CSF) samples of 58 consecutively recruited IIH patients using cell based assay and indirect immunohistochemistry.

RESULTS

GFAP-antibody was found in active period sera of 2 IIH patients with classical symptoms and good treatment response. Two remission period sera obtained at different time points from one of these cases showed lower titers of GFAP-antibody positivity. IgG from positive samples yielded an astrocytic immunoreactivity pattern. None of the CSF samples showed GFAP-antibodies.

CONCLUSIONS

These results suggest that anti-astrocyte autoimmunity might be present in a fraction of IIH patients. Exact pathogenic significance of this association needs to be further studied.

Oligoclonal bands and levels of interleukin 4, interleukin 10, and tumor necrosis factor alpha in idiopathic intracranial hypertension Egyptian patients

Background

Idiopathic intracranial hypertension (IIH) is a neurological disorder of unknown pathophysiology with many proposed theories that involve CSF dynamics but recently, involvement of inflammatory and autoimmune processes has been postulated.

Objectives

To investigate presence of oligoclonal bands (OCB) in cerebrospinal fluid (CSF) and serum cytokine level in patients with IIH.

Methods

This study was conducted on 27 IIH female patients and 21 age- and sex-matched control groups. Patient and control groups were subjected to measurement of interleukin-4 (IL-4), IL-10, and tumor necrosis factor α (TNF-α) levels in serum, and CSF oligoclonal bands was measured in the IIH patient group. Body mass index (BMI) was measured to both patients and control.

Results

Serum levels of IL-4, IL-10, and TNF alpha were significantly higher in IIH patients than controls (p <  0.001); 22% of IIH patients had positive OCB in CSF. There was a statistically significant difference regarding TNF-α level in OCB-positive and OCB-negative patients being higher in positive patients. No statistically significant correlation was found between serum levels of IL-4, IL-10, TNF-α, and BMI.

Conclusion

Autoimmune inflammatory process may play a role in pathophysiology of IIH.

Trigeminal Hyperexcitability in Idiopathic Intracranial Hypertension: A Blink Reflex Study

PURPOSE

To compare blink reflex examination findings in patients with idiopathic intracranial hypertension (IIH) with migraineurs and controls and to investigate the role of blink reflex data in the follow-up by evaluating their relationship with clinical symptoms.

METHODS

We included 23 patients with IIH, 15 migraineurs, and 16 controls. Blink reflex was studied with bilateral paired stimulations, and the 2R2/1R2 and 2R2c/1R2c area ratios, 1R2, 2R2, 1R2c, and 2R2c latencies were compared (R2:ipsilateral R2 response, R2c:contralateral R2 response).

RESULTS

2R2/1R2 area ratios at 200, 300, and 500 ms interstimulus intervals were significantly higher in the IIH group compared with the controls, and significantly higher 2R2/1R2 area ratio at 200 ms interstimulus interval was also detected in the IIH group compared with the migraine group. Significantly shorter 2R2 latencies were found at 500 and 800 ms interstimulus intervals in IIH group compared with the migraine group and controls. Significantly higher 2R2/1R2 area ratios at 500, 800 ms, and 2R2c/1R2c area ratios at 300, 500, and 800 ms were detected in patients with IIH in remission compared with patients with attacks.

CONCLUSIONS

The significant increase in R2 recovery rates in patients with IIH in remission suggests that there is an increased excitability in the trigeminal pathways. Our findings may provide a new perspective for IIH mechanism related to trigeminal hyperexcitability and evaluating new management strategies.

Glial and neuronal antibodies in patients with idiopathic intracranial hypertension

Headache and visual disturbances are the main presenting symptoms of idiopathic intracranial hypertension (IIH) characterized by increased intracranial pressure (ICP) with an unknown cause. We aimed to investigate the antibodies against optic neuritis-associated glial antigens, aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) and uncharacterized neuronal membrane antigens in IIH patients. Consecutive patients diagnosed according to Friedman revised diagnostic criteria and control subjects were included after their consent. All serum samples were analyzed for antibodies against AQP4 and MOG using cell-based immunofluorescent assays and for uncharacterized neuronal membrane antigens by indirect immunocytochemistry utilizing live neurons. Sera of 34 patients with IIH and 40 control subjects were investigated but none of the patients showed AQP4 and MOG antibodies. However, serum IgG of five IIH patients showed reactivity against membrane antigens of rat hippocampal and cortical neurons. Interestingly, three out of these five patients had nonspecific white matter lesions on MRI, whereas only four of all other patients had these lesions (p = 0.048). AQP4 and MOG antibodies do not seem to have a role in the pathophysiology of IIH. However, association of immunocytochemistry findings with the presence of white matter lesions may suggest that immunological factors contribute to the pathogenesis of IIH in at least some of the patients.

Transverse Sinus Stenosis Is the Most Sensitive MR Imaging Correlate of Idiopathic Intracranial Hypertension

BACKGROUND AND PURPOSE

Patients with idiopathic intracranial hypertension have transverse sinus stenosis on gadolinium-bolused MRV, but other MR imaging signs are less consistently seen. Our aim was to demonstrate that transverse sinus stenosis could be identified on conventional MR imaging, and this identification would allow improved diagnostic sensitivity to this condition.

MATERIALS AND METHODS

MR imaging and MRV images from 63 patients with idiopathic intracranial hypertension and 96 controls were reviewed by using 3 independent procedures. MRV images were graded for the presence and degree of stenosis of the transverse sinus. Postgadolinium coronal T1-weighted sequences were evaluated independent of MRV. The dimensions of the proximal and distal transverse sinus were measured from the MRV examinations, and the cross-sectional area of the transverse sinus was calculated. Correlation among the 3 modes of evaluation of the transverse sinus was conducted by using Wilcoxon/Kruskal-Wallis, Pearson, and Spearman ρ nonparametric statistical techniques.

RESULTS

Transverse sinus stenosis was identified bilaterally on MRV in 94% of patients with idiopathic intracranial hypertension and in 3% of controls. On coronal T1 postgadolinium MR images, transverse sinus stenosis was identified in 83% of patients with idiopathic intracranial hypertension and 7% of controls. Previously described MR imaging signs of intracranial hypertension were identified in 8%-61% of patients with idiopathic intracranial hypertension. Correlation among the 3 modes of evaluation was highly significant (P < .0001).

CONCLUSIONS

Even without the assistance of an MRV sequence, neuroradiologists can validly identify bilateral transverse sinus stenosis in patients with intracranial hypertension more reliably than other previously described MR imaging findings in this condition. We conclude that transverse sinus stenosis is the most useful and sensitive imaging indicator of this disease state.