Differentiation Between the Low and High Trans-Stenotic Pressure Gradient in Patients With Idiopathic Intracranial Hypertension Using 4D Flow MRI-Derived Hemodynamic Parameters.

BACKGROUND: Trans-stenotic pressure gradient (TPG) measurement is essential for idiopathic intracranial hypertension (IIH) patients with transverse sinus (TS) stenosis. Four-D flow MRI may provide a noninvasive imaging method for differentiation of IIH patients with different TPG. PURPOSE: To investigate the associations between 4D flow parameters and TPG, and to evaluate the diagnostic performance of 4D flow parameters in differentiating patients with high TPG (GroupHP) from low TPG (GroupLP). STUDY TYPE: Prospective. POPULATION: 31 IIH patients with TS stenosis (age, 38 ± 12 years; 23 females) and 5 healthy volunteers (age, 25 ± 1 years; 2 females). FIELD STRENGTH/SEQUENCE: 3T, 3D phase contrast MR venography, and gradient recalled echo 4D flow sequences. ASSESSMENT: Scan-rescan reproducibility of 4D flow parameters were performed. The correlation between TPG and flow parameters was analyzed. The netflow and velocity difference between inflow plane, outflow plane, and the stenosis plane were calculated and compared between GroupHP and GroupLP. STATISTICAL TESTS: Pearson's correlation or Spearman's rank correlation coefficient, Independent samples t-test or Wilcoxon rank-sum test, Intra-class correlation coefficient (ICC), Bland-Altman analyses, Receiver operating characteristic curves. A P value <0.05 was considered significant. RESULTS: Significant correlations were found between TPG and netflow parameters including Favg,out-s, Favg,in-s, Fmax,out-s, and Fmax,in-s (r = 0.525-0.565). Significant differences were found in Favg,out-s, Fmax,out-s, Favg,in-s, and Fmax,in-s between GroupHP and GroupLP. Using the cut-off value of 2.19 mL/sec, the Favg,out-s showed good estimate performance in distinguishing GroupHP from GroupLP (AUC = 0.856). The ICC (ranged 0.905-0.948) and Bland-Altman plots indicated good scan-rescan reproducibility. DATA CONCLUSIONS: 4D flow MRI derived flow parameters showed good correlations with TPG in IIH patients with TS stenosis. Netflow difference between outflow and stenosis location at TS shows the good performance in differentiating GroupHP and GroupLP cases. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Identifying idiopathic intracranial hypertension in a hospital-based chronic headache population: Utility of magnetic resonance imaging, magnetic resonance venography and trans-orbital sonography.

BACKGROUND: One of the most underestimated types of chronic headaches is headaches as a result of cerebro-spinal fluid dysregulation disorders. Idiopathic intracranial hypertension (IIH) presents with headache and visual symptoms and usually is associated with papilledema. We identified patients with IIH in a chronic headache population presenting to a hospital-based headache clinic, and studied its associations with clinical, sonographic and magnetic resonance imaging (MRI) findings. METHODS: Of 168 patients, 141 chronic headache patients were identified and completed the study procedures (semi-structured medical interview, fundus examination, MRI brain with magnetic resonance venography (MRV) and trans-orbital sonography (TOS)). Patients with abnormal findings underwent lumbar puncture for opening pressure. RESULTS: The prevalence of IIH was 27%. IIH patients were of higher age, had gnawing/throbbing headache in the vertex in most cases, and had higher body mass index. Fundus examination had a sensitivity of 79% and a specificity of 98% for the detection of IIH cases. Approximately 23% of IIH patients had no papilledema. The most sensitive MR sign was found to be transverse sinus stenosis. TOS showed optic nerve sheath dilation in 35.7% of IIH without papilledema cases. CONCLUSIONS: The prevalence of IIH is high in the chronic headache population and should be suspected in the headache clinic setting, particularly because there is significant overlap with migraine symptomatology. MRI/MR venography and TOS can be useful adjunct tests to identify IIH patients.

Role of diffusion tensor imaging in the evaluation of white matter integrity in idiopathic intracranial hypertension.

OBJECTIVES: To determine whether idiopathic intracranial hypertension (IIH) may affect white matter integrity and optic pathways by using diffusion tensor imaging (DTI) and to correlate the DTI metrics with intracranial pressure (ICP). METHODS: This study is a retrospective case-control study. A total of 42 patients who underwent lumbar puncture and those with elevated ICP, meeting the diagnostic criteria for IIH, were included in the study. All patients had supportive magnetic resonance imaging findings for the diagnosis of IIH. The headache control group comprised 36 patients who presented to the Neurology Department with infrequent episodic tension-type headache, had a normal neurologic examination, and had clinical and radiological findings suggestive of normal ICP. For each patient with IIH, clinical findings and ophthalmological measurements were recorded. The apparent diffusion coefficient (ADC), fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) values were calculated using a region of interest-based method in different white matter tracts and optic pathways and compared. RESULTS: A total of 42 patients diagnosed with IIH (three males, 39 females), with a mean (standard deviation [SD] age of 38.1 (8.9) years), and 36 headache controls (10 males, 26 females, mean [SD] age; 38.1 [9.4] years) were included in the study. The mean (SD) body mass index (BMI) of the patients with IIH was 25.2 (1.9) kg/m2, and the mean (SD) BMI of the headache controls was 23.3 (1.5) kg/m2 (p < 0.001). Decreased FA values and increased RD values in the cingulum were detected in patients with IIH compared to the headache controls (p = 0.003, Cohen's d = 0.681; p = 0.002 Cohen's d = -0.710). Decreased AD values in the left and right superior cerebellar peduncle and increased ADC values in the middle cerebellar peduncle were detected in patients with IIH compared to the headache controls (p < 0.001, Cohen's d = 0.961; p = 0.009, Cohen's d = 0.607; p = 0.015, Cohen's d = -0.564). Increased ADC and RD values and decreased FA values in optic nerve were detected in patients with IIH (p = 0.010, Cohen's d = -0.603; p = 0.004, Cohen's d = -0.676; p = 0.015 Cohen's d = 0.568). A positive correlation was found between the cerebrospinal fluid pressure and ADC values of the left and right superior and left inferior longitudinal fasciculus, genu of the corpus callosum, and right optic radiation (r = 0.43, p = 0.005; r = 0.31, p = 0.044; r = 0.39, p = 0.010; r = 0.35, p = 0.024; r = 0,41, p = 0.007). There was a positive correlation between the retinal nerve fiber layer thickness and the ADC values of the optic nerve (r = 0.32, p = 0.039). CONCLUSIONS: Intracranial hypertension can be associated with deteriorated DTI values, which might be interpreted as a sign of impaired white matter microstructural integrity in many brain regions beyond the periventricular white matter. Pressure-induced edema and axonal degeneration may be the potential underlying mechanisms of this microstructural damage.

Arachnoid granulations in idiopathic intracranial hypertension: Do they have an influence?

OBJECTIVE: The aim of this study was to investigate whether the relative narrowing of the dural venous sinuses by arachnoid granulations (AGs) is more pronounced in patients with idiopathic intracranial hypertension (IIH) compared to healthy controls. BACKGROUND: IIH is characterized by increased intracranial pressure, which is associated with symptoms such as headache and visual disturbances. The role of cerebral venous drainage obstruction in IIH is the subject of ongoing research. MATERIALS AND METHODS: In this retrospective case-control study, 3D contrast-enhanced magnetic resonance images of a cohort of 43 patients with IIH were evaluated for (1) the number of AGs per venous sinus and (2) the diameters of the dural venous sinuses at the site of an AG and at standardized measurement points. In addition, the minimum width of the transverse/sigmoid sinus was measured. All data were compared to the same data from a cohort of 43 control participants. RESULTS: Patients with IIH showed less relative sinus narrowing by AG compared to controls (median: 7%, interquartile range [IQR] 10% vs. 11%, IQR 9% in controls; p = 0.009). In patients with IIH, sinus diameter was larger at the site of an AG (70 ± 25 mm2) compared to its diameter at the standardized measurement point (48 ± 23 mm2; p = 0.010). In the superior sagittal sinus (SSS), patients with IIH had smaller AGs (median: 3 mm2, IQR 2 mm2 vs. 5 mm2, IQR 3 mm2 in controls; p = 0.023) while the respective sinus segment was larger (median: 69 mm2; IQR 21 mm2 vs. 52 mm2, IQR 26 mm2 in controls; p = 0.002). The right transverse sinus was narrower in patients with IIH (41 ± 21 mm vs. 57 ± 20 mm in controls; p < 0.001). CONCLUSIONS: In contrast to our hypothesis, patients with IIH showed less pronounced relative sinus narrowing by AG compared to controls, especially within the SSS, where AGs were smaller and the corresponding sinus segment wider. Smaller AGs could result in lower cerebrospinal fluid resorption, favoring the development of IIH. Conversely, the smaller AGs could also be a consequence of IIH due to backpressure in the SSS because of the narrower transverse/sigmoid sinus, which widens the SSS and compresses the AG.

Pituitary Dysfunction in Idiopathic Intracranial Hypertension: An Analysis of 80 Patients.

BACKGROUND: Empty sella is a commonly described imaging entity in patients with idiopathic intracranial hypertension (IIH). Though menstrual and hormonal disturbances have been associated with IIH, available literature lacks systematic analysis of pituitary hormonal disturbances in IIH. More so, the contribution of empty sella in causing pituitary hormonal abnormalities in patients of IIH has not been described. We carried out this study to systematically assess the pituitary hormonal abnormalities in patients with IIH and its relation to empty sella. METHODS: Eighty treatment naïve patients of IIH were recruited as per a predefined criterion. Magnetic resonance imaging (MRI) brain with detailed sella imaging and pituitary hormonal profile were done in all patients. RESULTS: Partial empty sella was seen in 55 patients (68.8%). Hormonal abnormalities were detected in 30 patients (37.5%), reduced cortisol levels in 20%, raised prolactin levels in 13.8%, low thyroid-stimulating hormone (TSH) levels in 3.8%, hypogonadism in 1.25%, and elevated levels of gonadotropins were found in 6.25% of participants. Hormonal disturbances were independent and were not associated with the presence of empty sella (p = 0.493). CONCLUSION: Hormonal abnormalities were observed in 37.5% patients with IIH. These abnormalities did not correlate with the presence or absence of empty sella. Pituitary dysfunction appears to be subclinical in IIH and responds to intracranial pressure reduction, not requiring specific hormonal therapies.

The diagnostic value of MRI findings in pediatric idiopathic intracranial hypertension: a case-control study.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is a rare medical condition in children. Based on the different radiological findings reported in various studies in pediatric IIH, this study was conducted to determine the diagnostic value of MRI findings in diagnosing IIH in children. METHODS: In this retrospective study, the medical records of all children aged 1 to 18 years who visited Ghaem Hospital in Mashhad, Iran, between 2012 and 2022 and were diagnosed with IIH were gathered. Forty-nine cases of children with IIH and 48 control cases of children with the first unprovoked seizure with no indications of increased intracranial pressure for comparison were selected. Patient demographic information and MRI findings were extracted. The comparison between different MRI findings in the case and control groups was conducted using statistical tests. RESULTS: In the case group, the mean diameter of the subarachnoid space expansion around the optic nerve was 5.96 ± 1.21, compared to 4.79 ± 0.33 in the control group, with statistically significant difference (P < 0.001). All the patients with flattening of the posterior globe or transverse sinus stenosis were in the case group, and the frequency of these findings in the case group was significantly higher than in the control group (P < 0.001). The majority of patients (95.5%) classified under category 3 and 4 of empty sella were part of the case group, and the statistical test results indicated a significant difference between the two groups (P < 0.001). The optic nerve sheath diameter cut-off of 5.35 mm, when used for expansion of the subarachnoid space around the optic nerve, with a sensitivity of 82% and a specificity of 100% in diagnosing IIH. CONCLUSION: The most reliable diagnostic indicators for diagnosing IIH in children are perioptic subarachnoid space expansion with high sensitivity, and posterior globe flattening and transverse sinus stenosis with high specificity.

Role of neuroimaging markers on predicting of idiopathic intracranial hypertension.

BACKGROUND: The goals of neuroimaging in idiopathic intracranial hypertension (IIH) are the exclusion of mimickers and effective management of disease. In recent studies, several imaging markers have been identified as potential predictors of IIH. PURPOSE: To investigate the predictive roles of novel radiological markers as the Meckel's cave area, alongside classical radiologic markers in identifying IIH such as the empty sella. MATERIAL AND METHODS: The patients were classified according to cerebrospinal fluid (CSF) opening pressure as the IIH group and control group. The observational, case-control study included 22 patients with IIH and 22 controls. Groups were compared for presence of empty sella, Meckel's cave area, fat area of posterior neck, fat thickness of scalp, presence of transverse sinus stenosis, and ophthalmic markers, such as increase of optic nerve (ON) sheath diameter. RESULTS: In the IHH group, higher occurrences of increased ON sheath diameter, ON tortuosity, flattening of the scleral surface, and transverse sinus stenosis were observed (P < 0.001, P < 0.001, P = 0.046, and P = 0.021, respectively). Meckel's cave area and fat area of posterior neck were similar in both groups (P = 0.444 and P = 0.794). CONCLUSION: Ophthalmic markers and transverse sinus stenosis could be utilized as radiologic features supporting early and precise diagnosis of IIH. However, enlargement of Meckel's cave area and measurements of fatty area of posterior neck are not helpful for diagnosis of IIH.

Ultrasound-guided initial diagnosis and follow-up of pediatric idiopathic intracranial hypertension.

BACKGROUND: Idiopathic intracranial hypertension in children often presents with non-specific symptoms found in conditions such as hydrocephalus. For definite diagnosis, invasive intracranial pressure measurement is usually required. Ultrasound (US) of the optic nerve sheath diameter provides a non-invasive method to assess intracranial pressure. Transtemporal US allows imaging of the third ventricle and thus assessment for hydrocephalus. OBJECTIVE: To investigate whether the combination of US optic nerve sheath and third ventricle diameter can be used as a screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure and exclude hydrocephalus as an underlying pathology. Further, to analyze whether both parameters can be used to monitor treatment outcome. MATERIALS AND METHODS: We prospectively included 36 children with idiopathic intracranial hypertension and 32 controls. Using a 12-Mhz linear transducer and a 1-4-Mhz phased-array transducer, respectively, optic nerve sheath and third ventricle diameters were determined initially and during the course of treatment. RESULTS: In patients, the mean optic nerve sheath diameter was significantly larger (6.45±0.65 mm, controls: 4.96±0.32 mm) and the mean third ventricle diameter (1.69±0.65 mm, controls: 2.99±1.31 mm) was significantly smaller compared to the control group, P<0.001. Optimal cut-off values were 5.55 mm for the optic nerve sheath and 1.83 mm for the third ventricle diameter. CONCLUSIONS: The combined use of US optic nerve sheath and third ventricle diameter is an ideal non-invasive screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure while ruling out hydrocephalus. Treatment can effectively be monitored by repeated US, which also reliably indicates relapse.

The additive value of complementing diagnostic idiopathic intracranial hypertension criteria by MRI - an external validation study.

BACKGROUND: Recently, diagnostic criteria including a standardized MRI criterion were presented to identify patients suffering from idiopathic intracranial hypertension (IIH) proposing that IIH might be defined by two out of three objective findings (papilledema, ≥ 25 cm cerebrospinal fluid opening pressure (CSF-OP) and ≥ 3/4 neuroimaging signs). METHODS: To provide independent external validation, we retrospectively applied the proposed diagnostic criteria to our cohort of patients with clinical suspicion of IIH from the Vienna IIH database. Neuroimaging was reevaluated for IIH signs according to standardized definitions by a blinded expert neuroradiologist. We determined isolated diagnostic accuracy of the neuroimaging criterion (≥ 3/4 signs) as well as overall accuracy of the new proposed criteria. RESULTS: We included patients with IIH (n = 102) and patients without IIH (no-IIH, n = 23). Baseline characteristics were balanced between IIH and no-IIH groups, but papilledema and CSF-OP were significantly higher in IIH. For the presence of ≥ 3/4 MRI signs, sensitivity was 39.2% and specificity was 91.3% with positive predictive value (PPV) of 95.2% and negative predictive value (NPV) 25.3%. Reclassifying our cohort according to the 2/3 IIH definition correctly identified 100% of patients without IIH, with definite IIH and suggested to have IIH without papilledema by Friedman criteria, respectively. CONCLUSION: The standardized neuroimaging criteria are easily applicable in clinical routine and provide moderate sensitivity and excellent specificity to identify patients with IIH. Defining IIH by 2/3 criteria significantly simplifies diagnosis without compromising accuracy.

Therapeutic effect of a single lumbar puncture in idiopathic intracranial hypertension.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is a neurological disorder characterized by increased intracranial pressure. Whilst lumbar puncture (LP) is necessary for the diagnosis of IIH, its therapeutic effect remains unclear. Our aim was to evaluate the therapeutic effect of a single LP in people with IIH (pwIIH). METHODS: In this prospective observational study, we analysed short-term neurological and ophthalmological outcomes in pwIIH before, one (D1) and seven days (D7) after the LP. The primary outcome was the change in papilledema degree from baseline. Secondary outcomes included visual outcomes, morphological changes in optical coherence tomography (peripapillary retinal nerve fibre layer [pRNFL] thickness and ganglion cell layer [GCL] volume) and transbulbar sonography (arachnoid optic nerve sheath diameter [AONSD]), and headache outcomes (peak and median headache severity and burden related to headache). RESULTS: We included 30 pwIIH (mean age 32.8 years [SD 8.4], 93.3% female, median cerebrospinal fluid [CSF] opening pressure 33.0 cmCSF [IQR 26.9-35.3], median body mass index (BMI) 34.8 kg/m2 [IQR 30.9-40.9]). The median papilledema grading at baseline was 2 (Friedman DI (1999) Pseudotumor cerebri. Neurosurg Clin N Am 10(4):609-621 viii); (Mollan SP, Aguiar M, Evison F, Frew E, Sinclair AJ (2019) The expanding burden of idiopathic intracranial hypertension. Eye Lond Engl 33(3):478-485); (Ab D, Gt L, Nj V, Sl G, Ml M, Nj N et al. (2007) Profiles of obesity, weight gain, and quality of life in idiopathic intracranial hypertension (pseudotumor cerebri). Am J Ophthalmol [Internet]. Apr [cited 2024 Jun 2];143(4). https://pubmed.ncbi.nlm.nih.gov/17386271/ ) and was significantly reduced at D7 (2 [1-2], p = 0.011). Median pRNFL thickness had decreased significantly at D7 (-9 µm [-62.5, -1.3], p = 0.035), with pRNFL thickness at baseline being associated with the pRNFL change (F(1,11) = 18.79, p = 0.001). Mean AONSD had decreased significantly at both D1 (-0.74 mm [0.14], p < 0.001) and D7 (-0.65 mm [0.17], p = 0.01), with AONSD at baseline being associated with the change in AONSD at both time points (D1: ß= -0.89, 95% CI -1.37, -0.42, p = 0.002; D7: ß= -0.85, 95% CI -1.42, -0.28, p = 0.007). Peak headache severity was slightly lower at D7 (-1/10 [-3, 0], p = 0.026), whereas median headache severity and headache burden remained unchanged. CONCLUSIONS: This short-term follow-up study in pwIIH undergoing a single LP suggests a moderate effect on ophthalmological but not headache outcomes. The usefulness of LP as a therapeutic measure in IIH remains controversial and should likely be reserved for patients with limited treatment options, e.g., in pregnancy or intolerability to medication.

Expanding the clinical spectrum of idiopathic intracranial hypertension.

PURPOSE OF REVIEW: Idiopathic intracranial hypertension (IIH) is a disorder of raised intracranial pressure (ICP). Although the majority of patients with IIH present classically with headache and papilledema, some patients may have unusual presentations or manifestations. Recent advancements in neuroimaging have facilitated the identification of other presentations associated with IIH. This review provides an overview of the expanding clinical spectrum of IIH. RECENT FINDINGS: Presentations of IIH that are considered unusual include highly asymmetric or unilateral papilledema, IIH without papilledema, and IIH associated with cranial nerve involvement. These presentations likely reflect differences in the way cerebrospinal fluid (CSF) pressure is transmitted intracranially. Radiological signs of intracranial hypertension are increasingly recognized in patients with IIH and provide further insights into the effects of raised ICP on intracranial structures. Osseous changes in the skull base leading to formation of meningoceles and encephaloceles have been identified in patients with IIH, spontaneous skull base CSF leak, and drug-resistant temporal lobe epilepsy, suggesting a possible association. SUMMARY: Clinicians should be familiar with the expanding clinical spectrum of IIH and the implications for the management of these presentations.

Editorial Comment: Estimation of venous sinus pressure drop in patients with idiopathic intracranial hypertension using 4D-flow MRI.

KEY POINTS: • Work-energy equation using 4D-flow MRI is a promising technique for non-invasive estimation of trans-stenotic pressure drop in patients with idiopathic intracranial hypertension.• Additional research with larger and multicentric prospective cohorts is needed to validate the results, along with improvement of the segmentation process with automated techniques and shortening of scanning times to allow for practical clinical use.

Estimation of venous sinus pressure drop in patients with idiopathic intracranial hypertension using 4D-flow MRI.

OBJECTIVE: We aimed to explore a non-invasive estimate of pressure drop in patients who undergo venous sinus stenting to treat idiopathic intracranial hypertension (IIH). METHODS: This prospective study included 28 IIH patients scheduled for venous stenting. 4D-flow MRI was acquired 24-48 h before venous manometry. Manometry-obtained pressure drop (Mp) was dichotomized into low (Lp: 0-8 mmHg) and high (Hp: 8-30 mmHg) groups. Hemodynamic indices were compared between Lp and Hp. Trans-stenotic pressure drop was estimated by work-energy equation, simplified Bernoulli equation, vorticity magnitude, and velocity difference between inlet and outlet and was compared with Mp. Measurement agreement, correlation, and accuracy were evaluated using the κ coefficient, Pearson's r, and confusion matrix-derived accuracy. RESULTS: Among 28 patients (mean age 38.8 ± 12.7), 19 (67.9%) were female. Work-energy equation-estimated pressure drop (WEp) had strong correlation (r = 0.91, 95% confidence interval [CI]: 0.81-0.96, p < 0.001) and high agreement (intraclass correlation coefficient = 0.90, 95% CI: 0.78-0.95, p < 0.001) with Mp. WEp classified Lp and Hp with an accuracy of 0.96. The κ value between WEp and Mp was 0.92 (95% CI: 0.78-1.00). In the work-energy equation, the viscosity energy term (Ve) had the largest weights, and the ratio of Ve to the summation of the three energy terms was 0.93 ± 0.07. Ve had strong correlation with mVort (r = 0.93, 95% CI: 0.85-0.97, p < 0.001), and mean vorticity magnitude was significantly elevated in Hp compared to that in Lp (259.8 vs. 174.9 mL/s, p < 0.001). CONCLUSION: Trans-stenotic pressure drop in IIH can be estimated using the work-energy equation with favorable accuracy. KEY POINTS: • Trans-stenotic pressure drop in patients with idiopathic intracranial hypertension can be estimated accurately with the work-energy equation using the 4D-flow MRI full velocity field. • Compared with traditional venous sinus manometry, the 4D-flow MRI-derived pressure drop is totally non-invasive and cost-saving. • 4D-flow MRI may help neurointerventionalist to select IIH patients suitable for venous sinus stenting.

Dural Venous Sinus Stent Placement Reduces Dosage Requirements for Carbonic Anhydrase Inhibitors in Patients with Idiopathic Intracranial Hypertension.

This retrospective single-center study evaluated the change in required dosage of acetazolamide and topiramate before and after dural venous sinus stent placement (VSSP) for idiopathic intracranial hypertension (IIH). Adults diagnosed with IIH who failed optimized medical management and were treated with VSSP were included. This study comprised 55 patients who underwent VSSP for the diagnosis of IIH. The median preprocedural dosage of acetazolamide and topiramate was 1,000 mg (range, 500-4,000 mg) and 100 mg (range, 0-200 mg), respectively, among patients able to tolerate the medications. The median postprocedural dosage of acetazolamide and topiramate was 375 mg (range, 0-4,000 mg), with a mean reduction of 52.9% (P = .001), and 0 mg (range, 0-200 mg), with a mean reduction of 45.9% (P = .005), respectively. Dural VSSP significantly reduced dosage requirements for acetazolamide and/or topiramate, potentially reducing the morbidity secondary to medication side effects.

B-mode transorbital ultrasonography for the diagnosis of idiopathic intracranial hypertension: an updated systematic review and meta-analysis.

OBJECTIVES: This systematic review and meta-analysis aimed to evaluate the role of B-mode transorbital ultrasonography (TOS) for the diagnosis of idiopathic intracranial hypertension (IIH) in adults. METHODS: MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) (1966-May 2022) were searched to identify studies reporting ultrasonographic data about the optic nerve sheath diameter (ONSD) and optic disc elevation (ODE) in adults with IIH compared to subjects without IIH. The quality of the included studies was evaluated by the Newcastle-Ottawa Quality. RESULTS: Fifteen studies were included (total of 439 patients). The values of ODE ranged from 0.6 to 1.3 mm in patients with IIH. The values of ONSD ranged from 4.7 to 6.8 mm in IIH patients and from 3.9 to 5.7 mm in controls. In IIH patients, the ONSD was significantly higher compared to controls (standardized mean difference: 2.5 mm, 95% confidence interval (CI): 1.6-3.4 mm). Nine studies provided data about the presence of papilledema and the pooled prevalence was 95% (95% CI, 92-97%). CONCLUSIONS: In adults, the thickness of ONSD and the entity of ODE were significantly associated with IIH. B-mode TOS enables to noninvasively detect increased ICP and should be performed, potentially routinely, in any patient with suspected IIH.

Posterior fossa volume in idiopathic intracranial hypertension: a magnetic resonance imaging-based study.

BACKGROUND: The etiology of idiopathic intracranial hypertension (IIH) is uncertain. Studies suggest the fundamental cause of the Chiari 1 malformation, a congenitally hypoplastic posterior fossa, may explain the genesis of IIH in some patients. PURPOSE: To assess the hypothesis that linear and volumetric measurements of the posterior fossa (PF) can be used as predictors of IIH. MATERIAL AND METHODS: A retrospective analysis of magnetic resonance imaging (MRI) studies on 27 patients with IIH and 14 matched controls was performed. A volumetric sagittal magnetization prepared rapid acquisition gradient echo sequence was used to derive 10 linear cephalometric measurements. Total intracranial and bony posterior fossa volumes (PFVs) were derived by manual segmentation. The ratio of PFV to total intracranial volume was calculated. RESULTS: In total, 41 participants were included, all women. Participants with IIH had higher median body mass index (BMI). No significant differences in linear cephalometric measurements, total intracranial volumes, and PFVs between the groups were identified. Linear measurements were not predictive of volumetric measurements. However, on multivariate logistic regression analysis, the likelihood of IIH decreased significantly per unit increase in relative PFV (odds ratio [OR]=3.66 × 10-50; 95% confidence interval [CI]=1.39 × 10-108 to 1.22 × 10-5; P = 0.04). Conversely, the likelihood of IIH increased per unit BMI increase (OR=1.19; 95% CI=1.04-1.47; P = 0.02). CONCLUSION: MRI-based volumetric measurements imply that PF alterations may be partly responsible for the development of IIH and Chiari 1 malformations. Symptoms of IIH may arise due to an interplay between these and metabolic, hormonal, or other factors.

Is Lumbar Puncture Needed? - Noninvasive Assessment of ICP Facilitates Decision Making in Patients with Suspected Idiopathic Intracranial Hypertension.

PURPOSE: Idiopathic intracranial hypertension (IIH) usually occurs in obese women of childbearing age. Typical symptoms are headache and sight impairment. Lumbar puncture (LP) is routinely used for both diagnosis and therapy (via cerebrospinal fluid drainage) of IIH. In this study, noninvasively assessed intracranial pressure (nICP) was compared to LP pressure (LPP) in order to clarify its feasibility for the diagnosis of IIH. MATERIALS AND METHODS: nICP was calculated using continuous signals of arterial blood pressure and cerebral blood flow velocity in the middle cerebral artery, a method which has been introduced recently. In 26 patients (f = 24, m = 2; age: 33 ±â€Š11 years), nICP was assessed one hour prior to LPP. If LPP was > 20 cmH2O, lumbar drainage was performed, LPP was measured again, and also nICP was reassessed. RESULTS: In total, LPP and nICP correlated with R = 0.85 (p < 0.001; N = 38). The mean difference of nICP-LPP was 0.45 ±â€Š4.93 cmH2O. The capability of nICP to diagnose increased LPP (LPP > 20 cmH2O) was assessed by ROC analysis. The optimal cutoff for nICP was close to 20 cmH2O with both a sensitivity and specificity of 0.92. Presuming 20 cmH2O as a critical threshold for the indication of lumbar drainage, the clinical implications would coincide in both methods in 35 of 38 cases. CONCLUSION: The TCD-based nICP assessment seems to be suitable for a pre-diagnosis of increased LPP and might eliminated the need for painful lumbar puncture if low nICP is detected.

Advances in the Understanding of the Complex Role of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension.

Idiopathic intracranial hypertension (IIH) is a disorder characterized by elevated intracranial pressure (ICP) that predominantly affects young obese women. IIH is a diagnosis of exclusion. That is, if increased ICP is suspected, magnetic resonance imaging and magnetic resonance venography of the brain are recommended to exclude secondary causes. Imaging findings, such as empty sella, orbital findings, meningocele, and encephalocele, are not diagnostic of ICP, nor does their absence exclude ICP either. Therefore, venous manometry is recommended as the gold standard for evaluation, regardless of previous anatomic imaging results. Venous manometry is an invasive examination that is frequently applied to derive physiologic information concerning the nature of the pressure gradient. However, the pathogenesis of IIH has not been fully elucidated. The presence of venous sinus stenosis in a subset of patients has provided some support for the potential mechanisms underlying this condition. Hence, this review provides an up-to-date discussion on the potential pathogenic mechanisms of IIH with a special focus on venous sinus stenosis. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 2.

Transorbital sonography: A non-invasive bedside screening tool for detection of pseudotumor cerebri syndrome.

BACKGROUND: Our objective was to assess optic nerve sheath diameter (a marker of elevated intracranial pressure) and optic disc elevation (a marker of papilledema) in pseudotumor cerebri syndrome using transorbital sonography. METHODS: The study was a prospective case-control study. We included patients with new-onset pseudotumor cerebri syndrome and matched healthy controls. All had fundoscopy, lumbar puncture with opening pressure and transorbital sonography. Sonography was assessed by a blinded observer. RESULTS: We evaluated 45 patients and included 23 cases. We recruited 35 controls. Optic nerve sheath diameter was larger in pseudotumor cerebri syndrome compared to controls (6.3 ± 0.9 mm versus 5.0 ± 0.5 mm, p < 0.001) and so was optic disc elevation (0.9 ± 0.4 mm versus 0.4 ± 0.1 mm, p < 0.001). The optimal cut-off point for optic nerve sheath diameter was 6 mm with a sensitivity of 74% for prediction of pseudotumor cerebri syndrome and 68% for prediction of elevated opening pressure. Specificity was 94%. The optimal cut-off point for optic disc elevation was 0.6 mm. Sensitivity was 100% and specificity 83% for prediction of pseudotumor cerebri syndrome. CONCLUSION: Optic disc elevation and optic nerve sheath diameter are increased in new-onset pseudotumor cerebri syndrome. Optic disc elevation achieved high specificity and excellent sensitivity for diagnosis of pseudotumor cerebri syndrome. Transorbital sonography (TOS) is a potential, non-invasive screening tool for pseudotumor cerebri syndrome in headache clinics.

Features of Idiopathic Intracranial Hypertension on MRI With MR Elastography: Prospective Comparison With Control Individuals and Assessment of Postintervention Changes.

BACKGROUND. Understanding of dynamic changes of MRI findings in response to intracranial pressure (ICP) changes in idiopathic intracranial hypertension (IIH) is limited. Brain stiffness, as assessed by MR elastography (MRE), may reflect changes in ICP. OBJECTIVE. The purpose of this study was to compare pituitary height, ventricular size, and brain stiffness between patients with IIH and control individuals and to evaluate for changes in these findings in patients with IIH after interventions to reduce ICP. METHODS. This prospective study included 30 patients (28 women, two men; median age, 29.9 years) with IIH and papilledema and 21 control individuals (21 women, 0 men; median age, 29.1 years), recruited from January 2017 to July 2019. All participants underwent 3-T brain MRI with MRE; patients with IIH underwent additional MRI examinations with MRE after acute intervention (lumbar puncture with normal closing pressure; n = 11) and/or chronic intervention (medical management or venous sinus stenting with resolution or substantial reduction in papilledema; n = 12). Pituitary height was measured on sagittal MP-RAGE images. Ventricular volumes were estimated using unified segmentation, and postintervention changes were assessed by tensor-based morphometry. Stiffness pattern score and regional stiffness values were estimated from MRE. RESULTS. In patients with IIH, median pituitary height was smaller than in control individuals (3.1 vs 4.9 mm, p < .001) and was increased after chronic (4.0 mm, p = .05), but not acute (2.3 mm, p = .50), intervention. Ventricular volume was not different between patients with IIH and control individuals (p = .33) and did not change after acute (p = .83) or chronic (p = .97) intervention. In patients with IIH, median stiffness pattern score was greater than in control individuals (0.25 vs 0.15, p < .001) and decreased after chronic (0.23, p = .11) but not acute (0.25, p = .49) intervention. Median occipital lobe stiffness was 3.08 kPa in patients with IIH versus 2.94 kPa in control individuals (p = .07) and did not change after acute (3.24 kPa, p = .73) or chronic (3.10 kPa, p = .83) intervention. CONCLUSION. IIH is associated with a small pituitary and increased brain stiffness pattern score; both findings may respond to chronic interventions to lower ICP. CLINICAL IMPACT. The "partially empty sella" sign and brain stiffness pattern score may serve as dynamic markers of ICP in IIH.