An Update on Imaging in Idiopathic Intracranial Hypertension

Intracranial pressure affects retinal venular complexity in idiopathic intracranial hypertension: a retrospective observational study

BACKGROUND

Increased intracranial pressure (ICP) in patients with idiopathic intracranial hypertension (IIH) affects the retinal microvasculature, which can be imaged and quantified by optical coherence tomography angiography (OCTA). We aimed to identify the mediating factor between ICP and OCTA parameters association in IIH patients.

METHODS

IIH patients with active intracranial hypertension were enrolled. OCTA imaging was performed after ICP measurement. We quantified the branching complexity of the retinal arterioles and venules from the superficial vascular complex of the OCTA image. Eyes of IIH patients were stratified into eyes with papilledema (IIH-P) and eyes without papilledema (IIH-WP). All participants underwent visual acuity (VA) examination.

RESULTS

One hundred and thirty-eight eyes from 70 IIH patients and 146 eyes from 73 controls were included. Compared to the control group, IIH patients and IIH-P had reduced arteriole complexity and increased venule complexity (p < 0.05). For IIH patients and IIH-P, increased retinal venule complexity correlated with increased ICP and reduced VA (p < 0.05); while decreased arteriole complexity only correlated with Frisen scores (p = 0.026). Papilledema mediated the effect (p < 0.001) between ICP and arteriole complexity while ICP had a direct effect (p < 0.001) on venule complexity.

CONCLUSION

Retinal venules imaged via OCTA may reflect ICP levels and may underpin the direct effect of increased ICP in IIH patients.

The utility of MRI radiological biomarkers in determining intracranial pressure

Intracranial pressure (ICP) is a physiological parameter that conventionally requires invasive monitoring for accurate measurement. Utilising multivariate predictive models, we sought to evaluate the utility of non-invasive, widely accessible MRI biomarkers in predicting ICP and their reversibility following cerebrospinal fluid (CSF) diversion. The retrospective study included 325 adult patients with suspected CSF dynamic disorders who underwent brain MRI scans within three months of elective 24-h ICP monitoring. Five MRI biomarkers were assessed: Yuh sella grade, optic nerve vertical tortuosity (VT), optic nerve sheath distension, posterior globe flattening and optic disc protrusion (ODP). The association between individual biomarkers and 24-h ICP was examined and reversibility of each following CSF diversion was assessed. Multivariate models incorporating these radiological biomarkers were utilised to predict 24-h median intracranial pressure. All five biomarkers were significantly associated with median 24-h ICP (p < 0.0001). Using a pair-wise approach, the presence of each abnormal biomarker was significantly associated with higher median 24-h ICP (p < 0.0001). On multivariate analysis, ICP was significantly and positively associated with Yuh sella grade (p < 0.0001), VT (p < 0.0001) and ODP (p = 0.003), after accounting for age and suspected diagnosis. The Bayesian multiple linear regression model predicted 24-h median ICP with a mean absolute error of 2.71 mmHg. Following CSF diversion, we found pituitary sella grade to show significant pairwise reversibility (p < 0.001). ICP was predicted with clinically useful precision utilising a compact Bayesian model, offering an easily interpretable tool using non-invasive MRI data. Brain MRI biomarkers are anticipated to play a more significant role in the screening, triaging, and referral of patients with suspected CSF dynamic disorders.

MRI signs of intracranial hypertension in morbidly obese and normal-weight individuals

PURPOSE

Idiopathic intracranial hypertension (IIH) is associated with intracranial abnormalities, although not obligatory, which can be detected with cranial MRI. Obesity is an important risk factor for IIH and a pathogenetic link is suspected but the extent to which these MRI signs are already related to obesity has not yet been examined. We investigated whether IIH-MRI signs are present more often in obese individuals with a BMI > 30 kg/m² than in individuals of normal weight.

MATERIALS AND METHODS

Brain MRI of 32 obese and 53 normal-weight participants from the Food-Chain-Plus cohort were analyzed for three main signs of IIH: (I) stenosis of the transverse sinus, (II) increased width of the optic nerve sheath, and (III) reduction of pituitary height. In addition, a scoring system for the MRI signs was applied. Furthermore, tortuosity of the optic nerve and flattening of the posterior globe were considered as additional MRI signs.

RESULTS

Obese participants had a significantly higher MRI score (p < 0.001) than those in the normal-weight cohort, with significant differences in quantitative measurements of cerebral venous sinus stenosis (p < 0.001), widening of the optic nerve sheath (p < 0.05), and flattening of the pituitary gland (p < 0.05) also always being observed more frequently and in a more pronounced manner in the obese group. Furthermore, our findings correlated significantly with BMI and proportionately with hip and waist circumference.

CONCLUSION

Obese individuals show a significantly higher prevalence of cerebral MRI signs related to IIH. This supports the hypothesis that obesity is a risk factor for possible intracranial hypertension and reinforces the suspicion that obesity is involved in the pathomechanism of IIH.

KEY POINTS

· Obesity is associated with changes such as those seen in IIH.. · BMI, weight, and body measurements correlate with the expression of MRI signs of IIH.. · To prevent IIH symptoms in obesity, the pathomechanism must be further clarified..

Autonomous Stabilization of Retinal Videos for Streamlining Assessment of Spontaneous Venous Pulsations

Spontaneous retinal Venous Pulsations (SVP) are rhythmic changes in the caliber of the central retinal vein and are observed in the optic disc region (ODR) of the retina. Its absence is a critical indicator of various ocular or neurological abnormalities. Recent advances in imaging technology have enabled the development of portable smartphone-based devices for observing the retina and assessment of SVPs. However, the quality of smartphone-based retinal videos is often poor due to noise and image jitting, which in return, can severely obstruct the observation of SVPs. In this work, we developed a fully automated retinal video stabilization method that enables the examination of SVPs captured by various mobile devices. Specifically, we first propose an ODR Spatio-Temporal Localization (ODR-STL) module to localize visible ODR and remove noisy and jittering frames. Then, we introduce a Noise-Aware Template Matching (NATM) module to stabilize high-quality video segments at a fixed position in the field of view. After the processing, the SVPs can be easily observed in the stabilized videos, significantly facilitating user observations. Furthermore, our method is cost-effective and has been tested in both subjective and objective evaluations. Both of the evaluations support its effectiveness in facilitating the observation of SVPs. This can improve the timely diagnosis and treatment of associated diseases, making it a valuable tool for eye health professionals.

Higher cerebrospinal fluid (CSF) opening pressure in patients with idiopatic intracranial hypertension (IIH) with permanent visual impairment

Objective The aim of this study was to identify potential visual prognostic markers in patients with idiopathic intracranial hypertension (IIH).  Methods Patients with IIH of an outpatient headache clinic in São Paulo, Brazil, were retrospectively evaluated and divided in two groups with and without the presence of permanent visual deficit attributed to IIH. Body mass index (BMI), opening CSF pressure, and the frequency of IIH related MRI abnormalities were compared between these two groups.  Results Twenty-nine patients, with 35,39±9,93 years, being twenty-eight female (96.55%) were included in the study. Reduced visual acuity attributed to IIH was registered in 16 (55.17%). According to BMI 17.4% had overweight and 82.6% were obese. Brain MRI was normal in 6 (20.69%). BMI, obesity, and the presence of MRI abnormalities were not associated with visual impairment. Initial CSF opening pressure was significantly higher in the group of patients with reduced visual acuity (40.4±13.14 x 30.5±3.41, P=0,015).  Conclusion Higher CSF opening pressure at onset was significantly associated with a higher percentage of visual impairment in patients with IIH suggesting this measure as a potential prognostic marker for patients with IIH.  

Diagnostic value of brain MR imaging and its correlation with clinical presentation and cognitive functions in idiopathic intracranial hypertension patients

Background

Idiopathic intracranial hypertension (IIH) is a neurological disorder of unknown etiology and ambiguous pathophysiology due to cerebrospinal fluid dysregulation. This study is designed to evaluate the role of brain magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) in diagnosis of IIH, to clarify the nature and extent of cognitive deficits, and to detect if there is a correlation between radiology, clinical findings, and cognitive dysfunctions in those patients.

Results

The study included 34 patients and 34 age-, sex-, body mass index (BMI)-, and education-matched healthy control subjects. MR brain imaging and Montreal cognitive assessment (MoCA) test were used for both groups. MRI and MRV sensitivity for IIH diagnosis were 85.2% and 85.3% with 100% and 94.1% specificity respectively. 44.1% had cognitive impairment, memory was the most affected domain, followed by attention, abstraction, and orientation with statistically significantly lower total MoCA score (p < 0.005). Domain comparisons reveal a statistically significantly lower memory/delayed recall (p < 0.001) and abstract scores (p < 0.007) in IIH cases versus control subjects. In comparing patients with cognitive impairment (CI) versus those without CI, there were statistically significantly higher CI in low education level, presence of diplopia, hormonal contraceptive use, abnormal MRI brain, papilledema grades, BMI, and opening pressure.

Conclusions

Presence of more than or equal 3 MR imaging findings, bilateral transverse sinus stenosis, and less than or equal 4 combined conduit score increase the specificity and sensitivity of MRI and MRV for IIH diagnosis. IIH had detrimental effect on different cognitive domains especially when patient have low education level, diplopia, papilledema ≥ grade III, high OP ≥ 61.5 cm H2O, and BMI ≥ 34 Kg/m2 with abnormal MRI and MRV findings.

Brain MRI and Ophthalmic Biomarkers of Intracranial Pressure

OBJECTIVE

To evaluate the utility of brain MRI and ophthalmic biomarkers for the prediction of intracranial hypertension, we have studied the association between 6 biomarkers and 24-hour intracranial pressure (ICP) monitoring results in 45 patients.

METHODS

This single-center observational study includes patients who underwent 24-hour ICP monitoring, brain MRI (within 3 months), and ophthalmic assessment (during ICP monitoring). Six biomarkers were investigated: pituitary gland shape, vertical tortuosity of the optic nerve, distension of the optic nerve sheath, optic disc protrusion (MRI), papilledema (slit lamp biomicroscopy), and spontaneous venous pulsations (SVP, infrared video recordings).

RESULTS

Forty-five patients (mean age 39 ± 14 years, 38 women) met the inclusion criteria. All 6 biomarkers had a significant association with 24-hour ICP. Concave pituitary gland was observed with moderately elevated median ICP. Protrusion of the optic disc (MRI), papilledema, and absence of SVP were associated with the highest median ICP values. Twenty patients had raised ICP (median 24-hour ICP >5.96 mm Hg, cutoff obtained through Youden index calculation). Patients with all normal biomarkers had normal median ICP in 94% (standard error 6%) of the cases. All patients with ≥3 abnormal biomarkers had intracranial hypertension. The combination of at least 1 abnormal biomarker in MRI and ophthalmic assessments was highly suggestive of intracranial hypertension (area under the curve 0.94, 95% confidence interval 0.93-0.94) CONCLUSIONS: Brain MRI and ophthalmic biomarkers can noninvasively guide the management of patients with suspected CSF dynamics abnormalities. Patients with multiple abnormal biomarkers (≥3) or a combination of abnormal MRI and ophthalmic biomarkers are likely to have intracranial hypertension and should be managed promptly.

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.