MR imaging findings in patients with secondary intracranial hypertension

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.

Clinical value of neuroimaging indicators of intracranial hypertension in patients with cerebral venous thrombosis

PURPOSE

Intracranial hypertension (IH) frequently complicates cerebral venous thrombosis (CVT). Distinct neuroimaging findings are associated with IH, yet their discriminative power, reversibility and factors favoring normalization in prospective CVT patients are unknown. We determined test performance measures of neuroimaging signs in acute CVT patients, their longitudinal change under anticoagulation, association with IH at baseline and with recanalization at follow-up.

METHODS

We included 26 consecutive acute CVT patients and 26 healthy controls. Patients were classified as having IH based on CSF pressure > 25 cmH2O and/or papilledema on ophthalmological examination or ocular MRI. We assessed optic nerve sheath diameter (ONSD), optic nerve tortuousity, bulbar flattening, lateral and IVth ventricle size, pituitary configuration at baseline and follow-up, and their association with IH and venous recanalization.

RESULTS

46% of CVT patients had IH. ONSD enlargement > 5.8 mm, optic nerve tortuousity and pituitary grade ≥ III had highest sensitivity, ocular bulb flattening and pituitary grade ≥ III highest specificity for IH. Only ONSD reliably discriminated IH at baseline. Recanalization was significantly associated with regressive ONSD and pituitary grade. Other neuroimaging signs tended to regress with recanalization. After treatment, 184.9 ± 44.7 days after diagnosis, bulbar flattening resolved, whereas compared with controls ONSD enlargement (p < 0.001) and partially empty sella (p = 0.017), among other indicators, persisted.

CONCLUSION

ONSD and pituitary grading have a high diagnostic value in diagnosing and monitoring CVT-associated IH. Given their limited sensitivity during early CVT and potentially persistent alterations following IH, neuroimaging indicators can neither replace CSF pressure measurement in diagnosing IH, nor determine the duration of anticoagulation.

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..

Does the superior ophthalmic vein dilate in acute intracranial hypertension due to hemorrhagic stroke?

A 65-year-old man presented with coma. The cranial computed tomography (CT) revealed a massive hematoma in the left cerebral hemisphere, accompanied by intraventricular hemorrhage (IVH) and ventriculomegaly. Contrast examination revealed ectatic superior ophthalmic veins (SOVs). The patient underwent emergent hematoma evacuation. Contrast CT performed on postoperative day (POD) 2 showed a remarkable reduction in the diameters of both SOVs. A second patient, a 53-year-old man, presented with consciousness disturbance and right hemiparesis. CT revealed a large hematoma in the left thalamus, accompanied by massive IVH. Contrast CT demonstrated the bold delineation of the SOVs. The patient underwent endoscopic IVH removal. Contrast CT performed on POD 7 showed a remarkable reduction in the diameters of both SOVs. A third patient, a 72-year-old woman, presented with severe headache. CT revealed diffuse subarachnoid hemorrhage and ventriculomegaly. Contrast CT demonstrated a saccular aneurysm on the internal carotid artery-anterior choroidal artery branching site with the bold delineation of the SOVs. The patient underwent microsurgical clipping. Contrast CT performed on POD 68 showed a remarkable reduction in the diameters of both SOVs. The SOVs may function as an alternative venous drainage pathway in the setting of acute intracranial hypertension due to hemorrhagic stroke.

Risk factors for the development of secondary intracranial hypertension in acute cerebral venous thrombosis

PURPOSE

Intracranial hypertension (IH) can complicate cerebral venous thrombosis (CVT), potentially causing permanent visual loss. Current knowledge on risk factors for the development of IH following CVT is scarce. We applied a compound classifier (CSF opening pressure > 25 cmH₂O, papilledema, or optic disc protrusion on MRI) as a surrogate for IH and studied the predictive value of thrombus location, the number of thrombosed segments, and thrombus volume.

METHODS

We prospectively included 26 patients with acute CVT and complete MRI data. IH was defined by CSF opening pressure > 25 cmH₂O, papilledema, or optic disc protrusion on MRI. Using high-resolution contrast-enhanced venography, we determined the thrombus location, number of thrombosed segments, and thrombus volume. We analyzed their association with IH by logistic regression, their predictive power by the area under the receiver operating characteristic curve, and their association with CSF opening pressure by linear regression.

RESULTS

IH occurred in 46% of CVT patients and was associated with higher thrombus volume (AUC 0.759, p = 0.025) and superior sagittal sinus thrombosis both alone (OR 2.086, p = 0.049) and combined with transverse sinus thrombosis (OR 2.014, p = 0.028). Effects in patients presenting CSF opening pressure > 25 cm H₂O and the compound classifier were consistent. Thrombus volume > 4 ml was the single most important predictor of higher CSF opening pressure (ß = 0.566, p = 0.035), increasing IH risk.

CONCLUSION

Larger thrombus volume, dominant transverse sinus occlusion, and extensive superior sagittal combined with transverse sinus thrombosis were associated with IH. Thrombus volumetry might identify patients at risk for IH and direct further clinical evaluation.

A survey on the effect of adding aspirin to anti-migraine drugs on the severity of headache in patients with chronic migraine headaches with lateral venous sinus stenosis in MRV

Introduction

One of the probable etiologies raised in patients with chronic migraine headaches is stenosis of the lateral venous sinuses of the brain, which is detectable using magnetic resonance venography (MRV). In this study, we decided to observe the effect of adding aspirin to anti-migraine medicines on the severity of headache in patients with chronic migraine headaches with lateral venous sinus stenosis in MRV.

Methods

The study was a double-blind randomized clinical trial. Patients were included in the study in two groups including 30 people. The first group was treated with propranolol and nortriptyline, and the second group was treated with propranolol, nortriptyline, and aspirin. The severity of headache, number of headaches during one month, and duration of a headache before treatment and one, two, and three months after treatment were examined. Data were analyzed utilizing SPSS software version 19 and statistical tests like t-test, Chi-squared test, Paired t-test, and repeated measure.

Results

The results showed that the mean severity of headache in the second group was significantly lower than the first group two months after treatment (P = 0.003) and three months after treatment (P = 0.002). Additionally, the number of headaches (P = 0.001) and duration of headache (P = 0.043) were significantly lower in the second group than the first group in the first three months after treatment. No statistically significant difference was observed between the frequency distribution of nausea/vomiting in the two groups.

Conclusion

The addition of aspirin to anti-migraine medicines is effective in improving the severity of headache in patients with migraine with lateral venous sinus stenosis of the brain.

Utility of Neuroimaging in the Management of Chronic and Acute Headache

Imaging plays an important role in identifying the cause of the much less common secondary headaches. Such headaches may be caused by a variety of pathologic conditions which can be categorized as intracranial and extracranial. Idiopathic intracranial hypertension imaging findings include "empty sella," orbital changes, and dural venous sinus narrowing. Intracranial hypotension (ICH) is frequently caused by CSF leaks. Imaging findings include loss of the CSF spaces, downward displacement of the brain, as well as dural thickening and enhancement. Severe cases of ICH may result in subdural hematomas. A variety of intracranial and skull base tumors may cause headaches due to dural involvement. Extracranial tumors and lesions that frequently present with headaches include a variety of sinonasal tumors as well as mucoceles. Neurovascular compression disorders causing headaches include trigeminal and glossopharyngeal neuralgia. Imaging findings include displacement and atrophy of the cranial nerve caused by an adjacent arterial or venous structure.

Papilledema: A Review of the Pathophysiology, Imaging Findings, and Mimics

Increased intracranial pressure is the most common cause of papilledema. Multiple etiologies such as cerebral edema, hydrocephalus, space occupying lesions, infection, and idiopathic intracranial hypertension among others should be considered. Imaging plays a critical role in the detection of pathologies that can cause papilledema. MRI with contrast and CE-MRV, in particular, are key for the diagnosis of idiopathic intracranial hypertension. This review will focus in common and infrequent causes of papilledema, the role of imaging in patients with papilledema as well as its potential mimickers.

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.

MRI of the optic nerve sheath and globe in cats with and without presumed intracranial hypertension

OBJECTIVES

The study aimed to: (1) test MRI repeatability of measurements of optic nerve sheath diameter (ONSD), optic nerve diameter (OND) and eye globe transverse diameter (ETD); (2) investigate the associations between the OND, ONSD and ETD; (3) assess whether these measurements are affected by age or body weight; and (4) test the association between ONSD, OND, ETD and ONSD:ETD ratio with presumed intracranial pressure (ICP) status.

METHODS

This was a retrospective and blinded study where patients were allocated to presumed normal or intracranial hypertension groups based on MRI findings. The ONSD and ETD were measured and recorded. Interclass correlation coefficient (ICC) was calculated to investigate interobserver agreement. Data were analysed using the Pearson correlation coefficient, two-sample t-test and general linear model ANOVA.

RESULTS

Seventy-seven cats were included, 62 with presumed normal ICP and 15 with presumed intracranial hypertension. The ICC showed moderate-to-good reliability for all measurements. Positive correlations were identified for: (1) ETD and weight; (2) ONSD and age; (3) OND and age; (4) ONSD and ETD; (5) ONSD:ETD ratio and presumed ICP status; and (6) ONSD and presumed ICP status. No difference was detected between the presumed normal and intracranial hypertension groups and ONSD, as well as ONSD:ETD ratio and presumed ICP status when patient age was considered.

CONCLUSIONS AND RELEVANCE

The measurement of the ONSD and the ONSD:ETD ratio on T2-weighted MRI might not be reliable as non-invasive tests for diagnosing intracranial hypertension in cats.

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.

MRI-findings in idiopathic intracranial hypertension (Pseudotumor cerebri)

BACKGROUND

 Pseudotumor cerebri, also known as idiopathic intracranial hypertension, is a disorder of increased intracranial pressure of unknown etiology. Main symptom is headache which has a characteristic similar to other headache diseases, therefore the idiopathic intracranial hypertension often remains undetected. The incidence is 1/100 000 with the number of unreported cases being much higher. This article highlights the essential role of MRI in the differential diagnosis.

METHODS

 A literature search was carried out on idiopathic intracranial hypertension and Pseudotumor cerebri in English and German. Original and Review articles as well as case reports were taken into account. Since the main focus of the article is MRI diagnostics, some images were selected to illustrate the characteristic MRI morphological features.

RESULTS AND CONCLUSION

 The diagnosis of idiopathic intracranial hypertension is based on an exclusion procedure. Most common syndromes are headache, transient visual obscurations, pulsatile tinnitus and nausea. In the presence of an underlying cause for the increased intracranial pressure one speaks of a secondary intracranial hypertension. The diagnostics include a detailed medical history, neurological and ophthalmic examination, lumbar puncture, and neuroradiological imaging procedures. MRI, in particular, has become increasingly important in recent years, since signs for changes in cerebrospinal fluid pressure are now detectable and well-defined. The therapeutic approaches are symptom-oriented and aim to lower the pressure. With a precise diagnosis and timely start of therapy, idiopathic intracranial hypertension has a good prognosis, especially with regard to the preservation of eyesight.

KEY POINTS

  · The idiopathic intracranial hypertension is an important differential diagnosis for unspecific headache and impaired vision. · Overweight women in childbearing age are particularly affected. · The most important component in diagnostics is MRI.

CITATION FORMAT

· Juhász J, Hensler J, Jansen O. MRT-Befunde bei der idiopathischen intrakraniellen Hypertension (Pseudotumor cerebri). Fortschr Röntgenstr 2021; DOI: 10.1055/a-1447-0264.

Transverse Sinus Stenosis in Refractory Chronic Headache Patients: An Observational Study

Background: Transverse sinus stenosis is a common brain MRI finding in chronic migraine (CM) and chronic tension-type headache (CTTH) patients in clinical practice; however, its clinical and diagnostic role is unclear. The aim of the study is to determine the frequency of transverse sinus stenosis in these headache patients resistant to preventive treatments and to verify whether this is a useful finding for identifying patients with intracranial hypertension. Methods: This is an observational study. Patients with refractory CM and CTTH underwent a 3T-magnetic resonance venography (MRV) before cerebrospinal fluid (CSF) opening pressure measurement. Transverse sinus stenosis was determined using the combined conduit score. Patients with opening pressure >200 repeated MRV study 1 month after CSF withdrawal to evaluate changes in neuroimaging findings. Results: We analyzed MRV studies of 40 patients (32 F, 8 M; mean age, 49.4 ± 10.8; mean body mass index, 26.7 ± 6.4; 39 CM and 1 CTTH with concomitant episodic migraine). Nineteen cases (47.5%) had evidence of transverse sinus stenosis: bilateral in seven patients (17.5%) and unilateral in 12 cases (30%). No statistically significant differences in transverse sinus stenosis distribution were found between patients with opening pressure <200 mmH₂O and those with opening pressure >200 mmH₂O. On Spearman bivariate test, there was no correlation between opening pressure and combined conduit score. No changes in neuroimaging findings were found 1 month after CSF withdrawal. Conclusion: Transverse sinus stenosis is a frequent radiological finding (47.5%) in CM and CTTH patients refractory to preventive treatments. However, this finding is not suggestive of intracranial hypertension. Whether transverse sinus stenosis may be a possible risk factor for chronic headache or a comorbidity needs to be evaluated in larger epidemiological studies.

Empty Sella Is a Sign of Symptomatic Lateral Sinus Stenosis and Not Intracranial Hypertension

BACKGROUND AND PURPOSE

Empty sella has been reported in patients with idiopathic intracranial hypertension and is thought to be a sign of elevation of intracranial pressure. However, it can also be found in patients with lateral sinus stenosis presenting with isolated pulsatile tinnitus without signs of intracranial hypertension. We hypothesized that the volume of the sella turcica would be similar in both groups of patients undergoing stent placement for lateral sinus stenosis.

MATERIALS AND METHODS

Consecutive patients with idiopathic intracranial hypertension or isolated venous pulsatile tinnitus and undergoing lateral sinus stent placement from January 2012 to December 2017 were included. The primary outcome was the estimated volume of the sella turcica based on preoperative CTA measurements. The ratio of the pituitary gland height/sellar height was calculated on preoperative MR imaging. Sellar volumes were compared among the 3 groups: pulsatile tinnitus, idiopathic intracranial hypertension, and a control group, matched by age and sex.

RESULTS

Eighty-eight patients underwent lateral sinus stent placement. The median age was 37 years, and 94% were women. No difference in age, sex, or body mass index was found among the groups. Patients undergoing venous stent placement had significantly higher sellar volumes than the control group (P < 0.001). There was no difference in the sellar volumes (P = .63) or gland/sellar height ratios (P = .25) between the pulsatile tinnitus and idiopathic intracranial hypertension groups.

CONCLUSIONS

Empty sella is found in 2 differing groups of patients undergoing lateral sinus stent placement, suggesting that it is a radiologic sign of symptomatic hemodynamic lateral sinus stenosis rather than elevated intracranial pressure.

Idiopathic Intracranial Hypertension Without Papilledema (IIHWOP) in Chronic Refractory Headache

Background: To determine the prevalence of Idiopathic intracranial hypertension without papilledema (IIHWOP) testing revised diagnostic criteria by Friedman in refractory chronic headache (CH) patients. Methods: This is a prospective observational study. Each patient underwent ophthalmologic evaluation and Optical Coherence Tomography; brain magnetic resonance venography (MRV) and a lumbar puncture (LP) with opening pressure (OP) measurement. CSF withdrawal was performed in patients with CSF OP > 200 mmH20. IIHWOP was defined according Friedman's diagnostic criteria. Effect of CSF withdrawal was evaluated clinically in a 6-month follow-up and with a MRV study at 1 month. Results: Forty-five consecutive patients were enrolled. Five were excluded due to protocol violations. Analyses were conducted in 40 patients (32 F, 8 M; mean age 49.4 ± 10.8). None had papilledema. Nine patients (22.5%) had OP greater than 200 mmH2O, two of them above 250 mmH2O. Two (5%) had neuroimaging findings suggestive of elevated intracranial pressure. One of them (2.5%) met the newly proposed diagnostic criteria by Friedman for IIHWOP. After CSF withdrawal seven (77.8%) of the nine patients improved. No changes in neuroimaging findings were found. Conclusions: We found a low prevalence (2.5%) of IIHWOP in refractory CH patients according to current diagnostic criteria. In agreement with Friedman's criteria, our results confirm that a diagnosis of IIHWOP should be based on CSF OP and the combination of neuroradiological findings. However, where to set the CSF OP upper limit in IIHWOP needs further field testing. Although IIHWOP is a rare clinical condition, it should be considered and treated in refractory CH patients.

Imaging of Intracranial Pressure Disorders

Intracranial pressure (ICP) is the pressure inside the bony calvarium and can be affected by a variety of processes, such as intracranial masses and edema, obstruction or leakage of cerebrospinal fluid, and obstruction of venous outflow. This review focuses on the imaging of 2 important but less well understood ICP disorders: idiopathic intracranial hypertension and spontaneous intracranial hypotension. Both of these ICP disorders have salient imaging findings that are important to recognize to help prevent their misdiagnosis from other common neurological disorders.

Analysis of petrous apex meningocele associated with meningioma: is there any relation with chronic intracranial hypertension?

PURPOSE

Petrous apex meningocele (PAM) is an uncommon cystic lesion involving the petrous apex. The underlying cause of PAM may be related to chronic elevated intracranial pressure. The aim of the study was to explore the relationship between PAM and meningioma and between PAM and other intracranial hypertension findings.

METHODS

Two hundred seventy-eight consecutive patients with meningiomas were retrospectively studied. Fifty age- and gender-matched controls were also enrolled in this study. The incidence of PAM, empty sella, tortuosity of the optic nerve, and hydrops of optic nerve sheath was evaluated. The maximum width, area, volume of each PAM, or Meckel's cave and volume of meningioma were measured in controls and patients, separately.

RESULTS

One hundred fifty-nine (57.19%) patients were detected with coexistent PAMs. One hundred twenty-five patients had bilateral PAMs, 34 had unilateral lesions, and the remaining 119 did not have PAM. Two subjects (4/50) had unilateral PAMs in normal controls. The maximum width, area, volume of PAM, or Meckel's cave were significantly larger in the patients with bilateral PAM group than those in the unilateral PAM group, in the group without PAM, and those in control group (p = 0.000). The volume of meningioma was positively correlated with the PAM volume (r = 0.48). There was a positive correlation for the incidence between PAM and (1) empty sella (r = 0.901) and (2) tortuosity of the optic nerves and hydrops of the optic sheath (r = 0.825).

CONCLUSION

Coexistence of PAMs with meningiomas is not rare in incidence, and it suggests a potential role for chronically elevated intracranial pressure and disturbance of CSF circulation in their pathophysiology.

Brain Imaging in Idiopathic Intracranial Hypertension

BACKGROUND

The primary role of brain imaging in idiopathic intracranial hypertension (IIH) is to exclude other pathologies causing intracranial hypertension. However, subtle radiologic findings suggestive of IIH have emerged with modern neuroimaging. This review provides a detailed description of the imaging findings reported in IIH and discusses their possible roles in the pathophysiology and the diagnosis of IIH.

EVIDENCE ACQUISITION

References were identified by searches of PubMed from 1955 to January 2015, with the terms "idiopathic intracranial hypertension," "pseudotumor cerebri," "intracranial hypertension," "benign intracranial hypertension," "magnetic resonance imaging," "magnetic resonance venography," "computed tomography (CT)," "CT venography," "imaging," and "cerebrospinal fluid (CSF) leak." Additional references were identified by hand search of relevant articles. When possible, we extracted the number of patients and control subjects from each study for each radiological finding. When at least 2 studies used the same criteria to define a radiological finding, all patients from these studies were pooled to obtain a mean sensitivity and specificity with 95% confidence interval.

RESULTS

Specific neuroimaging findings may suggest long-standing IIH, including empty sella, flattening of the posterior globes, optic nerve head protrusion, distention of the optic nerve sheaths, tortuosity of the optic nerve, cerebellar tonsillar herniation, meningoceles, CSF leaks, and transverse venous sinus stenosis.

CONCLUSION

Although IIH remains a diagnosis of exclusion, the most recently proposed diagnostic criteria have included neuroimaging findings to suggest IIH when major diagnostic criteria are not fulfilled. However, these findings are not diagnostic of IIH, and their presence is not required for the diagnosis of definite IIH. Their incidental discovery on brain imaging should not prompt invasive procedures, unless other signs of IIH, such as papilledema, are present.

Morphometric MRI changes in intracranial hypertension due to cerebral venous thrombosis: a retrospective imaging study

AIM

To evaluate whether some magnetic resonance imaging (MRI) signs suggesting idiopathic intracranial hypertension (IIH) could also be found in intracranial hypertension (IH) due to cerebral venous thrombosis (CVT) and to assess their possible contribution to diagnosing this disorder.

MATERIALS AND METHODS

Thirty-one patients with IH due to CVT were evaluated prospectively using MRI. A group of 33 age- and sex-matched healthy volunteers served as controls. The optic nerve and sheath, pituitary gland, and ventricles were assessed. The prevalence of each imaging feature was compared between the two groups.

RESULTS

Optic nerve sheath (ONS) dilatation and decreased pituitary gland height were the most valid signs suggesting IH in CVT patients: sensitivity 70.97% and 87.1%, respectively; specificity 96.97% and 72.73%, respectively; area under the curve 0.840 and 0.809, respectively. The MRI finding that showed the strongest association with IH in CVT patients was ONS dilatation (odds ratio 78.5).

CONCLUSIONS

The combination of T1-weighted volumetric MRI and magnetic resonance venography could be helpful for diagnosing IH with CVT. Abnormalities of the ONS and the pituitary gland were reliable diagnostic signs for IH due to CVT.

Management of spontaneous intracranial hypotension - Transorbital ultrasound as discriminator

OBJECTIVE

Spontaneous intracranial hypotension (SIH) is most commonly caused by cerebrospinal fluid (CSF) leakage. Therefore, we hypothesised that patients with orthostatic headache (OH) would show decreased optic nerve sheath diameter (ONSD) during changes from supine to upright position.

METHODS

Transorbital B-mode ultrasound was performed employing a high-frequency transducer for ONSD measurements in the supine and upright positions. Absolute values and changes of ONSD from supine to upright were assessed. Ultrasound was performed in 39 SIH patients, 18 with OH and 21 without OH, and in 39 age-matched control subjects. The control group comprised 20 patients admitted for back surgery without headache or any orthostatic symptoms, and 19 healthy controls.

RESULTS

In supine position, mean ONSD (±SD) was similar in patients with (5.38±0.91 mm) or without OH (5.48±0.89 mm; p=0.921). However, in upright position, mean ONSD was different between patients with (4.84±0.99 mm) and without OH (5.53±0.99 mm; p=0.044). Furthermore, the change in ONSD from supine to upright position was significantly greater in SIH patients with OH (-0.53±0.34 mm) than in SIH patients without OH (0.05±0.41 mm; p≤0.001) or in control subjects (0.01±0.38 mm; p≤0.001; area under the curve: 0.874 in receiver operating characteristics analysis).

CONCLUSIONS

Symptomatic patients with SIH showed a significant decrease of ONSD, as assessed by ultrasound, when changing from the supine to the upright position. Ultrasound assessment of the ONSD in two positions may be a novel, non-invasive tool for the diagnosis and follow-up of SIH and for elucidating the pathophysiology of SIH.

Imaging and interventions in idiopathic intracranial hypertension: A pictorial essay

Intracranial hypertension is a syndrome of elevated intracranial pressure that can be primary or secondary. The primary form, now termed idiopathic intracranial hypertension (IIH), was in the past a disease of exclusion and imaging played a limited role of excluding organic causes of raised intracranial pressure. However imaging markers have been described with patients with IIH at the orbit, sella and cerebral venous system. We wish to reiterate the characteristic imaging features of this poorly understood disease and also emphasise that stenting of the transverse sinus in select cases of IIH is an efficacious option.

Ultrasonographic demonstration of the superior ophthalmic vein in the orbit of premature infants with and without retinopathy of prematurity

Retinopathy of prematurity (ROP), which develops due to abnormal retinal vascularization in premature babies, can lead to irreversible vision loss. B-scan ocular ultrasonography is a noninvasive examination which makes it possible to image the eye and orbit. Our purpose was to echographically assess the orbit of premature babies with and without retinopathy of prematurity (ROP), with a focus on the superior ophthalmic vein (SOV) which is normally not detected by orbital ultrasound. A prospective study design was used after approved by the local institutional review board. ROP was diagnosed by routine ophthalmoscopic exam. Orbital ultrasound was performed by a single experienced ophthalmologist and ultra-sonographer who was masked to the routine ROP screening results. The results of the ophthalmoscopic exam were compared to the orbital ultrasound findings. The study group was divided into those diagnosed with ROP and those not diagnosed with ROP and were found to be comparable by age and weight at the time of the US examination. The SOV was dilated in 21 of 22 eyes (95.4%) with ROP and in only 5 of 32 eyes (15.6%) without ROP. The present study suggests an association between ROP and dilatation of the SOV.

Idiopathic Intracranial Hypertension: Diagnostic Accuracy of the Transverse Dural Venous Sinus Attenuation on CT Scans

Idiopathic intracranial hypertension (IIH) is a clinical disorder of unknown etiology. It may exhibit several non-specific imaging findings. We observed that patients with intracranial hypertension demonstrate intracranial venous sinus attenuation with changes in the contour and caliber of the distal transverse sinus. This can be seen on routine non-contrast sagittal reformatted CT images of the brain. We have termed this the venous attenuation sign (VAS). This study evaluated the VAS as a marker for IIH assessing the transverse sinuses on sagittal reformatted non-contrast CT for the presence of a VAS in 25 patients with IIH and 24 control patients. Scans were independently assessed in a blinded fashion by three readers. The readers identified the VAS in 96% of patients with IIH; 83.3% of the control patients were negative for VAS. Our study supports the VAS as an additional imaging marker which may be incorporated into the evaluation of patients suspected to have this condition.

Transverse sinus stenosis in adult patients with Chiari malformation type I

OBJECTIVE

Transverse sinus stenosis is an imaging finding very highly associated with elevated intracranial pressure (ICP). Patients with the Chiari I malformation may potentially have elevated ICP due to impairment of CSF flow at the foramen magnum. This study evaluated whether patients with Chiari I malformation have transverse sinus stenosis and other imaging findings indicative of elevated ICP.

MATERIALS AND METHODS

Thirty patients with Chiari I malformation treated surgically and 76 control subjects were identified retrospectively. All control subjects and all patients with Chiari I malformation (preoperatively) underwent standardized contrast-enhanced brain MRI including a contrast-enhanced 3D T1-weighted sequence from which curved reformats of the transverse sinuses were generated. Two different readers blinded to the diagnosis then independently evaluated these curved reformats for severity of transverse sinus stenosis. Orbital and skull-base findings previously described in association with elevated ICP were also evaluated. Frequency of MRI findings between the two groups was compared.

RESULTS

Patients with Chiari I malformation had significantly greater frequency of unilateral or bilateral transverse sinus stenosis than did control subjects (p < 0.001). There was complete interreader agreement on presence or absence of transverse sinus stenosis by patient (κ = 1.0 [95% CI, 0.89-1.0]). Logistic regression analysis controlling for age, sex, and body mass index found that transverse sinus stenosis significantly predicted Chiari I malformation versus control status (odds ratio, 11.2 [95% CI, 2.1-59.0]; p = 0.004) but that no other features were significantly associated with the Chiari I malformation. Patients with Chiari I malformation who had transverse sinus stenosis had significantly greater pituitary flattening than did those without transverse sinus stenosis (p = 0.02).

CONCLUSION

Patients with Chiari I malformation have higher likelihood of transverse sinus stenosis, which may reflect associated elevated ICP.

The superior ophthalmic vein: delineation with high-resolution magnetic resonance imaging

OBJECTIVE

To delineate the superior ophthalmic vein (SOV) with high-resolution magnetic resonance (MR) imaging.

METHODS

This retrospective study enrolled 302 consecutive outpatients, 101 patients, 51 males and 50 females, who underwent coronal T2-weighted imaging and 201 patients, 99 males and 102 females, who underwent three-dimensional (3D) phase-contrast (PC) MR angiography.

RESULTS

Coronal T2-weighted imaging clearly delineated the intraorbital course of SOV on serial images in all 101 subjects. The SOV could be topographically divided into three segments in relation to the superior rectus muscle. The SOV crossed over the optic nerve at the level of the anterior ethmoidal foramina in 87% of right orbits and 71% of left orbits. The mean outer diameter of the SOV at the crossing point was 1.7 mm on both sides, but the SOVs were asymmetric in the same individual in 75% of the subjects. 3D PC MR angiography showed that the bilateral SOVs were symmetrical in 16% of subjects, larger in the right orbit in 18%, and larger in the left orbit in 13%, and were unidentified in 52%. The SOV showed a consistent lateral course to the ophthalmic artery.

CONCLUSIONS

The SOV consistently courses lateral to the ophthalmic artery, but tends to show bilateral asymmetry in the outer diameter. The superior rectus muscle, anterior ethmoidal foramen, and anterior ethmoidal artery are valuable landmarks to identify the SOV during transcranial orbital surgery. Combination of high-resolution MR imaging and 3D PC MR angiography is useful for delineating the SOV.

Update on intracranial hypertension and hypotension

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Imaging signs in idiopathic intracranial hypertension: Are these signs seen in secondary intracranial hypertension too?

Background:

The purpose of this study was to evaluate the difference in the occurrence of the various “traditional” imaging signs of intracranial hypertension (IIH) on magnetic resonance imaging (MRI) in patients with idiopathic (IIH) and secondary intracranial hypertension.

Materials and Methods:

In a retrospective analysis, the MRI findings of 21 patients with IIH and 60 patients with secondary intracranial hypertension (41 with tumors; 19 with intracranial venous hypertension) were evaluated for the presence or absence of various “traditional” imaging signs of IIH (perioptic nerve sheath distention, vertical buckling of optic nerve, globe flattening, optic nerve head protrusion and empty sella) using the Fisher’s exact test. Odds ratios were also calculated. Statistical Package for the Social Sciences version 17.0 was used for statistical analysis. Subgroup analysis of the IIH versus tumors and IIH versus venous hypertension were performed.

Results:

Optic nerve head protrusion and globe flattening were significantly associated with IIH. There was no statistically significant difference in the occurrence of rest of the findings. On subgroup analysis, globe flattening and optic nerve head protrusion occurred significantly more often in IIH than in tumors. However, there was no statistically significant difference in the occurrence of any of these findings in patients with IIH and venous hypertension.

Conclusions:

IIH is a diagnosis of exclusion. While secondary causes of raised intracranial pressure (ICP) have obvious clinical findings on MRI, some conditions like cerebral venous thrombosis may have subtle signs and differentiating between primary and secondary causes may be difficult. In the absence of any evident cause of raised ICP, presence of optic nerve head protrusion or globe flattening can suggest the diagnosis of IIH.

Factors determining the clinical significance of an "empty" sella turcica

OBJECTIVE

Although often incidental, the "empty" sella turcica can reflect chronically elevated intracranial pressure (ICP). It is particularly common in the setting of idiopathic intracranial hypertension (IIH). This study evaluated which clinical and MRI findings could be used to differentiate patients with chronically elevated ICP from those with incidental empty sella turcica.

MATERIALS AND METHODS

Forty-five patients with definite IIH and 92 patients with "empty sella" reported on brain MRI were evaluated. Measurements of the sella turcica, diaphragm sella, pituitary gland, infundibulum, and scalp and neck soft tissues were made on MR images. These measurements, age, sex, clinical symptoms, and frequency of previously reported orbital findings of IIH were compared between the IIH and incidental empty sella turcica groups. Measurements on MRI were correlated with patient age in each group.

RESULTS

The IIH and incidental empty sella turcica groups had statistically similar sellar, pituitary, and infundibular measurements. The patients with IIH were significantly younger than the patients with incidental empty sella turcica (mean age, 36.1 vs 54.3 years, respectively; p < 0.05); were more likely to report headache (93.3% vs 32.6%; p < 0.05) and visual complaints (66.2% vs 28.3%; p < 0.05); showed greater mean scalp thickness (9.0 vs 6.4 mm; p < 0.05) and neck soft-tissue thickness (19.5 vs 13.8 mm; p < 0.05); and were more likely to have an orbital finding suggestive of IIH (93% vs 14%). Age modestly correlated with the width of the diaphragm sella (r = 0.53) in the IIH group only.

CONCLUSION

The significance of the MRI finding of an empty sella turcica can be determined using a combination of clinical and imaging findings.

Automated quantitation of the posterior scleral flattening and optic nerve protrusion by MRI in idiopathic intracranial hypertension

BACKGROUND AND PURPOSE

Subjective determination of the posterior sclera flattening and optic nerve protrusion in MRI is challenging because of the 3D nature of the globe morphology. This study aims to develop and compare quantitative measures of globe flattening and optic nerve protrusion with subjective rating, and assess relationships with papilledema grade and intraocular and CSF pressures.

MATERIALS AND METHODS

Data of 34 globes from 7 overweight female patients with idiopathic intracranial hypertension and 6 age- and weight-matched healthy female control subjects were assessed, as well as a subcohort of 4 of the patients with idiopathic intracranial hypertension who underwent follow-up MR imaging 2 weeks after lumbar puncture and initiation of treatment with acetazolamide. MR imaging examination included a 3D CISS sequence on 1.5T and 3T scanners with 0.6-mm isotropic resolution. Subjective ratings of globe flattening were obtained by experienced and inexperienced readers. Quantitative measures of globe flattening, nerve protrusion, and maximal deformation were derived by use of a 2D map of the distances from the globe center to the posterior wall.

RESULTS

Contingency coefficients for globe flattening agreements with subjective rating by the experienced and inexperienced readers were 0.72 and 0.56, respectively. Mean values of the 3 deformation measures were significantly poorer in the idiopathic intracranial hypertension group, with nerve protrusion demonstrating the strongest difference (P = .0002). Nerve protrusion was most strongly associated with papilledema grade with a contingency coefficient of 0.74 (P = .01), whereas globe flattening was negatively correlated with intraocular pressure (R = -0.75, P < .0001). Maximal deformation was negatively associated with CSF opening pressure (R = -0.86, P = .0001). After treatment, only the changes in nerve protrusion and maximal deformation were significant.

CONCLUSIONS

Automated measures of globe deformation improve reliability over subjective rating. Of the 2 globe deformation measures, nerve protrusion had the strongest predictive value for papilledema grade and had the highest sensitivity for assessment of treatment efficacy in idiopathic intracranial hypertension.

The role of cerebrospinal fluid pressure in glaucoma and other ophthalmic diseases: A review

Glaucoma is one of the most common causes of blindness in the world. Well-known risk factors include age, race, a positive family history and elevated intraocular pressures. A newly proposed risk factor is decreased cerebrospinal fluid pressure (CSFP). This concept is based on the notion that a pressure differential exists across the lamina cribrosa, which separates the intraocular space from the subarachnoid fluid space. In this construct, an increased translaminar pressure difference will occur with a relative increase in elevated intraocular pressure or a reduction in CSFP. This net change in pressure is proposed to act on the tissues within the optic nerve head, potentially contributing to glaucomatous optic neuropathy. Similarly, patients with ocular hypertension who have elevated CSFPs, would enjoy a relatively protective effect from glaucomatous damage. This review will focus on the current literature pertaining to the role of CSFP in glaucoma. Additionally, the authors examine the relationship between glaucoma and other known CSFP-related ophthalmic disorders.

MRI findings of elevated intracranial pressure in cerebral venous thrombosis versus idiopathic intracranial hypertension with transverse sinus stenosis

PURPOSE

To determine whether MRI signs suggesting elevated intracranial pressure (ICP) are preferentially found in patients with idiopathic intracranial hypertension (IIH) than in those with cerebral venous thrombosis (CVT).

METHODS

Among 240 patients who underwent standardized contrast-enhanced brain MRI/MRV at our institution between 9/2009 and 9/2011, 60 with abnormal imaging findings on MRV were included: 27 patients with definite IIH, 2 patients with presumed IIH, and 31 with definite CVT. Medical records were reviewed, and imaging studies were prospectively evaluated by the same neuroradiologist to assess for presence or absence of transverse sinus stenosis (TSS), site of CVT if present, posterior globe flattening, optic nerve sheath dilation/tortuosity, and the size/appearance of the sella turcica.

RESULTS

29 IIH patients (28 women, 19 black, median-age 28, median-body mass index, 34) had bilateral TSS. 31 CVT patients (19 women, 13 black, median-age 46, median-BMI 29) had thrombosis of the sagittal (3), sigmoid (3), cavernous (1), unilateral transverse (7), or multiple (16) sinuses or cortical veins (1). Empty/partially-empty sellae were more common in IIH (3/29 and 24/29) than in CVT patients (1/31 and 19/31) (p<0.001). Flattening of the globes and dilation/tortuosity of the optic nerve sheaths were more common in IIH (20/29 and 18/29) than in CVT patients (13/31 and 5/31) (p<0.04).

CONCLUSION

Although abnormal imaging findings suggestive of raised ICP are more common in IIH, they are not specific for IIH and are found in patients with raised ICP from other causes such as CVT.

Does bilateral transverse cerebral venous sinus stenosis exist in patients without increased intracranial pressure?

OBJECTIVE

Transverse cerebral venous sinus stenosis (TSS) is common among patients with idiopathic intracranial hypertension. TSS likely also exists among individuals with normal intracranial pressure (ICP) but the prevalence is unclear. The goal of this study was to identify patients with incidental TSS and normal ICP and describe their characteristics.

METHODS

Among 240 adult patients who underwent brain magnetic resonance imaging (MRI) with magnetic resonance venography (MRV) with contrast at our institution between September 2009 and September 2011, 44 had isolated TSS without further substantial imaging abnormality. Medical records were reviewed for symptoms of increased ICP, papilledema, cerebrospinal fluid (CSF) constituents and opening pressure (OP), and reason for brain imaging. Of these, 37 were excluded for confirmed or possible idiopathic intracranial hypertension. Of the remainder, 5 had CSF-OP≤25 cmH2O without papilledema, and 2 did not have measured ICP, but had no papilledema or symptoms of increased ICP. Imaging was re-interpreted to assess for signs suggestive of elevated ICP and to characterize the TSS further.

RESULTS

All patients were women (mean age: 41, mean BMI: 37.1). CSF contents were normal, but OPs were at the upper limit of normal (22-25 cmH2O). Indications for MRI/MRV included query pituitary abnormality (1), migraine (4), and anomalous-appearing optic nerves (2). All had bilateral TSS. Six had short TSS and an empty sella; 1 had long TSS and no empty sella; 1 had flattening of the posterior sclera; 2 had prominence of peri-optic nerve CSF.

CONCLUSION

Asymptomatic bilateral TSS exists in patients with ICP≤25 cmH2O, but is likely uncommon. CSF-OP was at the upper limit of normal in our patients, who also had other radiologic signs suggestive (but not specific) of chronically-raised ICP. Findings of bilateral TSS on imaging should prompt funduscopic examination for papilledema.

Update on the pathophysiology and management of idiopathic intracranial hypertension

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

The measurement of CSF flow through the aqueduct in normal and hydrocephalic children: from where does it come, to where does it go?

PURPOSE

Despite 100 years of study, the theories of cerebrospinal fluid (CSF) formation and absorption remain controversial. Measuring CSF flow through the aqueduct using magnetic resonance imaging (MRI) provides a unique insight into the physiology of CSF hydrodynamics. The published data in adults tend to refute rather than support the prevailing theories of CSF flow. There are limited data regarding this metric in children. This paper seeks to measure the aqueduct flow in normal and hydrocephalic children to help formulate a more complete theory of CSF flow.

METHODS

Twenty-four children with communicating hydrocephalus aged from 4 months to 16 years underwent MRI flow quantification of the aqueduct measuring the net flow. The patients were compared to 19 controls.

RESULTS

The controls revealed two different flow patterns: (1) an infantile pattern characterized by flow directed into the ventricular system and (2) a mature pattern with flow directed out of the ventricles, similar to the published findings in adults. In infants with communicating hydrocephalus, the aqueduct flow changed direction but was of similar magnitude compared with the controls (p = 0.001). In the older hydrocephalic children, the flow was elevated 7-fold, but the direction was unchanged compared to the controls (p = 0.002).

CONCLUSIONS

There is an abrupt change in the aqueduct CSF flow pattern at the age of 2 years from an infantile pattern to a mature pattern. These findings together with the findings in hydrocephalic children do not support the current theories of CSF hydrodynamics. A new theory of CSF circulation based on capillary absorption is presented.