Elsevier

Clinical Radiology

Volume 67, Issue 7, July 2012, Pages 656-663
Clinical Radiology

Accuracy of brain imaging in the diagnosis of idiopathic intracranial hypertension

https://doi.org/10.1016/j.crad.2011.12.002Get rights and content

Aim

To investigate the accuracy of individual and combinations of signs on brain magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) in the diagnosis of idiopathic intracranial hypertension (IIH).

Materials and methods

This study was approved by the institutional research ethics board without informed consent. Forty-three patients and 43 control subjects were retrospectively identified. Each patient and control had undergone brain MRI and MRV. Images were anonymized and reviewed by three neuroradiologists, blinded to clinical data, for the presence or absence of findings associated with IIH. The severity of stenosis in each transverse sinus was graded and summed to generate a combined stenosis score (CSS). The sensitivity, specificity, and likelihood ratios (LR) were calculated for individual and combinations of signs.

Results

Partially empty sella (specificity 95.3%, p < 0.0001), flattening of the posterior globes (specificity 100%, p < 0.0001), and CSS <4 (specificity 100%, p < 0.0001) were highly specific for IIH. The presence of one sign, or any combination, significantly increased the odds of a diagnosis of IIH (LR+ 18.5 to 46, p < 0.0001). Their absence, however, did not rule out IIH.

Conclusions

Brain MRI with venography significantly increased the diagnostic certainty for IIH if there was no evidence of a mass, hydrocephalus, or sinus thrombosis and one of the following signs was present: flattening of the posterior globes, partially empty sella, CSS <4. However, absence of these signs did not exclude a diagnosis of IIH.

Introduction

Idiopathic intracranial hypertension (IIH), also known as benign intracranial hypertension or pseudotumour cerebri, is characterized by increased cerebrospinal fluid (CSF) pressure in the absence of an identifiable structural cause.1, 2, 3 IIH typically occurs in young and overweight female patients who develop symptoms and signs of raised intracranial pressure, including headache, visual disturbances, pulsatile tinnitus, and papilloedema.1, 2, 3 Diagnosis is typically confirmed by a lumbar puncture, which demonstrates raised CSF pressure with normal composition.1, 2, 3 Neuro-imaging has been traditionally used to exclude other causes of increased intracranial pressure such as mass lesions, hydrocephalus, or venous sinus thrombosis.1, 2, 3

Certain signs on cross-sectional imaging have been reported to be associated with IIH,4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 including flattening of the posterior aspect of the globes, protrusion of the intraocular portion of the optic nerve, vertical tortuosity of the optic nerve, distension of the optic nerve sheaths, enhancement of the optic nerve head, partial empty sella turcica, slit-like ventricles, tight subarachnoid spaces. However, these cross-sectional imaging findings are non-specific and can be seen in association with other conditions or causes of raised intracranial pressure.18, 19, 20 Venography is also necessary in the workup of patients with IIH in order to rule out venous sinus thrombosis, which can mimic IIH in clinical presentation.21 A high proportion of patients with IIH have been found to have bilateral severe transverse sinus stenosis using magnetic resonance venography (MRV).22, 23 Thus, the combination of findings from cross-sectional imaging, in addition to the presence of non-thrombotic transverse sinus stenosis on MRV, would be expected to be highly specific for IIH. However, few studies have examined the diagnostic utility of these individual magnetic resonance imaging (MRI) signs for IIH4, 6, 11, 22, 23 or combinations thereof,4 and only one group has examined their inter-rater reliability.4, 22 No published study has specifically evaluated the utility of combining the cross-sectional imaging signs with findings on MRV in the diagnosis of IIH.

The objectives of the current study were threefold: (a) to assess the sensitivity, specificity, and inter-observer reliability of individual MRI imaging (cross-sectional and venographic) signs associated with IIH; (b) to compare the sensitivity of time of flight (TOF) and contrast-enhanced (CE) MRV techniques in the detection of severe transverse sinus stenosis; (c) to determine whether the combination of cross-sectional MRI and MRV findings increases the diagnostic certainty for IIH.

Section snippets

Materials and methods

This study was approved by The Ottawa Hospital Research Institute Research Ethics Board without informed consent.

Patients and control subjects characteristics

Forty-three patients (39 female, four male) and control subjects (28 female, 15 male) were included in the analysis (Table 1). Although there was a statistically significant difference in the gender ratio between the IIH and control groups (p < 0.01), the two groups were well matched in age (IIH mean age 34.3 ± 11.9; range 17–63 years and controls mean age 37.2 ± 14.6; range 18–65 years). There was no significant difference in the proportion of MRIs performed at 1.5 T versus 3 T field strength

Discussion

Several conclusions can be drawn from this analysis of the accuracy of MRI and MRV in the diagnosis of IIH. First, a brain MRI and MRV that demonstrated: (1) no evidence of a mass lesion, hydrocephalus, or sinus thrombosis, and (2) either one of flattening of the posterior globe, partially empty sella combined transverse sinus stenosis score CSS <4, or any combination of these signs, significantly increased the diagnostic certainty for IIH. The probability of a diagnosis of IIH was increased

Limitations

There are several limitations inherent to the design of this study. The conclusions, consequently, require validation in a prospectively collected population of patients and age and sex-matched control subjects. The calculated sensitivities and specificities are highly dependent on the prevalence of the disorder in the population being tested (50% in the present study), in addition to the composition of the control group. The control group in the present study was retrospectively identified and

References (37)

  • J.R. Jinkins et al.

    MR of optic papilla protrusion in patients with high intracranial pressure

    AJNR Am J Neuroradiol

    (1996)
  • M.J. Lim et al.

    Magnetic resonance imaging changes in idiopathic intracranial hypertension in children

    J Child Neurol

    (2010)
  • L. Manfre et al.

    Idiopathic intracranial hypertension: orbital MRI

    Neuroradiology

    (1995)
  • R. Silbergleit et al.

    Idiopathic intracranial hypertension (pseudotumor cerebri): MR imaging

    Radiology

    (1989)
  • H. Suzuki et al.

    MR imaging of idiopathic intracranial hypertension

    AJNR Am J Neuroradiol

    (2001)
  • L.A. Weisberg

    Computed tomography in benign intracranial hypertension

    Neurology

    (1985)
  • W.T. Yuh et al.

    MR imaging of pituitary morphology in idiopathic intracranial hypertension

    J Magn Reson Imaging

    (2000)
  • M.T. Zagardo et al.

    Reversible empty sella in idiopathic intracranial hypertension: an indicator of successful therapy?

    AJNR Am J Neuroradiol

    (1996)
  • Cited by (113)

    • ACR Appropriateness Criteria® Headache: 2022 Update

      2023, Journal of the American College of Radiology
    • Radiologic findings in idiopathic intracranial hypertension

      2023, Cerebrospinal Fluid Rhinorrhea: Comprehensive Guide to Evaluation and Management
    • Ophthalmologic evaluation of idiopathic intracranial hypertension

      2023, Cerebrospinal Fluid Rhinorrhea: Comprehensive Guide to Evaluation and Management
    • Pressure headache and blurry vision: Evaluation and treatment of idiopathic intracranial hypertension (IIH)

      2023, Symptomatic: The Symptom-Based Handbook for Ehlers-Danlos Syndromes and Hypermobility Spectrum Disorders
    View all citing articles on Scopus
    View full text