When diagnosing patients with idiopathic intracranial hypertension (IIH) or other diseases related to changes in intracranial pressure (ICP), it’s essential for doctors to perform brain imaging.1 In the past, this was achieved using magnetic resonance imaging (MRI) scans as well as ultrasonographic B-scanning, which can measure the optic disc height in addition to the presence of excessive fluid within the optic nerve sheath.2 But, until now, the verdict has been out on whether one was superior to the other. New research from the Mayo Clinic in Rochester, New York shows that MRI and B-scan ultrasound can both be used, either independently or in conjunction, to establish the likelihood of increased ICP in patients with papilledema from IIH.3
The study looked at 44 patients with papilledema, half from IIH and half from other causes. For the papilledema in IIH patients, MRI had an 82% specificity, according to the study, and B-scan’s sensitivity was 83%. Combining the two had a 96% specificity.
The researchers concluded that MRI can be used as a follow up if a B-scan is indeterminate, saying B-scans provide “an effective method of optic nerve sheath diameters measurement and is a sensitive marker for increased ICP. In cases where the diagnosis is unclear, MRI can be ordered for detection of intracranial features of IIH, such as the empty sella sign, which can increase the specificity of diagnosis when combined with the ONSD measurements.”
1. National Eye Institute. Idiopathic intracranial hypertension. April 2014. nei.nih.gov/health/iih/intracranial. Accessed June 6, 2018.|
2. Mollan S, Markey K, Benzimra J, et al. A practical approach to, diagnosis, assessment and management of idiopathic intracranial hypertension. BMJ. Practical Neuro. 2014;14:380-390.
3. Patterson D, Ho M, Leavitt, et al. Comparison of ocular ultrasonography and magnetic resonance imaging for detection of increased intracranial pressure. Front Neurol. 2018;9:278.