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Cerebrospinal Fluid Pressure Reduction Results in Dynamic Changes in Optic Nerve Angle on Magnetic Resonance Imaging

Hu, Ranliang, MD; Holbrook, John, MD; Newman, Nancy J., MD; Biousse, Valerie, MD; Bruce, Beau B., MD, PhD; Qiu, Deqiang, PhD; Oshinski, John, PhD; Saindane, Amit M., MD

doi: 10.1097/WNO.0000000000000643
Original Contribution: PDF Only

Background: Optic nerve sheath tortuosity is a previously reported, but incompletely characterized, finding in idiopathic intracranial hypertension (IIH). We hypothesized that optic nerve angle (ONA), as a quantitative measure of tortuosity, would change dynamically with cerebrospinal fluid (CSF) pressure status of patients with IIH immediately before and after lumbar puncture (LP).

Methods: Consecutive patients with suspected IIH referred for MRI and diagnostic LP were prospectively enrolled in this single institution, institutional review board–approved study. Each patient underwent a pre-LP MRI, diagnostic LP with opening pressure (OP) and closing pressure (CP), and then post-LP MRI all within 1 session. Sagittal and axial ONAs were measured on multiplanar T2 SPACE images by 2 neuroradiologists on pre- and post-LP MRI. Effects of measured pressure and CSF volume removal on changes in ONA were analyzed as was interrater reliability for ONA measurement.

Results: Ten patients with IIH were included {all female, median age 29 (interquartile range [IQR] 25–32)}. All patients had elevated OP (median 37, IQR 34–41 cm H2O), and significantly reduced CP (median 18, IQR 16–19 cm H2O, P < 0.001) after CSF removal (IQR 13–16 mL). Within patients, mean ONAs (sagittal and axial) were significantly lower before (162 ± 9°, 163 ± 10°) than after (168 ± 7°, 169 ± 5°) LP (P = 0.001, 0.008, respectively). Interrater reliability was higher with sagittal ONA measurements (0.89) than axial (0.72).

Conclusions: ONA changes with short-term CSF pressure reduction in patients with IIH, establishing optic nerve tortuosity as a dynamic process related to CSF status.

Department of Radiology and Imaging Sciences (RH, DQ, JO, and AMS), Emory University School of Medicine, Atlanta, Georgia; Northside Radiology Associates (JH), Atlanta, Georgia; and Department of Ophthalmology (NJN, VB, BBB), Emory University School of Medicine, Atlanta, Georgia.

Address correspondence to Ranliang Hu, MD, Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1364 Clifton Road NE, Suite BG20, Atlanta, GA 30322; E-mail: Ranliang.Hu@emory.edu

B. B. Bruce is a medicolegal consultant for Bayer and individual litigants on the topic of idiopathic intracranial hypertension. V. Biousse and N. J. Newman are consultants for GenSight Biologics. They are supported in part by an unrestricted departmental grant (Department of Ophthalmology) from Research to Prevent Blindness, Inc, New York, by NIH/NEI core grant P30-EY06360 (Department of Ophthalmology, Emory University School of Medicine), and by NIH/NINDS (RO1NSO89694). N. J. Newman is a consultant for Santhera Pharmaceuticals. J. Oshinski received research contract funding from Siemens Medical, the maker of the MRI scanner used in this study. The remaining authors report no conflicts of interest.

© 2018 by North American Neuro-Ophthalmology Society