Sonographic assessment of the optic nerve sheath diameter in the diagnosis of idiopathic intracranial hypertension Pablo del Saz-Saucedo a, ⁎, Olga Redondo-González b , Ángel Mateu-Mateu a , Rafael Huertas-Arroyo a , Rafael García-Ruiz a , Enrique Botia-Paniagua a a Neurology Department, La Mancha Centro General Hospital, Alcázar de San Juan, Ciudad Real, Spain b Investigation, Teaching and Training Unit, La Mancha Centro General Hospital, Alcázar de San Juan, Ciudad Real, Spain abstract article info Article history: Received 14 October 2015 Received in revised form 26 November 2015 Accepted 20 December 2015 Available online 21 December 2015 Objective: Sonographic assessment of the optic nerve sheath diameter (ONSD) is a useful technique in detecting raised intracranial pressure (ICP) in neurocritical care patients. Its utility in idiopathic intracranial hypertension (IIH) is less known. The aim of this study was to evaluate the diagnostic accuracy of ONSD for detecting IIH. Material and methods: Ultrasound measurement of ONSD was performed in 19 patients with IIH and in 11 pa- tients with different neurological diseases without raised ICP that required undergoing a lumbar puncture. The validity of this technique for diagnosing IIH was established with cerebrospinal fluid manometry values. Results: Patients with IIH showed significantly enlarged ONSD than those without IIH. The best cut-off point for detecting raised ICP was 6.3 mms, with a sensitivity, specificity and positive likelihood ratio of 94.7%, 90.9% and 10.4, respectively. After a therapeutic lumbar puncture an 87% of cases had a partial reduction of ONSD values. Conclusion: Sonographic assessment of ONSD seems to be a useful and reliable technique for detecting raised ICP. While the spinal manometry is not replaced in usual clinical settings, transorbital sonography alternatively al- lows a suitable and harmless screening of patients with suspected IIH. It would be desirable to perform an inter- nal validation of the technique in each hospital in order to get the optimal cut-off point. © 2015 Elsevier B.V. All rights reserved. Keywords: Cerebrospinal fluid Headache Intracranial hypertension Neurosonology Optic nerve 1. Introduction Intracranial hypertension (IH) is a common complication of multiple neurological diseases with raised intracranial pressure (ICP) that can lead to a secondary brain damage, so its early recognition is essential. Sonographic assessment of the optic nerve sheath diameter (ONSD) has proven to be a reliable test for non-invasive diagnosis of raised ICP in neurocritical patients [1–2]. However, the available information on its value to appraise idiopathic intracranial hyperten- sion (IIH) comes from a single observational study [3] and limited clinical isolated cases [4–9]. The optic nerve is a tubular structure of about 5 cm in length in which its intraorbital segment is evaluable sonographically. Histo- logically it is surrounded by the same meningeal layers as the brain [10–11]. The optic nerve appears as a hypoechoic linear structure lo- cated inside the optic nerve sheath (Fig. 1). Between the sheath and the optic nerve is situated the subarachnoid space, trabeculated and hyperechoic in appearance, whose dimensions are enlarged in IH sit- uations as this raised ICP is transmitted throughout the subarachnoid space to the optic nerve head [11–12].Therefore, the presence of an increased ONSD is an indirect sign of IH because changes in ICP have a direct influence on the perioptic subarachnoid space diame- ter. However, there is a discrepancy about the optimal ONSD cut- off reported in different published works [1–2,13]. The aim of this study is to evaluate the diagnostic accuracy of ONSD sonographic as- sessment comparing to spinal manometry, to assess the best cut-off value to predict the diagnosis of IIH and to evaluate the response of ONSD to immediate changes of ICP. 2. Material and methods 2.1. Subjects and setting We present a diagnostic phase I–II validity study [14] from the data collected between May 2011 and February 2014 in the Laboratory of Neurosonology at the Department of Neurology of La Mancha Centro General Hospital, which was carried out from a consecutive cohort of 30 patients with different degree of suspicion of IH. These patients had attended our department for undergoing a lumbar puncture with cere- brospinal fluid (CSF) manometry (gold standard technique) submitted Journal of the Neurological Sciences 361 (2016) 122–127 Abbreviations: ONSD, optic nerve sheath diameter; ICP, Intracranial pressure; IIH, Idiopathic intracranial hypertension; CSF, cerebrospinal fluid; CSFoP, CSF opening pressure; ODE, optic disc elevation; OND, optic nerve diameter; CCC, concordance correlation coefficient; AION, anterior ischemic optic neuropathy. ⁎ Corresponding author at: Hospital General La Mancha Centro, Pruebas Especiales de Neurología, Avenida de la Constitución s/n., Alcázar de San Juan, Ciudad Real PC 13600, Spain. E-mail address: pablodelsaz1@gmail.com (P. del Saz-Saucedo). http://dx.doi.org/10.1016/j.jns.2015.12.032 0022-510X/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of the Neurological Sciences journal homepage: www.elsevier.com/locate/jns