• Murat Yesilaras, Turgay Yilmaz Kilic, Suveyda Yesilaras, Ozge Duman Atilla, Dilek Öncel, and Mahmut Çamlar.
• Izmir Tepecik Research and Educational Hospital, Department of Emergency Medicine, Turkey. Electronic address: muratyesilaras@gmail.com.
• Am J Emerg Med. 2017 Oct 1; 35 (10): 1408-1413.

IntroductionThe aim of this study was to investigate the relationship between the optic nerve sheath diameter (ONSD) measured on non-contrast head computed tomography (CT) and the diagnosis and prognosis of spontaneous subarachnoid hemorrhage (SAH) on emergency department (ED) patients.MethodWe used a matched control group of patients with the same age and gender who were diagnosed in the ED with spontaneous SAH and who admitted to the ED with headache. Four emergency medicine attending physicians made the ONSD measurements. For measurements, the 3-mm posterior location where the optic nerve enters the eyeball was used.ResultsThis study was done with 61 spontaneous SAHs with an equal number of control patients. The median ONSD for control and spontaneous SAH groups was 5.76 [interquartile range (IQR): 0.96] mm and 6.72 (IQR: 1.42) mm, respectively (p<0.001). The area under the receiver operating characteristic curve was determined as 0.791 (confidence interval 95% 0.710-0.872). At an ONSD threshold value of 6.1 mm, the sensitivity and specificity of SAH was 72%. There was no significant relationship between ONSD and in-hospital mortality in spontaneous SAH patients (p>0.05). The intra-class correlation coefficients for inter and intra-rater reliability were 0.84 and 0.95, respectively.ConclusionIn patients with spontaneous SAH, the ONSD measured in the orbital sections of a head CT is strongly correlated with a SAH diagnosis. Assessment of ONSD in head CTs taken with spontaneous SAH suspicion may contribute to the diagnoses of spontaneous SAH.Copyright © 2017 Elsevier Inc. All rights reserved.

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