Association between increased intracranial pressure and optic nerve sheath diameter by ultra-sound

Zheng Yuan-yuan; Du Zhao-hui; Gan Quan; Sun Xiao-chen; Wang Zhi-li

doi:10.3969/j.issn.1002-1949.2016.11.006

Abstract：Objective To investigate the effectiveness and feasibility of optic nerve sheath di?ameter(ONSD)measured by ultrasound in detection/diagnosis of increased intracranial pressure(ICP). Methods This was a prospective double-blinded observational study. From September 2014 to Novem?ber 2015, 60 patients with brain injury were included. Each patient was performed decompressive crani?ectomy and implanted invasive intracranial pressure detector at the same time. After the operation was done and the patient went back to Intensive Care Unit, we used the bedside ultrasound to measure 3 mm behind the retina as optic nerve sheath diameter. The correlation between ICP and ONSD was assessed by SPSS 19.0. The diagnostic performance of ONSD was determined by recelver operating curve(ROC). Results There were 60 patients in our study which included 32 males and 28 females. The average age was 49.2(18 ~ 80). Diagnoses included intracerebral hemorrhage(31), traumatic brain injury(18), acute cerebral infarction(5), extradural hemorrhage(6). Spearman rank correlation coefficient of ON?SD and ICP was 0.778(95% CI 0.57 ~ 0.87, P<0.0001), demonstrating a significant correlation. A ROC curve was drawn to determine the optimal cut off value to distinguish an ICP greater than 20 mmHg. The area under the receiver operator characteristic curve(AUC)was 0.964(95%CI 0.923 ~1.000). Optimal cut-off of ONSD for detection of elevated ICP(>20 mm Hg)was 4.8 mm, with sensitivity 91%(30/33), specificity 89%(24/27). The positive predictive value was 91%(30/33), negative pre?dictive value was 89%(24/27). When ONSD was over 5.0 mm, the sensitivity was 79%(26/33), speci?ficity was 96%(26/27), with positive predictive value 96%(26/27)and negative predictive value 79%(26/33). Conclusion The results indicated that ONSD increased along with the rise of ICP, which is consistent with many previous studies. But the relationship between ONSD and ICP is not purely linear. Optimal ONSD for detection of ICP>20 mmHg was ≥4.8 mm. In conclusion, ONSD measure?ment is a non-invasive, accurate, convenient and efficient method to identify the rise of ICP. Although this method has high application value, it cannot displace other detection methods.