Ultrasound Measurement Of Optic Nerve Sheath Diameter And Its Improved Methods Assess The Accuracy Of Intracranial Hypertension

Objective:To study the accuracy of ultrasound measurement of optic nerve sheath diameter（ONSD）and its improved methods ONSD to eyeball transverse diameter（ETD）ratio and optic nerve subarachnoid diameter（ΔONSD）in evaluating intracranial hypertension.Methods:In this study,we collected lumbar puncture（LP）pressure measurements from patients with non-serious suspected intracranial pressure increase,collected general characteristics,clinical diagnosis of each patient,and used ultrasound to measure ONSD,OND,and ETD,calculated ONSD/ETD ratio andΔONSD,analyzed the influencing factors of ONSD,ONSD/ETD ratio,andΔONSD.The correlation between the aforementioned three methods and ICP was examined.The accuracy of the aforementioned three methods of identifying elevated intracranial pressure（ICP）was evaluated using the receiver operating characteristic curve（ROC）,and the Youden index was calculated to establish the ideal threshold.Results:A total of 125 patients with suspected increased intracranial pressure（69 patients with intracranial infection and 56 patients with non-intracranial infection）were included in the study.the median ICP was 175（105）mm H₂O,with 48 patients with increased ICP.the mean ONSD was 4.99±0.50 mm,the mean ONSD/ETD ratio was 0.22±0.02,and the meanΔONSD was 1.03±0.22 mm.The results of multiple regression analyses showed that ETD and OND were the influencing factors of ONSD,OND was the influencing factor of ONSD/ETD ratio,and ETD was the influencing factor ofΔONSD.All three measurements above were significantly correlated with ICP for ONSD（r=0.818,P<0.001）,ONSD/ETD ratio（r=0.776,P<0.001）,andΔONSD（r=0.851,P<0.001）.The area under the curve（AUC）value of ONSD was 0.947（95%CI:0.908-0.986）,with an optimal threshold of 5.04 mm,sensitivity of 91.7%,and specificity of 85.7%for the diagnosis of ICP elevation.The AUC of ONSD/ETD ratio was 0.961（95%CI:929-0.993）,with an optimal threshold of 0.22,sensitivity of 87.5%,and specificity of 94.8%.The AUC ofΔONSD was 0.977（95%CI:0.956-0.997）,with an optimal threshold of 1.08 mm,sensitivity of 91.7%,and specificity of 93.5%.When the two methods were combined,the AUC value ofΔONSD combined with the ONSD/ETD ratio was the highest,at 0.980（95%CI:0.960-1.000）.The AUC values of ONSD,ONSD/ETD ratio,andΔONSD for the intracranial infection and non-infection groups were 0.966 vs 0.924,0.975 vs 0.934,and0.989 vs 0.956,respectively,and the AUC values of ONSD combined with ONSD/ETD ratio,ONSD combined withΔONSD,andΔONSD combined with ONSD/ETD ratio were 0.984 vs.0.950,0.991 vs.0.959,and 0.992 vs.0.961,respectively.Conclusion:In this study,ONSD was influenced by ETD and OND,with ETD being the influencing element ofΔONSD and OND being the influencing factor of ONSD/ETD.ONSD,ONSD/ETD ratio andΔONSD were significantly correlated with ICP,and had strong diagnostic efficacy for increased ICP,among whichΔONSD had the strongest predictive ability.The combined use ofΔONSD and ONSD/ETD ratio may increase the accuracy of diagnosis.Compared with intracranial hypertension caused by non-infectious diseases,both single measurement and combined measurement methods are more effective in diagnosing intracranial hypertension caused by infectious diseases.