Diagnostic Value Of Bedside Ultrasound In Measuring The Diameter Of Optic Nerve Sheath In The Increase Of Intracranial Pressure

Objective: We aimed at evaluating the ONSD(optic nerve sheath diameter)of normal adults and patients who would undergo LP(lumbar puncture),and investigating the correlation between ONSD and increase of ICP(intracranial pressure),application value,as well as the potential factors influencing ONSD.Methods: 100 patients from internal medicine department and surgery department,who were suspected of having increased ICP and would undergo LP,were treated as case group,and 50 healthy subjects were regarded as control group.The ONSD of all subjects were measured using two-dimensional gray-scale ultrasound to collect relevant potential factors influencing ONSD.Linear correlation and linear regression were used to test the correlation between ONSD and the increase of ICP;multiple linear regression analysis was applied to test the factors influencing ONSD;multiple linear regression equations were adopted to predict ICP;and ROC(receiver operating characteristic curve)was used to determine the optimal critical value for the increase of ICP.Results: There was no statistical difference of ONSD between the patients with normal ICP(ICP<200mmHg),who underwent LP,and the control group measured by ultrasound;there was statistical difference of ONSD between the patients with increased ICP(ICP<200mmHg)and the patients with normal ICP,both of whom underwent LP;linear regression analysis showed that the correlation coefficient R between ONSD and ICP was 0.907,and the two were strongly correlated;the regression equation for ICP changes with ONSD is Y=-79.222+58.101 X.The measurement results of ONSD by two-dimensional gray-scale ultrasound were showed in ROC curve,in which AUC(area under curve)was 0.969,the standard error was 0.017,the P value was 0.000,the 95% confidence interval for reference was(0.935,1.003),the sensitivity was 0.921,the specificity was 0.973,the critical value,that is,ONSD,was 4.475 mm.According to the analysis of relevant influencing factors,the ONSD of male is higher thanthat of female,and the difference is statistically significant.Factors like age,height,weight,BMI(body mass index),SBP(systolic blood pressure),DBP(diastolic blood pressure)and ETD(eyeball transverse diameter)have no influence on ONSD.The ONSD of male is(4.46±1.23)mm,and the female is(3.90±1.19)mm.When the ONSD of male is no less than4.575 mm,it is diagnosed as positive,that is,the ONSD is abnormal,with a sensitivity of0.938 and a specificity of 1;when the ONSD of female is no less than 3.925 mm,it is diagnosed as positive,that is,the ONSD is abnormal,with a sensitivity of 0.871 and a specificity of 1.Conclusion: Through measurement by ultrasound,it is found that ONSD is positively correlated with the increase of ICP,the critical value of ONSD is not the same for different genders,the measurement of ONSD contributes to the evaluation of the increase of ICP in clinic,with reference value.