| Increased intracranial pressure (ICP) is considered to be an acute situation that isassociated with poor clinical outcomes, such as high rates of mortality in variousneurological diseases. Invasive ICP monitoring remains the gold standard for the diagnosisof ICP. However, due to the invasiveness of ICP monitoring, which can result incomplications such as hemorrhage and bacterial colonization, this technique should not beapplied to all patients with increased ICP. Additionally, a lack of neurosurgeons andcontraindications, such as coagulopathy or thrombocythemia, might reduce the feasibilityof invasive ICP monitoring. ultrasonographic ONSD has recently been used to assessincreased ICP. Thus, this noninvasive, simple, bedside methods for the assessment ofincreased ICP can speed diagnosis and reduce fatality. However，little is known about theindividual characteristics such as race, sex, body mass index (BMI), blood pressure, headcircumference, waistline that affect the ONSD as a predictor for ICP. Few evaluationexists regarding ONSD among Chinese sample. The normative values for ONSD amongChinese adults has not been established and the relationships between ONSD and specificdemographic and physiological characteristics has not been made clear. Furthemore, thecut-off point of this predictor in Chinese patients has not been established. It is not knownwhether the diagnostic accuracy of ONSD ultrasonography varies according to patientcharacteristics. Thus, we performed this study to in order to find answers to the abovequestions.Objective: We aimed to evaluate the ONSD of normal adults and patients who wouldundergo lumbar puncture. We wanted to evaluate the interobserver reliability and find thepotential factors influencing ONSD. Then, we aimed to establish the range of normalONSD and investigate the potential factors influencing ONSD and identify the ONSD criterion for raised ICP in a Chinese population.Methods:(1) Healthy adults were recruited during routine examinations betweenSeptember2012and February2013. Two-dimensional gray-scale sonography of ONSDexaminations were carried out. The following data were collected: age, sex, BMI,waistline, head circumference, systolic blood pressure (SBP), and diastolic blood pressure(DBP). We analyzed the bilateral ONSD and interobserver reliability.(2) We establishedthe range for normal ONSD and potential factors influencing ONSD in healthy Chineseadults. According to multiple linear regression results, participants were divided intodifferent groups according to related sex and BMI variables and we analyzed the ONSD ineach group.(3) The patients in neurological department who would undergo the lumbarpuncture (LP) were recruited between March2013and December2013. Two-dimensionalgray-scale sonography of ONSD examinations were carried out prior to the LPs. Theinterval between these two examinations was less than10min. The following data werecollected: age, sex, BMI, waistline, head circumference, systolic blood pressure (SBP),and diastolic blood pressure (DBP), ICP. We analyzed the potential factors influencingONSD in increased ICP group and normal ICP group.(2) The potential factors associatedwith ICP were analyzed. We investigated whether those factors had affected therelationship between ICP and ONSD.(5) We identified the ONSD criterion for thedetection of elevated ICP in a Chinese population. Bland-Altman analysis, multiple linearregression, multiple logistic regression, a receiver operating characteristic (ROC), curvewere performed.Results: In total,230healthy adults and279patients were included in the study.(1)There was no significant difference between left and right ONSD (t=-0.900，P=0.369).There was no significant difference between two observers (t=0.934， P=0.351).Bland-Altman analysis showed7.8%would be outside the95%consistent interval. Theinter-observer variation was0~0.0844.(2) The mean ONSD was3.458mm (SD0.2767),(95%CI:3.420~3.493). The minimum value was2.65mm and the maximum value was4.3mm. The ONSD distribution in this sample was considered normal. The normal rangeof ONSD in Chinese adults was2.967~4.181mm. The normal range of ONSD in underweight men, normal weight men, overweight weight men or obese men were3.188~3.618mm，3.048~4.094mm，3.254~4.286mm respectively. The normal range ofONSD in underweight women, normal weight women, overweight weight women orobese women were2.913~3.525mm，2.677~3.774mm，2.975~3.828mm respectively.After adjusting for potential confounds between these factors, sex and BMI wereindependently associated with ONSD. The ONSD of men was0.189mm bigger thanwomen. The ONSD increased by0.032mm/kg/m2of BMI.(3) In total,279subjects wereincluded in the study. One hundred and one patients presented with raised ICP. In normalICP group, sex, BMI and ICP were significant associated with ONSD. The ONSD of menwas0.161mm bigger than women. The ONSD increased by0.030mm/kg/m2of BMI. TheONSD increased by0.04mm/10mmH2O of ICP. In elevated ICP group, ICP wasindependently associated with ONSD. The ONSD increased by0.04mm/10mmH2O ofICP.(4) ONSD was a significant independent predictor of elevated ICP. The ICPincreased by67.677mmH2O/mm of BMI (R=0.765，P<0.001).(5) The ONSD cut-offpoint for the identification of elevated opening pressure on LP was4.1mm; this cut-offyielded a sensitivity of95%and a specificity of92%. ONSD is a strong and accuratepredictor of raised ICP. were independently associated with ONSD. Underweight womenhad the smallest ONSD.Conclusion: Two-dimensional gray-scale sonography of ONSD is a feasible methodto assess the ONSD with a high interobsever reliability. The normal range of ONSD inChinese adults maybe was2.967~4.181mm. Ultrasonographic measurements of ONSDamong normal Chinese adults were correlated with sex and BMI. ONSD is a strong andaccurate predictor of raised ICP. The cut-off point of this predictor in a Chinesepopulation was4.1mm. It was remarkably lower than that foreign diagnosis criteria. Thus,ethnic differences should be noted when using the ONSD as an indicator of increased ICP. |
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