Effects of acute controlled changes in end‐tidal carbon dioxide on the diameter of the optic nerve sheath: a transorbital ultrasonographic study in healthy volunteers

Jun

2017

Sci Rep

The optic nerve sheath diameter (ONSD) is considered as an indirect marker for intracranial pressure (ICP). However, the optimal cut-off value for an abnormal ONSD indicating elevated ICP and its associated factors have been unclear. Thus, we investigated normative values for the ONSD using ultrasonography and investigate the potential factors affecting it. We prospectively recruited healthy volunteers between September 2016 and March 2017. A total of 585 individuals were included, in which the mean ONSD was 4.11 mm [95% confidence interval (CI), 4.09–4.14 mm]. Although ONSD was correlated with sex (p = 0.015), height (p = 0.003), and eyeball transverse diameter (ETD) (p < 0.001) in simple linear regression analyses, multiple linear regression analysis revealed that only ETD was independently associated with ONSD (p < 0.001). Accordingly, we further established a normative value for the ONSD/ETD ratio and its associated factors. The mean ONSD/ETD ratio was 0.18 (95% CI, 0.18–0.18), but the ONSD/ETD ratio was not correlated with sex, height, weight, body mass index, and head circumference. Our findings suggest that the ONSD had a strong correlation with ETD, and ONSD/ETD ratio might provide more reliable data than ONSD itself as a marker of ICP.

Section: Discussionsupporting

confidence: 60%

Ultrasonographic measurement of the optic nerve sheath diameter and its association with eyeball transverse diameter in 585 healthy volunteers

Jun

2017

Sci Rep

Journal of Neuroimaging

“…). A total of 34 studies provided mean values for ONSD measurement . The pool of mean ONSD measurements was 4.78 mm (95% CI, 4.63‐4.94 mm; Fig.…”

Section: Resultsmentioning

confidence: 99%

Quantification of Optic Nerve and Sheath Diameter by Transorbital Sonography: A Systematic Review and Metanalysis

Schroeder

Katsanos

Richter

et al. 2020

BACKGROUND AND PURPOSE To date, normal values for optic nerve diameter (OND) and optic nerve sheath diameter (ONSD) for transorbital sonography (TOS) have only been reported by individual small‐scale studies, exposing a great variability in the measurement of the OND and ONSD. METHODS We performed a systematic review and metanalysis of available to date studies on TOS evaluation of adults without elevated intracranial pressure to provide an overview of the published literature, measuring methods and further specify normal values for OND and ONSD. RESULTS In total, we included 39 studies with 2,927 healthy volunteers (mean age 36.1 years, 44.4% female), so that a total of 5,854 eyes were examined. All pooled analyses were based on random effect models. Mean values for OND were provided in 13 studies. Calculated mean pooled OND value was 3.08 mm (95% confidence interval [CI], 2.9‐3.25), with low heterogeneity across studies (I2 = 12.7%). Thirty‐four studies provided mean values for ONSD measurement. The pool of mean ONSD measurements was 4.78 mm (95% CI, 4.63‐4.94), with evidence of substantial heterogeneity between estimates ONSD (I2 = 50.6%). There were no significant differences (P = .139) in the subsequent subgroup analysis for the different geographic continents. Also, no significant differences could be recorded for the effect of age (P = .824) or gender (P = .093). CONCLUSIONS TOS is a frequently described and widely used method. We provide reference values of OND and ONSD that are based on metanalytical analysis. Different measuring methods of ONSD result in higher heterogeneity. Subgroup analysis revealed no significant correlation between ONSD and age, gender, or geographic origin.

“…For instance, it was recently reported that the ONSD significantly increases with hypercapnia and subsequently reverts to baseline values once normocapnia is established. 21 Moreover, Maissan et al 22 reported that during tracheal stimulation, both the ICP and ONSD increased simultaneously, while after the procedure, the ONSD returned to the baseline diameter at the same rate as the ICP. It has been suggested that the changes in ONSD may reflect a temporary and reversible increase in ICP because of acute elevations in the intraabdominal pressure.…”

Section: Discussionmentioning

confidence: 99%

Ultrasonography Assessments of Optic Nerve Sheath Diameter as a Noninvasive and Dynamic Method of Detecting Changes in Intracranial Pressure

et al. 2018

IMPORTANCE The crtierion standard method for monitoring intracranial pressure (ICP) can result in complications and pain. Hence, noninvasive, repeatable methods would be valuable. OBJECTIVE To examine how ultrasonographic optic nerve sheath diameter (ONSD) correlated with noninvasive and dynamically monitored ICP changes. DESIGN, SETTING, AND PARTICIPANTS The ONSD was measured before the lumbar puncture (LP) in 60 patients on admission. Patients with elevated ICP were divided into group 1 (200 < LP Յ 300 mm H 2 O) and group 2 (LP > 300 mm H 2 O). Patients underwent follow-up ONSD and LP measurements within 1 month. We analyzed the correlations between the ONSD and ICP on admission and between the changes in ONSD and ICP, which were the respective changes in ONSD and ICP from admission to follow-up. MAIN OUTCOMES AND MEASURES The ultrasonographic ONSD and ICP were measured on admission and follow-up. The correlations between the ONSD and ICP on admission and between the changes in ONSD and ICP were analyzed using Pearson correlation analyses. RESULTS For 60 patients (Han nationality; mean [SD] age, 36.2 [12.04] years; 29 [48%] female) on admission, the ONSD and ICP values were strongly correlated, with an r of 0.798 (95% CI, 0.709-0.867; P < .001). Twenty-five patients with elevated ICP who completed the follow-up were included. The mean (SD) ONSD and ICP on admission were 4.50 (0.54) mm and 302.40 (54.26) mm H 2 O, respectively. The ONSD and ICP values obtained on admission were strongly correlated , with an r of 0.724 (95% CI, 0.470-0.876; P < .001). The mean (SD, range) changes in ICP and ONSD were 126.64 (52.51 mm H 2 O, 20-210 mm H 2 O) (95% CI, 106.24-146.07) and 1.00 (0.512 mm, 0.418-2.37 mm) (95% CI, 0.83-1.20), respectively. The change in ONSD was strongly correlated with the change in ICP, with an r of 0.702 (95% CI, 0.425-0.870; P < .001). The follow-up evaluations revealed that the elevated ICP and dilated ONSD had returned to normal, and no evidence of difference was found in the mean ONSDs between group 1 (3.49 mm; 95% CI, 3.34-3.62 mm) and group 2 (3.51 mm; 95% CI, 3.44-3.59 mm) (P = .778) at follow-up. CONCLUSIONS AND RELEVANCE The dilated ONSDs decreased along with the elevated ICP reduction. Ultrasonographic ONSD measurements may be a useful, noninvasive tool for dynamically evaluating ICP.