Optic nerve sheath diameter measured sonographically as non-invasive estimator of intracranial pressure: a systematic review and meta-analysis

Chiara Robba, Gregorio Santori, Marek Czosnyka, Francesco Corradi, Nicola Bragazzi, Llewellyn Padayachy, Fabio Silvio Taccone, Giuseppe Citerio

Although invasive intracranial devices (IIDs) are the gold standard for intracranial pressure (ICP) measurement, ultrasonography of the optic nerve sheath diameter (ONSD) has been suggested as a potential non-invasive ICP estimator. We performed a meta-analysis to evaluate the diagnostic accuracy of sonographic ONSD measurement for assessment of intracranial hypertension (IH) in adult patients. We searched on electronic databases (MEDLINE/PubMed®, Scopus®, Web of Science®, ScienceDirect®, Cochrane Library®) until 31 May 2018 for comparative studies that evaluated the efficacy of sonographic ONSD vs. ICP measurement with IID. Data were extracted independently by two authors. We used the QUADAS-2 tool for assessing the risk of bias (RB) of each study. A diagnostic meta-analysis following the bivariate approach and random-effects model was performed. Seven prospective studies (320 patients) were evaluated for IH detection (assumed with ICP > 20 mmHg or > 25 cmH2O). The accuracy of included studies ranged from 0.811 (95% CI 0.678‒0.847) to 0.954 (95% CI 0.853‒0.983). Three studies were at high RB. No significant heterogeneity was found for the diagnostic odds ratio (DOR), positive likelihood ratio (PLR) and negative likelihood ratio (NLR), with I2 < 50% for each parameter. The pooled DOR, PLR and NLR were 67.5 (95% CI 29‒135), 5.35 (95% CI 3.76‒7.53) and 0.088 (95% CI 0.046‒0.152), respectively. The area under the hierarchical summary receiver-operating characteristic curve (AUHSROC) was 0.938. In the subset of five studies (275 patients) with IH defined for ICP > 20 mmHg, the pooled DOR, PLR and NLR were 68.10 (95% CI 26.8‒144), 5.18 (95% CI 3.59‒7.37) and 0.087 (95% CI 0.041‒0.158), respectively, while the AUHSROC was 0.932. Although the wide 95% CI in our pooled DOR suggests caution, ultrasonographic ONSD may be a potentially useful approach for assessing IH when IIDs are not indicated or available (CRD42018089137, PROSPERO).