**Background:** Elevated intracranial pressure (eICP) is a serious medical emergency requiring prompt identification. Current gold standards (extra-ventricular drainage, intra-ventricular catheters) are invasive, require patient transportation, and involve radiation. Ocular ultrasound has emerged as a rapid, non-invasive bedside tool. This systematic review explored the utility of ultrasound-detected optic disc elevation (ODE) as an ultrasonographic finding of eICP and examined its sensitivity and specificity as a marker of eICP.
**Methods:** The review followed PRISMA guidelines and was registered in PROSPERO (CRD 42022251595). PubMed, EMBASE, and Cochrane Central were systematically searched for English articles published before April 2023. The initial search (April 7, 2021) yielded 1,703 citations; an updated search (April 10, 2023) added 216 citations. After deduplication, 1,260 unique articles from the initial search and 175 from the update were screened. Two independent reviewers screened titles, abstracts, and full texts, with a tie-breaking vote from an ultrasound fellowship-trained attending physician. Inclusion criteria: all English articles correlating optic disc height to papilledema or pseudopapilledema in human subjects. Case reports of only one patient were excluded. Data extraction followed the Cochrane Consumers and Communication Review Group template. Quality assessment used the QUADAS-2 tool. Meta-analysis was not planned due to heterogeneity of collected data.
**Key Results:** Twenty-nine studies published between 1994 and 2023 were included, comprising 1,249 adult and pediatric participants. Six studies were case series; seven were conducted exclusively in pediatric patients. All studies used B-scan ultrasonography with high-frequency transducers (3–20 MHz). Studies were globally distributed (11 in Europe, 10 in North America, 5 in Asia, 1 each in Oceania and Africa). Settings included emergency departments, neurology departments, ophthalmology departments, and intensive care units.
Mean ODE in patients with papilledema ranged from 0.6 mm (SD 0.5 mm) to 1.2 mm (SD 0.3 mm). Proposed cutoff values for ODE ranged from 0.3 mm to 1 mm. The majority of studies reported sensitivity between 70% and 90%, and specificity ranged from 69% to 100%, with most studies reporting a specificity of 100%. When comparing 0.6 mm versus 1.0 mm thresholds, the lower threshold resulted in a 9–20% increase in sensitivity at the expense of a 0–24% decrease in specificity. Area under the curve analyses determined optimal cut-off values between 0.55 mm and 0.66 mm.
Regarding correlation with CSF opening pressure, two studies found no correlation (Spearman's ρ = −0.016, P = 0.94; r = 0.27, p = 0.186), while four studies found positive correlations (r = 0.383, p = 0.025; r = 0.77, R² = 0.59, p < 0.001; r = 0.613, p < 0.001; r = 0.572, p = 0.004). One study found significantly decreased ONSD (6.8 ± 0.5 vs. 6.4 ± 0.6 mm; p = 0.006) and ODE (1.1 ± 0.3 vs. 0.9 ± 0.9 mm; p = 0.006) at 4 weeks post-lumbar puncture.
Combining ONSD and ODH measurements improved diagnostic accuracy: one study using ONSD > 4.5 mm and ODE > 1 mm yielded 90% sensitivity and 55% specificity; another found ODH > 0.63 mm combined with ONSD > 4.68 mm yielded 93% sensitivity and 92% specificity; a third reported ODH > 0.055 cm combined with ONSD > 0.615 cm yielded 87.50% sensitivity and 85.70% specificity.
Ultrasound visualized the optic disc in 100% of cases versus 40% for direct fundoscopy. Test-retest variability for ODE was 0.09 ± 0.04 mm (range 0.02–0.16 mm). Intraclass correlation coefficients for ODE were 0.81 (95% CI 0.75–0.89) for right eyes and 0.85 (95% CI 0.79–0.91) for left eyes.
For pseudopapilledema, ultrasound accuracy in distinguishing papilledema from pseudopapilledema was 74%. Papilledema was misinterpreted as pseudopapilledema in 60% of cases, and pseudopapilledema was misinterpreted as papilledema in 12% of cases.
Quality assessment (QUADAS-2) revealed that in 23 of 29 studies, patient selection may have introduced bias. The reference standard had low risk of bias in 13 studies, while the remainder were high risk or did not use a reference standard.
**Clinical Implications:** Ultrasound-detected ODE is a feasible, non-invasive test with high specificity and sensitivity that may aid physicians in monitoring and screening for eICP. The ability to rapidly rule-in papilledema in patients presenting with vague symptoms may significantly improve outcomes. ODE may be especially useful in resource-limited settings, situations where repeat radiation exposure is contraindicated, or in space medicine. However, eICP can take time to cause ODE, limiting applicability in acute settings such as traumatic brain injury or intracranial hemorrhage. The authors note that ICP monitoring carries risks including hemorrhage, bacterial infection, misplacement, and increased duration of mechanical ventilation and ICU stay. Larger, prospective studies are needed to assess the role of ODE in conjunction with other ultrasonographic signs (ONSD, crescent sign, 30-degree test) in patients with suspected eICP.