Optic Nerve Sheath Diameter on Computed Tomography Scans Reflects Elevated Intracranial Pressure in Patients with Craniosynostosis

BACKGROUND: Assessment for elevated intracranial pressure (ICP) helps guide interventional decision-making to treat craniosynostosis. However, noninvasive techniques for measuring ICP are limited. This study assessed whether optic nerve sheath diameter (ONSD) on low-dose computed tomographic (CT) scans is associated with ICP in patients with craniosynostosis. METHODS: Pediatric patients treated between 2014 and 2023 with craniosynostosis, intraoperative ICP measurements by direct subdural catheterization, and spectral domain-optical coherent tomographic (SD-OCT) data were included. ONSD was retrospectively assessed on preoperative CT scans by a masked neuroradiologist and compared with measures and proxies of ICP. RESULTS: Among the 132 patients included (median age, 6.9 years; interquartile range, 4.7 to 9.5 years), 41 (31.1%) had a syndromic diagnosis. Maximal ONSD was increased in patients with an ICP of 15 mmHg or greater (6.1 mm versus 5.5 mm; P < 0.01) and 20 mmHg or greater (6.3 mm versus 5.6 mm; P < 0.01). Maximal (r = 0.32; P < 0.001), minimum (r = 0.26; P = 0.003), and average (r = 0.29; P < 0.001) ONSD correlated with direct ICP measurements. ONSD and SD-OCT measurements were also correlated (maximum retinal nerve fiber layer, r = 0.21, P = 0.04; maximum retinal thickness, r = 0.24, P = 0.02). An ONSDmax threshold of 5.75 mm demonstrated 65% sensitivity and 64% specificity for detecting ICP of 15 mmHg or greater on optimized receiver operating characteristic curve analysis. Multivariable logistic regression generated an algorithm incorporating ONSDmax and age to detect an ICP of 20 mmHg or greater with 64% sensitivity and 80% specificity. CONCLUSIONS: ONSD measured on low-dose CT scans detected elevated ICP with moderate accuracy. Precision increased when patient age was taken into consideration. Given the ease of accessing CT scan data, this may be a helpful ICP proxy for clinical decision-making.