The Researchers Aimed to examine how ultrasonographic optic nerve sheath diameter ( ONSD ) Correlated With noninvasive and intracranial pressure Dynamically Monitored ( ICP ) changes.

The optic nerve is an outward form of the diencephalon during embryogenesis. It is wrapped by the nerve sheath, which is derived from 3 layers of meninges and protrudes towards the orbit.

Thus, the cerebrospinal fluid moves freely between the intracranial and intraorbital subarachnoid spaces.The intraorbital subarachnoid space surrounds the optic nerve, and it is subject to the same pressure changes as the intracranial subarachnoid space.

Thecrtierion standard method for intracranial pressure monitoring ( ICP ) can result in complications and pain. Hence, noninvasive, repeatable methods would be valuable.

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 ≤ 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.

Researchers 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.

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.

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.

The dilated ONSDs decreased along with the elevated ICP reduction . Ultrasonographic ONSD measurements may be a useful, noninvasive tool for dynamically evaluating ICP.