Noninvasive Evaluation of Intracranial Pressure Based on Ultrasound Measurement of Subarachnoid Space Area of Optic Nerve

Objective To measure the area of optic nerve subarachnoid and evaluate its sensitivity and specificity to predicting elevated intracranial pressure, so as to explore the mechanism of visual im-pairment and intracranial pressure in astronauts with this noninvasive method. Methods Based on the results of intracranial pressure measured by lumbar puncture, 51 subjects were divided into the elevat-ed intracranial pressure group and the normal intracranial pressure group. The general data were col-lected, and optic nerve sheath diameter(ONSD) at 3 mm behind the ball and area of optic nerve sub-arachnoid space(ONSASA) between 3～7 mm behind the ball were measured by ultrasonic examina-tion and Image J 1.51 analysis software. The prediction ability of these two indexes for elevated in-tracranial pressure was compared by receiver operating characteristic curve and area under curve. Results The optic nerve sheath diameter and the area of optic nerve subarachnoid were larger in the ele-vated intracranial pressure group, and the difference between the two groups was statistically signifi-cant. The area under curve of the area of optic nerve subarachnoid(0.894) to predict elevated in-tracranial pressure was larger than the optic nerve sheath diameter(0.764). Conclusion The measure-ment of area of optic nerve subarachnoid by ultrasonography can predict elevated intracranial pressure, which provides a possible and effective method to study the mechanism of visual impairment and in-tracranial pressure in space environment.