A study on the relationship between optic nerve sheath diameter and intracranial pressure increase after craniocerebral trauma surgery

Objective To evaluate the application of ultrasound measurement of optic nerve sheath diameter (ONSD) for predicting intracranial pressure (ICP) increase after craniocerebral trauma surgery. Methods A total of 120 patients who underwent decompressive craniectomy due to craniocerebral trauma in Department of Surgical ICU, Xinhua Hospital, Shanghai Jiaotong University School of Medicine from June to December 2018 were enrolled. Invasive ICP monitoring was performed by surgeons during surgery. According to invasive ICP values, the patients were divided into two groups: an increased ICP group (ICP>20 mmHg, 1 mmHg=0.133 kPa, n=60) and a normal ICP group (ICP≤20 mmHg, n=60), and their ONSD values were measured. The receiver operating characteristic(ROC) curve was used to investigate the optimal cut-off value of ONSD for detecting ICP elevation in patients after craniocerebral trauma surgery. Results The average ONSD of the eyes in the increased ICP group and the normal ICP group was (5.4±0.4) mm and(4.3±0.4) mm, respectively. The results of variance analysis showed that the difference of ONSD between the two groups were statistically significant (P<0.05). The correlation between the bedside ultrasound ONSD and the ICP of the corresponding individuals after craniocerebral trauma surgery was analyzed, where a significant correlation was determined (r=0.771). The cut-off value of ONSD based on the ROC curve was 4.9 mm, with a sensitivity of 88.3% and a specificity of 90.0%. Conclusions There is a significant correlation between ONSD and ICP. The optimal cur-off value for ICP elevation after craniocerebral trauma surgery is 4.9 mm. Due to measurement techniques, equipment, the experience of observers and the race of subjects, the optimal cut-off value of ONSD requires further studies. Key words: Optic nerve sheath diameter; Ultrasound; Intracranial pressure; Craniocerebral trauma