The efficiency of optic nerve sheath diameterto detect brain edema in unconscious patients

SUMMARY THE EFFICIENCY OF OPTIC NERVE SHEATH DIAMETERTO DETECT BRAIN EDEMA IN UNCONSCIOUS PATIENTS OBJECTIVES: The objective of this study was to investigate the efficiency of optic nerve sheath diameter (ONSD) expansion in detection of brain edema. METHOD: In this prospective observational study, unconscios patients overeighteen years-old, who admitted to Abant Izzet Baysal University School of Medicine Hospital Emergency Department between September 2014 andSeptember 2015, were enrolled. Before any diagnostic methods were used, both eyes were scanned with HITACHI ALOKA F 37 USG device with 7,5 mHz lineer transducer probe and ONSDs were measured. After that Cranial Computerized Tomography (CT) scan was performed the ONSD were measured bilateally on the CT images. ONSDs were measured with USG bilaterally in healthy volunteers too. All the measurements were recorded and Statistical Package for the Social Science for Windows version 22.0 (SPSS, Inc., Chicago, IL), was used for the data analysis. Sudent-t test is used when the datais distributed normally. Mann-Whitney U test is used when the data is not distributed normally. p <0,05 was accepted as significant. RESULTS:27 (%58,7) males and 19 (%41,3) females; totally 46 patients were enrolled. Patients' ONSDs were measured with ultrasound and CT scan images and the results were recorded. With the 5 mm, 5,5 mm and 6 mm cut-off value, there was no statistically significant relationship between brain edema and ONSD (p>0.05). As in the control group total of 67 volunteers' ONSD means with ultrasound was found no statistically significant difference (p> 0.05). There was no statistically significant difference too in 66 patients' CT sacans were reported in normal ranges (p >0.05). There is no significant difference between edema and ONSDs for age, gender, right, left, and both eyes in 41patients with brain edema (p >0,05). 41 patients with brain edema and 66 patients without brain edema were compared and there was a significant difference (p = 0,0001). As the cut-off value of 5 mm was taken, through the CT images sensitivity 87%, specificity 33%, >5,5 mm sensitivity 68%, specificity 59%, > 6 mm sensitivity 53%, specificity, 77%. When the cut off-value is taken as 6 mm specificity is increasing but sensitivity is decreasing. There was a significant diffence between the healthy participants' ONSDs with ultrasound and, patients with CT scans which were reported as normal (p = 0,000105). There is difference between measuring with ultrasound and CT. CONCLUSION: ONSD is expanding in patients with cerebral edema and can be measured by imaging methods. There is a significant difference between the measurement of ONSD with ultrasound and CT. KEYWORDS: Brain Edema, Optic Nerve Sheath Diameter, Ultrasonography