Role of consecutive bedside ultrasonographic measurement of optic nerve sheath diameter in diagnostic and follow up of patients presenting with head trauma in emergency department

Intracanial pressure increase due to traumatic brain injury, is one of the most common reasons for mortality and morbidity among young population. It is possible to prevent negative outcomes by early diagnose and treatment. Cranial computerized tomoghraphy is utilized as the first choice for diagnose and follow up of traumatic brain injury, but is not suitable for patients with unstable vital signs and radiation exposure is increased with every tomographic scan. Optic sheath nerve diameter (ONSD) measurement by ultrasonography (US) is being investigated as a new method for diagnosing intracranial pressure increase. In our study ONSD measurement by US is compared with the presence of lesion in CT to investigate the diagnostic convenience of US in TBI. Also, in patients who are diagnosed with TBI and are followed-up with serial cranial CTs in emergency department , simultaneous sonographic ONSD measurements are made and thus the role of US in patient follow-up is researched. Statistical analysis are made after patients are grouped according to their Glasgow Coma Scores (GCS), and determining 5.1mm as the cut-off value for ONSD via ROC analysis. Statistical analysis are repeated for 5.8mm taken as the cut off value. Corelation of medium degree( r = -0.384) and negative corelation of high significance(p<0.001) between ONSD and GCS are found. When ONSD cut-off value is taken as 5.8mm, it is seen that it has a high positive predictive value ; but at 5.8mm value it is found to be insufficient at determining presence of lesion in CT. It may be possible to obtain data of higher significance via studies in which ONSD measurement is compared with directly evaluated ICP increase by different measurement methods. In our study, our aim was to research the reliability of patient follow up with US instead of control CT scans. In mild head trauma group, evaluated with clinical findings, ONSD is thought to be convenient in the follow-up of intracranial pressure increase. When progression in 6th and 24th hour cranial CT findings and simultaneous ONSD measurement are compared, it is found that ONSD has high(89%) negative predictive value, thus, in mild head trauma group, we thought that evaluated with clinical findings, ONSD measurement may be used as an exclusion criteria. More studies conducted with more patients and more sensitive measurement modalities are needed for optic nerve sheath diameter to be used as a follow up parameter in medium and serious head trauma.