Effect of Cervical Collar on the Optic Nerve Sheath in Minor Head Trauma Patients

Head trauma is an important cause of morbidity and mortality. Increased intracranial pressure (ICP) can lead to decreased cerebral perfusion and tissue damage. It is important to be able to detect increased ICP on time, so that treatment can be initiated to prevent further brain damage. The measurement of optic nerve sheath diameter (ONSD) has been proposed as a non-invasive and rapid way to assess elevated ICP (1-2). Traditional ICP monitoring methods such as external ventricular devices are invasive and time-consuming and can only be performed by trained personnel at trauma centers.

The optic nerve is surrounded by a protective sheath and is found on the back of the globe. Easily evaluated with ultrasonics. This is typically done with a linear probe measuring the diameter of the optic nerve sheath 3 mm back from where the contrast is highest. The normal upper limit for adults is 5 mm, the values above are considered abnormal. Many studies have shown that an increased ONSD measured by bedside ultrasound correlates with increased IDC and in one study there is a correlation between ONSD> 5 mm and ICP> 20 cm H2O.

Cervical spine (c-arms) and cervical vertebrae are often temporarily immobilized in patients with head trauma. It has been shown that placement of c-arms increases IBP. The decrease in venous outflow caused by c-arms in the forehead is an important mechanism for this increase in ICP. The increase in ICP occurs simultaneously with the application of c-arms in cadaver. It is thought that increased ONSD in trauma patients may be related to c-arms.

If a c-collar application is found to increase ONSD, this trauma may make it difficult to use ONSD as an non-invasive estimate of ICP in patients.

To the best of our knowledge, there is a study in healthy individuals investigating the possible effect of c-collar administration on ONSD. However, there is no comparative study of patients with head trauma. The investigators tried to measure ONSD before and after placement of cervical limbs in cases with minor head trauma. The aim of our study is to identify changes in the optic nerve sheath measurement after placement of the c-arms, and to determine whether these changes are due to the time immobilized by the c-arms.