Improving visualization of the anterior subarachnoid space during cervical gas myelography

To improve definition of the spinal cord when it lies anteriorly, turning the patient from the lateral decubitus to the supine position and obtaining a horizontal-beam lateral radiograph of the cervical spine is recommended. Supine positioning permits improved visualization of the anterior subarachnoid space and evaluation of extradural lesions encroaching upon it, as well as abnormal fixation of the cord.