Normal intraoperative spinal sonography.

The normal intraoperative sonographic features of the spinal canal, spinal cord, conus medullaris, and cauda equina are described and illustrated. Important observations concerning the normal spinal cord include its highly reflective dorsal and ventral surfaces, its uniform hypoechogenicity, and the presence of a central echo. Other easily identified structures within the spinal canal include the dura-arachnoid layer, subarachnoid space, denticulate ligament, dorsal arachnoid septations, and the roots of the cauda equina. In addition the sonographic appearance of commonly encountered iatrogenically introduced material including Gelfoam, Pantopaque, cottonoid pledgets, suture material, Harrington rods, and freeze-dried dura is also demonstrated. These normal images can serve as a baseline for the interpretation of various pathologic conditions of the spinal canal and its contents as seen with intraoperative spinal sonography.