Comparative Studies of Discography and Myelography

The diagnosis of herniation or protrusion of an intervertebral disk can readily be made in the majority of instances on the basis of the history and a careful examination (5, 13). Occasionally, when the clinical findings are inconclusive, additional diagnostic studies are indicated. For this purpose, myelography has been utilized extensively, inasmuch as it affords more precise information concerning the level and extent of the herniated disk (4). In addition, it aids in determining whether one or more disks are involved and in excluding intradural or extradural lesions. The accuracy of the procedure as reported by different observers varies between 75 and 92.3 per cent (4, 17, 28). The negative errors often seem to occur in those cases in which the surgeon also is in doubt (32). During the last decade, Lindblom, his associates, and others have stated that the diagnosis of herniation of an intervertebral disk can be made by a direct puncture of the disk with the injection of 35 per cent Diodrast (8, 10, 12, 23-26). They are of the opinion that this diagnostic method is more accurate and more rapid than myelography, as well as less hazardous to the patient, and that it offers the surgeon a graphic demonstration of the pathological changes in a disk. In an effort to verify this conclusion, a study has been made of a relatively small comparative series of patients, 18 in number, in whom both disk punctures and Pantopaque myelography were done. In 9 other instances, discography alone was done. Technic of Discography The procedure employed in these studies is essentially the same as that described by Lindblom. Prior to the disk puncture, films are reviewed to be sure that there is no unusual anatomical configuration which might interfere with insertion of the needle. The technic of puncture is not difficult and may be mastered readily by anyone familiar with the anatomy of the lower lumbar spine. The well sedated patient is placed on the fluoroscopy table in a prone position (Fig. 1A), with several pillows under the abdomen to arch the back. Anteroposterior and transverse lateral films are taken and studied, though this step may be omitted as familiarity with the procedure is increased. Under fluoroscopic control, the fourth and fifth lumbar interspaces are localized and marked. The lumbar area is prepared aseptically and, after a local procaine anesthetic has been administered, a 4-inch 18-gauge needle and stylet are inserted into the fourth interspace, a little to one side of the mid-line, adjacent to the inferior edge of the fourth lumbar spinous process. The needle is then passed slightly inferior to the lamina and aimed at the mid-line of the intervertebral disk. The centering and insertion of the needle may be controlled by fluoroscopy. When the surgeon feels he is adjacent to the posterior longitudinal ligament overlying the annulus fibrosus of the intervertebral disk, a 6-inch 22-gauge inner needle is inserted 1.5 cm. directly into the disk.