Posterior protrusion of the intervertebral disk, an entity brought to attention by Mixter and Barr,1 who recognized the value of employing radiopaque oil as a diagnostic means, has taken its place with other pathologic conditions producing backache and sciatic pain.
I do not wish to imply that all posterior protrusions produce symptoms; however, a protrusion of sufficient size, advantageously placed, may produce pathologic changes in the nerve roots or the cauda equina sufficient to convince the most skeptical of its clinical significance.
The present study was undertaken in an attempt to present the clinical findings in a series of cases in which definite neural changes were noted at the time of exploration and removal of a posteriorly protruded intervertebral disk.
This group is composed of cases in which operation was performed at the Mayo Clinic in 1936 and 1937. All questionable cases and all cases in which no definite