To the Editor.—In sciatica, pain on coughing and segmental numbness are generally known symptoms. They are often mentioned in the literature, but their nature and clinical meaning have never been exactly defined. The new approach to the study of clinical findings in relation to disk changes, by lumbar diskography in our material,1,21,2 has not been generally noticed and understood, and it is significant that 22 book reviews on the monograph,2 in various journals, comment on the morphologic diagnosis but not on the analysis of the clinical findings.
Pain on coughing is found in disk rupture, the gelatinous contents of the nucleus pulposus being squeezed out of the disk to spread around the nerve root where they cause aseptic inflammation; it appears about one week after onset of the complaints. Numbness, however, is found in nerve compression, when a nonruptured disk exerts pressure to the root (these patients