Discography: can pain in a morphologically normal disc be due to an adjacent abnormal disc?

Symptomatic patients who had Magnetic Resonance Imaging findings of degenerative disc disease and who failed conservative treatment were identified. As a preoperative test, these patients underwent discography. The patients, who experienced pain with injection into a morphologically normal disc adjacent to a morphologically abnormal disc, were included in the study. These patients subsequently had repeat discograms, during which the adjacent abnormal disc was first anesthetized with 2% lidocaine and the discogram was repeated at the adjacent normal level. All patients were blinded as to the nature of the procedure. Nine patients were identified (7 males and 2 females). The average age was 46.5 years (32-68). Two patients had a previous L4-Sacrum anterior and posterior fusion while 2 patients had L5-Sacrum anterior and posterior fusions. These four patients had solid fusions on Computerized Tomography scan and had developed adjacent segment degeneration according to MRI. Overall, each patient underwent an average of four discograms, at the lowest mobile disc segments. All of the patients were found to have a painful but morphologically normal disc adjacent to a painful and morphologically abnormal disc. The morphologically abnormal disc was anesthetized and the discography repeated on the normal disc. Upon this repeat discography, none of the patients experience any pain. The authors recommend anesthetizing painful abnormal discs prior to discography of the adjacent discs. This technique may avoid unnecessary dismissal of patients from treatment because of an appropriate response to discography. The normal disc may be due to referred pain from an adjacent abnormal disc.