• Sang-Heon Lee, Richard Derby, Yung Chen, Kwan Sik Seo, and Mi Jung Kim.
• Spinal Diagnostics and Treatment Center, 901 Campus Drive, Suite 312, Daly City, CA 94015, USA.
• Spine J. 2004 Nov 1; 4 (6): 614-8.

Background ContextDiscogram studies have shown that pain reproduction correlates with the extent of annular disruption. However, it has not been assessed if pressure changes in the annulus fibrosus vary incrementally with intradiscal pressure.PurposeTo determine the relationship between intradiscal pressure and outer annular pressure during discography in intervertebral discs with and without annular tears.Study DesignIntradiscal and periannular pressures were measured simultaneously in vitro during intradiscal injection in porcine cadaver spines.MethodsTwenty fresh porcine cadaver lumbar spines with intervening discs were tested. Intradiscal and periannular pressures were measured simultaneously using two pressure sensors during intradiscal contrast injection. The tip of a 25-gauge needle connected with a pressure manometer was placed in the center of the nucleus pulposus. A second pressure transducer was located at the outer third of the annulus fibrosus. Needle and transducer locations were confirmed by fluoroscopy. To compare the intact and torn annulus fibrosus, annular disruptions were created with a 20-gauge needle and confirmed by fluoroscopy.ResultsDuring intradiscal injections of discs with an intact annulus, annulus fibrosus pressure remained low and a sharp increase in intradiscal pressure was observed. Significantly higher pressures were noted in the outer annulus in discs with annular tears (p<.01). Mean pressures at the central nucleus pulposus, the outer third of intact annuli and torn annuli were 93.4+/-40.9 psi, 14.8+/-1.9 psi and 85.7+/-24.8 psi, respectively.ConclusionsVolumetric injection of intervertebral discs with a torn annulus fibrosis during discography may increase intra-annular pressure similar to the increase in pressure that may occur during spinal loading activities. This effect may not occur in discs with an intact annulus fibrosus.

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