Conservative follow-up after epidural abscess and diskitis complicating instrumented metal interbody cage.

There have been few reports on the imaging diagnosis and treatment of infection of interbody cages used in posterior lumbar interbody fusion. Even in a patient undergoing posterior lumbar interbody fusion using a metal cage, magnetic resonance imaging (MRI) might be able to diagnose epidural abscesses and diskitis when titanium alloy implants are used. When infection of the instrumented cage is diagnosed, emergency debridement with or without removal of implants, including the cage, appropriate wound closure, and the administration of potent antibiotics is the standard treatment. This article describes the conservative follow-up of a patient with epidural abscess and diskitis following instrumented posterior lumbar interbody fusion using a metal cage without surgical intervention. A 40-year-old man had undergone instrumented posterior lumbar interbody fusion at the L5/S1 level approximately 1 year previously. He suddenly developed a fever (temperature, 38 degrees C) and severe lower back pain without apparent cause. Late infection was suspected from his symptoms and laboratory findings, and a wide spectrum antibiotic was administered. On MRI, the low and high signal areas near the end-plate of L5/S1 were detected by T1- and T2-weighted imaging, respectively, and an abscess was noted around the cage. We recommended debridement as treatment; however, he refused further surgical intervention by reason of symptomatic remission. Therefore, wide spectrum antibiotics were continued. Fortunately, no lower back pain has recurred. Examination by MRI during the clinical course clarified the presence and disappearance of an epidural abscess and diskitis. Although the outcome of this case was fortunate, this conservative treatment is unusual, and is not recommended as standard treatment.