The last group of paticnts for whom APLD must be considered the procedure of choice are those suspected of having infectious discitis. Although percutaneous fine-needle aspiration biopsy sampling of a suspected disc space has strong advocates owing to its inherent safety, the samples obtained are so small that the accuracy of negative bacteriological results is in doubt. The small sample also, although perhaps adequate for culture and Gram's stain, prevents any meaningful histo-logical evaluation, which can sometimes be important in making a rapid diagnosis in more unusual mycobacterial or fungal infections. The alternative to needle biopsy, open operative biopsy, has obvious disadvantages in this patient population. Automated aspiration biopsy of the suspected disc space is perhaps the best alternative for this clinical problem, combining the safety of skinny-needle biopsy with the ability to obtain large samples of pathological material, while thera-peutically debriding the disc space. Our own experience confirms the impression that automated biopsy in this setting is advantageous.14,15 Of the 12 automated disc aspiration biopsies we have carried out for suspected discitis, we obtained eight positive cultures. What is of great importance is that five of the patients with positive cultures had had negative needle aspirations. It was this experience that convinced us that a negative needle biopsy result for a suspected disc space infection is of virtually no value, and a procedure that obtains a better sample must follow.
When an unusual infection is considered (i.e., tuberculosis or a fungus), the use of an automated biopsy becomes even more compelling. Yu et al.16 described two cases in which automated biopsy results were used to diagnose unusual infections. They described two patients, one of whom was diagnosed with Candida discitis and the other with tuberculosis. Their article emphasized the large sample obtained with the automated biopsy, allowing histological identification of both infections by microscopy, and the initiation of specific therapy without having to wait for cultures. These authors also stressed the usefulness of automated biopsy for the debridement and treatment of infected discs. Both patients received immediate symptomatic relief after removal of large amounts of infected disc material.
In these patients, the procedure is carried out in the same manner as APLD, the only technical caveat being the need for special attention to the depth of the instrumentation within the disc. The infected an-nulus has poor integrity, particularly anteriorly. This could put the great vessels in danger if the instrumentation is passed too far forward in the disc. Careful monitoring of the oblique view in which the full depth of the instrument placement can be appreciated prevents this from happening.
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