Use of a Percutaneous Diskectomy Device to Facilitate the Diagnosis of Infectious Spondylitis ============================================================================================= * A.S. Wattamwar * A.O. Ortiz ## Abstract **SUMMARY:** For evaluation of suspected infectious spondylitis, 19 consecutive patients underwent imaging-guided spine biopsy with needle aspiration and a percutaneous diskectomy device to determine if the diskectomy device provided diagnostic value. In 79% of cases, the diskectomy device yielded a specimen when needle aspiration failed. A significantly greater yield of specimen was observed with the diskectomy device, and >50% of cases with failed needle aspiration had biopsies positive for infection. Infectious spondylodiskitis is an uncommon spinal disorder, which remains difficult to diagnose. A major potential obstacle to microbiologic and histopathologic diagnosis is the adequacy of specimen yield associated with spine biopsy.1 The “traditional” biopsy technique is based on an imaging-guided percutaneous needle (25- to 18-gauge caliber) placement and aspiration. When the aspiration is “dry” or yields no specimen, then a lavage with sterile normal saline is often performed. The objective of disk biopsy should be addressed with a technique that obtains a satisfactory amount of the disk tissue to be analyzed. Toward this end, we used a percutaneous diskectomy device (Dekompressor; Stryker Instruments, Kalamazoo, Michigan), which was designed to extract disk tissue from a target intervertebral disk by using imaging guidance (Fig 1). ![Fig 1.](http://www.ajnr.org/https://ajnr-sso.highwirestaging.com/content/ajnr/31/6/1157/F1.medium.gif) [Fig 1.](http://www.ajnr.org/content/31/6/1157/F1) Fig 1. Photograph of the percutaneous diskectomy device with its collection chamber and probe. The *arrow* indicates the depth gauge of the guide needle. ## Technique Nineteen patients underwent imaging-guided percutaneous spine biopsy during their clinical evaluation for suspected infectious spondylitis. Eleven patients were men, and 8 were women. All patients were adults with a mean age of 72 years. Patients were referred for biopsy after clinical and MR imaging findings resulted in a working diagnosis of spine infection. Four patients had undergone prior open spinal surgery for lumbar stenosis. Seven patients were already receiving intravenous antibiotic therapy at the time of their biopsy procedure. Every reasonable attempt was made to perform a biopsy procedure within 24 hours of request. All patients were placed in the prone position, and imaging guidance was used to locate the intervertebral disk space of interest. Imaging guidance consisted of fluoroscopy in 18 patients and CT guidance in 1 patient. All procedures were performed by an experienced interventional neuroradiologist by using a coaxial technique, local lidocaine anesthetic at the puncture site, and either intravenous sedative/anesthetic or intravenous anesthetic. A posterior, lateral, and extradural approach was used to access the disk. An initial aspiration attempt was made by using a 20-gauge spinal needle. The 20-gauge spinal needle was exchanged over a 22-gauge removable hub needle for either a 17- or 13-gauge guide needle. An aspiration attempt was made through the 17-gauge needle. A 6-inch percutaneous device was then coaxially deployed through the guide needle. The tip of the device and its excursion could be safely monitored under imaging guidance. With the probe tip in the disk space, the device was activated, and any fluid and disk material were harvested at the probe tip and were delivered to a collection chamber (Fig 2). At least 2 specimens (average, 3 specimens) were obtained during each procedure. After sample collection, the device was removed. The guide needle was again exchanged over a 22-gauge removable hub needle for a 12-gauge bone biopsy needle. A bone biopsy of the vertebral endplate was also obtained with the bone biopsy needle. All specimens were submitted for microbiologic and pathologic analysis. Patients were monitored in a recovery area postprocedure before leaving the department. ![Fig 2.](http://www.ajnr.org/https://ajnr-sso.highwirestaging.com/content/ajnr/31/6/1157/F2.medium.gif) [Fig 2.](http://www.ajnr.org/content/31/6/1157/F2) Fig 2. A close-up photograph of the handheld device shows purulent material (*arrow*) in the collection chamber in this patient with biopsy-proved *Enterococcus* infection. ## Results In 15 of the 19 patients, the diskectomy device yielded a specimen when needle aspiration (20 or 17 gauge) did not. In 3 of 4 patients in whom needle aspiration yielded a specimen, the biopsy was positive for infection. Not 1 single needle aspiration yielded disk tissue. Furthermore, not 1 single endplate biopsy yielded disk material as noted in the pathology report. In comparison, all 19 percutaneous diskectomy procedures yielded disk specimens in adequate amounts for both microbiologic and pathologic analysis. A significantly greater yield of specimen was observed (minimum, 3 mL of tissue fragments and fluid) in all 19 patients compared with