Tuberculous Spondylitis after Percutaneous Vertebroplasty: Misdiagnosis or Complication?
A 58-year-old woman, who had a history of complete recovery from pulmonary tuberculosis six years previously, was hospitalized for severe back pain after a fall. Plain radiographs and magnetic resonance imaging of the thoracic spine revealed a fresh compression fracture at the T12 thoracic vertebra (). Bone densitometry indicated that the spine density was below average; the mean spinal T-score was -3.98. Physical examination demonstrated marked tenderness on palpation of the T12 region. Except for the incapacitating pain, the vital signs were stable and there was no evidence of infection. The white blood cell (WBC) count was 6,900 cells/mm3 (normal range 3,000-10,500 cells/mm3). A hematological analysis demonstrated that erythrocyte sedimentation rate (ESR) of 12 mm/hr and C-reactive protein (CRP) of 0.5 mg/dL, which were all within normal range. The pain relief was refractory to medical treatment for 2 weeks; therefore, vertebroplasty was performed and there were no intraoperative complications. Antibiotic prophylaxis was not administered before the procedure. The back pain improved dramatically, and the patient was discharged two days after the procedure. However, three weeks after the vertebroplasty, the pain gradually worsened despite administration of analgesic agents; the patient was readmitted four weeks later. Moreover, the patient reported intermittent fever with cold sweats. At the time of re-admission, the patient had a low grade fever 37.5℃. Hematological investigation revealed a mild leukocytosis with a total WBC count of 11,000 cells/mm3, elevation of the erythrocyte sedimentation rate (ESR) to 42 mm/h (normal range <30 mm/h) and a C-reactive protein (CRP) concentration of 2.05 mg/dL (normal range <0.8 mg/dL). Radiography and computed tomographic scanning revealed severe kyphosis, and that the disc space at the T11-T12 level had collapsed (). MRI also showed heterogeneous signal intensity with the spondylitis (). Initially, the patient was impressed with a pyogenic spondylitis, and percutaneous needle biopsy from the T11 and T12 vertebrae was performed. The patient was treated with antibiotics empirically before the results of the culture were available. However, the culture of the biopsy specimens was negative and did not lead to the identification of the causative micro-organism, including acid fast bacilli. However, the polymerase chain reaction (PCR) test results, specific for Mycobacterium tuberculosis, were positive for three of the four specimens (one from T11 and two from T12). Medication for tuberculosis was started with the diagnosis of tuberculous spondylitis. After three weeks of tuberculosis drug therapy, the ESR and CRP decreased to nearly the normal range (30 and 0.38, respectively). However, the patient was not able to walk independently because of persistent pain and aggravated kyphosis. The patient underwent posterior fusion and instrumentation from T9 to L2 without neural decompression (). After surgery, pain relief was achieved. The medication for tuberculosis was continued for 14 months. By 20 months after the surgery, the patient could ambulate independently without difficulty and complained only of back stiffness when walking.