One-stage posterior-only approach in surgical treatment of single-segment thoracic spinal tuberculosis with neurological deficits in adults: a retrospective study of 34 cases

Written informed consent was obtained from all patients, and this study protocol was approved by the Ethics Committee of Xiangya Hospital. From January 2003 to January 2013, surgery therapy was performed on 34 patients with STSTND by the same surgeons at the same institution. Among these patients, 20 were male and 14 were female, and patient’s age ranged from 19 to 68 years old (average age, 40.3 years old). Involved levels were observed at two adjacent thoracic vertebras in 30 cases, while three or four vertebras with only one focus center were observed in four cases (Fig. 1). Surgery was considered in the presence of the following indications: (1) persistent back pain that was unresponsive to chemotherapy for two months; (2) progressive neurological deficit and angular deformity (≥30°) or instability is likely to appear; (3) radiologically severe spinal cord decompression (≥1/4 of the spinal canal diameter at the same level), significant vertebra destruction or collapse (≥1/3 of vertebral height), and/or paraspinal abscess with necrotic disc or inflammatory granulation tissues (≤5 cm away from the diseased focus); (4) multilevel vertebrae were involved, in which only one center was required to be debrided and short bone fusion was performed (less than two levels); (5) the elderly or patients with poor health who could not tolerate too much trauma; and (6) patients who underwent anterior operation, in which their anatomical structure was unclear. Patients that presented with the following conditions were excluded: (1) no neurological deficits; (2) multilevel lesions or several focus centers that require anterior long-segment bone fusion; (3) accompanied by paraspinal or deep muscle abscesses beyond its scope and severe kyphosis deformity (more than 50°), in which combined anterior and posterior surgery would be given priority. Diagnosis was based on clinical and hematological criteria. Preoperative kyphosis angle was 34.1 ± 12.3° (range, −10-45°). The American Spinal Injury Association (ASIA) classification of spinal cord injury was employed to assess neurological deficits. Based on ASIA classification, three patients were classified as grade A, five patients were classified as grade B, 15 patients were classified as with grade C, and 11 patients were classified as grade D (Table 1 and Fig. 2). Visual analogue scale (VAS), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) of patients upon admission were 7.8 ± 2.1, 40.2 ± 6.3 mm/h, and 22.4 ± 5.7 mg/L, respectively (Table 1).

Chemotherapy was administered shortly after clinical diagnosis was suspected. Anti-TB drugs with HREZ chemotherapy regimen that consisted of isoniazid (5–10 mg/kg/day with no more than 300 mg/day), rifampicin (5–10 mg/kg/day with no more than 300 mg/day), ethambutol (15 mg/kg/day with no more than 500 mg/day), and pyrazinamide (25 mg/kg/day with no more than 750 mg/day) was administered 2–4 weeks before surgery. When progressive neurological deficits appeared and severe back pain was unresponsive to chemotherapy, we appropriately shortened the time of drug treatment. Surgical management was performed when ESR, CRP and temperature returned to normal levels or significantly decreased, and when anemia and hypoproteinemia were rectified completely.

Patients were placed in the prone position after administering general endotracheal anesthesia. Patients (involving T1-4) were placed in a halo with a weight of 3 kg during the operation. Through a midline incision, posterior spinal elements including lamina, facet joints and transverse processes were exposed (extraperiosteal dissection); extending one vertebrae above and below the involved segments. Transpedicular screws were allowed to be fixed on the side of the vertebral lamina based on preoperative symptoms and imaging. Generally, we preferred a longer segmental fixation that was at least two levels superior and inferior to the level of decompression. Transpedicular screws were also placed in the affected vertebrae if the upper part of the vertebrae was not destroyed by infection. After transpedicular screws were implanted, C-arm X-ray was used to confirm its accuracy. A temporary pre-bent rod was installed on the mild side of the lesion to avoid spinal cord injury induced by instability of the spine during decompression and focal debridement. Then, the severe side of the lesion, which caused clinical symptoms or presented with paraspinal abscess at the decompression side, was selected. A unilateral facetectomy and laminectomy up to the medial pedicle edge were performed. Then, the adjacent rib 1.0–1.5 cm beside the thoracic spine was cut off, and thoracic nerve roots on the focal side were sacrificed for better exposure, if necessary. Generally, decompression range was based on the extent of spinal canal stenosis and the scope of paraspinal abscess. A suitable flush tube was plunged into the paravertebral abscess to wash with appropriate pressure until no pus outflow was observed. Then, the necrotic disc and collapsed vertebrae were removed through to healthy bleeding bone using curettes. When the abscess was beyond the flush tube extension, the patient was repositioned by adjusting the operating table to facilitate the abscess into the focus (postural drainage). Sequentially, rods were tightened, and the kyphosis was slowly and carefully rectified with the help of the compression and stretch of the internal fixation instrument. If the space created after focal debridement was too large, allograft bone would be selected for posterior fusion at the segment that underwent decompression and focal debridement. If necessary, the other side was treated in the same way. If the bone graft was loose or bone defects were present, we embedded relatively large bone particles or blocks into the gap by implementing an impacted graft. Afterwards, 1.0 g of streptomycin and 0.2 g of isoniazid were locally administered, negative pressure drainage and incision sutures were performed postoperatively, and resected specimens were collected for bacterial culture and pathological diagnosis.

The drainage tube was pulled out when drainage volume was less 30 ml. Patients continued oral HREZ chemotherapy postoperatively. Six months later, pyrazinamide was discontinued. Then, patients received nine- to 12-month regimens of HRE chemotherapy (6HREZ/9-12HRE) [11]. Ambulation was allowed one week after surgery with a brace. All patients were examined clinically and radiologically in one week, and in three, six and 12 months after surgery; and then, once a year thereafter.