Tuberculous vertebral osteomyelitis
Tuberculosis of the central nervous system accounts for approximately 1% of all cases of tuberculosis and 50% of these involve the spine.
Spinal tuberculosis is more common in children and young adults. The incidence of spinal tuberculosis is increasing in developed nations. Genetic susceptibility to spinal tuberculosis has been demonstrated.
Vertebral granulomatous infections are found in 10–20% of TB cases in developed nations and upwards of 20–41% in undeveloped nations 1).
The most common levels involved are the lower thoracic and upper lumbar levels. Has a predilection for the vertebral body, sparing the posterior elements. Psoas abscess is common (the psoas major muscle attaches to the bodies and intervertebral discs from T12-L5). Sclerosis of the involved vertebral body may occur.
M. tuberculosis is the most common etiology of vertebral granulomatous infection.
Immunocompromise has been found to increase the incidence of musculoskeletal lesions. While 3–5% of patients with pulmonary TB develop musculoskeletal lesions, this number substantially rises to nearly 60% in patients with HIV 2).
Characteristically, there is destruction of the intervertebral disk space and the adjacent vertebral bodies, collapse of the spinal elements, and anterior wedging leading to kyphosis and gibbus formation. The thoracic region of vertebral column is most frequently affected. Formation of a ‘cold’ abscess around the lesion is another characteristic feature. The incidence of multi-level noncontiguous vertebral tuberculosis occurs more frequently than previously recognized. Common clinical manifestations include constitutional symptoms, back pain, spinal tenderness, paraplegia, and spinal deformities.
Typically symptomatic for many months.
Neurologic deficit develops in 10–47% of patients 3) , and may be due to medullary and radicular artery inflammation in most cases. The infection itself rarely extends into the spinal canal 4) , however, epidural granulation tissue or fibrosis or a kyphotic bony deformity may cause cord compression 5).
For the diagnosis of spinal tuberculosis magnetic resonance imaging is more sensitive imaging technique than x-ray and more specific than computed tomography. Magnetic resonance imaging frequently demonstrates involvement of the vertebral bodies on either side of the disk, disk destruction, cold abscess, vertebral collapse, and presence of vertebral column deformities.
Neuroimaging-guided needle biopsy from the affected site in the center of the vertebral body is the gold standard technique for early histopathological diagnosis.
The available gadgetry of investigations, such as AFB smear, culture of Mycobacterium tuberculosis, and Uniplex PCR, suffers from a lack of adequate sensitivity and/or a lack of rapidity. Therefore, many times a diagnosis is made either very late in the disease process or sometimes empirical therapy has to be started because a definite diagnosis could not be made. All of these are not ideal situations for a clinician.
MPCR using IS6110, protein b, and MPB64 primers has a high sensitivity and specificity in rapid diagnosis of spinal tuberculosis. This is particularly useful for paucibacillary infections like spinal tuberculosis. However, further studies using large sample sizes are needed to confirm the practical applicability of this technique 6).
Esposito et al., highlighted the importance of suspecting this disorder in children with both aspecific systemic and neurological symptoms, in order to reach a timely diagnosis for appropriate and targeted intervention, avoiding the risk of overtreatment and malpractice claims 7).
In the context of evidence-based medicine and the rational use of antibiotics, it is clear that antibiotics should be preferred according to the culture antibiogram results in the treatment of infectious diseases 8).
Surgery may be required in selected cases, e.g. large abscess formation, severe kyphosis, an evolving neurological deficit, or lack of response to medical treatment.
The role of surgical debridement and fusion with TB is controversial, and good results may be obtained with either medical treatment or surgery. Surgery may be more appropriate when definite cord compression is documented or for complications such as abscess or sinus formation 9) or spinal instability.
Fifty-nine adult patients with thoracic and thoracolumbar spinal tuberculosis underwent single-stage transpedicular debridement, posterior instrumentation and fusion. These patients were followed for a minimum of 5 years. Patients were assigned to one of two groups according to the infected anatomic segment. In the thoracic spinal tuberculosis group, there were 28 cases (17 males, 11 females) with a mean age of 38.9 years; in the thoracolumbar spinal tuberculosis group, there were 31 cases (19 males, 12 females) with a mean age of 40.3 years. All cases were evaluated clinically using the visual analog scale (VAS), Kirkaldy Willis criteria and the ASIA impairment scale (ASIA). Radiographs were performed for measuring the angle of kyphosis and scoliosis. Complications related to surgery were recorded.
All patients successfully resolved their infections, experienced one or more ASIA grades of improvement, and improved in their VAS pain scores at final follow-up. In both groups, patient-reported outcomes reached over 90% excellent or good results using Kirkaldy-Willis criteria. The loss of kyphotic angle correction was 2.6° in the thoracic spinal tuberculosis group and 3.2° in the thoracolumbar spinal tuberculosis group. No scoliosis was observed in either group. Fifty-eight (98.3%) cases achieved solid bony fusion. In the thoracolumbar spinal tuberculosis group, one patient experienced screw loosening, and another patient with nonunion and rod breakage underwent revision surgery.
The technique of single-stage transpedicular debridement, posterior instrumentation and fusion is an effective method for the treatment of thoracic and thoracolumbar spinal tuberculosis in adults. Long-term postoperative clinical and radiological outcomes were satisfactory 12).
Kim et al., performed a retrospective review of the medical records of patients with culture negative pyogenic spondylitis (CNPS) and tuberculous spondylitis (TS). They compared the characteristics of 71 patients with CNPS with those of 94 patients with TS.
Patients with TS had more previous histories of tuberculosis (9.9 vs 22.3 %, p = 0.034), simultaneous tuberculosis other than of the spine (0 vs 47.9 %, p < 0.001), and positive results in the interferon-gamma release assay (27.6 vs 79.2 %, p < 0.001). Fever (15.5 vs. 31.8 %, p = 0.018), psoas abscesses (15.5 vs 33.0 %, p = 0.011), and paravertebral abscesses (49.3 vs. 74.5 %, p = 0.011) were also more prevalent in TS than CNPS.
Different from or contrary to the previous comparisons between CPPS and TS, fever, psoas abscesses, and paravertebral abscesses are more common in patients with TS than in those with CNPS 13).
Many previous studies in Korea usually reported that tuberculous spondylitis is the predominant infection. However, in the study of Jeong et al., the number of pyogenic infection was 3 times greater than that of tuberculous spinal disease. Etiological agents were identified in a half of all infectious spinal disease. For better outcomes, we should try to identify the causative microorganism before antibiotic therapy and make every effort to improve the result of culture and biopsy 14).