Among all 129 cases in this study, 35 cases were cured under conservative treatment, while 11 cases underwent surgical treatment ultimately after failure of conservative treatment and the left 83 cases underwent anterior, posterior or combined surgical approach at the first visit. The detail of patients were shown in Table 1. Severity scoring system is based on the retrospective analysis of the 129 patients who were treated medically and surgically. Three major variables were identified critical to clinical decision-making in spinal tuberculosis:
- The stability of spinal infectious segments, which includes the kyphosis angle and “risk factors”, determined by imaging appearance;
- Neurologic status, which includes the cause of the spinal cord injury and the severity of spinal cord deficit
- The efficacy of the anti-tuberculosis drug therapy. These three main characteristics were thought to be largely independent predictors of clinical outcome. Within each of the three categories, subgroups were identified and arranged from least to most significant. The three major components of the severity scoring system and their subgroups are described as follows.
Table 1
Characteristics of patients
| Conservative treatment | Surgical treatment | Changing treatment★ |
Cases (No.) | 35 | 83 | 11 |
Location of the lesion (No.) | | | |
lower cervical segment | 9 | 15 | 2 |
cervical-thoracic segment | 0 | 2 | 0 |
thoracic segment | 15 | 31 | 4 |
thoracolumbar junction | 1 | 8 | 0 |
lumbar segment | 10 | 19 | 5 |
lumbosacral segment | 0 | 8 | 0 |
Neurological status (No.) | | | |
AIS A, B or C | 0 | 13 | 0 |
AIS D or radicular pain | 8 | 26 | 4 |
Normal | 27 | 44 | 7 |
Psoas abscess (No.) | 12 | 21 | 1 |
★Changing treatment: cases underwent surgical treatment ultimately after failure of conservative treatment |
Stability of spinal tuberculosis:
Two elements including kyphosis angle and “risk factors” for progression of kyphosis were both used to assess the stability of spinal tuberculosis (Table 2).
Table 2
Assessing the stability of infectious vertebral segments
Kyphosis angle | Risk factors★ | Points |
< 30° | No | 2 |
> 30° | No | 3 |
< 30° | Yes | 4 |
> 30° | Yes | 5 |
★Risk factors: it includes 1) accumulative loss of vertebral bodies above 0.75 or collapse of vertebral segment, 2) focus at cervical-thoracic, thoracolumbar junction or lumbosacral segment 3) spondylolysis, 4) retropulsion, and 5) lateral translation. Occurrence of any one of the above-mentioned “risk factors” can be considered as “Yes”. |
- Kyphosis angle was calculated on the lateral X-ray:two lines are drawn, one paralleling the superior surface of the first vertebra cephalic to the destructive segments and the other paralleling the inferior surface of the first vertebra caudal to the destructive segments. Kyphosis angle of 30° is defined as a cutoff value for the subgroup division.
- “Risk factors” include (Figure 1): 1) accumulative loss of vertebral bodies above 0.75 or collapse of vertebral segment, 2) focus at cervical-thoracic, thoracolumbar junction or lumbosacral segment 3) spondylolysis, 4) retropulsion, and 5) lateral translation. Occurrence of any one of the above-mentioned “risk factors” can be considered as “Yes”. The “risk factors” for progression of kyphosis is determined by careful review of radiographic studies to determine the pattern of anatomic destruction. In most cases, this requires integration of information from plain radiographs, CT-scan, and MRI. The vertebral segment is included in the description of the infectious morphology.
Neurologic Status
In assessing neurologic status, both neurologic function and mechanical compression of spinal cord or nerve root play an important role in the choice of treatment (Table 3). Thus, it comprises one of the three main characteristics in this classification algorithm.
Table 3
Evaluation of Neurologic Status
Neurological deficit (AIS) grading | Mechanical compression | Points |
AIS A, B or C | —— | 4 |
AIS D or radicular pain | Kyphotic vertebral body, sequestrum or extensive multi-segment epidural abscess | 3 |
AIS D or radicular pain | Tubercular debris or (and) caseous tissue | 2 |
AIS D or radicular pain | Epidural abscess involved single segment | 1 |
Normal | —— | 0 |
Currently, there is still no particular evaluation system about spinal cord injury used for neurological deficit of spinal tuberculosis. According to the literature report, American Spinal Injury Association (ASIA) impairment scale (AIS) grade is commonly used in evaluating the neurological status of spinal tuberculosis7,10,11. Hence, to facilitate communication and application, the neurologic status in this study is evaluated using American Spinal Injury AIS grade and radicular pain.
Mechanical compression of the cord includes: 1) kyphosis vertebral body, sequestrum and extensive multi-segment epidural abscess; 2) tubercular debris and caseous tissue; 3) single-segment epidural abscess. It requires integration of information from CT-scan and MRI to determine the characteristics of mechanical compression.
Anti-TB Drugs
Effective anti-TB drugs are the mainstay of treatment for spinal tuberculosis. Many reports have shown that conservative therapy alone can achieve excellent results in patients without severe kyphosis deformity or paraplegia12,13. Thus, drug therapy is important to spinal classification and treatment algorithms. Multidrug anti-tubercular treatment is essential with the first-line drugs including isoniazid, rifampicin, pyrazinamide, ethambutol, or streptomycin. It should be noted that evaluating the efficiency of anti-TB drugs in this study include not only the function of anti-TB bacillus,but the improvement in neurological status and the progression of kyphosis.
Efficacy of anti-TB drugs is categorized as “improvement”, “nonresponse” and “deterioration” (Table 4). This assessment can be made from carefully comparing the patients’ clinical data at the first visit (before using anti-TB drugs) with those following for at least 2–4 weeks later (after using anti-TB drugs for at least 2–4 weeks). Patients’ clinical data includes symptoms, physical examination, erythrocyte sedimentation rate (ESR), signs of plain film, CT, and MRI images.
Table 4
Evaluation of anti-tubercular drug therapy efficacy
First visiting | Follow-up | Points |
Improvement | Improvement | 1 |
—— | Nonresponse | 2 |
—— | Deterioration | 3 |
The key points of “improvement” are: 1) the amelioration of neurological status, 2) the gradual absorption of pathological tissue compressing the spinal cord, 3) no change or even decrease of kyphosis angle, 4) gradual decrease of ESR.
The “nonresponse” is defined as: 1) no evidences of neurological status improvement, 2) no absorption of the pathological tissue compressing the spinal cord, 3) no decrease or even increase of patient pain and (or) ESR. The “nonresponse” is the evaluation applied at the time of follow-up for at least 2–4 weeks.
The “deterioration” is defined as the worse of neurological deficit or (and) the increase of kyphosis angle above 10° according to the clinical signs and imaging data at any follow-up time comparing to previous data.
The severity scoring system for spinal TB
A comprehensive severity scoring system is calculated based on the three major characteristics to assist in determining treatment. Each subgroup in the three main variables has a numerical value associated with it in order to provide a comprehensive severity score. One to five points (1 point considered as least severe; 5 points as most severe) are assigned to reflect the degree of severity of the spinal mechanical stability or neurologic deficit. For the cases with multiple contiguous or noncontiguous infectious segments of spine, only the most severely involved segment is scored.
- Cases with kyphosis angle <30° but without signs of “risk factors” for progression of kyphosis are assigned as 2 points. Cases with kyphosis angle <30° and signs of “risk factors” are assigned as 4 points. The kyphosis angle >30° without signs of “risk factors” is assigned 3 points, while the kyphosis angle >30° with signs of “risk factors” is assigned 5 points (Table 2).
- A patient with an intact neurologic examination is assigned 0 point. AIS D and (or) radicular pain caused by single-segment epidural abscess compression is given 1 point; AIS D caused by the mechanical compression of tubercular debris and caseous tissue is assigned a score of 2 points, while caused by kyphotic vertebral body, sequestrum or(and) extensive multi-segment epidural abscess is assigned 3 points. AIS A, B or C is given 4 points (Table 3).
- “Improvement” (follow up for at least two weeks) is assigned 1 point. The “nonresponse” is assigned 2 points, while the “deterioration” is assigned 3 points (Table 4).
How to apply this severity scoring system
- A comprehensive severity score of 4 or less suggests a conservative treatment that includes essential anti-TB drugs, wearing brace, etc.
- While a total score of 6 or more should consider surgical intervention.
- A score of 5 might be treated either conservatively or surgically.
It should be clear that when patients visit for the first time, the anti-TB treatment is valid by default, that is, the subgroup (“Improvement”) score is 1 point (Table 4). When doctors finished evaluating a patient with spinal TB according to the severity scoring system for the first time, if the total score was assigned 5 or less (5 or ≤4) and the conservative treatment was selected, follow-up should be required to be performed every 2-4 weeks. At the time of follow-up, it is necessary to re-evaluate cases according to the severity scoring system. Examples to illustrate the application of the severity scoring system are listed in Figure 2-12.