Spinal epidural abscesses - The role for non-operative management: A systematic review

External performance of the spinal infection treatment evaluation (SITE) score and spinal instability spondylodiscitis score (SISS) in predicting operative intervention for de novo spinal infections

BACKGROUND CONTEXT

As the incidence of de novo spinal infections has risen with increasing global medical complexity and intravenous drug use, so has the uncertainty around standard of care and surgical decision making. Nonoperative management has increased in popularity albeit with frequent failure rates in up to one-third of patients. Although clinical decision making has largely been guided by clinician experience and institutional preference, two recent scoring system-the Spinal Instability Spondylodiscitis Score (SISS) and the Spinal Infection Treatment Evaluation score (SITE) provide a promising potential avenue towards evidence-based pathways.

PURPOSE

The aim of the current study was to compare external performance of the SITE and the SISS score in predicting operative decision making in patients with de novo spinal infections seen at a tertiary urban referral center, using real-world clinical decision making as a comparison. A secondary aim was to elucidate areas with low reliability or floor or ceiling effects as possible targets for score improvement.

STUDY DESIGN/SETTING

Retrospective external validation study utilizing consecutive cases from an academic tertiary referral center PATIENT SAMPLE: Adult patients undergoing treatment for spondylodiscitis or spinal epidural abscess OUTCOME MEASURES: Using the surgical intervention as the ground truth, the primary outcomes were performance metrics of the SITE and SISS score including receiver operating characteristic curves, specificity, sensitivity, and interrater reliability for both score and classification. Of note, the SITE score increases in severity with lower scores, whereas the SISS score increases in severity with higher scores.

METHODS

A panel of three blinded raters scored the clinical data.

RESULTS

Two-hundred thirteen patients were included, of which 62% (144/213) underwent nonoperative medical management and 38% (80/213) underwent operative management. Mean SITE numerical scores were lower (more severe) in the operative group (5.63 vs. 7.45, p<.001). The most frequent categorical group for the SITE score was "severe" in both the operative group (93%, 74/80, mean score 5.63) and the nonoperative group (68%, 90/133, mean score 7.45). The mean SISS score did not differ between operative and nonoperative groups (6.73 vs. 6.25, p=.2). ICC agreement was "almost perfect" for the SITE score (0.86, 95% CI 0.82-0.89) and "substantial" for the SISS score (0.68, 95% CI 0.56-0.76). Performance metrics for the SITE score were "good" (AUC 0.743, 95% CI 0.67-0.81), and for the SISS score were "poor" (AUC 0.557, 95% CI 0.47-0.64). ROC analysis for SITE identified a cutoff score of 6.5 to optimize sensitivity and specificity at 0.692 and 0.700, respectively. If using the established cutoff of 8 for "severe" infection as described in the original scoring system, the sensitivity was 0.813, specificity, 0.504, positive predictive value (PPV) 0.496, and negative predictive value (NPV) 0.817. ROC analysis for SISS similarly proposed a cutoff score of 8.0 which yielded a sensitivity and specificity of 0.350 and 0.797, respectively. If using the established cutoff of 10 for "unstable lesion" as described in the original scoring system, the sensitivity was 0.125, specificity 0.917, PPV 0.476, and NPV 0.635.

CONCLUSIONS

This study reports external performance metrics for the SITE and SISS score, demonstrating good performance for SITE and poor performance for SISS in predicting operative intervention with almost perfect SITE and substantial SISS agreement among raters. Ceiling effects may limit clinical utility of the SITE score. Subscales which require raters to determine percent vertebral body involvement or posterolateral involvement performed worse. Future work can focus on further discrimination within the "severe" infection group and improvement of low-performing subscales to improve clinical impact.

Efficacy of Additional Surgical Decompression on Functional Outcome in Pyogenic Spinal Epidural Abscess With No Neurological Deficit

Objective

The aim of this study was to investigate the efficacy of additional surgical decompression with antibiotics to treat pyogenic spinal epidural abscess (SEA) with no neurological deficits.

Methods

We retrospectively reviewed the data of patients diagnosed with spontaneous pyogenic SEA in the thoracolumbosacral area who presented with sciatica and no motor deficits in the lower extremities. The treatment took place in a single tertiary hospital. The effects of additional surgical decompression (decompressive laminectomy) and other clinical variables on functional outcome were assessed using the short form 36 (SF-36).

Results

Fifty-nine patients (49 men and 10 women, mean age 65.73±12.29 [41-89] years) were included in the analysis. Surgical decompression had been performed in 31 patients (Group S, treated with additional surgical decompression and antibiotics). There were five (15.2%, 5/33) unplanned operations to control leg sciatica among the patients with initially non-surgical plans, and 28 patients were finally treated with only antibiotics (group N-S). Group S showed a statistically significant increased cost of hospitalization compared to group N-S (15,856.37±7,952.83 vs. 10,672.62±4,654.17 US dollars, p=0.004) with no superiority of 6-month functional outcome after the completion of antibiotic treatment (53.65±4.74 vs. 51.75±7.96 SF-36 scores, p=0.266).

Conclusion

Although there is a possibility of requiring an unplanned operation to control leg sciatica during conservative antibiotic treatment, overall, additional surgical decompression in pyogenic SEA presenting with no motor deficit of the lower extremity showed increased medical burden and no greater benefit in terms of functional outcomes.

Long-term quality of life and functional outcomes after management of spinal epidural abscess

BACKGROUND/CONTEXT

In recent years, the incidence of spinal epidural abscesses (SEA) has tripled in number and nonoperative management has risen in popularity. While there has been a shift towards reserving surgical intervention for patients with focal neurologic deficits, a third of patients will still fail medical management and require surgical intervention. Failure to understand long-term quality of life and functional outcomes hinders effective decision making and prognostication.

PURPOSE

To describe patterns and associated factors impacting long-term quality of life following treatment of spinal epidural abscess.

STUDY DESIGN/SETTING

Multicenter cohort study at two urban academic tertiary referral centers and two community centers.

PATIENT SAMPLE

Adult patients treated for a spinal epidural abscess.

OUTCOME MEASURES

EuroQoL 5-Dimension 5L (EQ5D), Neuro-Quality of Life Lower Extremity - Mobility (Short Form; NeuroQoL-LE), Patient-Reported Outcomes Measurement Information System Physical Function (short form 4a; PROMIS PF), and PROMIS Global Mental Health score (PROMIS Mental).

METHODS

Eligible patients were enrolled and administered questionnaires. Multivariable analysis assessed the influence of ambulatory status on HRQL, adjusting for covariates including age, biologic sex, Charlson comorbidity index, intravenous drug use, management approach, and ASIA grade on presentation.

RESULTS

Sixty-one patients were enrolled (mean age 60.5 years, 46% male). Thirty-four patients (58%) underwent operative management. Mean standard deviation (SD) results for HRQL measures were: EQ5D 0.51 (0.37), EQ5D visual analogue scale 60.34 (25.11), NeuroQoL Lower extremity 41.47 (10.64), PROMIS physical function 39.49 (10.07), and PROMIS Global Mental Health 44.23 (10.36). Adjusted analysis demonstrated ambulatory status at presentation, and at 1 year, to be important drivers of HRQL, irrespective of other factors including IVDU and ASIA grade. Patients with independent ambulatory function at 1 year had mean EQ5D utility of 0.65 (95% CI 0.55, 0.75), whereas those requiring assistive devices saw a 49% decrease with mean EQ5D utility of 0.32 (0.14, 0.51). Ambulatory status was associated with global and physical function but did not impact overall health self-assessment or mental health scores.

CONCLUSIONS

We found that ambulatory status was the most important factor associated with long-term HRQL regardless of other factors such as ASIA grade or IVDU. Given prior literature demonstrating the protective effect of operative intervention on ambulatory function, this highlights ambulatory dysfunction as a potential indication for surgery and a marker of poor long-term prognosis, even in the absence of focal neurologic deficits. Our work also highlights the importance of optimized long-term rehabilitation strategies aimed to preserve ambulatory function in this high-risk population.

LEVEL OF EVIDENCE

Level III, cohort study.

A comprehensive clinical analysis of the use of percutaneous endoscopic debridement for the treatment of early lumbar epidural abscesses

Objective

The purpose of this study is to evaluate the safety and efficacy of a percutaneous endoscopic debridement and drainage for lumbar infections with early epidural abscesses.

Methods

Eight cases of early epidural abscess underwent lumbar intervertebral space debridement and drainage by percutaneous endoscopic. Laboratory indicators, pathogenic microorganisms and complications were documented, and the ASIA scores were used to assess preoperative and postoperative neurological function changes. Additionally, the VAS was used to evaluate the therapeutic effect.

Results

The average duration of the drainage tube was 11.25 ± 3.96 days (7-20 days), and the epidural abscess was eliminated after the tube was taken out. Postoperative CRP (14.40 ± 12.50 mg/L) and ESR (48.37 ± 16.05 mm/1 h) were significantly lower than the preoperative CRP (62.5 ± 61.1 mg/L) and ESR (75.30 ± 26.20 mm/1 h). The VAS score after the operation (2.50 ± 0.92 points) was significantly lower than the one before the surgery (8.25 ± 0.83 points). 5 patients experienced lower extremity pain and neurological dysfunction prior to surgery, however, after drainage, the lower extremity pain dissipated and the lower extremity muscle strength improved in one patient. All 8 patients were followed up for a period of (28.13 ± 10.15) months, including 3 patients with spinal segmental instability who had lumbar bone graft and internal fixation for the second stage. At the end of the follow-up, all 8 patients were clinically cured without any progressive nerve injury, paraplegia or recurrence of infection.

Conclusion

Percutaneous Endoscopic Debridement and Drainage is an effective way to drain intraspinal abscesses, thus avoiding any potential progressive harm to the spinal cord.

A novel scoring system concept for de novo spinal infection treatment, the Spinal Infection Treatment Evaluation Score (SITE Score): a proof-of-concept study

OBJECTIVE

De novo infections of the spine are an increasing healthcare problem. The decision for nonsurgical or surgical treatment is often made case by case on the basis of physician experience, specialty, or practice affiliation rather than evidence-based medicine. To create a more systematic foundation for surgical assessments of de novo spinal infections, the authors applied a formal validation process toward developing a spinal infection scoring system using principles gained from other spine severity scoring systems like the Spine Instability Neoplastic Score, Thoracolumbar Injury Classification and Severity Score, and AO Spine classification of thoracolumbar injuries. They utilized an expert panel and literature reviews to develop a severity scale called the "Spinal Infection Treatment Evaluation Score" (SITE Score).

METHODS

The authors conducted an evidence-based process of combining literature reviews, extracting key elements from previous scoring systems, and obtaining iterative expert panel input while following a formal Delphi process. The resulting basic SITE scoring system was tested on selected de novo spinal infection cases and serially refined by an international multidisciplinary expert panel. Intra- and interobserver reliabilities were calculated using the intraclass correlation coefficient (ICC) and Fleiss' and Cohen's kappa, respectively. A receiver operating characteristic analysis was performed for cutoff value analysis. The predictive validity was assessed through cross-tabulation analysis.

RESULTS

The conceptual SITE scoring system combines the key variables of neurological symptoms, infection location, radiological variables for instability and impingement of neural elements, pain, and patient comorbidities. Ten patients formed the first cohort of de novo spinal infections, which was used to validate the conceptual scoring system. A second cohort of 30 patients with de novo spinal infections, including the 10 patients from the first cohort, was utilized to validate the SITE Score. Mean scores of 6.73 ± 1.5 and 6.90 ± 3.61 were found in the first and second cohorts, respectively. The ICCs for the total score were 0.989 (95% CI 0.975-0.997, p < 0.01) in the first round of scoring system validation, 0.992 (95% CI 0.981-0.998, p < 0.01) in the second round, and 0.961 (95% CI 0.929-0.980, p < 0.01) in the third round. The mean intraobserver reliability was 0.851 ± 0.089 in the third validation round. The SITE Score yielded a sensitivity of 97.77% ± 3.87% and a specificity of 95.53% ± 3.87% in the last validation round for the panel treatment decision.

CONCLUSIONS

The SITE scoring concept showed statistically meaningful reliability parameters. Hopefully, this effort will provide a foundation for a future evidence-based decision aid for treating de novo spinal infections. The SITE Score showed promising inter- and intraobserver reliability. It could serve as a helpful tool to guide physicians' therapeutic decisions in managing de novo spinal infections and help in comparison studies to better understand disease severity and outcomes.