Abstract
Background: Despite advances in imaging, as well as antibiotic and surgical treatment, spinal epidural abscess (SEA) remains a challenging problem in end-stage renal disease (ESRD) patients. This investigation assesses the influence of ESRD on clinical manifestations, complications, and outcomes in patients with SEA. Methods: This study retrospectively reviewed medical records of 41 patients with SEA treated during 2003–2006. The patients comprised two groups: group I (patients with ESRD) and group II (patients without ESRD). Patient characteristics, including age, gender, comorbidities, clinical presentations, laboratory data, locations of epidural abscess, and outcome, were recorded and compared. Results: The final sample comprised 41 patients. The mean age of the subjects was 62 + 12 years. The sample included 12 patients with ESRD and 29 without ESRD. The development of symptoms was similar for both groups. Group I patients displayed higher serum erythrocyte sedimentation rate (ESR) (108 + 26 vs. 81 + 31 mm/h, p = 0.014) and lower serum hematocrit (27.1 + 4.3 vs. 33.7 + 5.1%, p < 0.001) than group II patients. Overall survival at 3 months was 88.9% and 93.1% for patients in groups I and II, respectively (p = 0.876). Meanwhile, patients that underwent surgical decompression of epidural abscess received more surgeries than group I patients (1.08 vs. 0.55, p = 0.086), although the difference was not significant. Conclusions: ESRD is a risk factor for repeat surgery in patients with SEA. This investigation suggests that ESRD patients with SEA may require aggressive surgical intervention despite ESRD not affecting their long-term prognosis.
INTRODUCTION
The prevalence of spinal epidural abscess (SEA) appears to be increased with increased use of invasive procedures. Previous investigations found a relationship of SEA in patients with end-stage renal disease (ESRD) catheter-related bacteremia.Citation1 The abscess length,Citation2 degree of leukocytosis, and C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR)Citation3,4 were reported to correlate with outcome in non-ESRD patients. Although certain patients can be treated conservatively, surgical drainage and antibiotic use are the cornerstones of treatment for SEA in non-ESRD patients. Decompressive laminectomy and debridement of infected tissues should be urgently performed because of the difficulty of predicting neurologic impairment.
No recommended management has been reported for SEA patients with ESRD. Therefore, this study comprehensively reviewed our experience with SEA in ESRD and non-ESRD patients to observe the presenting clinical symptoms, to observe the laboratory and radiographic features, and to determine the effectiveness of aggressive surgical intervention combined with antibiotic treatment.
METHODS
Patient Information and Data Collection
The local Institutional Review Board approved the study protocol. From 1 January 2003 to 31 December 2006, a total of 41 patients with SEA were identified via computerized discharge diagnosis and manual chart review. The sample was divided into two groups: group I, 12 patients with ESRD on dialysis; and group II, 29 patients without ESRD. The medical records, laboratory data, hospital notes, radiological studies, and operative reports of all patients with SEA were reviewed. Laboratory data were obtained using standardized techniques. The attending neurosurgeon decided whether to administer treatment with antibiotics, surgical decompression, or both. Demographic characteristics, clinical features, pathogens, and medical and surgical treatment were compared between the two groups.
Management
All patients included in this study were treated with antibiotics immediately after diagnosis. The antibiotic regimen was modified after determining culture and sensitivity. Approximate duration antibiotic treatment was administered from 4 to 16 weeks via clinical evaluation. Efficacy of antimicrobial therapy and required treatment duration could be established by monitoring reduction in ESR, CRP, pain, improvement in function, and resolution of radiographic abnormalities. Administration of parenteral antibiotics was halted following 4 weeks provided the abscesses were drained, the patient displayed clinical improvement, and the ESR reduced by half. The most common surgical procedure was anterior laminectomy. The key objective was to use suction-irrigation to remove pus, debride granulation tissue, and drain all affected areas.
Statistical Analysis
Continuous variables were summarized using means and standard deviation, with comparisons performed using the Wilcoxon rank sum test. Fisher’s exact test was employed to compare categorical variables. All statistical tests were two-tailed, and the level of significance was set to p = 0.05 or less. Data were analyzed using SPSS 13.0 for Windows 95 (SPSS Inc., Chicago, IL, USA).
RESULTS
Patient Demographics
This study identified 41 patients (group I: 12 ESRD patients; group II: 29 non-ESRD patients) over the 3-year sample period. Group I comprised 5 males and 7 females, aged 57.3 ± 6.4 years, and group II comprised 19 men and 12 women, aged 64.2 ± 12.9 years. Data analysis demonstrated that patients with ESRD were younger (p = 0.029), and had higher rates of diabetes (p = 0.034) and hypertension (p < 0.001). lists patient demographic data and clinical characteristics. compares patient laboratory results, and identifies significant differences in hematocrit values and serum ESR, corresponding to the ESRD and non-ESRD diagnoses for both groups.
Table 1. Patients’ demographic data and clinical characteristics.
Table 2. Comparison of ESRD and non-ESRD patients.
Microbiology
Staphylococcus aureus was the most frequently isolated microorganism (group I: 41.7%; group II: 34.7%). In group I, oxacillin-sensitive S. aureus was the responsible pathogen in two patients (25%), oxacillin-resistance S. aureus in two patients (16.7%), Enterococcus in two patients (16.7%), and five patients (41.47%) exhibited no growth. Meanwhile, in Group II oxacillin-sensitive S. aureus was the responsible pathogen in six patients (20.9%), oxacillin-resistance S. aureus in four patients (13.8%), Streptococcus viridans in one patient (3.4%), Candida albicans in one patient (3.4%), Streptococcus group D in one patient (3.4%), Salmonellae choleraesuis in two patients (6.9%), and five patients (48.3%) exhibited no growth.
Clinical Features
The most common symptoms in ESRD patients included back pain (100%), leg weakness (83%), neurologic deficit (75%), unsteady gait (58%), and abdominal pain (50%). In non-ESRD patients, the predominant clinical symptoms included back pain (96.6%), leg weakness (58.6%), fever (55.2%), neurologic deficit (55.2%), and unsteady gait (31%). Data analysis demonstrated that ESRD patients were significantly more likely to exhibit symptoms of abdominal pain (p < 0.001) and sensory deficit (p = 0.016). The affected spine levels in groups I and II were as follows: thoracic spine (16.7% vs. 34.5%), lumbar spine (83.3% vs. 69%), sacrum spine (41.7% v.s.17.2%). Thus, affected spine level did not differ between the two groups.
Laboratory Findings
Mean peripheral white blood cell count (×103) measured on admission was 13.0 ± 7.1 in group I and 11.5 ± 6.4 in group II (p = 0.52). Moreover, mean hematocrit was 27.1 ± 4.3% in group I and 33.7 ± 5.1% in group II (p < 0.001). Furthermore, serum CRP was 126.7 ± 87 mg/dL and 120 ± 111 mg/dL (p = 0.858), respectively. The mean serum ESR was 108 ± 26 mm/h in group I and 81 ± 31 mm/h in group II (p = 0.014). Finally, mean albumin was 2.88 ± 0.68 mg/dL in group I and 3.03 ± 0.5 mg/dL in group II (p = 0.492).
Short-Term Outcome
The number of surgical interventions in group I was as follows: medical treatment only (41.6%), one surgery (25%), two surgeries (16.7%), and three surgeries (16.7%). The number of surgical interventions in group II was as follows: medical treatment only (58.6%), one surgery (27.6%), two surgeries (13.8%), and three surgeries (0%). Thus, there was no significant difference between the two groups, though patients in the ESRD group received more surgical interventions. lists patient outcomes. The 3-month survival rates were 88.9% in group I and 93.1% in group II, and thus did not differ significantly (p = 0.876).
Table 3. Number of surgical intervention and clinical outcome.
DISCUSSION
This investigation conducts a retrospective study of SEA in ESRD and non-ESRD patients from a tertiary referring medical center. The sample comprised 41 patients diagnosed with SEA over a 3-year period. Infectious complications were found to be the main causes of morbidity and mortality in patients with ESRD. Moreover, vascular access was identified as a major source of various infections. Complications of hemodialysis (HD) catheter-related blood stream infections included endocarditis, osteomyelitis, septic arthritis, septic pulmonary emboli, and SEA.Citation5 Although the incidence of SEA in catheter-related blood stream infections is just 1.2%, neurologic impairment is a significant clinical complication. Most patients with SEA have predisposing factors, such as underlying disease, spinal abnormality or intervention, or potential local or systemic source of infection. In patients receiving HD, indwelling vascular access with catheter or graft is a predisposing condition. Bacteria access the epidural space through contiguous or hematogenous dissemination. Repeated puncture, through permanent arteriovenous fistula or artificial graft, defective vessel wall, and immune dysregulation, underlies the prevalence of bacteremia in dialysis patients. The predominant pathogen in both ESRD and non-ESRD groups is Staphylococcus, with its invasion of the skin enabled by some predisposing condition.
Clinical features of SEA included back pain at the level of the affected spine; nerve-root pain radiating from the involved spinal area; motor weakness, sensory deficit, and bladder and bowel dysfunction; and paralysis.Citation6 The findings presented here suggest that patients with ESRD had higher prevalence of abdominal pain and sensory deficit. Moreover, Bremer et al.Citation7 stated that SEA can present as abdominal pain. Sensory deficit may be related to the larger number of diabetes patients in the ESRD group. Early recognition is crucial because the outcome of SEA is influenced by the severity and duration of neurological deficit before surgery.Citation8
This investigation found no significant difference in CRP and leukocytosis between the two groups. Univariate analysis identified a correlation between MRI findings, degree of leukocytosis, and levels of ESR or CRP. The data revealed significantly higher ESR in the ESRD group. Increased ESR in HD patients may be associated with acute-phase response, anemia, and aging.Citation9 Image study was indicated for all patients in ESRD with neurologic deficit, severe focal back pain, or unexplained fever with raised ESR.
In non-ESRD group, most studies identify surgical drainage with systemic antibiotics as the mainstay treatment.Citation10–12 Several investigations suggested that decompressive laminectomy and debridement of infected tissues should be performed as soon as possible.Citation13 Patients may be treated medically when they decline surgical intervention, have high surgery risks, or exhibit pan spinal infection. Owing to more frequent bleeding, infection complications, and side effects of anesthesia, surgery in chronic renal failure patients is significantly more risky than in normal renal function individuals.Citation14,15 Savage et al.Citation16 reported that medical treatment with antibiotics is a viable alternative to surgery for patients without systemic sepsis or neurological symptoms. However, the limited literature does not clarify the role and outcome of medical treatment or surgical intervention,Citation17 particularly in patients with ESRD, and thus close clinical follow-up is required. All patients with neurologic deficit should undergo urgent spinal decompression and abscess drainage. Clinicians must be aware of the role of aggressive surgical intervention in ESRD patients with SEA. Urgent surgical intervention is required to preserve function in such patients. Although patients in the ESRD group were older and had lower hematocrit, the outcomes were the same as for aggressive surgical intervention with antibiotic therapy. The mortality rate in the series reported here (11.1% in group I and 6.9% in group II) is within the range of 5–32% (in recent reports or from the recent literature).Citation18–23 The above discussion indicates that optimal outcomes require multidisciplinary care.Citation24
Despite presenting some encouraging results, this study suffers several limitations. First, this investigation surveyed only one institution, and thus the results cannot be directly extrapolated to other patient populations. Second, the retrospective nature of this study meant that accurate documentation of signs and symptoms of SEA and physical examination by the admitting physicians was occasionally lacking, even after careful review of the medical records. Moreover, some laboratory information was unavailable during the experimental period. Finally, this study sheds no real light on the prevalence of SEA in the HD population because many patients were referred from other HD centers.
CONCLUSION
The study confirms that the prognosis of SEA is no worse in patients with ESRD compared to patients without ESRD. Patients with ESRD were younger and had higher comorbidity. ESRD and non-ESRD patients exhibited similar clinical presentations, except for higher serum ESR and lower mean hematocrit in ESRD patients. The affected spine levels and pathogenic organisms did not differ significantly between the two groups. Finally, aggressive surgical intervention and antibiotics are needed in ESRD patients with SEA.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
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