| Japanese Journal of Clinical Oncology | Pages |
Spinal Epidural Abscess Associated with Epidural Catheterization: Report of a Case and a Review of the Literature
Introduction
Case Report
Discussion
References
Spinal Epidural Abscess Associated with Epidural Catheterization: Report of a Case and a Review of the Literature
INTRODUCTION
Epidural anesthesia is accepted as a reasonable technique for the management of regional pain following major surgery. Epidural abscess subsequent to catheter insertion is an extremely rare complication. Scott and Hibbard (1) reported only one (0.00019%) epidural abscess in 505 000 patients given epidural anesthesia in the UK. Because of difficulty in its diagnosis, epidural abscess often results in irreversible neurological deterioration (2-4). We present a case of epidural abscess associated with epidural catheterization and a review of the literature, including a discussion of its pathogenesis, clinical presentation, management and outcome.
CASE REPORT
A 53-year-old man was admitted for treatment for left lung cancer which had invaded the second to fourth ribs. His past history was unremarkable, except for herpes zoster infection involving the facial dermatome 3 months prior to admission. A left upper lobectomy with lymph node dissection and combined resection of the second to fourth ribs was performed under general anesthesia. Using the loss of resistance technique, an epidural catheter was inserted without difficulty under sterile conditions at the Th7-Th8 interspace before thoracotomy. The catheter was advanced 6 cm into the epidural space and secured with a sterile transparent dressing. After the operation, morphine hydrochloride solution (20 mg in 50 ml of sterile saline) was injected continuously at a rate of 0.4 ml/h through the epidural catheter.
The postoperative course was uneventful until the patient's body temperature rose to over 38°C on postoperative day 8. The epidural catheter was immediately removed, as the site of catheter insertion presented a reddish node. He complained of severe headache and physical examination revealed a tonic neck reflex on postoperative day 9. On postoperative day 10, he had left-sided abdominal distension. Plain abdominal X-ray film showed a distended descending colon without niveau. The white blood cell count and C-reactive protein level were 23 000/µl and 19 mg/dl, respectively. Neither blood nor CSF yielded any bacteria, but the culture from the epidural catheter tip gave methicillin-resistant Staphylococcus aureus (MRSA). He was then started on intravenous vancomycin and fosfomysin on the basis of the culture result.
However, the patient showed persistent fever and went on to develop a gait disturbance and weakness in his lower extremities. An MRI scan of the thoracic and lumber spine was performed on postoperative day 11 (Figs 1 and 2). The T2 weighted MR image showed marked narrowing of the spinal canal and an abnormal signal from the posterior epidural space between Th7 and Th9 (Figure 2). He was immediately sent to the operating theatre for emergency decompression and drainage of the abscess. A Th8 and Th9 laminectomy was performed and purulent material drained. Cultures from the operative site were MRSA-positive. Treatment by continuous irrigation (90 ml/h) of the operative wound with gentamycin was commenced in addition to systemic treatment and the symptoms improved rapidly after the second operation. Cultures from the drainage samples became negative 7 days after the emergency operation. Within 1 month, the patient recovered motor power and most of the sensation in the lower extremities and was able to walk with minimal assistance. Four months after the laminectomy, recovery was almost complete except for urinary retention.
Figure 1. T1 weighted MR image showed abnormal signal area in the epidural space between Th7 and Th9 (indicated by arrows). Figure 2. T2 weighted MR image showed marked narrowing of the spinal canal and an abnormal signal from the posterior epidural space between Th7 and Th9 (indicated by arrows). Many reports have been published regarding epidural abscess unrelated to anesthesia which has an estimated incidence of 0.2-1.2 per 10 000 hospital admissions (3-6). Most of these cases are the consequence of trauma, spinal procedure, spreading of infection or hematogenous seeding from a distant focus (3,4,6). Despite the fact that the incidence of epidural catheter contamination is reported to be as high as 22%, epidural abscess associated with epidural catheter is extremely rare (7). A MEDLINE search of the National Library of Medicine database yielded 29 additional cases of catheter-related epidural abscess (1,2,5,8-26). Tables 1-1 summarize the clinical features of all 30 patients with epidural abscess. Epidural abscess can have a highly variable presentation, which can make diagnosis difficult (Table 2). Symptoms may be subtle and patients often have other obvious medical problems. Symptoms in catheter-associated cases occur at varying times, ranging from 1 day to 5 months after catheter placement (Table 1). The median duration of catheterization was 4 days and the median time to onset of the clinical symptoms after catheter placement was 8 days. Moreover, 15 (58%) of the 26 patients showed significant symptoms after removal of the epidural catheter. Delayed presentation and the rapid progression of the neurological changes may make diagnosis difficult. Table 1. Table 2. Table 3. Conventionally, radiological diagnosis of epidural abscess has relied on myelography (3,4,6). However, MRI has now become the main diagnostic tool, eliminating the need for dural puncture and has also been used successfully in a patient allergic to contrast material (19-26). Narrowing of the spinal canal in the T2 weighted MR image is important information, suggesting an epidural abscess. In addition, it can provide greater detail in the demarcation of the extent of the lesion (19,23). The presence of a liquid pus in the epidural space is usually detected as high-intensity area on T2 weighted MR image and slightly hypo-intensity area (relative to cord) on T1 weighted MR image (Figs 1 and 2). Gd-enhanced MR imaging is useful in the diagnosis of epidural abscess in the phlegmonous stage which corresponds to granulomatous thickened tissues with embedded microabscess without collection of liquid pus. The most common causative organism (52-95%) in catheter-unrelated epidural abscess is Staphylococcus aureus (3,4); this has also been the commonest infecting organism (70%) in catheter-related cases (Table 3). Staphylococcus epidermidis and methicillin-resistant Staphylococcus aureus (MRSA) have each been identified in three cases (13%). Recently, strains of MRSA have been considered as potential pathogens in patients undergoing major surgery and in immunocompromised patients (19). All cases in which identified MRSA has been reported occurred after 1992, suggesting that the spectrum of causative organisms is broadening. To isolate the organisms and select suitable antibiotics in patients with a delayed presentation after catheter removal, surgical intervention is essential. The immune status of the patient is considered to be an important factor in developing an epidural abscess. Diabetes mellitus, chronic renal failure, alcoholism, malignancy and steroid injection lead to an increased incidence of epidural abscess (11,14,15,29). Eleven (37%) of the 30 cases with catheter-related epidural abscess had some risk factors for altered immune status on admission (Table 1). Our patient had also received treatment for herpes zoster only 3 months before admission. Herpes zoster frequently occurs in patients who have a reduced immune response or have associated malignant disease. The activation of herpes zoster lesions appears to be related to suppression of cell-mediated immunity (30). Thus, our patient may have been immunocompromised due to the lung cancer and/or the herpes zoster infection. The site of catheter insertion is another factor in the development of epidural abscess. Table 4 summarizes the management of and the outcome for the 26 patients with epidural abscess divided into three groups on the basis of the catheter insertion site. Of the 26 cases, 10 (38%) involved thoracic catheters, 15 (58%) lumbar catheters and one (4%) cervical catheter. Thoracic catheters are associated with a disproportionately high incidence of epidural abscess, especially considering that lumbar placement is far more common than thoracic (31), and this may reflect the relative difficulty in locating the thoracic epidural space compared with the lumbar space, which may result in a greater incidence of epidural hematoma, able to act as a nidus for infection (2). Table 4. 
DISCUSSION
Epidural site (No. of patients)
Cervical
1
Thoracic
10
Lumbar
15
Not stated
4
Duration of catheterization (days)
Median
4
Range
1-42
Time after insertion to symptom (days)
Median
8
Range
1-150
Underlying disorders (No. of patients)
Cancer
3
Herpes zoster
3
Steroid therapy
3
Diabetes mellitis
1
Reumatoid arthritis
1
Chronic renal failure
1
Obesity
1
Symptom
No. of patients
Back pain
20
Fever
18
Leg weakness
12
Sensory deficit
12
Bladder dysfunction
9
Inflammation at catheter site
8
Headache
5
Stiff neck
5
Nausea
3
Abdominal pain
2
Vomiting
2
Somnolence
1
Staphylococcus aureus
16
Staphylococcus epidermidis
3
MRSA
3
Pseudomonas aeruginosa
1
Not stated
7
Catheter site
Cervical (1 patient)
Thoracic (10 patients)
Lumbar (15 patients)
Management
Surgical drainage and laminectomy
1
10
9
Percutaneous abscess drainage
0
0
2
Antibiotic therapy alone
0
0
4
Outcome
Complete recovery
1
1
12
Persistent neurological problem
0
9
3
Sensory deficit
0
3
2
Leg weakness
0
2
1
Bladder dysfunction
0
4
0
The management of epidural abscess consists of early diagnosis, surgical exploration and drainage and the use of appropriate antibiotics. Surgical decompression was not required in six patients without significant neurological deficits, who recovered following antibiotic treatment or percutaneous drainage. However, medical management occasionally carries a significant risk, since the outcome is closely related to the length of time the abscess has been present and the degree of neurological impairment (3,4). Thus a delay in decompression may result in permanent neurological damage, and surgical intervention should be indicated in the patient complicating significant neurological deficits with radiological findings of epidural abscess as soon as possible.
The outcome of a catheter-related epidural abscess was also affected by the site of catheter insertion. Despite surgical decompression and drainage, nine of the 10 patients with a thoracic epidural abscess continued to have neurological deficits, whereas 12 of the 15 patients with a lumbar epidural abscess recovered completely. It is possible that the anatomical characteristics of the thoracic epidural space may result in rapid progression and irreversible neurological changes.
There has been an increasing trend towards epidural anesthesia and analgesia and the placement of catheters in the epidural space for the management of chronic and postoperative pain is becoming increasingly popular. Early diagnosis of epidural abscess would be facilitated by a greater awareness of the problem and immediate surgical decompression, combined with antibiotics, is necessary for the treatment of an epidural abscess. In addition, thoracic catheters are associated with a disproportionately high incidence of epidural abscess and persistent neurological sequelae following treatment.
References
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