1 Department of Anaesthesiology and Critical Care Medicine, 2 Department of Gynecology and Obstetrics and 3 Department of Neuroradiology, Tübingen University Hospital, Tübingen, Germany
*Corresponding author: Department of Anaesthesiology and Critical Care Medicine, Tübingen University Hospital, Hoppe-Seyler-Strasse 3, D-72076 Tübingen, Germany. E-mail: torsten.schroeder{at}uni-tuebingen.de
Accepted for publication: January 29, 2004
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Abstract |
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Br J Anaesth 2004; 92: 8968
Keywords: anaesthesia, obstetric; anaesthetic techniques, epidural; complications, abscess
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Introduction |
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Case report |
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The catheter was removed approximately 6 h after insertion. During the following days the patient suffered from progressively severe back pain. She did not show any signs of infection, such as fever, leucocytosis, elevated C-reactive protein, or signs of local infection at the insertion site. Additionally, no sensory, or motor neurological abnormalities were noted.
Five days after delivery, the back pain became unbearable. At that time, the white blood cell count was 10.1 x 109 litre1 and C-reactive protein had increased to 26.0 mg dl1. A contrast-enhanced lumbar CT study was performed but was inconclusive. However, a median, sagittal T2-weighted magnetic resonance image (MRI) showed an intraspinal, ellipsoid fluid collection in the dorsal epidural space at disc level L2L3 with compression of the dural sac (Fig. 1). Axial T1 MRI (after administration of contrast fluid) showed an intraspinal hypointense triangular-shaped fluid collection with peripheral rim enhancement in a dorsal epidural location, typical of epidural abscess formation at the disc space L2L3 (Fig. 2). Empirical antibiotic treatment with ceftriaxone, rifampin and metronidazole was started. The following day, the patient developed a sensory deficit in the left lower limb. Posterior surgical decompression and drainage of a pustular abscess was performed on that day. Antibiotic therapy was changed to clindamycin for 4 weeks, after oxacillin-sensitive S. aureus had been cultured from the abscess fluid. She recovered quickly with no remaining neurological deficit.
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Discussion |
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Several routes might be possible for the introduction of microorganisms into the epidural space. Infection might have originated from the skin flora, by haematological spread of bacteria, via contaminated local anaesthetics, or directly during insertion of a contaminated catheter. Antiseptics have proved to be effective in decontaminating the transient skin flora but not the deeply placed resident flora, which remains colonized even after skin disinfection. The risk of haematogenous seeding of an infection from the wound after vaginal delivery is minimal, but cannot be excluded completely. The intraluminal spread of microorganisms via a contaminated local anaesthetic solution is also very unlikely and was prevented by the use of an in-line bacterial filter. In our case, the attending anaesthetist wore a facemask, and sterile gloves, but no sterile gown. This is common practice in our institution. It is generally believed that a sterile environment prevents direct contamination, but no systematic investigation was conducted. A survey from Australasia showed that there were wide variations in what was considered to be essential aseptic precautions for placement of epidural catheters on the labour ward. Most likely, variations exist in other countries, including Germany. The authors of the survey suggested essential aseptic precautions, including wearing a facemask, sterile gloves and sterile gown, removal of wristwatch, handwashing, proper skin preparation, and a properly placed sterile drape.5 Since a clean, aseptic work field is inexpensive and easy to achieve, it is prudent to respect these recommendations.
Back pain is the leading complaint during the development of a spinal epidural abscess, and is reported in up to 90% of cases.3 However, the incidence of back pain is high after delivery, regardless of the use of epidural analgesia.6 Therefore, back pain without accompanying signs of infection rarely allows the diagnosis of abscess formation. Our patient complained about increasing back pain over 5 days, but the examination of the catheter insertion site did not show any evidence for local infection and the white blood cell count was not elevated until day 5. A CT study was initiated in the absence of neurological deficits but a clear diagnosis could only be established after MRI. MRI is the most common imaging technique for the diagnosis of spinal epidural abscess, with a sensitivity of close to 100%. CT myelography is reported to be as sensitive as MRI but is an invasive procedure which carries the risk of additionally contaminating the subarachnoidal space. Therefore, a CT myelography should only be performed when MRI is not available or not possible, e.g. in cases of incompatible implants. A CT scan without myelography is of little diagnostic information, and therefore not considered to be the method of choice.7
S. aureus is isolated from epidural abscesses in more than 50% of patients and aerobic and anaerobic streptococci account for approximately 15% of the isolates. Gram-negative rods are found in approximately 1520% and anaerobes in 2%, and rare cases include the isolation of Cryptococcus, Nocardia, Aspergillus, Eikenella, Mycobacterium and others. Approximately 15% of abscesses are culture-negative.1 3 8 Thus, the empirical antibiotic treatment should definitely cover S. aureus, streptococci and Gram-negative rods, especially in cases with septic symptoms. It is recommended that treatment should be continued for up to 6 weeks and should be extended to 8 weeks in cases of accompanying osteomyelitis.9 In our case, the organism was not phage-typed and traced. The source of infection remains unclear.
Conservative management is possible in cases without any neurological symptoms.10 In patients with neurological signs, the degree of thecal sac compression correlates with permanent neurological damage. Therefore, urgent surgical decompression and debridement is the treatment of choice when neurological signs have developed. In our case, broad-spectrum antibiotic treatment was started as soon as the diagnosis was made. However, when the patient developed a sensory deficit, immediate surgical decompression and debridement was performed. Once neurological symptoms have developed, severe disabilities or even death have been reported in up to 50% of patients. Several factors are associated with negative outcomes, such as higher age, a high degree of thecal sac compression, sepsis, and a long duration of symptoms. Favourable outcomes have been reported for abscesses located in the lumbosacral area and for patients with pustular abscesses.11 In this case the patient had all advantageous factors and recovered without neurological deficit.
In summary, spinal epidural abscess formation after epidural analgesia for labour and delivery in previously healthy women is rare, but should be taken into consideration in cases with severe back pain, even in the absence of infectious signs and neurological deficits. MRI is considered the diagnostic tool of choice, and surgical treatment is necessary once neurological deficits have developed to avoid permanent neurological sequelae.
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Acknowledgement |
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References |
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