- Email: [email protected]
Vertebral osteomyelitis and psoas abscess occurring after obstetric epidural anesthesia
Vertebral Osteomyelitis and Psoas Abscess Occurring After Obstetric Epidural Anesthesia Bee B. Lee, M.B.B.S., F.A.N.Z.C.A., Warwick D. Ngan Kee, M.B.Ch.B., M.D., F.A.N.Z.C.A., and James F. Griffith, M.B., B.Ch., F.R.C.R. Background and Objectives: Back pain and infectious complications occasionally occur after epidural anesthesia in obstetrics, and accurate diagnosis can be difficult. We report a patient who developed low back pain soon after obstetric epidural anesthesia and was diagnosed 6 months later with lumbar vertebral osteomyelitis, discitis, and a psoas abscess. Case Report: A 34-year-old woman developed persistent low back pain after receiving epidural anesthesia for labor analgesia and cesarean delivery. After 6 months, a diagnosis of lumbar vertebral osteomyelitis, discitis, and psoas abscess was made, and surgery was performed. Because of the temporal and anatomical relationships between epidural catheterization and the development of symptoms, the preceding epidural anesthesia was initially suspected as a potential cause. However, because the posterior spinal elements were unaffected and the infectious agent was subsequently identified as tuberculous, the cause was eventually determined as unlikely to be related to the epidural procedure. Conclusion: Investigation of severe back pain after epidural anesthesia should include consideration of infectious causes, such as vertebral osteomyelitis and discitis, which may not be causally related to the epidural catheterization itself. Reg Anesth Pain Med 2002;27:220-224. Key Words:
Back pain, Epidural anesthesia, Infection, Obstetrics, Osteomyelitis, Psoas abscess.
I
nfectious complications have been occasionally reported after epidural analgesia and anesthesia in obstetrics. These have included epidural abscesses,1 meningitis,2 and osteomyelitis.3 We describe a patient who complained of persistent low back pain for 6 months after obstetric epidural anesthesia before a diagnosis of lumbar vertebral osteomyelitis, discitis, and psoas abscess was made.
Case Report A 34-year-old 65-kg primigravida was admitted in early labor at 39 weeks gestation, and the obstet-
From the Departments of Anaesthesia and Intensive Care (B.B.L., W.D.N.K.) and Diagnostic Radiology and Organ Imaging (J.F.G.), The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China. Accepted for publication August 1, 2001. Funded internally by departmental sources, The Chinese University of Hong Kong. Reprint requests: Bee B. Lee, M.B.B.S., F.A.N.Z.C.A., Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China. E-mail: [email protected] © 2002 by the American Society of Regional Anesthesia and Pain Medicine. 1098-7339/02/2702-0003$35.00/0 doi:10.1053/rapm.2002.28712
220
ric anesthetic team was consulted. Fifteen years previously she had been diagnosed with juvenile ocular myasthenia gravis (Osserman group 1) for which she had been prescribed pyridostigmine; however, after 3 years, she had stopped medication on her own accord and described no progression of symptoms during subsequent years or during her pregnancy. Her antenatal history had been otherwise uneventful. On examination, she had bilateral ptosis, but normal motor power of the limbs with no fatigue and a normal vital capacity. After discussion with the patient, vaginal delivery under epidural analgesia was planned. After transfer to the labor ward, an epidural catheter was inserted through a 16-gauge Tuohy needle at the L3-4 interspace using full aseptic precautions without difficulty. Epidural analgesia was initiated with 5 mL of 0.125% ropivacaine, followed by an infusion of 0.0625% ropivacaine with fentanyl 3 g/mL at 6 to 10 mL/hr. With this regimen, the patient was comfortable, and augmentation of labor was commenced using an oxytocin infusion. However, progress of labor was poor and after 8 hours, the obstetrician recommended cesarean delivery. The epidural block was extended uneventfully for
Regional Anesthesia and Pain Medicine, Vol 27, No 2 (March–April), 2002: pp 220 –224
Psoas Abscess After Epidural Anesthesia
surgery using 0.75% ropivacaine and fentanyl. The epidural catheter was removed intact immediately after the completion of surgery. Immediately postpartum, it was noted that she had mild back pain, but investigation was not thought necessary, as there were no other associated signs or symptoms. However, after discharge from hospital, her low back pain persisted. The pain was dull in nature, localized near to the site of the lumbar epidural insertion, mild to moderate in intensity, and occurred intermittently. It gradually deteriorated over the subsequent months with radiation to both thighs especially during walking. There were no associated sensory, motor, or sphincter disturbances, no fever, and the patient could manage with normal daily activities including caring for her baby and performing the daily housework. She consulted several general medical practitioners who found no abnormal physical findings and prescribed simple analgesics. Initially no investigations were performed, and she did not seek anesthetic followup. She received no spinal manipulation or steroids. Eventually at 6 months postpartum, a lumbar spine radiograph (Fig 1) was performed, which showed changes consistent with vertebral osteomyelitis and discitis at L3 and L4. She was then referred back to our hospital for further management. Computerized tomography (CT) and magnetic resonance imaging (MRI) scans showed severe L3-4 discitis and vertebral osteomyelitis with a large left psoas abscess extending from the L2 to the S1 level with extradural spread (Figs 2 and 3). The paravertebral mass was biopsied under CT guidance. Two days later, operative drainage of the psoas abscess and anterior spinal fusion at the L3-4 level was performed under general anesthesia. At operation, 300 mL of pus was drained from the abscess, and pus and necrotic bone at the L3-4 disc space and vertebral bodies were debrided. The posterior epidural space and bony elements were disease-free. Postoperatively, the patient was transferred to the intensive care unit for monitoring and observation, but did not require ventilation, and she made an uneventful recovery. Initially, the patient’s recent obstetric epidural catheterization was implicated as a likely source of the patient’s spinal infection. During surgery, the surgeons commented that the lesions appeared to be of a pyogenic nature with no macroscopic appearance of caseation. Together with the preceding history of epidural catheterization and the level of spinal involvement, a delayed complication of epidural anesthesia was considered to be the most likely explanation. The patient and her husband
•
Lee et al.
221
Fig 1. Lateral radiograph of the lumbar spine. There is reduction of the L3-4 disc space with destruction of the opposing endplates. These radiographic appearances are characteristic of discitis with early vertebral osteomyelitis.
also queried whether the infection was secondary to epidural anesthesia, because the patient’s symptoms had started soon after delivery and were localized to the lumbar spine. However, although no acid alcohol fast bacilli were identified in the percutaneous biopsy or any of the operative specimens, histopathologic examination showed granulomatous inflammation highly suspicious of tuberculosis. Therefore, the etiology was considered unlikely to be related to the epidural procedure. This was also supported by both the radiologic and intraoperative findings that the posterior elements of the lumbar spine (both bone and epidural space) were not involved. Antituberculous therapy was started empirically, and the patient was discharged home after 2
222
Regional Anesthesia and Pain Medicine Vol. 27 No. 2 March–April 2002
insertion and because of the temporal association of the diagnosis of spinal infection and the epidural procedure. Although the posterior vertebral bony elements and epidural space were shown by crosssectional imaging (both CT and MRI) and surgery to be clear, suggesting that the infection was unlikely to be related to the epidural procedure, it was not until microbiologic results had confirmed a tuberculous cause that other causes were considered. Similar to this case, we have previously reported a case in which severe back pain occurred after insertion of an epidural catheter for postoperative analgesia after radical hysterectomy.4 As with the current case, the symptoms were initially considered to be a complication of the epidural technique, but
Fig 2. T2-weighted sagittal MRI of the lumbar spine. There is discitis of the L3-4 disc with osteomyelitis of the adjacent vertebral bodies. The inflammatory infiltrate has extended beneath the anterior and posterior longitudinal ligaments.
weeks. After 6 weeks, the diagnosis of tuberculous osteomyelitis was confirmed when Mycobacterium species were cultured from broth cultures of the psoas muscle biopsy, as well as intraoperative specimens of pus from the psoas abscess and necrotic bone fragments.
Discussion Although they are rare, infectious complications after epidural anesthesia are well described. When they occur, an anesthetic-related cause may be difficult to refute. Our case was interesting because the patient’s spinal infection was initially suspected by both the patient and the attending orthopedic surgeons to be a complication of her recent obstetric anesthetic epidural catheterization. This was mainly because the patient’s pain had been localized to the same general area as the site of epidural catheter
Fig 3. (A) T2-weighted axial MRI at the level of L3. There is osteomyelitis of the L3 vertebral body with an abscess extending into the left psoas muscle (labeled A). Note how the posterior epidural space is clear. (B) T1weighted axial MRI following contrast at the same level as (A). The abscess tracking from the vertebral body to the left psoas muscle is clearly delineated. This clearly shows how the infection is confined to the vertebral body with no involvement of the posterior elements.
Psoas Abscess After Epidural Anesthesia
subsequent investigations showed an unrelated cause, namely, ureteral obstruction. Accurate diagnosis of severe back pain after epidural anesthesia can be difficult. Although direct contamination during the procedure of epidural anesthesia has occasionally been reported,5 most diagnoses of infectious complications of epidural anesthesia are based on circumstantial evidence. Back pain is well known to occur after childbirth, but recent literature does not support a causal relationship with epidural anesthesia.6-9 This pain is usually not severe and often postural in nature.10 However, when back pain occurs that is severe, atypical, or associated with neurologic dysfunction or systemic signs of infection, thorough examination and investigation are indicated. Where available, MRI is the imaging investigation of choice. For epidural abscesses that occur after epidural anesthesia, the most common causative organism is Staphylococcus aureus.1 There have been few published reports of vertebral osteomyelitis that have occurred after epidural catheterization. Pinczower and Gyorke3 reported a case of a 76-year-old man with a history of recent Pseudomonas lung infection who developed osteomyelitis of the L1 spinous process 3 weeks after epidural catheterization. In that case, an MRI scan showed evidence of an epidural tract in the L2-3 interspace left by the epidural catheter. There was no involvement of the anterior spinal elements. Tham et al.11 reported a case of L1-4 discitis and osteomyelitis, caused by Pseudomonas, in a 61-year-old man that was diagnosed 8 months after an epidural catheter was inserted as part of anesthesia care for elective abdominal aortic aneurysm repair. The exact source of the infection was unclear, but the epidural catheter was implicated as a possible cause even though there was no evidence of epidural space infection. Conversely, Lynch and Zech12 commented that the L1-2 spondylitis from Pseudomonas aeruginosa diagnosed 15 weeks after epidural anesthesia in their 42-year-old patient was not likely to have been caused by the previous epidural catheter, because there was no concurrent epidural abscess. In their opinion, in the absence of any local inflammation or a direct communication with the epidural catheter, hematogenous spread of bacteria was the more likely mechanism. In our case, because the etiologic agent was Mycobacterium tuberculosis and because there was no involvement of the posterior bony elements or epidural space, we were confident in reassuring the patient that a causal relationship between the epidural anesthesia and her subsequent spinal infection was highly unlikely. This was the first case of
•
Lee et al.
223
tuberculous vertebral osteomyelitis in a postpartum patient that we have found. In Hong Kong, in 2000, there were 7,500 new cases of tuberculosis reported to the Department of Health, of which 2.5% involved bone and joint. Our patient coincidentally had a history of myasthenia gravis. Her disease was mild and did not impact significantly on her perioperative care. Of note, she was not taking steroids or immunosuppressive agents that could have increased her susceptibility to infection. The cases of vertebral osteomyelitis to which we have referred above occurred in patients who likely had some degree of immunocompromise, for example, from chronic alcohol abuse or steroids. In summary, severe back pain and infectious spinal conditions that occur after epidural anesthesia are not necessarily causally related to the epidural procedure. Investigation of these cases should include consideration of other infectious causes of back pain, such as vertebral osteomyelitis, discitis, epidural, and psoas abscess. Surgical treatment may occasionally be indicated.13 Thorough microbiologic investigation is important to identify the causative micro-organism, the likely source of infection, and to guide appropriate drug therapy.
References 1. Ngan Kee WD, Jones MR, Thomas P, Worth RJ. Extradural abscess complicating extradural anaesthesia for Caesarean section. Br J Anaesth 1992;69:647652. 2. Ready LB, Helfer D. Bacterial meningitis in parturients after epidural anesthesia. Anesthesiology 1989;71: 988-990. 3. Pinczower GR, Gyorke A. Vertebral osteomyelitis as a cause of back pain after epidural anesthesia. Anesthesiology 1996;84:215-217. 4. Ngan Kee WD. An unusual case of back pain after epidural anesthesia: ureteral obstruction. Anesth Analg 1993;77:1295-1297. 5. North JB, Brophy BP. Epidural abscess: A hazard of spinal epidural anaesthesia. Aust N Z J Surg 1979;49: 484-485. 6. Breen TW, Ransil BJ, Groves PA, Oriol NE. Factors associated with back pain after childbirth. Anesthesiology 1994;81:29-34. 7. Russell R, Dundas R, Reynolds F. Long term backache after childbirth: prospective search for causative factors. BMJ 1996;312:1384-1388. 8. Macarthur AJ, Macarthur C, Weeks SK. Is epidural anesthesia in labor associated with chronic low back pain? A prospective cohort study. Anesth Analg 1997; 85:1066-1070. 9. Howell CJ, Kidd C, Roberts W, Upton P, Lucking L,
224
Regional Anesthesia and Pain Medicine Vol. 27 No. 2 March–April 2002
Jones PW, Johanson RB. A randomised controlled trial of epidural compared with non-epidural analgesia in labour. Br J Obstet Gynaecol 2001;108:27-33. 10. Russell R, Groves P, Taub N, O’Dowd J, Reynolds F. Assessing long term backache after childbirth. BMJ 1993;306:1299-1303. 11. Tham EJ, Stoodley MA, Macintyre PE, Jones NR. Back pain following postoperative epidural analgesia:
An indicator of possible spinal infection. Anaesth Intensive Care 1997;25:297-301. 12. Lynch J, Zech D. Spondylitis without epidural abscess formation following short-term use of an epidural catheter. Acta Anaesthesiol Scand 1990;34:167-170. 13. Patzakis MJ, Rao S, Wilkins J, Moore TM, Harvey PJ. Analysis of 61 cases of vertebral osteomyelitis. Clin Orthop 1991;264:178-183.
Back pain, Epidural anesthesia, Infection, Obstetrics, Osteomyelitis, Psoas abscess.
I
nfectious complications have been occasionally reported after epidural analgesia and anesthesia in obstetrics. These have included epidural abscesses,1 meningitis,2 and osteomyelitis.3 We describe a patient who complained of persistent low back pain for 6 months after obstetric epidural anesthesia before a diagnosis of lumbar vertebral osteomyelitis, discitis, and psoas abscess was made.
Case Report A 34-year-old 65-kg primigravida was admitted in early labor at 39 weeks gestation, and the obstet-
From the Departments of Anaesthesia and Intensive Care (B.B.L., W.D.N.K.) and Diagnostic Radiology and Organ Imaging (J.F.G.), The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China. Accepted for publication August 1, 2001. Funded internally by departmental sources, The Chinese University of Hong Kong. Reprint requests: Bee B. Lee, M.B.B.S., F.A.N.Z.C.A., Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China. E-mail: [email protected] © 2002 by the American Society of Regional Anesthesia and Pain Medicine. 1098-7339/02/2702-0003$35.00/0 doi:10.1053/rapm.2002.28712
220
ric anesthetic team was consulted. Fifteen years previously she had been diagnosed with juvenile ocular myasthenia gravis (Osserman group 1) for which she had been prescribed pyridostigmine; however, after 3 years, she had stopped medication on her own accord and described no progression of symptoms during subsequent years or during her pregnancy. Her antenatal history had been otherwise uneventful. On examination, she had bilateral ptosis, but normal motor power of the limbs with no fatigue and a normal vital capacity. After discussion with the patient, vaginal delivery under epidural analgesia was planned. After transfer to the labor ward, an epidural catheter was inserted through a 16-gauge Tuohy needle at the L3-4 interspace using full aseptic precautions without difficulty. Epidural analgesia was initiated with 5 mL of 0.125% ropivacaine, followed by an infusion of 0.0625% ropivacaine with fentanyl 3 g/mL at 6 to 10 mL/hr. With this regimen, the patient was comfortable, and augmentation of labor was commenced using an oxytocin infusion. However, progress of labor was poor and after 8 hours, the obstetrician recommended cesarean delivery. The epidural block was extended uneventfully for
Regional Anesthesia and Pain Medicine, Vol 27, No 2 (March–April), 2002: pp 220 –224
Psoas Abscess After Epidural Anesthesia
surgery using 0.75% ropivacaine and fentanyl. The epidural catheter was removed intact immediately after the completion of surgery. Immediately postpartum, it was noted that she had mild back pain, but investigation was not thought necessary, as there were no other associated signs or symptoms. However, after discharge from hospital, her low back pain persisted. The pain was dull in nature, localized near to the site of the lumbar epidural insertion, mild to moderate in intensity, and occurred intermittently. It gradually deteriorated over the subsequent months with radiation to both thighs especially during walking. There were no associated sensory, motor, or sphincter disturbances, no fever, and the patient could manage with normal daily activities including caring for her baby and performing the daily housework. She consulted several general medical practitioners who found no abnormal physical findings and prescribed simple analgesics. Initially no investigations were performed, and she did not seek anesthetic followup. She received no spinal manipulation or steroids. Eventually at 6 months postpartum, a lumbar spine radiograph (Fig 1) was performed, which showed changes consistent with vertebral osteomyelitis and discitis at L3 and L4. She was then referred back to our hospital for further management. Computerized tomography (CT) and magnetic resonance imaging (MRI) scans showed severe L3-4 discitis and vertebral osteomyelitis with a large left psoas abscess extending from the L2 to the S1 level with extradural spread (Figs 2 and 3). The paravertebral mass was biopsied under CT guidance. Two days later, operative drainage of the psoas abscess and anterior spinal fusion at the L3-4 level was performed under general anesthesia. At operation, 300 mL of pus was drained from the abscess, and pus and necrotic bone at the L3-4 disc space and vertebral bodies were debrided. The posterior epidural space and bony elements were disease-free. Postoperatively, the patient was transferred to the intensive care unit for monitoring and observation, but did not require ventilation, and she made an uneventful recovery. Initially, the patient’s recent obstetric epidural catheterization was implicated as a likely source of the patient’s spinal infection. During surgery, the surgeons commented that the lesions appeared to be of a pyogenic nature with no macroscopic appearance of caseation. Together with the preceding history of epidural catheterization and the level of spinal involvement, a delayed complication of epidural anesthesia was considered to be the most likely explanation. The patient and her husband
•
Lee et al.
221
Fig 1. Lateral radiograph of the lumbar spine. There is reduction of the L3-4 disc space with destruction of the opposing endplates. These radiographic appearances are characteristic of discitis with early vertebral osteomyelitis.
also queried whether the infection was secondary to epidural anesthesia, because the patient’s symptoms had started soon after delivery and were localized to the lumbar spine. However, although no acid alcohol fast bacilli were identified in the percutaneous biopsy or any of the operative specimens, histopathologic examination showed granulomatous inflammation highly suspicious of tuberculosis. Therefore, the etiology was considered unlikely to be related to the epidural procedure. This was also supported by both the radiologic and intraoperative findings that the posterior elements of the lumbar spine (both bone and epidural space) were not involved. Antituberculous therapy was started empirically, and the patient was discharged home after 2
222
Regional Anesthesia and Pain Medicine Vol. 27 No. 2 March–April 2002
insertion and because of the temporal association of the diagnosis of spinal infection and the epidural procedure. Although the posterior vertebral bony elements and epidural space were shown by crosssectional imaging (both CT and MRI) and surgery to be clear, suggesting that the infection was unlikely to be related to the epidural procedure, it was not until microbiologic results had confirmed a tuberculous cause that other causes were considered. Similar to this case, we have previously reported a case in which severe back pain occurred after insertion of an epidural catheter for postoperative analgesia after radical hysterectomy.4 As with the current case, the symptoms were initially considered to be a complication of the epidural technique, but
Fig 2. T2-weighted sagittal MRI of the lumbar spine. There is discitis of the L3-4 disc with osteomyelitis of the adjacent vertebral bodies. The inflammatory infiltrate has extended beneath the anterior and posterior longitudinal ligaments.
weeks. After 6 weeks, the diagnosis of tuberculous osteomyelitis was confirmed when Mycobacterium species were cultured from broth cultures of the psoas muscle biopsy, as well as intraoperative specimens of pus from the psoas abscess and necrotic bone fragments.
Discussion Although they are rare, infectious complications after epidural anesthesia are well described. When they occur, an anesthetic-related cause may be difficult to refute. Our case was interesting because the patient’s spinal infection was initially suspected by both the patient and the attending orthopedic surgeons to be a complication of her recent obstetric anesthetic epidural catheterization. This was mainly because the patient’s pain had been localized to the same general area as the site of epidural catheter
Fig 3. (A) T2-weighted axial MRI at the level of L3. There is osteomyelitis of the L3 vertebral body with an abscess extending into the left psoas muscle (labeled A). Note how the posterior epidural space is clear. (B) T1weighted axial MRI following contrast at the same level as (A). The abscess tracking from the vertebral body to the left psoas muscle is clearly delineated. This clearly shows how the infection is confined to the vertebral body with no involvement of the posterior elements.
Psoas Abscess After Epidural Anesthesia
subsequent investigations showed an unrelated cause, namely, ureteral obstruction. Accurate diagnosis of severe back pain after epidural anesthesia can be difficult. Although direct contamination during the procedure of epidural anesthesia has occasionally been reported,5 most diagnoses of infectious complications of epidural anesthesia are based on circumstantial evidence. Back pain is well known to occur after childbirth, but recent literature does not support a causal relationship with epidural anesthesia.6-9 This pain is usually not severe and often postural in nature.10 However, when back pain occurs that is severe, atypical, or associated with neurologic dysfunction or systemic signs of infection, thorough examination and investigation are indicated. Where available, MRI is the imaging investigation of choice. For epidural abscesses that occur after epidural anesthesia, the most common causative organism is Staphylococcus aureus.1 There have been few published reports of vertebral osteomyelitis that have occurred after epidural catheterization. Pinczower and Gyorke3 reported a case of a 76-year-old man with a history of recent Pseudomonas lung infection who developed osteomyelitis of the L1 spinous process 3 weeks after epidural catheterization. In that case, an MRI scan showed evidence of an epidural tract in the L2-3 interspace left by the epidural catheter. There was no involvement of the anterior spinal elements. Tham et al.11 reported a case of L1-4 discitis and osteomyelitis, caused by Pseudomonas, in a 61-year-old man that was diagnosed 8 months after an epidural catheter was inserted as part of anesthesia care for elective abdominal aortic aneurysm repair. The exact source of the infection was unclear, but the epidural catheter was implicated as a possible cause even though there was no evidence of epidural space infection. Conversely, Lynch and Zech12 commented that the L1-2 spondylitis from Pseudomonas aeruginosa diagnosed 15 weeks after epidural anesthesia in their 42-year-old patient was not likely to have been caused by the previous epidural catheter, because there was no concurrent epidural abscess. In their opinion, in the absence of any local inflammation or a direct communication with the epidural catheter, hematogenous spread of bacteria was the more likely mechanism. In our case, because the etiologic agent was Mycobacterium tuberculosis and because there was no involvement of the posterior bony elements or epidural space, we were confident in reassuring the patient that a causal relationship between the epidural anesthesia and her subsequent spinal infection was highly unlikely. This was the first case of
•
Lee et al.
223
tuberculous vertebral osteomyelitis in a postpartum patient that we have found. In Hong Kong, in 2000, there were 7,500 new cases of tuberculosis reported to the Department of Health, of which 2.5% involved bone and joint. Our patient coincidentally had a history of myasthenia gravis. Her disease was mild and did not impact significantly on her perioperative care. Of note, she was not taking steroids or immunosuppressive agents that could have increased her susceptibility to infection. The cases of vertebral osteomyelitis to which we have referred above occurred in patients who likely had some degree of immunocompromise, for example, from chronic alcohol abuse or steroids. In summary, severe back pain and infectious spinal conditions that occur after epidural anesthesia are not necessarily causally related to the epidural procedure. Investigation of these cases should include consideration of other infectious causes of back pain, such as vertebral osteomyelitis, discitis, epidural, and psoas abscess. Surgical treatment may occasionally be indicated.13 Thorough microbiologic investigation is important to identify the causative micro-organism, the likely source of infection, and to guide appropriate drug therapy.
References 1. Ngan Kee WD, Jones MR, Thomas P, Worth RJ. Extradural abscess complicating extradural anaesthesia for Caesarean section. Br J Anaesth 1992;69:647652. 2. Ready LB, Helfer D. Bacterial meningitis in parturients after epidural anesthesia. Anesthesiology 1989;71: 988-990. 3. Pinczower GR, Gyorke A. Vertebral osteomyelitis as a cause of back pain after epidural anesthesia. Anesthesiology 1996;84:215-217. 4. Ngan Kee WD. An unusual case of back pain after epidural anesthesia: ureteral obstruction. Anesth Analg 1993;77:1295-1297. 5. North JB, Brophy BP. Epidural abscess: A hazard of spinal epidural anaesthesia. Aust N Z J Surg 1979;49: 484-485. 6. Breen TW, Ransil BJ, Groves PA, Oriol NE. Factors associated with back pain after childbirth. Anesthesiology 1994;81:29-34. 7. Russell R, Dundas R, Reynolds F. Long term backache after childbirth: prospective search for causative factors. BMJ 1996;312:1384-1388. 8. Macarthur AJ, Macarthur C, Weeks SK. Is epidural anesthesia in labor associated with chronic low back pain? A prospective cohort study. Anesth Analg 1997; 85:1066-1070. 9. Howell CJ, Kidd C, Roberts W, Upton P, Lucking L,
224
Regional Anesthesia and Pain Medicine Vol. 27 No. 2 March–April 2002
Jones PW, Johanson RB. A randomised controlled trial of epidural compared with non-epidural analgesia in labour. Br J Obstet Gynaecol 2001;108:27-33. 10. Russell R, Groves P, Taub N, O’Dowd J, Reynolds F. Assessing long term backache after childbirth. BMJ 1993;306:1299-1303. 11. Tham EJ, Stoodley MA, Macintyre PE, Jones NR. Back pain following postoperative epidural analgesia:
An indicator of possible spinal infection. Anaesth Intensive Care 1997;25:297-301. 12. Lynch J, Zech D. Spondylitis without epidural abscess formation following short-term use of an epidural catheter. Acta Anaesthesiol Scand 1990;34:167-170. 13. Patzakis MJ, Rao S, Wilkins J, Moore TM, Harvey PJ. Analysis of 61 cases of vertebral osteomyelitis. Clin Orthop 1991;264:178-183.