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Complications from the use of regional anesthesia have been reported from the onset of its use. The first report of spinal headache was in 1899 by August Bier on his own experience with a spinal anaesthetic performed using a Quinke cut needle. He also noted a complaint of backache with his experience.(1) The now infamous 'Wooley and Roe' case of 1954 led to the almost virtual abandonment of spinal and epidural techniques in Britain for more than 2 decades(2).
The usual list quoted to patients regarding risks associated with regional anaesthesia include block failure, backache, infection (localized and CNS), headache, accidental intravascular injection, inadvertent total spinal, neurologic injury (from peripheral nerve injury to paralysis) and death or brain injury. As one recites this list, the actual likelihood of suffering this complication is often not well communicated to the patient. This may reflect a lack of real comprehension by the informer, but often results from the tendency by the patient to recall only the most sinister of complications.
Before we can make an appropriate presentation to their patient on risk and complication of anaesthesia, we must make an assessment ourselves of the magnitude of the risk. A report from 1991 looked at malpractice claims filed against anaesthesiologists in a 10-year period from 1975-1985 (3). A comparison was made between ob and non-ob claims. A total of 1,541 cases were reviewed, of which 12% were ob-related claims and 88% were non-ob claims. The following comparisons were made regarding the types of injuries claimed. (Table 1)
| % non - ob claim (n=1,351) |
% ob claims (n=190) |
% ob-regional (n=124) |
% ob-general (n=62) |
|
|---|---|---|---|---|
| Patient death | 39(524) | 22(41) | 12(15) | 42(26) |
| Neonatal brain damage | 20(38) | 19(23) | 24(15) | |
| Headache | 1(10) | 12(23) | 19(23) | 0(0) |
| Neonatal death | <0.5(1) | 9(17) | 7(8) | 10(6) |
| Pain during anesthesia | <0.5(5) | 8(16) | 13(16) | 0(0) |
| Patient nerve damage | 16(209) | 8(16) | 10(12) | 7(4) |
| Patient brain damage | 13(174) | 7(14) | 7(9) | 8(5) |
| Emotional distress | 2(30) | 6(12) | 7(9) | 5(3) |
| Back pain | 1(8) | 5(9) | 7(9) | 0(0) |
This review demonstrated that patient death, nerve injury and brain damage were more common in the non-ob population than the ob population. However among the ob population, claims for more trivial events such as headache, pain during anaesthesia, emotional distress and back pain were more common. When the authors compared anaesthetic techniques in the ob group, they found (as would be expected) that there was a significantly higher number of claims resulting from maternal death in the general anaesthesia group. While headache, pain during anaesthesia and back pain were more common complaints in the group receiving regional anaesthesia. How should we interpret this data? Major complications are more frequent in the patients who have general anesthesia than regional anaesthesia. Risk should be put in the context of options available.
In the triennial Report on Confidential Enquiries into Maternal Deaths in the United Kingdom 1988-1990, there were 4 deaths directly attributable to anaesthesia. (4) Three of these were a result of pulmonary complication either during or after general anaesthesia. One was due to pulmonary complications which occurred after aggressive treatment of hypotension in a patient with an underlying cardiac arrythmia.. Ten deaths were indirectly associated with anaesthesia. Nine were as a result of respiratory insufficiency either due to intraoperative or postoperative complications of general anesthesia and/or post operative pain management. One was a result of severe intraoperative haemorrhage which could not be controlled after 4 hours of surgery and resuscitative measures. This patient had an epidural anaesthetic and it was felt that the sympathectomy could have contributed to the failure at resuscitative efforts. (4) What is all of this trying to tell us? I think it should be apparent that, when discussing complications of regional anesthesia with patients, one should not dwell on the fact that death could occur with regional anaesthesia, rather the patient should be made aware that death is more of a risk when general anaesthesia is used in the pregnant patient.
A major category of injury which is remembered by patients is the risk of nerve injury. This encompasses a very broad spectrum of injury from transient peripheral nerve palsy to paralysis. An analysis of closed claims revealed that nerve injury is more likely with general anaesthesia than regional anaesthesia (61 vs 36%). (5) Ulnar nerve palsy and brachial plexus injury were the most common, followed by lumbosacral nerve root injury.
When one examines the issue of nerve injury, we must keep in mind the high incidence of nerve injury associated with obstetrical delivery itself (without the use of epidural block). The incidence of obstetric related neurologic complication is reported from 1:2000 to 1:6400.(6) The types of neurologic injury seen, which related to the pregnant state or delivery, are detailed in Table 2.
| Complication | Usual Cause | Sensory Deficit | Motor Deficit |
|---|---|---|---|
| Prolapsed disc | spontaneous occurrence in 1:6000 deliveries | variable | variable |
| Lumbosacral trunk L4,L5 | compression of head against sacrum, higher incidence with use of mid/high forceps | hypoesthesia lateral calf and foot | weak hip adductor foot drop weak quad |
| Femoral nerve L2,L3,L4 | lithotomy, hyperacute hip flexion with pushing and retractors at C/S | hypoesthesia ant thigh and medial calf, absent patellar reflex | quad paralysis with impaired knee extension |
| Lateral femoral cutaneous L2,L3 | lithotomy or retractors | numbness anterolateral thigh | |
| Sciatic nerve L4,L5,S1,S2,S3 | lithotomy or IM injection | pain from post gluteal to foot | inability to flex leg |
| Obturator nerve L2,L3,L4 | lithotomy, acute flexion of thigh | hypoesthesia medial thigh | inability to adduct leg |
| Common Peroneal L4,L5,S1,S2 | lithotomy with compression of the lateral aspect of the knee | anterolateral calf and dorsum of foot and toes | plantar flexion with inversion deformity -drop foot |
| Saphenous nerve L2,L3,L4 | lithotomy position | medial foot and anteromedial aspect lower leg |
Epidural anesthesia can be associated with neurologic problems, ranging from headache to paralysis. The injuries which immediately come to mind include: prolonged neural blockade, backache, trauma to nerve roots, cauda equina syndrome, epidural hematoma, epidural abscess, adhesive arachnoiditis, meningitis and postdural puncture headache.
Looking back on the data collected by Chadwick et al, (3) it is apparent that the anesthesiologist is more likely to be involved in a suit for a minor injury than a major injury. One should therefore be prepared to discuss these minor issues with their patients. The incidence of back pain following epidural block continues to be an area of controversy. Headache has also been identified as a complication associated with high risk of suit. The risk of accidental dural puncture (ADP) depends on the skill of the operator. A rate of 1% is generally quoted.
Direct trauma to the spinal cord after epidural anesthesia for labor would be very rare, as the epidural space is usually entered below the conus medullaris. In 90% of adults, the cord ends above the second lumbar vertebrae. However, in 10% of adults, it extends to the third lumbar vertebrae. Nerve root trauma has been reported in 0.07% of patients after epidural anesthesia. Pain and/or paraesthesia during needle placement, or injection of medication, usually warn of risk for injury and should be acted upon.
More catastrophic nerve injury has been reported. These have been in association with epidural hematoma, epidural abscess, adhesive arachnoiditis, anterior spinal artery syndrome or cauda equina syndrome. When one discusses these complications, it is important to keep in perspective their very low incidence. Epidural abscess has been reported in a frequency of 1:505,000 patients who had epidurals. (The incidence is 2:10,000 in patients without regional anesthesia.)(12)
Anterior spinal artery syndrome is the consequence of decreased arterial supply to the cord and results in motor weakness, or paralysis and loss of pain and temperature sensation. In approximately 15% of the population the artery of Adamkiewicz originates from as high as the T5 level. In this population the conus medularis is supplied by branches from the internal iliac artery. It is postulated that there may be an increased risk of cord ischemia due to fetal head compression of the branches of the internal iliac artery.
Cauda equina syndrome and adhesive arachnoiditis share a common etiology - chemical toxicity. Cauda equina syndrome has been reported as a consequence of local anesthetic toxicity. Recently, controversy has arisen over the use of hyberbaric 5% lidocaine for spinal anesthesia; however, lidocaine in the epidural space still appears to be safe.(14)
Epidural hematoma is a complication which we learn about early in our career and many spend a great deal of time fearing someday they will see one. The actual incidence of epidural hematoma is unknown. It is reported to occur spontaneously in patients who have not received regional anaesthesia (16) and in patients who have received regional anesthesia (17),(18) In a review of the literature from 1906-1994 by Vandermeulen et al. identified 61 cases of spinal- epidural hematoma, 46 of which were associated with epidural anesthesia. Twenty three of the 46 epidural cases were associated with the use of anticoagulants, 4 were associated with thrombocytopenia and the remaining 19 cases had no risk factors reported. Five of these cases were in pregnant women. Two of these were reported to have thrombocytopenia, 1 had an epidural ependymona and 2 had no identifiable risk factors. Risk factors for epidural hematoma have included difficult or bloody tap, pre existing coagulopathy and use of anti coagulants. The risk of a bloody tap in the obstetric population has been reported to be as high as 18%. Thrombocytopenia is identified as a risk factor, however the platelet count below which it is risky to use regional anesthesia is still somewhat controversial. In the review by Owens et al (17) no patients were identified with hematoma and a platelet count >50,000 in those whom thrombocytopenia was considered a risk factor. Current dogma uses a platelet count >100,000 as the safe threshold. However many experienced anaesthesiologist would challenge this. When questioning the use of regional anesthesia for fear of epidural hematoma one must always consider the risks of alternate treatments (general anesthesia) and the benefits regional anesthesia may afford the mother and fetus.
Infection or meningitis as a complication is rare as well. Concern in obstetric practice has focus around the use of regional block anaesthesia in the presence of maternal chorioamnionitis. Laboratory studies suggest that if the CSF is entered after systemic administration of antibiotic that risk of contamination with bacteria is nil. (19)
The use of epidural anesthesia/analgesia has become the standard of care in obstetrical practice. As with any adventure in life it can be associated with complications. Fortunately the incidence of serious complication with epidural anesthesia is rare in experienced hands. They do however occur even with the most experienced and good intentioned practitioner. The risks of general anaesthesia in obstetrics are well documented. (21) One must temper these risk against the potential complications associated with epidural anaesthesia in your discussion with the patient.
In 1954 Lord Justice Denning in his judgement of the Wooley and Roe case made a very insightful comment on complications of medical procedures. "We should be doing a disservice to the community at large if we were to impose liability on hospitals and doctors for everything that happens to go wrong. We must insist on due care for the patient at every point, but we must not condemn as negligence that which is only a misadventure." (2) It is unfortunate that today's legal community are not as forgiving.
2. Cope RW. The Wooley and Roe Case. Anaesthesia 1995;50:162-173.
3. Chadwick et al. A comparison of obstetric and non-obstetric anesthesia malpractice claims. Anesthesiology 1991;74:242-9.
4. Metters JS et al eds. Report on Confidential Enquiries into Maternal Deaths in the United Kingdom 1988-1990. London HMSO1994
5. Kroll et al. Nerve injury associated with anaesthesia. Anesthesiology 1990;73:202-7
6. Rosenbaum RB, et al. Pheripheral nerve and neuromuscular disorders. Neurologic Clinics 1994; 12(3):461-478)
7. Macarthur C et al. Epidural anaesthesia and long term backache after childbirth. Br Med J 1990;301:9-12
8. Breen TW, et al. Factors associated with back pain after childbirth. Anesthesiology 1994;81:29-34.
9. MacDonald R. A dural puncture rate of 1% is unacceptable in epidural practice. Controversies in Obstetric Anaesthesia. International Journal of Obstetric Anaesthesia 1994;3;50-51.
10. Norris MC, et al. Needle bevel direction and headache after inadvertent dural puncture. Anesthesiology 1989;70:729-31.
11. Norris MC, et al. Complications of labor analgesia: epidural verses combined spinal epidural techniques. Anesth Analg 1994;79:529-37.
12. Hlavin ML, et al. Spinal epidural abscess: a ten year perspective. Neurology 1990;27:177.
13. Bromage, PR. Neurologic complications of regional anaesthesia for obstetrics. In: Shnider S. and Levinson G (Eds): Anesthesia for Obstetrics. Williams and Wilkins, Baltimore, 1993;433-53.
14. deJong, RH. Last round for a heavy weight? Anesth Analg 1994;78:3-4.
15. Fukuda T et al. Unintentional epidural administration of thiamyal. Reg Anesth 1994;19:361.
16 Scott BB. Spinal epidural hematoma.JAMA 1976;235:513.
17. Owens EL et al. Spinal subarachnoid hematoma after lumbar puncture and heparinization: A case report, review of the literature, and discussion of anesthetic implications. Anesth Analg 1986;65:1201-7.
18. Vandermeulen EP et al. Anticoagulants and spinal epidural anesthesia. Anesth Analg 1994;79:1165-77.
19. Carp H et al. The association between meningitis and dural puncture in bacteremic rats. Anesthesiology 1992;76:739.
20. Vaddadi A et al. Epidural anesthesia in women with chorioamnionitis: a retrospective study Anesthesiology 1989;71:A863
21 Muir H. General anaesthesia for obstetrics, is it obsolete? Can J Anaesth 1994;41:R20-25.
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5-Dec-96, Revised 6-Mar-97
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