1 Anaesthetic Department, 2 Day Procedure Unit and 3 Department of Paediatrics, Norfolk and Norwich University Hospital, Norwich NR4 7UZ, UK
*Corresponding author. E-mail: anna@lipp.org.uk
Accepted for publication: July 25, 2003
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Abstract |
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Methods. We carried out a prospective, observational study to find out how many children had leg weakness after ilio-inguinal nerve block. We studied 200 children having day-case surgery in the groin under a general anaesthetic with an ilio-inguinal nerve block. All children performed a simple leg-raising test with each leg before induction of general anaesthesia with a standardized ilio-inguinal nerve block on the side of surgery. When the child was awake and comfortable after surgery, they repeated the leg-raising test.
Results. Sixteen of 182 children (8.8%) had leg weakness after surgery on the side of the nerve block only, as detected by a leg-raising test.
Conclusions. Leg weakness consistent with a femoral nerve block occurs after ilio-inguinal nerve block in approximately one in nine children.
Br J Anaesth 2004; 92: 2734
Keywords: anaesthetic techniques, ilio-inguinal nerve block; anaesthesia, day-case
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Introduction |
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A well recognized textbook of regional anaesthesia4 specifically describes ilio-inguinal nerve block as being free of the complications of lower limb motor block, and it has been stated that the risk of a femoral nerve block after an ilio-inguinal nerve block is so negligible that patients need not be warned about this risk.5
We performed a prospective, observational study with two aims: to find out how common leg weakness is after ilio-inguinal nerve block and to investigate the practical use of a leg-raising test to demonstrate leg weakness in children.
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Methods and results |
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All children in the study were encouraged to perform a leg-raising test with each leg before going to the anaesthetic room. The child was asked to lift each leg in turn off the bed to touch a ball held in a net approximately 30 cm directly above them with the foot. This manoeuvre produced extension of the knee against gravity.
After induction of general anaesthesia, an ilio-inguinal nerve block was performed on the side of surgery using plain bupivicaine 0.25%, 0.25 ml kg1 body weight, injected with a regional block needle at a point 1.5 cm medial to the anterior superior iliac spine. The needle was advanced until a pop was felt. After aspiration, half the bupivicaine was injected then the needle was redirected towards the anterior superior iliac spine and the remaining anaesthetic injected. Additional analgesia was given by the anaesthetist during surgery.
In the recovery room, the nurse assessed whether analgesia was adequate and gave appropriate additional analgesia if necessary. When the child was awake and completely comfortable they were asked to repeat the leg-raising test with each leg in turn. If the child was able to touch the ball with one leg but not the other, we considered this to be the result of leg weakness. If the child was unwilling to do the leg-raising test with either leg we excluded them from the study. In total 200 children were recruited, of whom 182 cooperated with the leg-raising test before and after surgery.
Analgesia was judged inadequate by the recovery nurse in six children and additional analgesia was given: morphine 0.1 mg kg1 in one patient and acetaminophen suspension in three patients; the analgesia given to the other two patients was not recorded. No leg weakness was noted in the six children in whom analgesia was inadequate.
Of the 182 children who completed the leg-raising tests, 16 (8.8%, 95% confidence intervals 5.113.9%) had postoperative leg weakness on the side of the nerve block. There was no significant difference in the proportion of children with leg weakness in different age groups (Fishers exact two-sided test, P=0.57) nor was there a trend with age (2 linear trend P=0.69).
All children with leg weakness were discharged on the same day (except one who was admitted because they were epileptic) with instructions to the parents to support or carry their child until they could bear their own weight safely. In all children the leg weakness had resolved by the next day when a follow-up telephone call was made.
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Comment |
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The leg-raising test we used was specifically designed to demonstrate femoral nerve function to see if the theoretical situation described above occurs in practice. The apparent weakness was unlikely to be caused by pain as none of the children who were judged to be in pain showed leg weakness and those with leg weakness were all comfortable when they performed the leg-raising test.
We have shown that one in nine children who have had an ilio-inguinal nerve block have leg weakness afterwards, consistent with a femoral nerve block. We have also demonstrated a high level of compliance by children performing a postoperative leg-raising test that can be used to detect leg weakness.
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References |
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2 Rosario DJ, Skinner PP, Raftery AT. Transient femoral nerve palsy complicating preoperative ilioinguinal nerve blockade for inguinal herniorrhaphy. Br J Surg 1994; 81: 897[ISI][Medline]
3 Rosario D, Jacob S, Luntley J, Skinner P, Rafter A. Mechanism of femoral nerve palsy complicating percutaneous ilio-inguinal field block. Br J Anaesth 1997; 78: 31418
4 Wildsmith J, Armitage E. Principles and Practice of Regional Anaesthesia. Edinburgh: Churchill Livingstone, 1993; 1613
5 McNicol LR. A complication of ilio-inguinal block for inguinal hernia repair. Anaesthesia 1988; 43: 706