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K.R.GHANI , R. MCMILLAN and S. PATERSON-BROWN
Department of Surgery, Royal Infirmary of Edinburgh, Lauriston Place, Edinburgh EH3 9YW
Keywords: Transient femoral nerve palsy, inguinal hernia, nerve block, local anaesthetics, post-operative complications
Background: Transient femoral nerve palsy (TFNP) has been reported in patients undergoing inguinal hernia repair involving the use of ilio-inguinal nerve block. Ilio-inguinal nerve blocks can be administered under vision by the surgeon or by the anaesthetist using a standard blind technique. There has been no study that has specifically examined the incidence of this complication and whether its development is related to the type of method used to administer the block.Patients and Methods: Data on patients undergoing surgery in the Royal Infirmary Edinburgh Day Case Unit are collected prospectively. All patients who undergo inguinal hernia repair are given ilio-inguinal field blocks, either preoperatively by anaesthetists (blind technique) or peri-operatively under direct vision by surgeons. Several cases of TFNP were initially identified during the process of surgical audit and this led to a retrospective analysis over a period of one year. Results: During a 12-month period, 194 patients underwent 200 open inguinal hernia repairs (188 unilateral and 6 bilateral), under general anaesthesia. Ten patients (5%) developed TFNP resulting in overnight admission. Surgeons administered 101 blocks under direct vision of which 4 (4%) resulted in TFNP, whereas 6 out of 99 (6%) blind blocks resulted in TFNP (p=0.49, df=1, Chi2 test). Discussion and Conclusion: TFNP is a recognised complication following ilioinguinal nerve blockade for inguinal hernia surgery. Our series shows that ilio-inguinal block given under direct vision does not appear to reduce the chance of this complication occurring. This may result from the fact that this complication could be due to local infiltration into the operative field rather than direct infiltration around the femoral nerve. As inguinal hernia repair undertaken as a day case procedure increases, the awareness of this complication is important to avoid morbidity
J.R.Coll.Edinb., 47, August 2002, 626 - 629
Inguinal hernia repair is the most common elective surgical procedure performed in the UK and whether performed under general, regional or local anaesthesia, is usually undertaken as a day case.1 According to the Royal College of Surgeons of England guidelines, at least 30% of elective hernia repairs should be performed as day-cases and overall, 50% of inguinal hernia repairs are performed on a day case basis in the UK.2,3 The advantages of day case surgery include greater patient satisfaction and reduced financial costs to the health service.4,5
It is now common practice, when inguinal hernia surgery is carried out under general anaesthesia, to incorporate an ilio-inguinal nerve block. This is done in order to reduce post-operative opiate requirement and post-operative pain6-8 and, therefore, facilitate discharge from hospital the same day. However, transient femoral nerve palsy (TFNP) can occur following ilio-inguinal nerve block and is a recognized complication of this procedure.9,10
The first reported cases of TFNP after inguinal hernia surgery involving an ilio-inguinal nerve block were noted in children.6 In 81 children undergoing inguinal herniotomy and receiving blind pre-operative ilio-inguinal blockade, Shandling and Steward (1980) found that 3 patients (3.7%) developed a transient block of the femoral nerve in the limb of the operated side.6 This complication has also been noted to occur in children receiving ilio-inguinal blocks under direct vision, with infiltration of the local anaesthetic agent by the surgeon into the internal ring and inguinal canal.11
In adults, TFNP was first reported in 1988.12 Lewis and Fell (1988) described two cases of inguinal hernia repair under general anaesthesia, where blind pre-operative blockade of the ilio-inguinal nerve led to the inadvertent palsy of the femoral nerve which resolved after a period of 16 hours. Since this report in 1988, there have been several reports of TFNP occurring after a blind ilio-inguinal block.9,13-16 In adults, TFNP has also been shown to occur following ilio-inguinal block undertaken under direct vision.17 Szell (1994) describes a case where an inguino-scrotal hernia was repaired under local anaesthesia, with infiltration of bupivacaine in the inguinal canal and around the sac, which resulted in transient quadriceps paresis and sensory loss in the distribution of the femoral nerve.17 During the routine audit review of our six monthly day case unit data, we identified several patients with this complication. This prompted us to review our twelve months data, which we report here.
Data on all patients undergoing inguinal hernia surgery in the day surgery unit at the Royal Infirmary Edinburgh are recorded prospectively. These include patient and operation details and a telephone follow-up. Duration of procedure, anaesthetist, surgeon, anaesthetic type, block administered by surgeon or anaesthetist and any complications are included. Over a period of one-year analysis of these data were carried out retrospectively.
At the time of surgery all patients were given an ilio-inguinal nerve block either by an anaesthetist using a standard method (blind technique) or under direct vision by a surgeon.18 The blind block was performed with a regional block needle and the direct vision block used a 21G or 23G needle. Anaesthetists infiltrated pre-operatively with 20mls 0.5% bupivacaine and, on completion of all the operations, the surgeons infiltrated 10mls of 0.5% bupivacaine into the site of the incision. When surgeons administered the blocks, 20mls 0.5% bupivacaine was used in total for both the ilio-inguinal block and wound infiltration.
Over a 12-month period, 200 open inguinal hernia repairs in 194 patients (188 unilateral and 6 bilateral) were undertaken under general anaesthesia (age 20-92 years, M:F = 9:1). Ten (5%) patients developed TFNP in the limb of the operated side (age 22-70 years, M:F=8:2).
These patients developed sensory loss over the anterior aspect of the thigh and weakness of extension at the knee joint. After 24 hours these symptoms and signs had resolved completely, however, all 10 patients remained in hospital overnight. No patients undergoing bilateral hernia repair developed TFNP.
Surgeons administered 101 ilio-inguinal nerve blocks under vision whilst anaesthetists administered 99 blind ilio-inguinal nerve blocks. Table 1 shows the number of patients developing TFNP according to the type of block given. The 10 patients who developed TFNP had ilio-inguinal blocks administered by 4 surgeons (3 consultants and 1 specialist registrar), and 6 anaesthetists (5 consultants and 1 specialist registrar). Using Chi2 analysis, these results were not statistically significant (p=0.49, df=1). The decision as to who performed the block depended upon the anaesthetists’ preference.
On the first post-discharge day, telephone follow-up was carried out and, despite this complication, all 10 patients would recommend day surgery. A further 6 patients (without TFNP) remained overnight due to poor pain control. Of these 6 patients, 4 had ilio-inguinal blocks administered by surgeons (3 consultants and 1 specialist registrar) and 2 by anaesthetists (both consultants).
Ilio-inguinal nerve blocks can be performed by the anaesthetist before the operation using a blind technique, or by the surgeon at the start of the operation under direct vision.10 Most blocks are undertaken using a long acting agent such as bupivacaine.
In our series of 200 general anaesthetic open inguinal hernia repairs we have found an incidence of TFNP of 5%. Although our study is small, there has been no series in adults published that has mentioned the incidence of TFNP as a specific complication. However, in a large series of 3175 local anaesthetic primary inguinal hernia repairs conducted by the London Hernia Centre, it was reported that 8 out of the 3175 (0.25%) repairs resulted in anterior thigh muscle weakness that recovered.19 Presumably this lower figure resulted from the fact that local anaesthetic infiltration along the planned incision site was carried out rather than a formal ilio-inguinal nerve block.
The reported time of onset of TFNP following surgery varies from 2 to 6 hours but this will be dependent on the speed of mobilisation by the patient. An interesting finding is the report of a delayed onset of TFNP in a patient who was walking 60 minutes after the operation only to develop a palsy 45 minutes later.16 The duration of the palsy can vary but more important is the fact that in all cases reported the weakness resolves completely after a period of 36 hours.
This complication is not without potential significant morbidity and has been reported to have led to a compound fracture of the tibia and fibula in one patient and a minor head injury in another, both as a result of a fall when attempting to weight bear. 9,17 It should be borne in mind that femoral nerve palsy after inguinal hernia surgery could be due to surgical trauma, as demonstrated in a case under spinal anaesthesia where a suture was discovered in the femoral nerve after exploration of the groin.20
The occurance of TFNP after the use of a local anaesthetic agent, either in a field block or as part of local infiltration into the operative field, can be explained by the anatomy of ilio factors. In the posterior abdominal wall the fascia of iliacus covers the exiting femoral nerve, which lies over the iliacus muscle. The iliac fascia is continuous anteriorly with the transversalis fascia of the anterior abdominal wall. Thus, any agent in the layer between transversalis fascia and transversus abdominis in the anterior abdominal wall also lies in the same plane that is between ilacus fascia and the iliacus muscle. Rosarioet al (1997) demonstrated the mechanism of TFNP after a very simple cadaveric study.21 They injected methylene blue dye into the anterior abdominal wall of numerous cadavers in the supine position. The dye was injected into the plane between the transversalis fascia and transversus abdominis. They discovered that in every cadaver the blue dye was found to pool around the femoral nerve in the posterior abdominal wall. The amount of dye used was not a limiting factor, as the correct placement of just one millilitre of dye in the correct plane led to the same result. Thus, the occurrence of TFNP is due to tracking of anaesthetic agent along fascial planes. This should not occur if the local anaesthetic agent is injected into the plane just beneath external oblique and no deeper than internal oblique. Notaras (1995), who has yet to come across a case of TFNP in his practice, advocates this careful ‘layered’ approach.22
|
TFNP |
No TFNP |
|
| 'Blind' ilioinguinal nerve block | 6 | 93 |
| 'Direct vision' ilioinguinal 4 97 nerve block |
4 |
97 |
Table 1: The number of inguinal hernia repairs resulting in TFNP after ‘blind’ and ‘direct vision’ ilio-inguinal nerve block
In our series, of the 10 patients who developed TFNP, 6 received blind blocks from anaesthetists and 4 received blocks under vision from surgeons. It has been suggested that blocks be given under direct vision by surgeons to reduce the chance of TFNP occurring.23 However, in our series this was not the case albeit there were only a small number of patients with this complication. As a result, we suggest that extra care should be taken to inject the anaesthetic agent below the external oblique but no deeper. Whether it is possible to do this using the blind technique must be open to question and although no difference was seen between the blind and open technique in this study, no conclusion can be reached as to whether the open technique is indeed inherently safer. Although a randomised controlled trial could be carried out the simpler recommendation would be for the surgeon to carryout the block following induction of general anaesthesia.
The incidence of TFNP was 5% in our study, although because of the relatively small numbers concerned a true reflection on incidence cannot be confirmed. All patients receiving ilio-inguinal nerve blocks should be advised of this complication, and TFNP must be looked for during early mobilization after surgery to prevent accidents. As inguinal hernia repairs undertaken as a day case procedure increase, TFNP and its implications become more important. It is recognised in day case units in countries like Australia and Israel to the extent that active extension of the knee assessed by nurses before the patient is allowed to weight bear.24,25 We recommend that the same apply in the UK. However, when TFNP is recognised and the patient has been counseled pre-operatively, it might still be possible for the patient to be discharged the same day as long as the appropriate transport and domestic arrangements are made and a district nurse can visit the patient the following day. Mobility is of course the major problem and perhaps use of crutches should be considered. Thus, TFNP is not an absolute indication for overnight stay and does not necessarily have to influence same day discharge provided everyone is fully aware of the implications and appropriate action is taken and support provided.
We are grateful to the other Consultant General Surgeons and Anaesthetists who work in the Day Case Unit for their support in this study.
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Copyright: 20 May 2002
Correspondence: Mr S. Paterson-Brown, Dept of Surgery, Royal Infirmary of Edinburgh, Lauriston Place, Edinburgh, EH9 1JD
Edinburgh Surgical Masterclass
COLORECTAL SURGERY
19th & 20th September 2002
CPD = 12 Credits
Convener - Professor Robin Phillips
Local Convener - Professor Malcolm Dunlop
Topics to be discussed will be --Recent advances in colon cancer; Management of inflammatory bowel disease; Incontinence surgery; consultants corner - discussion of difficult colorectal cases.
The registration fee for the Masterclass is £295.00 (Trainees £275.00). The fee includes a copy of the relevant volume of the Companion to Specialist Surgical Practice (2nd Edition), all refreshments, lunches and Masterclass Dinner. For an application form and detailed programme, please apply to the Career Information Service. Tel: 44 (0) 131 668 9222 or m.lowrie@rcsed.ac.uk
KING JAMES IV PROFESSORSHIP LECTURES
Tuesday 17th September 2002 at 5.30pm
CPD = 1 Credit
“Transcallosal Resection of Hypothalmic Hamartoma in 17 children with Intractable Gelastic Epilepsy: Surgical Technique and Outcome”
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The Lecture is open to all health care professionals and will be delivered in the Symposium Hall of the College. Admission is by ticket only - available from Mrs Maureen Lowrie - 0131 668 9209/ m.lowrie@rcsed.ac.uk (There is no charge for tickets)