Evaluation of genitofemoral nerve block, in addition to ilioinguinal and iliohypogastric nerve block, during inguinal hernia repair in children

N. Sasaoka*, M. Kawaguchi, K. Yoshitani, H. Kato, A. Suzuki1 and H. Furuya

Department of Anesthesiology, Nara Medical University, Nara, Japan. 1 Department of Anesthesiology, Izumisano Municipal Hospital, Izumisano, Osaka, Japan

* Corresponding author. E-mail: ne6n-ssok{at}asahi-net.or.jp

Accepted for publication September 24, 2004.


    Abstract
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Background. Ilioinguinal and iliohypogastric (IG-IH) nerve block has been widely used in children undergoing inguinal hernia repair. This technique may provide insufficient analgesia for intraoperative management as the inguinal region may receive sensory innervation from genitofemoral nerve. We proposed that addition of a genitofemoral nerve block might improve the quality of analgesia.

Methods. Ninety-eight children undergoing inguinal hernia repair were assigned randomly to receive either IG-IH nerve block (Group I) or IG-IH and genitofemoral nerve blocks (Group II). Systolic arterial pressure (SAP) and heart rate (HR) were recorded before surgery (control), after skin incision, at sac traction and at the end of surgery. Postoperative analgesic requirements and incidence of complications were recorded until discharge.

Results. At sac traction, SAP and HR were significantly higher in Group I (P<0.05), and the incidence of episodes of increased HR was also significantly higher in Group II (29 vs 12%, respectively, P<0.05). There were no significant differences in SAP and HR at other time points, postoperative analgesic requirements or incidence of complications between the groups.

Conclusions. The benefit of the additional genitofemoral nerve block to IG-IH nerve block was limited only to the time of sac traction without any postoperative effect. This suggests there is little clinical benefit in the addition of a genitofemoral nerve block.

Keywords: nerve block, genitofemoral ; nerve block, iliohypogastric ; nerve block, ilioinguinal ; surgery, inguinal hernia repair


    Introduction
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Preoperative ilioinguinal and iliohypogastric (IG-IH) nerve block has been widely used to provide analgesia in children undergoing surgery for inguinal hernia repair.17 However, it has been shown that this technique provided insufficient analgesia for complete intraoperative management and must be supplemented by analgesics and general anaesthesia.1 Inadequate block of these nerves may be evident during sac handling, resulting in tachycardia and tachypnoea. We therefore consider that the efficacy of IG-IH nerve block can be improved upon.

It has been demonstrated that IG-IH and genitofemoral nerves have a variable origin, course, and distribution in the inguinal region.8 9 Consequently the inguinal region may also receive sensory innervation from the genitofemoral nerve. Genitofemoral entrapment neuralgia as a result of inguinal surgery has been reported.810 We therefore proposed that the addition of genitofemoral nerve block to IG-IH nerve block may improve the quality of analgesia for surgery in the inguinal region. The study prospectively investigated the additional efficacy of the genitofemoral nerve block to IG-IH nerve block for pain management in children undergoing inguinal hernia repair.


    Methods
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
After institutional approval and parental written consent, 100 children (aged 6 months to 10 yr, ASA I and II) undergoing unilateral inguinal hernia repair were enrolled. Patients with bilateral or recurrent hernias or allergy to local anaesthetics were excluded. No premedicant drugs were administered. General anaesthesia was induced by inhalation of nitrous oxide and sevoflurane followed by placement of a laryngeal mask and was maintained with nitrous oxide (70%) and sevoflurane (2%) in oxygen with spontaneous respiration. No sedatives or opioids were administered intraoperatively. After induction of anaesthesia, the patients were randomly assigned to one of two groups by sealed, serially numbered envelopes. In Group I, patients received IG-IH nerve block by infiltration of bupivacaine 0.25% solution with a dose of 0.75 mg kg–1 into the area just medial to the anterior superior iliac spine. The injection was below the aponeurosis of the external oblique muscle using a 25-gauge short-bevelled regional block needle. In Group II, patients received IG-IH and genitofemoral nerve blocks. The IG-IH nerve block was performed as described above. The genitofemoral nerve block was performed immediately proximal to the pubic tubercle on a line linking the anterior superior iliac spine to the pubic symphysis, below the aponeurosis of the external oblique muscle, as described previously.11 Bupivacaine (0.25%), 0.375 mg kg–1, was given at each site (Fig. 1).



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Fig 1 Course of the ilioinguinal, iliohypogastric, and genitofemoral nerves. The circle indicates area infiltrated with local analgesic for each block. The centre of the circle (dotted line) indicates the point of insertion of the needle for each nerve block.

 
SAP and HR were recorded before the start of surgery (control), immediately after skin incision, at sac traction and at the end of surgery. Change in SAP and HR (% control value) and the incidence of episodes of increase (>10% from control) in SAP and HR were evaluated. Postoperatively, pain was assessed by a recovery nurse, who was unaware of the group allocation, at 30-min intervals up to 5 h after surgery. Rescue medication of diclofenac 1 mg kg–1 per rectum was available. Postoperative analgesic requirements and the incidence of complications, such as vomiting, were recorded.

We considered an increase of more than 10% in HR at skin incision or sac traction to be clinically relevant. Based on our previous studies and a pilot study and assuming an SD of 20 beats min–1, a type 2 error protection of 0.05 and a power of 0.80, 49 patients in each group were required for appropriate study power. Continuous variables were expressed as mean (SD). Patient characteristics and haemodynamic variables before the surgery between the groups were compared using the Student's t-test. Percentage changes of SAP and HR were analysed by using two-way analysis of variance with repeated measurements, followed by Student–Newman–Keuls test for multiple comparisons. Categorical data are presented as absolute numbers (%) and were analysed by using Fisher's exact test or {chi}2-test. A P-value <0.05 was considered statistically significant.


    Results
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Fifty patients received IG-IH nerve block (Group I) and 50 had IG-IH and genitofemoral nerve blocks (Group II). Two subjects in Group II were not included in the analysis as they did not undergo the surgery. The remaining 98 patients were therefore included. There were no statistically significant differences in age, weight, sex, and the duration of both surgery and anaesthesia (Table 1).


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Table 1 Patient characteristics. Values are expressed as mean (SD) [range] or numbers. There were no significant differences between the groups

 
Before surgery (control), SAP values in Groups I and II were 97 (13) and 99 (14) mm Hg, respectively (NS). In Group I, SAP increased significantly at sac traction as compared with the control and Group II (P<0.05). SAP was unchanged throughout the study period in Group II (Fig. 2A). However, the episodes of increased SAP were similar in the two groups (nine of 48 [19%] and five of 50 [10%], respectively).



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Fig 2 Intraoperative changes in SAP (A) and HR (B). Data are expressed as mean (SD) as percentage (%) changes of control value. *P<0.05 vs Group II at the indicated time point by Student–Newman–Keuls method. {dagger}P<0.05 vs control by Student–Newman–Keuls method. SAP=systolic arterial pressure; HR=heart rate; SI=skin incision; ST=sac traction; Final=end of surgery.

 
HR before surgery (control) was similar in the two groups (119 [20], 112 [19] beats min–1, respectively). In both groups, the HR significantly increased at the sac traction as compared with the control (P<0.05) (Fig. 2B) but was significantly lower in Group II with an incidence of six of 50 compared with 14 of 48 in Group I (P<0.05).

There were no significant differences in postoperative analgesic requirements and the incidence of complications between the groups (Table 2). No patient developed a haematoma related to the block during the study period.


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Table 2 Postoperative analgesic requirements and incidence of complications. Values are expressed as number (%). There were no significant differences between the groups

 

    Discussion
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
This study shows that the addition of the genitofemoral nerve block to the IG-IH nerve block significantly reduced the incidence and extent of increase of SAP and HR at sac traction in children undergoing inguinal hernia repair. However, there were no significant differences in SAP and HR at the other time points, postoperative analgesic requirements or the incidence of complications between the groups.

The inguinal area receives sensory innervation from ilioinguinal, iliohypogastric, and genitofemoral nerves. The genital branch of the genitofemoral nerve generally passes along the psoas major through the internal inguinal ring. In male subjects, it descends behind the spermatic cord and supplies motor fibres to the cremasteric muscle and sensory fibres to a part of scrotal skin. In female subjects, it accompanies the round ligament and supplies partial sensation to the skin of the mons pubis and labium majus. Therefore, it has been considered that the addition of the genitofemoral nerve block would be effective in cases making incision in scrotal skin. However, previously published studies9 10 showed great variation in the sensory innervation of the inguinal region, with free communication between branches of the three nerves. Morikawa11 pointed out that only 37% of cases investigated were found to have the typical pattern, as described in textbooks. We therefore considered that incomplete effect of IG-IH nerve block in some patients might be due, in part, to the involvement of the genitofemoral nerve in the innervation of the inguinal region.

Back in 1980, von Bahr12 illustrated the anaesthetic techniques for inguinal herniorrhaphy, in which the IG-IH nerve block was combined with the genitofemoral nerve block. This suggested that the use of this combination technique was not uncommon at that time. Shandling and colleagues3 also reported genitofemoral nerve block along with IG-IH nerve block in some patients early in their series of inguinal heriotomy. However, this technique was abandoned later because it was of doubtful benefit and constituted a potential cause of haematoma formation within the cord. Subsequently there have been no reports of genitofemoral nerve block for inguinal hernia repair.

To the best of our knowledge, this is the first report to evaluate the efficacy of the additional genitofemoral nerve block to the IG-IH nerve block during inguinal hernia repair. The results suggested that genitofemoral nerve may be also involved in nociceptive afferent inputs during the inguinal hernia repair and the addition of the genitofemoral nerve may be useful at the time of sac traction, in some cases. However, as the incidence of episodes of increased SAP and HR in response to sac traction was 19 and 29%, respectively, in Group I, this implies that 71–81% of patients, without such haemodynamic changes, did not require the additional genitofemoral nerve block. The benefit of the genitofemoral nerve block was noted only at the time of sac traction. There were no postoperative benefits of the addition of the genitofemoral nerve block, which suggests any clinical advantage of adding a genitofemoral nerve block to IG-IH nerve block appears is minimal.

Although, in this study, the addition of a genitofemoral nerve block did not produce any adverse effects, possible effects such as cord haematoma3 should be kept in mind. Although the exact incidence of adverse effects with the addition of the genitofemoral nerve block is unknown, its indication should be carefully determined considering the risk of such sequela.

In summary, the addition of a genitofemoral nerve block attenuated the SAP and HR responses at sac traction, suggesting that it may be involved in nociceptive afferent input during inguinal hernia repair. However, benefit was noted only at the sac traction and not after the operation. This block is unlikely to be of great clinical use for children undergoing common inguinal hernia repair.


    References
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
1 Yaster M, Maxwell LG. Pediatric regional anesthesia. Anesthesiology 1989; 70: 324–38[ISI][Medline]

2 Gunter JB, Gregg T, Varughese AM, et al. Levobupivacaine for ilioinguinal/iliohypogastric nerve block in children. Anesth Analg 1999; 89: 647–9[Free Full Text]

3 Shandling B, Steward DJ. Regional analgesia for postoperative pain in pediatric outpatient surgery. J Pediatr Surg 1980; 15: 477–80[ISI][Medline]

4 Smith BA, Jones SE. Analgesia after herniotomy in a paediatric day unit. Br Med J 1982; 285: 1466[Medline]

5 Dalens B, Ecoffey C, Joly A, et al. Pharmacokinetics and analgesic effect of ropivacaine following ilioinguinal/iliohypogastric nerve block in children. Paediatr Anaesth 2001; 11: 415–20[CrossRef][ISI][Medline]

6 Lim SL, Ng Sb A, Tan GM. Ilioinguinal and iliohypogastric nerve block revisited: single shot versus double shot technique for hernia repair in children. Paediatr Anaesth 2002; 12: 255–60[CrossRef][ISI][Medline]

7 Trotter C, Martin P, Youngson G, Johnston G. A comparison between ilioinguinal-iliohypogastric nerve block performed by anaesthetist or surgeon for postoperative analgesia following groin surgery in children. Paediatr Anaesth 1995; 5: 363–7[ISI][Medline]

8 Ala-Kokko TI, Karinen J, Räihä E, Kiviluoma K, Alahuhta S. Pharmacokinetics of 0.75% ropivacaine and 0.5% bupivacaine after ilioinguinal-iliohypogastric nerve block in children. Br J Anaesth 2002; 89: 438–41[Abstract/Free Full Text]

9 Rab M, Ebmer J, Dellon AL. Anatomic variability of the ilioinguinal and genitofemoral nerve: Implications for the treatment of groin pain. Plast Reconstr Surg 2001; 108: 1618–23[ISI][Medline]

10 Starling JR, Harms BA, Schroeder ME, Eichman PL. Diagnosis and treatment of genitofemoral and ilioinguinal entrapment neuralgia. Surgery 1987; 102: 581–6[ISI][Medline]

11 Morikawa R. Course, distribution and their variety of nerves derived from the lumbar plexus to supply the abdominal wall. Acta Anat Nippon 1971; 46: 312–38[Medline]

12 von Bahr V. Local anesthesia for inguinal herniorrhaphy. In: Eriksson E, ed. Illustrated Handbook in Local Anesthesia. Philadelphia: WB Saunders, 1980; 52–4





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