REVIEW URRENT C OPINION
Chronic pain after surgery in children Lone Nikolajsen a and Lone D. Brix b
Purpose of review To present the recent literature on chronic postsurgical pain in children. Recent findings Chronic postsurgical pain is an important problem in children, however, with a lower prevalence than in adults. Summary The literature on the topic is sparse. Prospective studies, including clinical examination, quantitative sensory testing, and long-term follow-up, are needed to increase our knowledge about the prevalence, risk factors, and underlying mechanisms. Keywords children, chronic pain, postsurgical pain, prevalence, risk factors
INTRODUCTION Substantial literature documents that chronic postsurgical pain, defined as pain that develops after surgery and lasts at least 2 months [1], is a potential risk of almost any surgical procedure in adults. Prevalence rates vary from 5 to 80%, depending on the type of surgery [2,3]. The consequences of chronic postsurgical pain are significant, not only in terms of suffering and reduced quality of life for the individual patient, but also with regard to the subsequent costs to the healthcare and social support systems of our societies. Several risk factors have been identified in adults, including female gender, psychosocial and genetic factors, and preoperative and postoperative pain [4]. Nerve injury during surgery is also an important risk factor as many patients with chronic postoperative pain present with hyperalgesia and allodynia in the affected area, which are characteristic symptoms of neuropathic pain [2]. In contrast to the adult literature, there is a scarcity of data on chronic postsurgical pain in children [5]. Little is known about its prevalence, possible predisposing risk factors, and its impact on activities of daily living. Considering the large number of surgical procedures performed in children each year, there is a large population at risk. The purpose of this review is to present the current knowledge of chronic postsurgical pain in children. The opinions expressed are based on evidence supported by the authors’ own research and daily practice as pain clinicians, when available.
DEFINITION OF CHRONIC POSTSURGICAL PAIN IN CHILDREN No acknowledged definition on chronic postsurgical pain in children exists. In adults, it has been suggested that chronic pain after surgery should be defined as pain that develops after a surgical procedure and lasts at least 2 months; in addition, other causes of the pain have to be excluded, in particular pain preceding the surgery, but also infection or continuing malignancy [1]. This definition has been criticized, especially the time frame of 2 months. We propose to use a time frame of 3 months and to include information about the severity of pain, that is the intensity and frequency of the pain and its impact on daily activities. Just stating prevalence rates without information about the severity of pain makes comparison across studies difficult. For example, in a study on chronic pain after inguinal hernia repair in childhood, substantial pain was defined as pain occurring often or always and rated greater than 3 on a 10-point visual analog scale [6].
a Department of Anesthesiology and Danish Pain Research Center, Aarhus University Hospital, Aarhus and bDepartment of Anesthesiology, Horsens Regional Hospital, Horsens, Denmark
Correspondence to Lone Nikolajsen, Danish Pain Research Center, Aarhus University Hospital, Norrebrogade 44, Building 1A, 8000 Aarhus C, Denmark. Tel: +45 78464317; fax: +45 78463269; e-mail: lone. [email protected] Curr Opin Anesthesiol 2014, 27:507–512 DOI:10.1097/ACO.0000000000000110
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KEY POINTS Chronic postsurgical pain is an important problem in children. The prevalence seems to be lower than in adults.
had pain 4–6 years after surgery. A small proportion of the patients with pain used word descriptors suggestive of neuropathic pain [12]. A recent prospective study on pain after spinal fusion surgery showed that 11% of 190 patients reported moderate to severe pain after 1 year, but 35% of the patients had pain before surgery [11 ]. The prevalence of pain caused by surgery itself, however, may be difficult to determine in these studies as most of the patients had pain before the operation. &
Further research is needed to increase our knowledge about the prevalence, risk factors, and underlying mechanisms.
PREVALENCE OF CHRONIC PAIN AFTER DIFFERENT SURGICAL PROCEDURES Selected recent studies on chronic pain after different surgical procedures in childhood will be presented below. Earlier studies may be referred to in case no recent studies are available. An overview of the studies can be seen in Table 1.
Mixed surgeries Page´ et al. [7 ,8,18] studied the prevalence of postsurgical pain up to 12 months after surgery in a series of prospective studies on the basis of same population of 83 children aged 8–18 years. The children and their parents answered questionnaires about pain and various other items, such as anxiety and catastrophizing 48–72 h, 2 weeks, and 6 and 12 months after major orthopedic surgery, laparotomy, and thoracotomy. Using a cut-off score of 3 on a numeric rating scale (NRS, 0–10), 14 of 61 (23%) and 13 of 59 (22%) children had pain greater than 3 on the NRS after 6 and 12 months, respectively. The functional disability was mild, and pain was only present daily in one child after 12 months. In a cross-sectional study, a structured telephone interview was carried out in children between the ages of 2 and 17 years who had undergone general surgery, urologic surgery, or orthopedic surgery in the preceding 10 months. Fifteen (13%) of 113 children reported current pain related to the surgery. The average intensity of pain was 4.2 on an NRS (0–10), and in most children the pain had some interference with daily activities [9]. &
Amputation Several studies have suggested that amputation in childhood is associated with a lower risk of developing phantom pain. For example, Wilkins et al. [13] studied 60 amputees aged 8–18 years who were missing a limb either because of congenital limb deficiency or surgery/trauma. Phantom pain was reported by 3.7% in the congenital group and by 48.5% in the surgical group, which is lower than the reported prevalence of 50–85% after amputation in adults.
Thoracic surgery Kristensen et al. [14] studied 88 adult patients who had undergone thoracotomy because of coarctation of the aorta between the age of 0 and 25 years. Only three patients (3.4%) had pain after a mean followup period of 30 years, and pain only had impact on daily activities in one patient. The patients also underwent quantitative sensory testing (QST), which revealed hypophenomena and hyperphenomena in most patients regardless of their pain status, suggesting that the specificity for chronic pain is low. However, the use of pain descriptors, such as painful cold, electrical shocks, and pin and needles, suggests that the pain is of neuropathic origin. In adults, it has been suggested that a neuropathic component is only present in half of post-thoracotomy-pain patients [19]. In a recent study questionnaire including 121 children, 26 (21%) children reported present pain and/or pain within the last week located to the scar area a median of 3.8 years after cardiac surgery via sternotomy [15 ]. In 12 of the 26 children with pain, the intensity was more than 4 on an NRS (0–10). In the same study, another group of 13 children underwent QST 3 months after the surgery. None of the children had pain at the time of examination, but QST revealed sensory abnormalities, such as hyperalgesia and brush and cold allodynia, in 10 of the children. Thus, chronic postsurgical pain after thoracotomy seems to be less frequent in children than in &
Spinal surgery At least three studies have examined pain after spinal surgery [10,11 ,12]. A multicenter study based on a database of 295 children and adolescents who underwent scoliosis surgery found that the prevalence of back pain decreased from 78% before surgery to 64% after 2 years; however, in 20% the pain increased [10]. Another study on scoliosis surgery showed similar results as 52% of 105 patients &
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Prospective cohort, Questionnaire
Retrospective cohort, Postal questionnaire Retrospective cohort, Postal questionnaire
Mixed
Mixed
Spinal (scoliosis)
Spinal (scoliosis)
Spinal (fusions)
Amputation
Thoracic surgery (thoracotomy)
Thoracic surgery (sternotomy)
Inguinal hernia repair
Inguinal hernia repair
Page´ et al. (2013)[8]
Fortier et al. (2011) [9]
Landmanet al. (2011) [10]
Sieberg et al. & (2013) [11 ]
Wong et al. (2007) [12]
Wilkins et al. (1998) [13]
Kristensen et al. (2010) [14]
Lauridsen et al. & (2014) [15 ]
Zendejaset al. (2010) [16]
Kristensen et al. (2012) [17]
C, congenital; S, surgical.
Prospective cohort, Questionnaire
Mixed
Page´ et al. & (2013a)[7 ]
Retrospective cohort, Postal questionnaire
Retrospective survey
Retrospective survey
Retrospective survey, Questionnaire
Telephone interview
Prospective cohort, Telephone interviews
Prospective cohort, Telephone interviews
Cross-sectional questionnaire survey. Retrospective cohort
Inguinal hernia repair
Aasvang and Kehlet (2007) [6]
Design
Surgical procedure
Authors (year)
156 contacted, 98 responded
322 contacted, 213 responded
171 contacted, 121 responded
88 patients
247 contacted, 60 responded, Congenital: 27 Surgical : 33
122 contacted, 105 responded
190 participated, 77 completed 5-years follow-up
295
113
83 participated, 59 completed follow-up
83 participated, 59 completed follow-up
1075 contacted, 651 responded
No. of participants
0.5–12 (4.4þ/-2.4)
0–18 3.5 (8 days– 17.8 years)
0–12 3.8 (0–12.9)
0–25 9.4þ/-6
8–18 C: 12.4þ/-2.6 S: 12.7þ/-2.4
8–18
8–21
8–22
2–17 (12.4þ/-3.9)
8–18 (13.8þ/-2.4)
8–18 (13.8þ/-2.4)
3 months
Overall 29% reported phantom pain C : 3.7% S : 48.5%
9.5% with back pain and 6.7% with pelvic pain at follow-up; 50.9% recalled postoperative pain duration >3 months
11% after 1 year; 15% after 2 years; 15% 5 years; (35% with preoperative pain)
20.3% increase in pain, 40% decrease in pain, 38.6% no change in pain after 2 years, compared with preoperative pain
13.3% after 9 (þ/-4.8) months
22% after 12 months
22% after 12 months
13.5%
No. of patients with chronic postoperative surgical pain (%)
Pain intensity between 2 and 8 (Bieri Faces Pain Scale, 0–10), aggravation of pain by everyday activities
Little impact on daily activities
NRS>4 in 46%
NRS: 2–8, no or little impact on daily activities
NRS¼5.3, no or little impact on daily activities
Impact of pain on daily life/ sleep at follow-up: Back pain : 3.3/17.1%; Pelvic pain: 6.7/3.8%
Moderate to severe
64% with mild to severe pain after 2 years
NRS¼4.2, 30% with interference of pain on daily activities and sleep
NRS>4, moderate/severe Low levels of functional disability
NRS>4, moderate/severe Low levels of functional disability
2% with frequent and moderate/severe pain with impact on sports and leisure activities
Intensity of pain and /or impact on daily activities
Table 1. Selected studies on chronic postsurgical pain in children. The studies by Page´ et al. are based on the same patient population but focus on different aspects. NRS: Numeric rating scale
Chronic pain after surgery in children Nikolajsen and Brix
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adults, in which prevalence rates are reported to be between 20 and 60%.
Inguinal hernia repair Aasvang and Kehlet [6] carried out a nationwide questionnaire study on patients aged 18–19 years who had undergone inguinal hernia repair before the age of 5 years. After a mean follow-up period of 16.8 years, 88 (13.5%) of 651 patients reported chronic groin pain, but only 13 (2%) reported moderate or severe pain, and the pain was most often associated with leisure activities or sports. In another study with a median follow-up period of 49 years, chronic groin pain was reported in seven (3.2%) of 213 patients who had undergone surgery at a median age of 3.5 years [16]. More recently, Kristensen et al. [17] reported that only five (5%) of 98 children, with a mean age of 4.6 years at the time of surgery, had pain located in the inguinal region 3.2 years after inguinal hernia repair. QST performed in three of the children with pain showed sensory abnormalities in the painful area. Thus, the prevalence of chronic pain after inguinal hernia repair seems to be lower when surgery is performed in childhood as the prevalence of chronic pain after adult hernia surgery is reported to be 10% [3].
RISK FACTORS Risk factors for the development of chronic postsurgical pain in children will be summarized below.
in children aged 0–6 years at the time of surgery than in those aged 7–12 years at the time of surgery. Likewise, in the herniotomy study by Kristensen et al. [17], the mean age of the children was 4.6 years at the time of surgery, but the five children with chronic pain were slightly older at the time of surgery (5, 6, 7, 7, and 7 years old, respectively).
Postoperative pain In adults, acute postoperative pain is one of the strongest predictors of chronic pain after surgery, but only very few studies have addressed postoperative pain as a risk factor in children. For example, Page´ et al. [7 ] found that children who reported more pain unpleasantness 2 weeks after surgery were more likely to report chronic pain 6 months after surgery than children who reported less pain unpleasantness. &
Preoperative pain Pre-existing pain is likely to increase the risk of chronic pain after surgery. This has been documented in adults, but there is currently no data available supporting such an association in children.
Psychological and other factors Psychological aspects, such as depression and anxiety, are likely to play an important role. It has been shown that anxiety at 6 months after surgery predicts the maintenance of chronic pain after 12 months [7 ]. There may also be parental influences on the children’s experience of pain. Page´ et al. [8] showed that parent catastrophizing scores 48–72 h after surgery predicted child pain intensity reports 12 months later. Studies on scoliosis surgery have shown that children and adolescents who perceive themselves as more deformed and have a greater desire to change the appearance of their scoliosis report more pain, and experience less reduction in pain after surgery [10]. Ethnicity may also affect the risk of chronic pain after surgery in children [9]. Possible risk factors are summarized in Fig. 1. &
Gender Gender may affect the risk of chronic pain, including pain after surgery. Several studies on various other pain conditions have shown that girls report more severe pain and more frequently than boys [20,18], but none of the above-mentioned studies on chronic pain after surgery were able to find any sex differences.
Age &
Some studies, but not all [11 ], suggest that very young age at the time of surgery is associated with a lower risk of developing chronic postsurgical pain. For example, Wilkins et al. [13] found that the prevalence of phantom pain was 20.5% among amputees who lost their limb before the age of 6 years, and 85.7% among amputees who lost their limb after the age of 6 years. Also, in the thoracotomy study by Kristensen et al. [14], the recalled duration of postoperative pain was much shorter 510
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DISCUSSION From the above studies, it can be concluded that chronic pain after surgery is also an important problem in children, however, with a lower prevalence than in adults. This finding may have several explanations. First of all, it cannot be excluded that the pain has simply dissipated over time in the two retrospective studies with very long follow-up Volume 27 Number 5 October 2014
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Chronic pain after surgery in children Nikolajsen and Brix
Psychosocial factors Age h
Sex (girls h?)
Genetics
Chronic postsurgical pain in children
Extensive surgery
Preoperative pain
Postoperative pain Nerve damage after surgery
FIGURE 1. Risk factors for the development of chronic postsurgical pain in children.
periods [14,6]. Also, the surgical procedure is often simpler in children and recovery is faster [21]. Bones, tendons, and ligaments are more indulgent and flexible in children, and surgery may therefore be less harmful in children. An immature peripheral and central nervous system combined with the enhanced neuronal plastic capacity in the child’s brain may contribute to a lower risk of developing chronic pain [22]. Furthermore, psychological aspects may play a different role in children. For example, psychological aspects such as fear of surgery have been found to be associated with more acute pain in adults [23], whereas children may not worry about surgery to the same extent as adults.
METHODOLOGICAL ISSUES The sparse literature on the topic is inflicted with several methodological problems. First of all, most studies are questionnaire studies. This means that the quality and reliability of the data are open to question in some cases as the cognitive ability to understand the meaning of the questions and the purpose of the study may vary among children. Also, it is not known to what extent children are supported by their parents in answering the questionnaire. Second, most studies are retrospective and
therefore some of the information, for example information about pain before surgery and immediate postoperative pain, is subject to recall bias. Third, the follow-up period is very long in some of the studies, and it is possible that the pain has simply dissipated over time. Prospective study designs, including clinical examination of the children, will solve some of these issues.
CONCLUSION In conclusion, chronic postsurgical pain is less frequently reported in children than in adults, but it is still an important problem that should not be neglected. Unfortunately, the literature on the topic is sparse. Prospective studies, including clinical examination, QST, and long-term follow-up, are needed to increase our knowledge about the prevalence, risk factors, and underlying mechanisms. The adult literature points to inadequately managed postoperative pain as a significant risk factor. Literature in children is missing. However, if the same would be true in children, a major avenue for the prevention of chronic pain after surgery is to improve the management of acute postoperative pain. It is hoped that further research will help us develop more effective treatment plans for the benefit of children undergoing surgery.
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Acknowledgements We thank Helle O. Andersen for language revision and technical assistance with the manuscript. Disclosure of funding: No funding was received for this work. Conflicts of interest There are no conflicts of interest.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. Macrae WA. Chronic pain after surgery. Br J Anaesth 2001; 87:88–98. 2. Kehlet H, Jensen TS, Woolf CJ. Persistent postsurgical pain: risk factors and prevention. Lancet 2006; 367:1618–1625. 3. Macrae WA. Chronic postsurgical pain: 10 years on. Br J Anaesth 2008; 101:77–86. 4. Althaus A, Hinrichs-Rocker A, Chapman R, et al. Development of a risk index for the prediction of chronic postsurgical pain. Eur J Pain 2012; 16:901–910. 5. Ahn JC, Fortier MA, Kain ZN. Acute to chronic postoperative pain in children: does it exist? Pain Manag 2012; 2:421–423. 6. Aasvang EK, Kehlet H. Chronic pain after childhood groin hernia repair. J Pediatr Surg 2007; 42:1403–1408. 7. Page´ MG, Stinson J, Campbell F, et al. Identification of pain-related psycho& logical risk factors for the development and maintenance of pediatric chronic postsurgical pain. J Pain Res 2013; 6:167–180. This is a detailed prospective study of chronic postsurgical pain and psychological risk factors. 8. Page´ MG, Campbell F, Isaac L, et al. Parental risk factors for the development of pediatric acute and chronic postsurgical pain: a longitudinal study. J Pain Res 2013; 6:727–741.
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9. Fortier MA, Chou J, Maurer EL, Kain ZN. Acute to chronic postoperative pain in children: preliminary findings. J Pediatr Surg 2011; 46:1700–1705. 10. Landman Z, Oswald T, Sanders J, et al. Prevalence and predictors of pain in surgical treatment of adolescent idiopathic scoliosis. Spin (Phila Pa 1976) 2011; 36:825–829. 11. Sieberg CB, Simons Le, Edelstein MR, et al. Pan prevalence and trajectories & following pediatric spinal fusion surgery. J Pain 2013; 14:1694–1702. This is a prospective study including data obtained prior to surgery and until 5 years after surgery. 12. Wong GT, Yuen VM, Chow BF, Irwin MG. Persistent pain in patients following scoliosis surgery. Eur Spine J 2007; 16:1551–1556. 13. Wilkins KL, McGrath PJ, Finley GA, Katz J. Phantom limb sensations and phantom limb pain in child and adolescent amputees. Pain 1998; 78:7–12. 14. Kristensen AD, Pedersen TA, Hjortdal VE, et al. Chronic pain in adults after thoracotomy in childhood or youth. Br J Anaesth 2010; 104:75–79. 15. Lauridsen MH, Kristensen AD, Hjortdal VE, et al. Chronic pain in children after & cardiac surgery via sternotomy. Cardiol Young 2013; 18:1–7. This is the first study to address chronic pain after sternotomy in children. A subset of children underwent quantitative sensory testing. 16. Zendejas B, Zarroug AE, Erben YM, et al. Impact of childhood inguinal hernia repair in adulthood: 50 years of follow-up. J Am Coll Surg 2010; 211:762– 768. 17. Kristensen AD, Ahlburg P, Lauridsen MC, et al. Chronic pain after inguinal hernia repair in children. Br J Anaesth 2012; 109:603–608. 18. Page´ MG, Stinson J, Campbell F, et al. Pain-related psychological correlates of pediatric acute postsurgical pain. J Pain Res 2012; 5:547–558. 19. Steegers MA, Snik DM, Verhagen AF, et al. Only half of the chronic pain after thoracic surgery shows a neuropathic component. J Pain 2008; 9:955– 961. 20. Keogh E, Eccleston C. Sex differences in adolescent chronic pain and painrelated coping. Pain 2006; 123:275–284. 21. Stewart DW, Ragg PG, Sheppard S, Chalkiadis GA. The severity and duration of postoperative pain and analgesia requirements in children after tonsillectomy, orchidopexy, or inguinal hernia repair. Paediatr Anaesth 2012; 22:136–143. 22. Florence SL, Jain N, Pospichal MW, et al. Central reorganization of sensory pathways following peripheral nerve regeneration in fetal monkeys. Nature 1996; 382:69–71. 23. Peters ML, Sommer M, De Rijke JM, et al. Somatic and psychological predictors of long-term unfavourable outcome after surgical intervention. Ann Surg 2007; 245:487–494.
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Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Chronic pain after surgery in children Lone Nikolajsen a and Lone D. Brix b
Purpose of review To present the recent literature on chronic postsurgical pain in children. Recent findings Chronic postsurgical pain is an important problem in children, however, with a lower prevalence than in adults. Summary The literature on the topic is sparse. Prospective studies, including clinical examination, quantitative sensory testing, and long-term follow-up, are needed to increase our knowledge about the prevalence, risk factors, and underlying mechanisms. Keywords children, chronic pain, postsurgical pain, prevalence, risk factors
INTRODUCTION Substantial literature documents that chronic postsurgical pain, defined as pain that develops after surgery and lasts at least 2 months [1], is a potential risk of almost any surgical procedure in adults. Prevalence rates vary from 5 to 80%, depending on the type of surgery [2,3]. The consequences of chronic postsurgical pain are significant, not only in terms of suffering and reduced quality of life for the individual patient, but also with regard to the subsequent costs to the healthcare and social support systems of our societies. Several risk factors have been identified in adults, including female gender, psychosocial and genetic factors, and preoperative and postoperative pain [4]. Nerve injury during surgery is also an important risk factor as many patients with chronic postoperative pain present with hyperalgesia and allodynia in the affected area, which are characteristic symptoms of neuropathic pain [2]. In contrast to the adult literature, there is a scarcity of data on chronic postsurgical pain in children [5]. Little is known about its prevalence, possible predisposing risk factors, and its impact on activities of daily living. Considering the large number of surgical procedures performed in children each year, there is a large population at risk. The purpose of this review is to present the current knowledge of chronic postsurgical pain in children. The opinions expressed are based on evidence supported by the authors’ own research and daily practice as pain clinicians, when available.
DEFINITION OF CHRONIC POSTSURGICAL PAIN IN CHILDREN No acknowledged definition on chronic postsurgical pain in children exists. In adults, it has been suggested that chronic pain after surgery should be defined as pain that develops after a surgical procedure and lasts at least 2 months; in addition, other causes of the pain have to be excluded, in particular pain preceding the surgery, but also infection or continuing malignancy [1]. This definition has been criticized, especially the time frame of 2 months. We propose to use a time frame of 3 months and to include information about the severity of pain, that is the intensity and frequency of the pain and its impact on daily activities. Just stating prevalence rates without information about the severity of pain makes comparison across studies difficult. For example, in a study on chronic pain after inguinal hernia repair in childhood, substantial pain was defined as pain occurring often or always and rated greater than 3 on a 10-point visual analog scale [6].
a Department of Anesthesiology and Danish Pain Research Center, Aarhus University Hospital, Aarhus and bDepartment of Anesthesiology, Horsens Regional Hospital, Horsens, Denmark
Correspondence to Lone Nikolajsen, Danish Pain Research Center, Aarhus University Hospital, Norrebrogade 44, Building 1A, 8000 Aarhus C, Denmark. Tel: +45 78464317; fax: +45 78463269; e-mail: lone. [email protected] Curr Opin Anesthesiol 2014, 27:507–512 DOI:10.1097/ACO.0000000000000110
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Pain medicine
KEY POINTS Chronic postsurgical pain is an important problem in children. The prevalence seems to be lower than in adults.
had pain 4–6 years after surgery. A small proportion of the patients with pain used word descriptors suggestive of neuropathic pain [12]. A recent prospective study on pain after spinal fusion surgery showed that 11% of 190 patients reported moderate to severe pain after 1 year, but 35% of the patients had pain before surgery [11 ]. The prevalence of pain caused by surgery itself, however, may be difficult to determine in these studies as most of the patients had pain before the operation. &
Further research is needed to increase our knowledge about the prevalence, risk factors, and underlying mechanisms.
PREVALENCE OF CHRONIC PAIN AFTER DIFFERENT SURGICAL PROCEDURES Selected recent studies on chronic pain after different surgical procedures in childhood will be presented below. Earlier studies may be referred to in case no recent studies are available. An overview of the studies can be seen in Table 1.
Mixed surgeries Page´ et al. [7 ,8,18] studied the prevalence of postsurgical pain up to 12 months after surgery in a series of prospective studies on the basis of same population of 83 children aged 8–18 years. The children and their parents answered questionnaires about pain and various other items, such as anxiety and catastrophizing 48–72 h, 2 weeks, and 6 and 12 months after major orthopedic surgery, laparotomy, and thoracotomy. Using a cut-off score of 3 on a numeric rating scale (NRS, 0–10), 14 of 61 (23%) and 13 of 59 (22%) children had pain greater than 3 on the NRS after 6 and 12 months, respectively. The functional disability was mild, and pain was only present daily in one child after 12 months. In a cross-sectional study, a structured telephone interview was carried out in children between the ages of 2 and 17 years who had undergone general surgery, urologic surgery, or orthopedic surgery in the preceding 10 months. Fifteen (13%) of 113 children reported current pain related to the surgery. The average intensity of pain was 4.2 on an NRS (0–10), and in most children the pain had some interference with daily activities [9]. &
Amputation Several studies have suggested that amputation in childhood is associated with a lower risk of developing phantom pain. For example, Wilkins et al. [13] studied 60 amputees aged 8–18 years who were missing a limb either because of congenital limb deficiency or surgery/trauma. Phantom pain was reported by 3.7% in the congenital group and by 48.5% in the surgical group, which is lower than the reported prevalence of 50–85% after amputation in adults.
Thoracic surgery Kristensen et al. [14] studied 88 adult patients who had undergone thoracotomy because of coarctation of the aorta between the age of 0 and 25 years. Only three patients (3.4%) had pain after a mean followup period of 30 years, and pain only had impact on daily activities in one patient. The patients also underwent quantitative sensory testing (QST), which revealed hypophenomena and hyperphenomena in most patients regardless of their pain status, suggesting that the specificity for chronic pain is low. However, the use of pain descriptors, such as painful cold, electrical shocks, and pin and needles, suggests that the pain is of neuropathic origin. In adults, it has been suggested that a neuropathic component is only present in half of post-thoracotomy-pain patients [19]. In a recent study questionnaire including 121 children, 26 (21%) children reported present pain and/or pain within the last week located to the scar area a median of 3.8 years after cardiac surgery via sternotomy [15 ]. In 12 of the 26 children with pain, the intensity was more than 4 on an NRS (0–10). In the same study, another group of 13 children underwent QST 3 months after the surgery. None of the children had pain at the time of examination, but QST revealed sensory abnormalities, such as hyperalgesia and brush and cold allodynia, in 10 of the children. Thus, chronic postsurgical pain after thoracotomy seems to be less frequent in children than in &
Spinal surgery At least three studies have examined pain after spinal surgery [10,11 ,12]. A multicenter study based on a database of 295 children and adolescents who underwent scoliosis surgery found that the prevalence of back pain decreased from 78% before surgery to 64% after 2 years; however, in 20% the pain increased [10]. Another study on scoliosis surgery showed similar results as 52% of 105 patients &
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Prospective cohort, Questionnaire
Retrospective cohort, Postal questionnaire Retrospective cohort, Postal questionnaire
Mixed
Mixed
Spinal (scoliosis)
Spinal (scoliosis)
Spinal (fusions)
Amputation
Thoracic surgery (thoracotomy)
Thoracic surgery (sternotomy)
Inguinal hernia repair
Inguinal hernia repair
Page´ et al. (2013)[8]
Fortier et al. (2011) [9]
Landmanet al. (2011) [10]
Sieberg et al. & (2013) [11 ]
Wong et al. (2007) [12]
Wilkins et al. (1998) [13]
Kristensen et al. (2010) [14]
Lauridsen et al. & (2014) [15 ]
Zendejaset al. (2010) [16]
Kristensen et al. (2012) [17]
C, congenital; S, surgical.
Prospective cohort, Questionnaire
Mixed
Page´ et al. & (2013a)[7 ]
Retrospective cohort, Postal questionnaire
Retrospective survey
Retrospective survey
Retrospective survey, Questionnaire
Telephone interview
Prospective cohort, Telephone interviews
Prospective cohort, Telephone interviews
Cross-sectional questionnaire survey. Retrospective cohort
Inguinal hernia repair
Aasvang and Kehlet (2007) [6]
Design
Surgical procedure
Authors (year)
156 contacted, 98 responded
322 contacted, 213 responded
171 contacted, 121 responded
88 patients
247 contacted, 60 responded, Congenital: 27 Surgical : 33
122 contacted, 105 responded
190 participated, 77 completed 5-years follow-up
295
113
83 participated, 59 completed follow-up
83 participated, 59 completed follow-up
1075 contacted, 651 responded
No. of participants
0.5–12 (4.4þ/-2.4)
0–18 3.5 (8 days– 17.8 years)
0–12 3.8 (0–12.9)
0–25 9.4þ/-6
8–18 C: 12.4þ/-2.6 S: 12.7þ/-2.4
8–18
8–21
8–22
2–17 (12.4þ/-3.9)
8–18 (13.8þ/-2.4)
8–18 (13.8þ/-2.4)
3 months
Overall 29% reported phantom pain C : 3.7% S : 48.5%
9.5% with back pain and 6.7% with pelvic pain at follow-up; 50.9% recalled postoperative pain duration >3 months
11% after 1 year; 15% after 2 years; 15% 5 years; (35% with preoperative pain)
20.3% increase in pain, 40% decrease in pain, 38.6% no change in pain after 2 years, compared with preoperative pain
13.3% after 9 (þ/-4.8) months
22% after 12 months
22% after 12 months
13.5%
No. of patients with chronic postoperative surgical pain (%)
Pain intensity between 2 and 8 (Bieri Faces Pain Scale, 0–10), aggravation of pain by everyday activities
Little impact on daily activities
NRS>4 in 46%
NRS: 2–8, no or little impact on daily activities
NRS¼5.3, no or little impact on daily activities
Impact of pain on daily life/ sleep at follow-up: Back pain : 3.3/17.1%; Pelvic pain: 6.7/3.8%
Moderate to severe
64% with mild to severe pain after 2 years
NRS¼4.2, 30% with interference of pain on daily activities and sleep
NRS>4, moderate/severe Low levels of functional disability
NRS>4, moderate/severe Low levels of functional disability
2% with frequent and moderate/severe pain with impact on sports and leisure activities
Intensity of pain and /or impact on daily activities
Table 1. Selected studies on chronic postsurgical pain in children. The studies by Page´ et al. are based on the same patient population but focus on different aspects. NRS: Numeric rating scale
Chronic pain after surgery in children Nikolajsen and Brix
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adults, in which prevalence rates are reported to be between 20 and 60%.
Inguinal hernia repair Aasvang and Kehlet [6] carried out a nationwide questionnaire study on patients aged 18–19 years who had undergone inguinal hernia repair before the age of 5 years. After a mean follow-up period of 16.8 years, 88 (13.5%) of 651 patients reported chronic groin pain, but only 13 (2%) reported moderate or severe pain, and the pain was most often associated with leisure activities or sports. In another study with a median follow-up period of 49 years, chronic groin pain was reported in seven (3.2%) of 213 patients who had undergone surgery at a median age of 3.5 years [16]. More recently, Kristensen et al. [17] reported that only five (5%) of 98 children, with a mean age of 4.6 years at the time of surgery, had pain located in the inguinal region 3.2 years after inguinal hernia repair. QST performed in three of the children with pain showed sensory abnormalities in the painful area. Thus, the prevalence of chronic pain after inguinal hernia repair seems to be lower when surgery is performed in childhood as the prevalence of chronic pain after adult hernia surgery is reported to be 10% [3].
RISK FACTORS Risk factors for the development of chronic postsurgical pain in children will be summarized below.
in children aged 0–6 years at the time of surgery than in those aged 7–12 years at the time of surgery. Likewise, in the herniotomy study by Kristensen et al. [17], the mean age of the children was 4.6 years at the time of surgery, but the five children with chronic pain were slightly older at the time of surgery (5, 6, 7, 7, and 7 years old, respectively).
Postoperative pain In adults, acute postoperative pain is one of the strongest predictors of chronic pain after surgery, but only very few studies have addressed postoperative pain as a risk factor in children. For example, Page´ et al. [7 ] found that children who reported more pain unpleasantness 2 weeks after surgery were more likely to report chronic pain 6 months after surgery than children who reported less pain unpleasantness. &
Preoperative pain Pre-existing pain is likely to increase the risk of chronic pain after surgery. This has been documented in adults, but there is currently no data available supporting such an association in children.
Psychological and other factors Psychological aspects, such as depression and anxiety, are likely to play an important role. It has been shown that anxiety at 6 months after surgery predicts the maintenance of chronic pain after 12 months [7 ]. There may also be parental influences on the children’s experience of pain. Page´ et al. [8] showed that parent catastrophizing scores 48–72 h after surgery predicted child pain intensity reports 12 months later. Studies on scoliosis surgery have shown that children and adolescents who perceive themselves as more deformed and have a greater desire to change the appearance of their scoliosis report more pain, and experience less reduction in pain after surgery [10]. Ethnicity may also affect the risk of chronic pain after surgery in children [9]. Possible risk factors are summarized in Fig. 1. &
Gender Gender may affect the risk of chronic pain, including pain after surgery. Several studies on various other pain conditions have shown that girls report more severe pain and more frequently than boys [20,18], but none of the above-mentioned studies on chronic pain after surgery were able to find any sex differences.
Age &
Some studies, but not all [11 ], suggest that very young age at the time of surgery is associated with a lower risk of developing chronic postsurgical pain. For example, Wilkins et al. [13] found that the prevalence of phantom pain was 20.5% among amputees who lost their limb before the age of 6 years, and 85.7% among amputees who lost their limb after the age of 6 years. Also, in the thoracotomy study by Kristensen et al. [14], the recalled duration of postoperative pain was much shorter 510
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DISCUSSION From the above studies, it can be concluded that chronic pain after surgery is also an important problem in children, however, with a lower prevalence than in adults. This finding may have several explanations. First of all, it cannot be excluded that the pain has simply dissipated over time in the two retrospective studies with very long follow-up Volume 27 Number 5 October 2014
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Chronic pain after surgery in children Nikolajsen and Brix
Psychosocial factors Age h
Sex (girls h?)
Genetics
Chronic postsurgical pain in children
Extensive surgery
Preoperative pain
Postoperative pain Nerve damage after surgery
FIGURE 1. Risk factors for the development of chronic postsurgical pain in children.
periods [14,6]. Also, the surgical procedure is often simpler in children and recovery is faster [21]. Bones, tendons, and ligaments are more indulgent and flexible in children, and surgery may therefore be less harmful in children. An immature peripheral and central nervous system combined with the enhanced neuronal plastic capacity in the child’s brain may contribute to a lower risk of developing chronic pain [22]. Furthermore, psychological aspects may play a different role in children. For example, psychological aspects such as fear of surgery have been found to be associated with more acute pain in adults [23], whereas children may not worry about surgery to the same extent as adults.
METHODOLOGICAL ISSUES The sparse literature on the topic is inflicted with several methodological problems. First of all, most studies are questionnaire studies. This means that the quality and reliability of the data are open to question in some cases as the cognitive ability to understand the meaning of the questions and the purpose of the study may vary among children. Also, it is not known to what extent children are supported by their parents in answering the questionnaire. Second, most studies are retrospective and
therefore some of the information, for example information about pain before surgery and immediate postoperative pain, is subject to recall bias. Third, the follow-up period is very long in some of the studies, and it is possible that the pain has simply dissipated over time. Prospective study designs, including clinical examination of the children, will solve some of these issues.
CONCLUSION In conclusion, chronic postsurgical pain is less frequently reported in children than in adults, but it is still an important problem that should not be neglected. Unfortunately, the literature on the topic is sparse. Prospective studies, including clinical examination, QST, and long-term follow-up, are needed to increase our knowledge about the prevalence, risk factors, and underlying mechanisms. The adult literature points to inadequately managed postoperative pain as a significant risk factor. Literature in children is missing. However, if the same would be true in children, a major avenue for the prevention of chronic pain after surgery is to improve the management of acute postoperative pain. It is hoped that further research will help us develop more effective treatment plans for the benefit of children undergoing surgery.
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Acknowledgements We thank Helle O. Andersen for language revision and technical assistance with the manuscript. Disclosure of funding: No funding was received for this work. Conflicts of interest There are no conflicts of interest.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. Macrae WA. Chronic pain after surgery. Br J Anaesth 2001; 87:88–98. 2. Kehlet H, Jensen TS, Woolf CJ. Persistent postsurgical pain: risk factors and prevention. Lancet 2006; 367:1618–1625. 3. Macrae WA. Chronic postsurgical pain: 10 years on. Br J Anaesth 2008; 101:77–86. 4. Althaus A, Hinrichs-Rocker A, Chapman R, et al. Development of a risk index for the prediction of chronic postsurgical pain. Eur J Pain 2012; 16:901–910. 5. Ahn JC, Fortier MA, Kain ZN. Acute to chronic postoperative pain in children: does it exist? Pain Manag 2012; 2:421–423. 6. Aasvang EK, Kehlet H. Chronic pain after childhood groin hernia repair. J Pediatr Surg 2007; 42:1403–1408. 7. Page´ MG, Stinson J, Campbell F, et al. Identification of pain-related psycho& logical risk factors for the development and maintenance of pediatric chronic postsurgical pain. J Pain Res 2013; 6:167–180. This is a detailed prospective study of chronic postsurgical pain and psychological risk factors. 8. Page´ MG, Campbell F, Isaac L, et al. Parental risk factors for the development of pediatric acute and chronic postsurgical pain: a longitudinal study. J Pain Res 2013; 6:727–741.
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9. Fortier MA, Chou J, Maurer EL, Kain ZN. Acute to chronic postoperative pain in children: preliminary findings. J Pediatr Surg 2011; 46:1700–1705. 10. Landman Z, Oswald T, Sanders J, et al. Prevalence and predictors of pain in surgical treatment of adolescent idiopathic scoliosis. Spin (Phila Pa 1976) 2011; 36:825–829. 11. Sieberg CB, Simons Le, Edelstein MR, et al. Pan prevalence and trajectories & following pediatric spinal fusion surgery. J Pain 2013; 14:1694–1702. This is a prospective study including data obtained prior to surgery and until 5 years after surgery. 12. Wong GT, Yuen VM, Chow BF, Irwin MG. Persistent pain in patients following scoliosis surgery. Eur Spine J 2007; 16:1551–1556. 13. Wilkins KL, McGrath PJ, Finley GA, Katz J. Phantom limb sensations and phantom limb pain in child and adolescent amputees. Pain 1998; 78:7–12. 14. Kristensen AD, Pedersen TA, Hjortdal VE, et al. Chronic pain in adults after thoracotomy in childhood or youth. Br J Anaesth 2010; 104:75–79. 15. Lauridsen MH, Kristensen AD, Hjortdal VE, et al. Chronic pain in children after & cardiac surgery via sternotomy. Cardiol Young 2013; 18:1–7. This is the first study to address chronic pain after sternotomy in children. A subset of children underwent quantitative sensory testing. 16. Zendejas B, Zarroug AE, Erben YM, et al. Impact of childhood inguinal hernia repair in adulthood: 50 years of follow-up. J Am Coll Surg 2010; 211:762– 768. 17. Kristensen AD, Ahlburg P, Lauridsen MC, et al. Chronic pain after inguinal hernia repair in children. Br J Anaesth 2012; 109:603–608. 18. Page´ MG, Stinson J, Campbell F, et al. Pain-related psychological correlates of pediatric acute postsurgical pain. J Pain Res 2012; 5:547–558. 19. Steegers MA, Snik DM, Verhagen AF, et al. Only half of the chronic pain after thoracic surgery shows a neuropathic component. J Pain 2008; 9:955– 961. 20. Keogh E, Eccleston C. Sex differences in adolescent chronic pain and painrelated coping. Pain 2006; 123:275–284. 21. Stewart DW, Ragg PG, Sheppard S, Chalkiadis GA. The severity and duration of postoperative pain and analgesia requirements in children after tonsillectomy, orchidopexy, or inguinal hernia repair. Paediatr Anaesth 2012; 22:136–143. 22. Florence SL, Jain N, Pospichal MW, et al. Central reorganization of sensory pathways following peripheral nerve regeneration in fetal monkeys. Nature 1996; 382:69–71. 23. Peters ML, Sommer M, De Rijke JM, et al. Somatic and psychological predictors of long-term unfavourable outcome after surgical intervention. Ann Surg 2007; 245:487–494.
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