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A comparison of shoulder dystocia-associated transient and permanent brachial plexus palsies
A Comparison of Shoulder Dystocia-Associated Transient and Permanent Brachial Plexus Palsies Robert B. Gherman, MD, Joseph G. Ouzounian, MD, Andrew J. Satin, MD, T. Murphy Goodwin, MD, and Jeffrey P. Phelan, MD, JD OBJECTIVE: To estimate differences between shoulder dystocia-associated transient and permanent brachial plexus palsies.
(Obstet Gynecol 2003;102:544 – 8. © 2003 by The American College of Obstetricians and Gynecologists.)
METHODS: We performed a retrospective case-control analysis from national birth injury and shoulder dystocia databases. Study patients had permanent brachial plexus palsy and had been entered into a national birth injury registry. Cases of Erb or Klumpke palsy with documented neonatal neuromuscular deficits persisting beyond at least 1 year of life were classified as permanent. Cases of transient brachial plexus palsy were obtained from a shoulder dystocia database. Non-shoulder dystocia–related cases of brachial plexus palsy were excluded from analysis. Cases of permanent brachial plexus palsy (n ⴝ 49) were matched 1:1 with cases of transient brachial plexus palsy.
Brachial plexus injury has been reported to complicate up to 21% of all deliveries complicated by shoulder dystocia.1–3 The majority of these palsies will resolve with conservative therapy, resulting in a 1.6% rate of permanent brachial plexus injury associated with shoulder dystocia.4 To date, most of the studies dealing with brachial plexus palsy have not specifically commented upon permanent brachial plexus palsy. Important questions concerning the natural history and pathogenesis of shoulder-dystocia related brachial plexus injury therefore continue to remain unanswered. We sought to estimate maternal or fetal characteristics that could be used to differentiate between transient and permanent shoulder dystocia-associated brachial plexus injuries.
RESULTS: Transient brachial plexus palsy cases had a higher incidence of diabetes mellitus than those with permanent brachial plexus palsy (34.7% versus 10.2%, odds ratio [OR] 4.68, 95% confidence interval [CI] 1.42, 16.32). Patients with permanent brachial plexus palsies had a higher mean birth weight (4519 ⴞ 94.3 g versus 4143.6 ⴞ 56.5 g, P < .001) and a greater frequency of birth weight greater than 4500 grams (38.8% versus 16.3%, OR, 0.31, 95% CI 0.11, 0.87). There were, however, no statistically significant differences between the two groups with respect to multiple antepartum, intrapartum, and delivery outcome measures. CONCLUSION: Transient and permanent brachial plexus palsies are not associated with significant differences for most antepartum and intrapartum characteristics. From the Department of OB/GYN, Division of Maternal/Fetal Medicine, National Naval Medical Center, Bethesda, Maryland; Department of OB/GYN, Division of Maternal/Fetal Medicine, Kaiser Permanente, Baldwin Park, California; Uniformed Services University of the Health Sciences, Department of OB/GYN, Bethesda, Maryland; Department of OB/GYN, Division of Maternal/Fetal Medicine, Women’s and Children’s Hospital, University of Southern California School of Medicine, Los Angeles, California; and Childbirth Injury Prevention Foundation, Pasadena, California. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, the Department of Defense, or the United States Government.
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MATERIALS AND METHODS We performed a retrospective case-control analysis from computer-stored databases. Study patients had permanent brachial plexus palsy and were part of a national registry of children with neonatal brachial plexus injury.5 This database included litigated cases that had occurred in community and teaching hospitals throughout the United States. Under the supervision of two of this study’s authors (JPP and JGO), data were abstracted from the referred legal cases. Obstetric residents, attending obstetricians, certified nurse midwives, and family practice physicians had performed the deliveries. Only cases of brachial plexus palsy that occurred in conjunction with shoulder dystocia were included. Shoulder dystocia was defined as the need for the performance of ancillary obstetric maneuvers after initial attempts at gentle downward traction were unsuccessful in delivering the fetal head. Transient brachial plexus palsies, obtained from a previously established shoulder dystocia database6,7 served as the control group. This database was created
VOL. 102, NO. 3, SEPTEMBER 2003 © 2003 by The American College of Obstetricians and Gynecologists. Published by Elsevier.
0029-7844/03/$30.00 doi:10.1016/S0029-7844(03)00660-4
by two of the study’s authors (RBG and TMG) by reviewing the maternal and neonatal charts of cases of shoulder dystocia that occurred between January 1, 1991, and July 1, 1996, at Los Angeles County/University of Southern California Women’s Hospital. The 49 cases of transient brachial plexus palsy were drawn from a cohort that included 291 cases of shoulder dystocia, yielding a transient injury rate of 16.8%. The consecutive cases of transient brachial plexus palsy were matched 1:1 by the closest date of delivery, with cases from the study group. This study had previously been approved by the investigational review board. Neither of the two databases used in this study were funded by the government or by a professional liability organization. Cases of Erb or Klumpke palsy with documented neonatal neuromuscular deficits persisting beyond at least 1 year of life were classified as permanent. This time frame was chosen because it represented a period during which most infants are able to make an acceptable functional recovery.8,9 Cases of brachial plexus palsy that occurred in the absence of shoulder dystocia were excluded from this analysis. We likewise excluded from review any case in which we were unable to establish neonatal follow-up for at least 1 year after delivery. The maternal medical records that we reviewed included the prenatal care data and labor record. Neonatal information was gathered both from the hospital postdelivery neonatal records and long-term follow-up. For the latter, we reviewed pediatric, physical rehabilitation, neurologic, and neurosurgical records. Maternal outcomes assessed included maternal age, gravidity, parity, maternal weight at delivery, estimated gestational age as determined by the last menstrual period or ultrasound, and the presence of diabetes (either insulin dependent or non-insulin dependent). We coded charts for the intrapartum variables of oxytocin administration, epidural anesthesia, length of the active phase, length of the second stage of labor, need for operative vaginal delivery (either vacuum or forceps), and the number of ancillary obstetric maneuvers used to alleviate the shoulder dystocia. The maneuvers included McRoberts maneuver, suprapubic pressure, proctoepisiotomy, Woods corkscrew maneuver, Rubin maneuver, posterior arm extraction, or Zavanelli maneuver. The active phase of labor was determined to have begun when the examination found the cervix to be 4 cm dilated. The second stage of labor of labor was considered prolonged as defined by the American College of Obstetrician and Gynecologists.10 Medical and nursing records were reviewed to determine the time difference between the delivery of the fetal head and the delivery of the fetal body. If this information was not available, then the delivering provider’s
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Table 1. Comparison of Select Antepartum Characteristics in Mothers of Neonates With Transient Versus Permanent Brachial Plexus Palsy Transient (n ⫽ 49)
Permanent (n ⫽ 49)
P, OR (95% CI)
Maternal age (y) 27.6 ⫾ 0.9 Gravidity 3.53 ⫾ 0.3 Parity Nulliparous 8 (16.3) Multiparous 41 (83.7) Maternal weight 179.9 ⫾ 4.8 at delivery (lb) Prior shoulder 2 (4.1) dystocia Estimated 39.6 ⫾ 0.3 gestational age (wk) ⬍ 37 2 (4.1) 37–40 19 (38.8) ⬎ 40 28 (57.1) Diabetes 17 (34.7)
29.1 ⫾ 0.8 3.45 ⫾ 0.3
.67 .86
15 (30.6) 34 (69.4) 206.1 ⫾ 6.7
.10, 0.44 (0.15, 1.28) .54
4 (8.2)
.68
39.2 ⫾ 0.2
.23
3 (6.1) 11 (22.5) 35 (71.4) 5 (10.2)
.004, 4.68 (1.42, 16.32)
OR ⫽ odds ratio; CI ⫽ confidence interval. Data are mean ⫾ standard deviation or n (%).
estimate of time was noted as the time required to alleviate the shoulder dystocia. These records were also reviewed to determine whether fundal pressure had been applied to alleviate the shoulder dystocia. Neonatal data included birth weight, the presence of bone fracture (either clavicular or humeral fracture), other nerve injury, and the location of the brachial plexus palsy. Statistical methods used included Student t test and analysis of variance for continuous variables with normal or near-normal distributions. The Mann-Whitney U test was used as a nonparametric test. For proportional data, 2 (with Yates correction) and Fisher tests were used, where appropriate, with calculation of odds ratio [OR] and Cornfield 95% confidence limits.11 All analyses were two sided, with a P value less than 0.05 considered statistically significant. RESULTS In the permanent palsy group (n ⫽ 49) almost all of the brachial plexus palsies evaluated were of the Erb or Duchenne type, with only three cases of Klumpke palsy present. In the transient palsy cohort (n ⫽ 49), there were 47 cases of unilateral Erb palsy, one case of bilateral Erb palsy, and one case of Klumpke palsy. Among the transient brachial plexus palsies, an additional 17 cases were associated with spontaneous vaginal deliveries. An additional four cases of permanent brachial plexus palsy were excluded because they did not occur in the setting of shoulder dystocia.
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Table 2. Comparison of Select Intrapartum Characteristics
Oxytocin administration Epidural anesthesia Length of active phase (min) Length of second stage ⬎2h ⬍ 15 min Operative delivery Number of maneuvers to alleviate shoulder dystocia Time to alleviate shoulder dystocia (min)
Transient (n ⫽ 49)
Permanent (n ⫽ 49)
P, OR (95% CI)
31 (63.3) 13 (26.5) 304 ⫾ 36.8 87 ⫾ 11.1 14 (28.6) 4 (8.2) 8 (16.3) 2.6 ⫾ 0.6 1.8 ⫾ 0.3
28 (57.1) 19 (38.8) 282 ⫾ 18.2 59 ⫾ 6.7 7 (14.3) 8 (16.3) 13 (26.5) 2.9 ⫾ 0.4 2.1 ⫾ 0.4
.32, 1.29 (0.53, 3.15) .20, 0.57 (0.22, 1.46) .64 .58 .08, 2.40 (0.79, 7.47) .22, 0.46 (0.11, 1.85) .22, 0.54 (0.18, 1.60) .71 .56
Abbreviations as in Table 1. Data are mean ⫾ standard deviation or n (%).
As listed in Table 1, there were no statistically significant differences between transient and permanent brachial plexus palsies with respect to mean maternal age, gravidity, parity, maternal weight at delivery, history of prior shoulder dystocia, and estimated gestational age at delivery. There were also no differences found between the two groups with respect to the number of cases that had estimated gestational ages greater than 40 weeks. Cases of transient brachial plexus palsy were associated with an increased incidence of diabetes mellitus. There was, however, no statistically significant difference with respect to the need for insulin among the diabetic patients (ten of 17 [transient] versus four of five [permanent], P ⫽ .38). No statistically significant differences were found between the two groups with respect to several intrapartum variables, including oxytocin administration (either for labor induction or augmentation), epidural anesthesia, the mean length of the active phase of labor, the mean length of the second stage of labor, and the need for
operative vaginal delivery. An estimate of the time interval between delivery of the fetal head and body was obtained in most of the transient (n ⫽ 36, 73.5%) and permanent palsies (n ⫽ 46, 93.9%). The two cohorts also did not differ with respect to the number of maneuvers or the amount of time needed to alleviate the shoulder dystocia (Table 2). Although fundal pressure was used more often in cases of shoulder dystocia associated with permanent brachial plexus palsy (one of 49 versus six of 49), this difference did not achieve statistical significance (P ⫽ .11, OR 0.15, 95% confidence interval [CI] 0.01, 1.34). More patients in the transient palsy group had a second stage of labor longer than 2 hours, but this difference did not reach statistical significance. There was no significant difference in the rate of prolonged second stage between the transient and permanent palsy groups (four of 49 versus three of 49, P ⫽ .41, OR 1.36, 95% CI 0.24, 8.23). Infants with permanent brachial plexus palsy had higher mean birth weight (4519 ⫾
Table 3. Comparison of Select Neonatal Characteristics
Birth weight (g) ⬍ 3500 3501–4000 4000–4500 4500–5000 ⬎ 5000 Birth weight ⬎ 4500 g Birth weight ⬎ 4000 g Bone fracture Clavicle Humerus Other nerve injury Location Right Left
Transient (n ⫽ 49)
Permanent (n ⫽ 49)
4143 ⫾ 56.5 3 (6.1) 12 (24.5) 26 (53.1) 8 (16.3) 0 (0) 8 (16.3) 34 (69.4) 8 (16.3) 7 1 0 (0)
4519 ⫾ 94.3 1 (2) 11 (22.5) 18 (36.7) 8 (16.3) 11 (22.5) 19 (38.8) 37 (75.5) 12 (24.5) 10 2 0 (0)
31 (63.3) 18 (36.7)
26 (53.1) 23 (46.9)
P, OR (95% CI) ⬍.001
.01, 0.31 (0.11, 0.87) .36, 0.74, (0.27, 1.96) .32, 0.60 (0.20, 1.81) ⬎.99 .31, 1.52 (0.63, 3.70)
Abbreviations as in Table 1. Data are mean ⫾ standard deviation or n (%).
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94.3 g versus 4143 ⫾ 56.5 g, P ⫽ .001, Table 3). A large proportion of cases of brachial plexus palsy in both groups had a birth weight greater than 4000 g. Although no differences were found with respect to this birth weight level, there were more cases with birth weights greater than 4500 grams in the permanent brachial plexus palsy group (38.8% versus 16.3%, P ⫽ .01, OR 0.31, 95% CI 0.11, 0.87). The most common comorbidity associated with brachial plexus palsy was clavicular fracture, which occurred in 14.3% (seven of 49) of the transient group and 20.4% (ten of 49) of the permanent group. DISCUSSION In this retrospective case-control study, we found that there was an increased prevalence of diabetes mellitus among mothers whose infants had transient brachial plexus injury. Infants with permanent brachial plexus palsies had a higher mean birth weight and a higher percentage of cases with birth weight greater than 4500 g. There were, however, no statistically significant differences between the two groups with respect to multiple antepartum, intrapartum, and delivery outcomes. Which cases of transient brachial plexus palsy will resolve is an important clinical question that is commonly posed. We performed a MEDLINE search of the English language literature between 1980 and 2002 using the search terms “brachial plexus palsy” and “shoulder dystocia” and found no studies that specifically compared neonates with transient and permanent brachial plexus palsy. Essentially all of the previous studies of brachial plexus palsy have follow-up limited to the immediate postpartum period, with the data coming from medical record searches, database queries, or birth certificate investigations.12–15 Among 63 infants with Erb palsy, Ouzounian et al5 found that most of their mothers were not diabetic (89%), not obese (76%), had normal labor (91%), and did not have a midpelvic operative delivery (79%). In addition, 59% of the cases occurred in infants with a birth weight less than 4500 g and 19% occurred in infants with a birth weight less than 4000 g. Using multivariable analysis that included birth weight and infant sex determination, Wolf et al16 found that risk factors for 16 cases of nonrecovered brachial plexus palsy were similar to 56 control cases. We found it notable that clavicular fracture occurred in 14.3% and 20.4% of transient and permanent palsies, respectively. Among studies that carefully evaluated neonatal shoulder dystocia–associated morbidity, the rate of clavicular fracture (1.7–9.5%) appears to be half that of transient brachial plexus palsy.2 Conversely,
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approximately one third of brachial plexus palsies are associated with concomitant bone fracture, most commonly the clavicle (94%).7 The pathogenesis for clavicular fracture associated with brachial plexus palsy is currently unknown. An excessive amount of pressure might be placed on the clavicle by the overlying symphysis pubis; the application of suprapubic pressure can also result in transverse or oblique fractures.17 It is likewise possible that a complex relationship exists between clavicular fracture, fetal size, and pelvic angle orientation.18 Our study found a surprisingly high percentage (12%) of permanent brachial plexus palsies in which fundal pressure had been used. Although it is not entirely clear whether fundal pressure alone is associated with an increased risk of permanent neurologic injury, its application has been associated with a high incidence of orthopedic and neurologic damage, lower thoracic spinal cord injury, and increased intrauterine pressure.19,20 We acknowledge that this study would have been stronger if it had been designed as a prospective cohort study rather than as a case-control study. The former type of research effort would have involved detailed neonatal follow-up for at least 1 year on a large cohort of neonates with brachial plexus injury. Many of the details are lost as these children are followed up in specialty clinics or move with their families. In addition, the actual incidence of permanent brachial plexus injury associated with shoulder dystocia is exceedingly low. For example, among 250 reported cases of shoulder dystocia only three infants had persistent palsy after 1 year of pediatric neurologic follow-up.6 Recent studies have reported that shoulder dystocia complicates approximately 1% of all vaginal deliveries, that the rate of transient shoulder dystocia–related brachial plexus injury is 15%, and that the rate of permanent neurologic injury is 5%.2,4 Consequently, a researcher would have to gain access to the data from 1.3 million vaginal deliveries in order to describe 100 permanent brachial plexus injuries. Our study had approximately 80% power (95% confidence level) for the outcome measure of an increased rate of diabetes mellitus among the transiently injured group. This finding, however, should be interpreted with caution. We are currently unable to provide the specific racial breakdown for the cases and controls. We do acknowledge that the rate of Hispanic patients in the transient brachial plexus palsy cohort is most likely higher because this database included patients from Los Angeles County/University of Southern California School of Medicine Women’s and Children’s Hospital. This institution is a large tertiary care referral center with a primarily indigent Hispanic patient population. Moreover, patients of Hispanic descent are at increased risk for the development of gestational diabetes. Interest-
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ingly, however, that the transient nerve injuries occurred in smaller infants who were more likely to be from diabetic mothers. This may perhaps illustrate a lower threshold for shoulder dystocia in diabetic patients, a finding that is consistent with anthropometric data.21 Recent studies found that shoulder dystocia itself may be a causal factor for the neonate’s brachial plexus injury.4,22,23 During a shoulder dystocia event, there are significant compressive forces exerted on the fetal neck by the symphysis pubis. In Gonik et al’s mathematic model, clinician-applied traction to the fetal head was estimated to produce 22.9 kPa of pressure between the fetal neck and symphysis pubis.24 Uterine and maternal expulsive efforts, however, resulted in contact pressures that ranged from 91.1 to 202.5 kPa. Because transient brachial plexus palsy is rather common with shoulder dystocia but permanent nerve injury is exceedingly rare, this implies that each fetus may possess a unique threshold for injury. Further studies, including comparison of neurosurgical findings with obstetric antecedents and development of a tool to gauge excessive downward traction, are urgently needed. REFERENCES 1. American College of Obstetricians and Gynecologists. Shoulder dystocia. Washington, DC: American College of Obstetricians and Gynecologists, ACOG Practice Bulletin #40, November 2002. 2. Gherman RB. Shoulder dystocia: An evidence-based evaluation of the obstetric nightmare. Clin Obstet Gynecol 2002;45:345–62. 3. Pollack RN, Buchman AS, Yaffe H, Divon MY. Obstetrical brachial plexus palsy: Pathogenesis, risk factors, and prevention. Clin Obstet Gynecol 2000;43:236–46. 4. Gherman RB, Ouzounian JG, Goodwin TM. Brachial plexus palsy: An in utero injury? Am J Obstet Gynecol 1999;180:1303–7. 5. Ouzounian JG, Korst LM, Phelan JP. Permanent Erb’s palsy: A lack of relationship with obstetrical risk factors. Am J Perinatol 1998;15:221–3. 6. Gherman RB, Goodwin TM, Souter I, Neumann K, Ouzounian JG, Paul RH. The McRoberts’ maneuver for the alleviation of shoulder dystocia: How successful is it? Am J Obstet Gynecol 1997;176:656–61. 7. Gherman RB, Ouzounian JG, Goodwin TM. Obstetrical maneuvers for shoulder dystocia and associated fetal morbidity. Am J Obstet Gynecol 1998;178:1126–30. 8. Eng GD, Binder H, Getson P, O’Donnell R. Obstetrical brachial plexus palsy (OBPP) outcome with conservative management. Muscle Nerve 1996;19:884–91. 9. Michelow BJ, Clarke HM, Curtis CG, Zuker RM, Seifu Y, Andrews DF. The natural history of obstetrical brachial plexus palsy. Plast Reconstr Surg 1994;93:675–80.
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10. American College of Obstetricians and Gynecologists. Operative vaginal delivery. Washington, DC: College of Obstetricians and Gynecologists, ACOG Practice Bulletin #17, June 2000. 11. Visintainer PF, Tejani N. Understanding and using confidence intervals in clinical research. J Matern Fetal Med 1998;7:201–6. 12. Nocon JJ, McKenzie DK, Thomas LJ, Hansell RS. Shoulder dystocia: An analysis of risks and obstetric maneuvers. Am J Obstet Gynecol 1993;168:1732–9. 13. Baskett TF, Allen AC. Perinatal implications of shoulder dystocia. Obstet Gynecol 1995;86:14–7. 14. Gilbert WM, Nesbitt TS, Danielsen B. Associated factors in 1611 cases of brachial plexus injury. Obstet Gynecol 1999;93:536–40. 15. Gordon M, Rich H, Deutschberger J, Green M. The immediate and long-term outcome of obstetric birth trauma. I. Brachial plexus paralysis. Am J Obstet Gynecol 1973;117:51–6. 16. Wolf H, Hoeksma AF, Oei SL, Bleker OP. Obstetric brachial plexus injury: Risk factors related to recovery. Eur J Obstet Gynecol Reprod Biol 2000;88:133–8. 17. Oppenheim WL, Davis A, Growdon WA, Dorey FJ, Davlin LB. Clavicle fracture in the newborn. Clin Orthopedic Res 1990;250:176–80. 18. Gonik B, Allen R, Sorab J. Objective evaluation of shoulder dystocia phenomenon: Effect of maternal pelvic orientation on force reduction. Obstet Gynecol 1989;74:44–7. 19. Hankins GDV. Lower thoracic spinal cord injury—A severe complication of shoulder dystocia. Am J Perinatol 1998;15:443–4. 20. Buhimschi CS, Buhimschi IA, Malinow AM, Kopelman JN, Weiner CP. The effect of fundal pressure manoeuvre on intrauterine pressure in the second stage of labour. Br J Obstet Gynaecol 2002;109:520–6. 21. Modanlou HD, Komatsu G, Dorchester W, Freeman RK, Bosu SK. Large-for-gestational age neonates: Anthropometric reasons for shoulder dystocia. Obstet Gynecol 1982;60:414–23. 22. Sandmire HF, DeMott RK. Erb’s palsy: Concepts of causation. Obstet Gynecol 2000;95:940–942. 23. Sandmire HF, DeMott RK. Erb’s palsy causation: A historical perspective. Birth 2002;29:52–4. 24. Gonik B, Walker A, Grimm M. Mathematic modeling of forces associated with shoulder dystocia: A comparison of endogenous and exogenous sources. Am J Obstet Gynecol 2000;182:689–91. Reprints are not available. Received February 10, 2003. Received in revised form April 15, 2003. Accepted June 2, 2003.
OBSTETRICS & GYNECOLOGY
(Obstet Gynecol 2003;102:544 – 8. © 2003 by The American College of Obstetricians and Gynecologists.)
METHODS: We performed a retrospective case-control analysis from national birth injury and shoulder dystocia databases. Study patients had permanent brachial plexus palsy and had been entered into a national birth injury registry. Cases of Erb or Klumpke palsy with documented neonatal neuromuscular deficits persisting beyond at least 1 year of life were classified as permanent. Cases of transient brachial plexus palsy were obtained from a shoulder dystocia database. Non-shoulder dystocia–related cases of brachial plexus palsy were excluded from analysis. Cases of permanent brachial plexus palsy (n ⴝ 49) were matched 1:1 with cases of transient brachial plexus palsy.
Brachial plexus injury has been reported to complicate up to 21% of all deliveries complicated by shoulder dystocia.1–3 The majority of these palsies will resolve with conservative therapy, resulting in a 1.6% rate of permanent brachial plexus injury associated with shoulder dystocia.4 To date, most of the studies dealing with brachial plexus palsy have not specifically commented upon permanent brachial plexus palsy. Important questions concerning the natural history and pathogenesis of shoulder-dystocia related brachial plexus injury therefore continue to remain unanswered. We sought to estimate maternal or fetal characteristics that could be used to differentiate between transient and permanent shoulder dystocia-associated brachial plexus injuries.
RESULTS: Transient brachial plexus palsy cases had a higher incidence of diabetes mellitus than those with permanent brachial plexus palsy (34.7% versus 10.2%, odds ratio [OR] 4.68, 95% confidence interval [CI] 1.42, 16.32). Patients with permanent brachial plexus palsies had a higher mean birth weight (4519 ⴞ 94.3 g versus 4143.6 ⴞ 56.5 g, P < .001) and a greater frequency of birth weight greater than 4500 grams (38.8% versus 16.3%, OR, 0.31, 95% CI 0.11, 0.87). There were, however, no statistically significant differences between the two groups with respect to multiple antepartum, intrapartum, and delivery outcome measures. CONCLUSION: Transient and permanent brachial plexus palsies are not associated with significant differences for most antepartum and intrapartum characteristics. From the Department of OB/GYN, Division of Maternal/Fetal Medicine, National Naval Medical Center, Bethesda, Maryland; Department of OB/GYN, Division of Maternal/Fetal Medicine, Kaiser Permanente, Baldwin Park, California; Uniformed Services University of the Health Sciences, Department of OB/GYN, Bethesda, Maryland; Department of OB/GYN, Division of Maternal/Fetal Medicine, Women’s and Children’s Hospital, University of Southern California School of Medicine, Los Angeles, California; and Childbirth Injury Prevention Foundation, Pasadena, California. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, the Department of Defense, or the United States Government.
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MATERIALS AND METHODS We performed a retrospective case-control analysis from computer-stored databases. Study patients had permanent brachial plexus palsy and were part of a national registry of children with neonatal brachial plexus injury.5 This database included litigated cases that had occurred in community and teaching hospitals throughout the United States. Under the supervision of two of this study’s authors (JPP and JGO), data were abstracted from the referred legal cases. Obstetric residents, attending obstetricians, certified nurse midwives, and family practice physicians had performed the deliveries. Only cases of brachial plexus palsy that occurred in conjunction with shoulder dystocia were included. Shoulder dystocia was defined as the need for the performance of ancillary obstetric maneuvers after initial attempts at gentle downward traction were unsuccessful in delivering the fetal head. Transient brachial plexus palsies, obtained from a previously established shoulder dystocia database6,7 served as the control group. This database was created
VOL. 102, NO. 3, SEPTEMBER 2003 © 2003 by The American College of Obstetricians and Gynecologists. Published by Elsevier.
0029-7844/03/$30.00 doi:10.1016/S0029-7844(03)00660-4
by two of the study’s authors (RBG and TMG) by reviewing the maternal and neonatal charts of cases of shoulder dystocia that occurred between January 1, 1991, and July 1, 1996, at Los Angeles County/University of Southern California Women’s Hospital. The 49 cases of transient brachial plexus palsy were drawn from a cohort that included 291 cases of shoulder dystocia, yielding a transient injury rate of 16.8%. The consecutive cases of transient brachial plexus palsy were matched 1:1 by the closest date of delivery, with cases from the study group. This study had previously been approved by the investigational review board. Neither of the two databases used in this study were funded by the government or by a professional liability organization. Cases of Erb or Klumpke palsy with documented neonatal neuromuscular deficits persisting beyond at least 1 year of life were classified as permanent. This time frame was chosen because it represented a period during which most infants are able to make an acceptable functional recovery.8,9 Cases of brachial plexus palsy that occurred in the absence of shoulder dystocia were excluded from this analysis. We likewise excluded from review any case in which we were unable to establish neonatal follow-up for at least 1 year after delivery. The maternal medical records that we reviewed included the prenatal care data and labor record. Neonatal information was gathered both from the hospital postdelivery neonatal records and long-term follow-up. For the latter, we reviewed pediatric, physical rehabilitation, neurologic, and neurosurgical records. Maternal outcomes assessed included maternal age, gravidity, parity, maternal weight at delivery, estimated gestational age as determined by the last menstrual period or ultrasound, and the presence of diabetes (either insulin dependent or non-insulin dependent). We coded charts for the intrapartum variables of oxytocin administration, epidural anesthesia, length of the active phase, length of the second stage of labor, need for operative vaginal delivery (either vacuum or forceps), and the number of ancillary obstetric maneuvers used to alleviate the shoulder dystocia. The maneuvers included McRoberts maneuver, suprapubic pressure, proctoepisiotomy, Woods corkscrew maneuver, Rubin maneuver, posterior arm extraction, or Zavanelli maneuver. The active phase of labor was determined to have begun when the examination found the cervix to be 4 cm dilated. The second stage of labor of labor was considered prolonged as defined by the American College of Obstetrician and Gynecologists.10 Medical and nursing records were reviewed to determine the time difference between the delivery of the fetal head and the delivery of the fetal body. If this information was not available, then the delivering provider’s
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Table 1. Comparison of Select Antepartum Characteristics in Mothers of Neonates With Transient Versus Permanent Brachial Plexus Palsy Transient (n ⫽ 49)
Permanent (n ⫽ 49)
P, OR (95% CI)
Maternal age (y) 27.6 ⫾ 0.9 Gravidity 3.53 ⫾ 0.3 Parity Nulliparous 8 (16.3) Multiparous 41 (83.7) Maternal weight 179.9 ⫾ 4.8 at delivery (lb) Prior shoulder 2 (4.1) dystocia Estimated 39.6 ⫾ 0.3 gestational age (wk) ⬍ 37 2 (4.1) 37–40 19 (38.8) ⬎ 40 28 (57.1) Diabetes 17 (34.7)
29.1 ⫾ 0.8 3.45 ⫾ 0.3
.67 .86
15 (30.6) 34 (69.4) 206.1 ⫾ 6.7
.10, 0.44 (0.15, 1.28) .54
4 (8.2)
.68
39.2 ⫾ 0.2
.23
3 (6.1) 11 (22.5) 35 (71.4) 5 (10.2)
.004, 4.68 (1.42, 16.32)
OR ⫽ odds ratio; CI ⫽ confidence interval. Data are mean ⫾ standard deviation or n (%).
estimate of time was noted as the time required to alleviate the shoulder dystocia. These records were also reviewed to determine whether fundal pressure had been applied to alleviate the shoulder dystocia. Neonatal data included birth weight, the presence of bone fracture (either clavicular or humeral fracture), other nerve injury, and the location of the brachial plexus palsy. Statistical methods used included Student t test and analysis of variance for continuous variables with normal or near-normal distributions. The Mann-Whitney U test was used as a nonparametric test. For proportional data, 2 (with Yates correction) and Fisher tests were used, where appropriate, with calculation of odds ratio [OR] and Cornfield 95% confidence limits.11 All analyses were two sided, with a P value less than 0.05 considered statistically significant. RESULTS In the permanent palsy group (n ⫽ 49) almost all of the brachial plexus palsies evaluated were of the Erb or Duchenne type, with only three cases of Klumpke palsy present. In the transient palsy cohort (n ⫽ 49), there were 47 cases of unilateral Erb palsy, one case of bilateral Erb palsy, and one case of Klumpke palsy. Among the transient brachial plexus palsies, an additional 17 cases were associated with spontaneous vaginal deliveries. An additional four cases of permanent brachial plexus palsy were excluded because they did not occur in the setting of shoulder dystocia.
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Table 2. Comparison of Select Intrapartum Characteristics
Oxytocin administration Epidural anesthesia Length of active phase (min) Length of second stage ⬎2h ⬍ 15 min Operative delivery Number of maneuvers to alleviate shoulder dystocia Time to alleviate shoulder dystocia (min)
Transient (n ⫽ 49)
Permanent (n ⫽ 49)
P, OR (95% CI)
31 (63.3) 13 (26.5) 304 ⫾ 36.8 87 ⫾ 11.1 14 (28.6) 4 (8.2) 8 (16.3) 2.6 ⫾ 0.6 1.8 ⫾ 0.3
28 (57.1) 19 (38.8) 282 ⫾ 18.2 59 ⫾ 6.7 7 (14.3) 8 (16.3) 13 (26.5) 2.9 ⫾ 0.4 2.1 ⫾ 0.4
.32, 1.29 (0.53, 3.15) .20, 0.57 (0.22, 1.46) .64 .58 .08, 2.40 (0.79, 7.47) .22, 0.46 (0.11, 1.85) .22, 0.54 (0.18, 1.60) .71 .56
Abbreviations as in Table 1. Data are mean ⫾ standard deviation or n (%).
As listed in Table 1, there were no statistically significant differences between transient and permanent brachial plexus palsies with respect to mean maternal age, gravidity, parity, maternal weight at delivery, history of prior shoulder dystocia, and estimated gestational age at delivery. There were also no differences found between the two groups with respect to the number of cases that had estimated gestational ages greater than 40 weeks. Cases of transient brachial plexus palsy were associated with an increased incidence of diabetes mellitus. There was, however, no statistically significant difference with respect to the need for insulin among the diabetic patients (ten of 17 [transient] versus four of five [permanent], P ⫽ .38). No statistically significant differences were found between the two groups with respect to several intrapartum variables, including oxytocin administration (either for labor induction or augmentation), epidural anesthesia, the mean length of the active phase of labor, the mean length of the second stage of labor, and the need for
operative vaginal delivery. An estimate of the time interval between delivery of the fetal head and body was obtained in most of the transient (n ⫽ 36, 73.5%) and permanent palsies (n ⫽ 46, 93.9%). The two cohorts also did not differ with respect to the number of maneuvers or the amount of time needed to alleviate the shoulder dystocia (Table 2). Although fundal pressure was used more often in cases of shoulder dystocia associated with permanent brachial plexus palsy (one of 49 versus six of 49), this difference did not achieve statistical significance (P ⫽ .11, OR 0.15, 95% confidence interval [CI] 0.01, 1.34). More patients in the transient palsy group had a second stage of labor longer than 2 hours, but this difference did not reach statistical significance. There was no significant difference in the rate of prolonged second stage between the transient and permanent palsy groups (four of 49 versus three of 49, P ⫽ .41, OR 1.36, 95% CI 0.24, 8.23). Infants with permanent brachial plexus palsy had higher mean birth weight (4519 ⫾
Table 3. Comparison of Select Neonatal Characteristics
Birth weight (g) ⬍ 3500 3501–4000 4000–4500 4500–5000 ⬎ 5000 Birth weight ⬎ 4500 g Birth weight ⬎ 4000 g Bone fracture Clavicle Humerus Other nerve injury Location Right Left
Transient (n ⫽ 49)
Permanent (n ⫽ 49)
4143 ⫾ 56.5 3 (6.1) 12 (24.5) 26 (53.1) 8 (16.3) 0 (0) 8 (16.3) 34 (69.4) 8 (16.3) 7 1 0 (0)
4519 ⫾ 94.3 1 (2) 11 (22.5) 18 (36.7) 8 (16.3) 11 (22.5) 19 (38.8) 37 (75.5) 12 (24.5) 10 2 0 (0)
31 (63.3) 18 (36.7)
26 (53.1) 23 (46.9)
P, OR (95% CI) ⬍.001
.01, 0.31 (0.11, 0.87) .36, 0.74, (0.27, 1.96) .32, 0.60 (0.20, 1.81) ⬎.99 .31, 1.52 (0.63, 3.70)
Abbreviations as in Table 1. Data are mean ⫾ standard deviation or n (%).
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94.3 g versus 4143 ⫾ 56.5 g, P ⫽ .001, Table 3). A large proportion of cases of brachial plexus palsy in both groups had a birth weight greater than 4000 g. Although no differences were found with respect to this birth weight level, there were more cases with birth weights greater than 4500 grams in the permanent brachial plexus palsy group (38.8% versus 16.3%, P ⫽ .01, OR 0.31, 95% CI 0.11, 0.87). The most common comorbidity associated with brachial plexus palsy was clavicular fracture, which occurred in 14.3% (seven of 49) of the transient group and 20.4% (ten of 49) of the permanent group. DISCUSSION In this retrospective case-control study, we found that there was an increased prevalence of diabetes mellitus among mothers whose infants had transient brachial plexus injury. Infants with permanent brachial plexus palsies had a higher mean birth weight and a higher percentage of cases with birth weight greater than 4500 g. There were, however, no statistically significant differences between the two groups with respect to multiple antepartum, intrapartum, and delivery outcomes. Which cases of transient brachial plexus palsy will resolve is an important clinical question that is commonly posed. We performed a MEDLINE search of the English language literature between 1980 and 2002 using the search terms “brachial plexus palsy” and “shoulder dystocia” and found no studies that specifically compared neonates with transient and permanent brachial plexus palsy. Essentially all of the previous studies of brachial plexus palsy have follow-up limited to the immediate postpartum period, with the data coming from medical record searches, database queries, or birth certificate investigations.12–15 Among 63 infants with Erb palsy, Ouzounian et al5 found that most of their mothers were not diabetic (89%), not obese (76%), had normal labor (91%), and did not have a midpelvic operative delivery (79%). In addition, 59% of the cases occurred in infants with a birth weight less than 4500 g and 19% occurred in infants with a birth weight less than 4000 g. Using multivariable analysis that included birth weight and infant sex determination, Wolf et al16 found that risk factors for 16 cases of nonrecovered brachial plexus palsy were similar to 56 control cases. We found it notable that clavicular fracture occurred in 14.3% and 20.4% of transient and permanent palsies, respectively. Among studies that carefully evaluated neonatal shoulder dystocia–associated morbidity, the rate of clavicular fracture (1.7–9.5%) appears to be half that of transient brachial plexus palsy.2 Conversely,
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approximately one third of brachial plexus palsies are associated with concomitant bone fracture, most commonly the clavicle (94%).7 The pathogenesis for clavicular fracture associated with brachial plexus palsy is currently unknown. An excessive amount of pressure might be placed on the clavicle by the overlying symphysis pubis; the application of suprapubic pressure can also result in transverse or oblique fractures.17 It is likewise possible that a complex relationship exists between clavicular fracture, fetal size, and pelvic angle orientation.18 Our study found a surprisingly high percentage (12%) of permanent brachial plexus palsies in which fundal pressure had been used. Although it is not entirely clear whether fundal pressure alone is associated with an increased risk of permanent neurologic injury, its application has been associated with a high incidence of orthopedic and neurologic damage, lower thoracic spinal cord injury, and increased intrauterine pressure.19,20 We acknowledge that this study would have been stronger if it had been designed as a prospective cohort study rather than as a case-control study. The former type of research effort would have involved detailed neonatal follow-up for at least 1 year on a large cohort of neonates with brachial plexus injury. Many of the details are lost as these children are followed up in specialty clinics or move with their families. In addition, the actual incidence of permanent brachial plexus injury associated with shoulder dystocia is exceedingly low. For example, among 250 reported cases of shoulder dystocia only three infants had persistent palsy after 1 year of pediatric neurologic follow-up.6 Recent studies have reported that shoulder dystocia complicates approximately 1% of all vaginal deliveries, that the rate of transient shoulder dystocia–related brachial plexus injury is 15%, and that the rate of permanent neurologic injury is 5%.2,4 Consequently, a researcher would have to gain access to the data from 1.3 million vaginal deliveries in order to describe 100 permanent brachial plexus injuries. Our study had approximately 80% power (95% confidence level) for the outcome measure of an increased rate of diabetes mellitus among the transiently injured group. This finding, however, should be interpreted with caution. We are currently unable to provide the specific racial breakdown for the cases and controls. We do acknowledge that the rate of Hispanic patients in the transient brachial plexus palsy cohort is most likely higher because this database included patients from Los Angeles County/University of Southern California School of Medicine Women’s and Children’s Hospital. This institution is a large tertiary care referral center with a primarily indigent Hispanic patient population. Moreover, patients of Hispanic descent are at increased risk for the development of gestational diabetes. Interest-
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ingly, however, that the transient nerve injuries occurred in smaller infants who were more likely to be from diabetic mothers. This may perhaps illustrate a lower threshold for shoulder dystocia in diabetic patients, a finding that is consistent with anthropometric data.21 Recent studies found that shoulder dystocia itself may be a causal factor for the neonate’s brachial plexus injury.4,22,23 During a shoulder dystocia event, there are significant compressive forces exerted on the fetal neck by the symphysis pubis. In Gonik et al’s mathematic model, clinician-applied traction to the fetal head was estimated to produce 22.9 kPa of pressure between the fetal neck and symphysis pubis.24 Uterine and maternal expulsive efforts, however, resulted in contact pressures that ranged from 91.1 to 202.5 kPa. Because transient brachial plexus palsy is rather common with shoulder dystocia but permanent nerve injury is exceedingly rare, this implies that each fetus may possess a unique threshold for injury. Further studies, including comparison of neurosurgical findings with obstetric antecedents and development of a tool to gauge excessive downward traction, are urgently needed. REFERENCES 1. American College of Obstetricians and Gynecologists. Shoulder dystocia. Washington, DC: American College of Obstetricians and Gynecologists, ACOG Practice Bulletin #40, November 2002. 2. Gherman RB. Shoulder dystocia: An evidence-based evaluation of the obstetric nightmare. Clin Obstet Gynecol 2002;45:345–62. 3. Pollack RN, Buchman AS, Yaffe H, Divon MY. Obstetrical brachial plexus palsy: Pathogenesis, risk factors, and prevention. Clin Obstet Gynecol 2000;43:236–46. 4. Gherman RB, Ouzounian JG, Goodwin TM. Brachial plexus palsy: An in utero injury? Am J Obstet Gynecol 1999;180:1303–7. 5. Ouzounian JG, Korst LM, Phelan JP. Permanent Erb’s palsy: A lack of relationship with obstetrical risk factors. Am J Perinatol 1998;15:221–3. 6. Gherman RB, Goodwin TM, Souter I, Neumann K, Ouzounian JG, Paul RH. The McRoberts’ maneuver for the alleviation of shoulder dystocia: How successful is it? Am J Obstet Gynecol 1997;176:656–61. 7. Gherman RB, Ouzounian JG, Goodwin TM. Obstetrical maneuvers for shoulder dystocia and associated fetal morbidity. Am J Obstet Gynecol 1998;178:1126–30. 8. Eng GD, Binder H, Getson P, O’Donnell R. Obstetrical brachial plexus palsy (OBPP) outcome with conservative management. Muscle Nerve 1996;19:884–91. 9. Michelow BJ, Clarke HM, Curtis CG, Zuker RM, Seifu Y, Andrews DF. The natural history of obstetrical brachial plexus palsy. Plast Reconstr Surg 1994;93:675–80.
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10. American College of Obstetricians and Gynecologists. Operative vaginal delivery. Washington, DC: College of Obstetricians and Gynecologists, ACOG Practice Bulletin #17, June 2000. 11. Visintainer PF, Tejani N. Understanding and using confidence intervals in clinical research. J Matern Fetal Med 1998;7:201–6. 12. Nocon JJ, McKenzie DK, Thomas LJ, Hansell RS. Shoulder dystocia: An analysis of risks and obstetric maneuvers. Am J Obstet Gynecol 1993;168:1732–9. 13. Baskett TF, Allen AC. Perinatal implications of shoulder dystocia. Obstet Gynecol 1995;86:14–7. 14. Gilbert WM, Nesbitt TS, Danielsen B. Associated factors in 1611 cases of brachial plexus injury. Obstet Gynecol 1999;93:536–40. 15. Gordon M, Rich H, Deutschberger J, Green M. The immediate and long-term outcome of obstetric birth trauma. I. Brachial plexus paralysis. Am J Obstet Gynecol 1973;117:51–6. 16. Wolf H, Hoeksma AF, Oei SL, Bleker OP. Obstetric brachial plexus injury: Risk factors related to recovery. Eur J Obstet Gynecol Reprod Biol 2000;88:133–8. 17. Oppenheim WL, Davis A, Growdon WA, Dorey FJ, Davlin LB. Clavicle fracture in the newborn. Clin Orthopedic Res 1990;250:176–80. 18. Gonik B, Allen R, Sorab J. Objective evaluation of shoulder dystocia phenomenon: Effect of maternal pelvic orientation on force reduction. Obstet Gynecol 1989;74:44–7. 19. Hankins GDV. Lower thoracic spinal cord injury—A severe complication of shoulder dystocia. Am J Perinatol 1998;15:443–4. 20. Buhimschi CS, Buhimschi IA, Malinow AM, Kopelman JN, Weiner CP. The effect of fundal pressure manoeuvre on intrauterine pressure in the second stage of labour. Br J Obstet Gynaecol 2002;109:520–6. 21. Modanlou HD, Komatsu G, Dorchester W, Freeman RK, Bosu SK. Large-for-gestational age neonates: Anthropometric reasons for shoulder dystocia. Obstet Gynecol 1982;60:414–23. 22. Sandmire HF, DeMott RK. Erb’s palsy: Concepts of causation. Obstet Gynecol 2000;95:940–942. 23. Sandmire HF, DeMott RK. Erb’s palsy causation: A historical perspective. Birth 2002;29:52–4. 24. Gonik B, Walker A, Grimm M. Mathematic modeling of forces associated with shoulder dystocia: A comparison of endogenous and exogenous sources. Am J Obstet Gynecol 2000;182:689–91. Reprints are not available. Received February 10, 2003. Received in revised form April 15, 2003. Accepted June 2, 2003.
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