Introduction

Neonatal brachial plexus palsy (NBPP) can be defined as a flaccid paresis of an upper extremity due to traumatic stretching of the brachial plexus, with the passive range of motion greater than the active.¹ The first description of NBPP was reported in the 18th century, and the noticeably shortened weak arm of Kaiser Wilhelm II of Germany has been attributed to NBPP.² Approximately 1200 reports regarding NBPP exist in Medline from 1948 to the present, with nearly 100 of those reports within the last year. Increased interest in this condition has paralleled the improvement in outcomes that is attributed to increased recognition of this condition, improved care, and expanding research via interdisciplinary collaborations.

Incidence

The incidence of this condition varies based on geography of the reported regions and baby size, but published values range from 0.10 to 5.1 cases per 1000 live births.^3–12 For instance, in the United States, analysis of data from the Kids’ Inpatient Database of over 11 million recorded births over 3 non-consecutive years yielded a mean +/− standard error of 1.51 +/− 0.02 cases per 1000 live births.¹³ Bilateral brachial plexus palsies occur in 8.3–23% of cases, primarily occurring with breech presentation.^14–17 Advancements in modern neonatal and obstetric care, including more frequent use of Caesarian sections, were purported to decrease the incidence of NBPP,^18,19 but recent published reports have not supported this idea.^20–22

Risk factors

NBPP has been associated with several maternal characteristics including advanced age (>35 yrs),²³ pelvic anatomy²⁴ high body mass indices (BMI),^25,26 diabetes,²⁷ and primiparity.²⁸ Diabetes was present in 21% (vs 3–5% in the normal population) and hypertension was present in 17% (vs 2–3%) of women whose babies had NBPP (unpublished data). The most significant characteristic of the baby is high birth weight (>4 kg)^7,8,18,27,29 although the relationship between increasing birth weight and increasing severity of NBPP remains uncertain. Approximately 14% of babies with NBPP had 5-minute Apgar scores of less than 7 (vs 3.8%);³⁰ similarly, others report 49% of babies had an Apgar score of < or = to 7 at one minute.^23,30 Labor and delivery factors include breech position,³¹ shoulder dystocia,³² forceps delivery,^7,22 vacuum extraction,⁷ clavicle fracture,^22,23 precipitous delivery, prolonged labor (second stage),²⁸ and mode of delivery. These factors are addressed in detail in Chapter 5.

Classification of clinical presentation

The most useful classification scheme was proposed by Gilbert and Tassin,³³ refined by Narakas (Table 4.1),^34,35 and supported by Birch.³⁶ The brachial plexus comprises the C5 through T1 nerve roots, and Group I represents the clinical findings resulting from nerve injury of C5 and C6, hallmarked by paresis of the deltoid and biceps but active function in limb extensors, wrist and hand. The clinical findings in Group II are related to injury of C5, C6 and C7. In addition to paresis of the deltoid and biceps, paresis of triceps and wrist extensors is also obvious; however, the long flexors and intrinsic muscles of the hand are relatively unaffected. Group III represents paresis of the entire arm consistent with injury of C5, C6, C7, C8, and T1. Group IV manifests as a paralyzed limb with the additional presence of Horner’s syndrome (ptosis, meiosis, anhydrosis) that implies injury to the all the nerve roots of the brachial plexus with a very severe proximal injury to the lower nerve roots. This Gilbert and Tassin/Narakas classification of NBPP was proposed following a prospective study of the natural history of the condition, discussed further in the next section. As such, when used between 2 and 4 weeks after birth (when neurapraxic lesions would be recovering), this system permits definition of the extent of injury and, more importantly, may guide prognosis.

Table 4.1 Gilbert and Tassin/Narakas classification scheme used for grading the severity of NBPP and for prognosis

Other classification schemes are based on the anatomy and physiology of nerve injury. Sunderland reported a physiologic scheme comprising four types of injuries in increasing severity (neurapraxia, neuroma, rupture, and avulsion)³⁷. He and others use an anatomical scheme comprising four categories based on anatomical location: upper, intermediate, lower and total plexus palsy.^38,39 The concept of an upper plexus palsy involving C5, C6 and sometimes C7 was initially defined anatomically by Erb in 1874⁴⁰ after Duchenne in 1872 described four cases of complete paralysis involving loss of shoulder control and elbow flexion.⁴¹ The upper palsy, also called Erb’s palsy is the most common type of NBPP.^36,42 Erb’s palsy is visually recognized by the stereotyped “waiter’s tip posture” with the arm adducted, shoulder internally rotated, wrist flexed, fingers extended. Intermediate palsy was described by Jolly in 1896⁴³ and Thomas in 1905,⁴⁴ and this condition was thought to involve C7, C8 and Tl roots with the arms abducted, the elbows flexed, and the fingers/hands flaccid. Subsequently the muscles supplied by C8 and Tl spontaneously recovered to some extent but not those supplied by C7. A majority of these cases were bilateral and thought to be related to an obscure obstetric practice. Lower plexus palsy was described by Dejerine-Klumpke.^45,46 This type of NBPP is rare^9,47 but can be recognized by a flaccid hand in an otherwise active arm. Total plexus palsy is essentially the condition as described for Narakas Grades III and IV, and it is a devastating condition with total loss of function of the arm.

Natural history

The natural history of NBPP, around which the determination of optimal treatment revolves, remains the subject of speculation and is debated in many published reports. The evolution of NBPP is difficult to define because of the various combinations of lesions within the elements of the brachial plexus. Further difficulties include the interpretation of what constitutes recovery and the potential bias introduced by the referral patterns of reporting physicians,^48,49 as many patients with Erb’s palsy recover spontaneously and are not referred to the specialists who publish most reports. With these caveats in mind, many authors provide an encouraging view of the natural history of NBPP with over 80% occurrence of a favorable outcome or complete recovery^{14,15,50–53} whereas other authors provide a contrasting view with less than 50% good recovery or persisting disabilities.^49,54–58 Regardless of the neurologic recovery, functional recovery can yet be compromised by musculoskeletal defects, (e.g. contractures, joint subluxation) even with appropriate therapy management.⁵⁹

Most practitioners agree that as the extent and severity of NBPP increase, the potential for recovery decreases.^15,60,61 A detailed prospective study by Gilbert and Tassin³³ reported that 32% made a complete recovery. These patients were characterized by early rapid improvements in arm function with recovery of deltoid and biceps before 2 months of age. Forty-three percent made far less than full recovery. This group of patients was characterized by slow progress, with no evidence of biceps recovery until after 6 months of age. Their study led to the following prognostic conclusions: 90% of patients with Group I NBPP progressed to full spontaneous recovery if there were clinical signs of recovery before 2 months of age. Approximately 65% of patients with Group II palsy recovered fully, but the remainder had persisting defects in shoulder and elbow movement. The timing of recovery of this group of patients is delayed with clinical signs of recovery not evident until 3 to 6 months of age. For Group III patients, less than 50% recover fully spontaneously, with the majority of patients disabled by significant deficits of movement throughout the arm; in approximately 25% of patients, even wrist and finger extension remain functionally compromised. Patients with Group IV NBPP have little if any chance for a full spontaneous recovery; the stark reality is the expectation of a complete neurologic deficit of motor and sensory function in the affected arm. This classification/prognostication system attributed to Gilbert and Tassin, and Narakas remains a popular classification system not only for describing the severity of the pathology but also as a strong predictor of outcomes.²²

Similarly, most practitioners agree that early recovery is associated with favorable outcomes.⁶² The Collaborative Perinatal Study reported that 93% of patients who went on to full spontaneous recovery had done so by 4 months of age.¹⁵ Metaizeau et al. reported that patients who showed no signs of clinical improvement by 3 months did not recover function adequately, and those who continued not to show improvement by 6 months had essentially no chance of adequate functional recovery.⁶³ Bennet and Harrold reported that their patients who recovered fully began to show clinical signs of improvement by 2 weeks of age.¹⁴ Yet other authors contend that all patients who recover satisfactorily achieve biceps and deltoid function by 3 months of age,^64,65 and failure of recovery of anti-gravity power in the proximal muscle groups by 6 months of age essentially presages future moderate to severe weakness in the affected extremity.^66,67 Note, however, that early elbow flexion alone is likely not a sufficient criterion to recommend for or against nerve repair reconstruction.⁶⁸

The predictors of recovery described above use simple clinical muscle assessments, but some authors have constructed paradigms based of more complicated statistical analyses of multiple independent clinical variables,^50,69 but these models show only modest improvement in predicting recovery.

Assessment of the NBPP patient