Willem Pondaag

Natural history of obstetric brachial plexus palsy: a systematic review

Obstetric brachial plexus palsy (OBPP) is caused by traction to the brachial plexus during labour.1,2 In the majority of cases delivery of the upper shoulder is blocked by the mother’s pubic symphysis (shoulder dystocia). If additional traction is applied to the child’s head, the angle between the neck and the shoulder is forcefully widened, overstretching the ipsilateral brachial plexus. The resulting traction injury may vary from neurapraxia or axonotmesis to neurotmesis and avulsion of rootlets from the spinal cord. Recently, the exact origin of OBPP was again a matter of debate.3 It was suggested that intrauterine maladaptation, not nerve traction, causes the plexopathy. The incidence of OBPP varies from 1.6 to 2.9 per 1000 births in prospective studies.4,5 The upper brachial plexus is most commonly affected, resulting in paresis of the shoulder and biceps muscles, as first described by Erb and Duchenne.6 Hand function is additionally impaired in approximately 15% of patients;4,7,8 isolated injury to the lower plexus (Déjèrine-Klumpke’s type) is rare.9 The extent of neural damage can only be assessed by evaluating recovery in the course of time because nerve lesions of different severity initially present with the same clinical features. Neurapraxia and axonotmesis eventually result in complete recovery. Neurotmesis and root avulsion, on the other hand, result in permanent loss of arm function, which may lead in time to the development of skeletal malformations, cosmetic deformities, behavioural problems, and socioeconomic limitations.10–14 At present, most authors advise surgical exploration of the brachial plexus if spontaneous recovery is considered insufficient at a preset age.15–17 Absence of biceps function at 3 months of age is regarded as the key indicator for surgical exploration by some authors.15,18 Others use a combined score of different movements to decide whether nerve surgery should be performed at 9 months.16 Ancillary testing, in particular electromyography, is not considered reliable enough for prognostication.19,20 Methods of repair include nerve grafting after resection of the neuroma and nerve transfer in the case of root avulsion.15,21–25 Results achieved by these surgical approaches are claimed to be superior to the outcome in conservatively treated patients with equally severe lesions.15,26–28 However, this comparison relies on historical controls;29 no randomized study has been performed.6,30 In this context, the true percentage of infants who do not recover from OBPP becomes important as these children might benefit from reconstructive surgery. Reliable data on the frequency and severity of functional deficits in the natural course of OBPP are a prerequisite for developing adequate treatment strategies. Furthermore, such data would provide parents of newborn infants with OBPP with realistic information on prognosis. The prognosis of OPBB is generally considered to be very good, with complete or almost complete spontaneous recovery in over 90% of patients.25,31–35 However, this view is based on a limited number of studies37 which are cited indiscriminately without considering the methodology used. In the present review we performed a systematic literature search38 to clarify the natural course of untreated OBPP. Ideally, a study on the natural course of OBPP should be a prospective analysis of a demographic population with sufficient followup and clear end-stage assessment. We applied four predefined criteria to assess the methodological quality of the available studies: study-design, population, duration of follow-up, and assessment of end-stage.39

Obstetric lesions of the brachial plexus.

The few studies on prognosis of obstetric lesions of the brachial plexus that are not hampered by selection bias or a short follow‐up suggest that functional impairment persists in 20–25% of cases, more than commonly thought. Electromyography (EMG), potentially useful for prognosis, is often considered of little value. Denervation in the first week of life has been interpreted as evidence of an antenatal lesion, but is the logical result of the short axonal length affected. EMG performed at close to the time of possible intervention (3 months) usually shows a discrepancy: motor unit potentials are seen in clinically paralyzed muscles. This can be explained in five ways: an overly pessimistic clinical examination; overestimation of EMG recruitment due to small muscle fibers; persistent fetal innervation; developmental apraxia; or misdirection, in which axons reach inappropriate muscles. Further research into the pathophysiology of obstetric lesions of the brachial plexus is needed to improve prognostication.

Obstetric Brachial Plexus Injuries

Obstetric brachial plexus lesions (OBPLs) are typically caused by traction to the brachial plexus during labor. The incidence of OBPL is about 2 per 1000 births. Most commonly, the C5 and C6 spinal nerves are affected. The prognosis is generally considered to be good, but the percentage of children who have residual deficits may be as high as 20% to 30%. Surgery should be restricted to severe cases in which spontaneous restoration of function is not likely to occur (ie, in neurotmesis or root avulsions). In this article, the authors present an overview of our current understanding of the neuropathophysiology of OBPLs. The studies of preoperative electromyographic and intraoperative nerve action potential and compound motor action potentials, and of results of nerve surgery, of which some parts have been published, are discussed.

ELECTROMYOGRAPHY, NERVE ACTION POTENTIAL, AND COMPOUND MOTOR ACTION POTENTIALS IN OBSTETRIC BRACHIAL PLEXUS LESIONS: VALIDATION IN THE ABSENCE OF A GOLD STANDARD

OBJECTIVEObstetric brachial plexus lesions (OBPLs) are caused by traction to the brachial plexus during labor. Typically, in these lesions, the nerves are usually not completely ruptured but form a “neuroma-in-continuity.” Even in the most severe OBPL lesions, at least some axons will pass through this neuroma-in-continuity and reach the tubes distal to the lesion site. These axons may be particularly prone to abnormal branching and misrouting, which may explain the typical feature of co-contraction. An additional factor that may reduce functional regeneration is that improper central motor programming may occur. Surgery should be restricted to severe cases in which spontaneous restoration of function will not occur, i.e., in neurotmesis or root avulsions. A major problem is how to predict whether function will be best after spontaneous nerve outgrowth or after nerve reconstructive surgery. When a decision has been made to perform an early surgical exploration, what to do with the neuroma-in-continuity can be a problem. The intraoperative appraisal is difficult and depends on experience, but even in experienced hands, misjudgment can be made. METHODSWe performed an observational study to assess whether early electromyography (at the age of 1 month) is able to predict severe lesions. Additionally, the value of intraoperative nerve action potential and compound motor action potentials was investigated. RESULTSSevere cases of OBPL can be identified at 1 month of age on the basis of clinical findings and needle electromyography of the biceps. This outcome needs independent validation, which is currently in progress. Nerve action potential and compound motor action potential recordings show statistically significant differences on the group level between avulsion, neurotmesis, axonotmesis, and normal. For the individual patient, a clinically useful cutoff point could not be found. Intraoperative nerve action potential and compound motor action potential recordings do not add to the decision making during surgery. CONCLUSIONThe absence of a “gold standard” for the assessment of the severity of the OBPL lesion makes prognostic studies of OBPL complex. The currently available assessment strategies used to obtain the best possible solutions are discussed.

Needle electromyography at 1 month predicts paralysis of elbow flexion at 3 months in obstetric brachial plexus lesions.

Aim  Treatment decisions in obstetric brachial plexus lesions are often based on clinical paralysis of elbow flexion at 3 months of age, when electromyography (EMG) is misleading because motor unit potentials (MUPs) occur in clinically paralytic muscles. We investigated whether EMG at 1 week or 1 month identifies infants with flexion paralysis at 3 months, allowing early referral.

Obstetric Brachial Plexus Lesions: CT Myelography

PURPOSE To evaluate the value of computed tomographic (CT) myelography in the detection of root damage and differentiation of root avulsions from neurotmesis in a large cohort of patients with an obstetric brachial plexus lesion (OBPL). MATERIALS AND METHODS Institutional review board approval was obtained. Informed consent was waived by the medical ethics committee. One hundred eighteen patients with OBPL born in the cephalic position and six patients born in the breech position were selected for surgery by two neurosurgeons in a multidisciplinary team. Functional loss of the C5 through T1 innervated muscles was noted. All patients underwent preoperative CT myelography at an average age of 19 weeks. CT myelographic examination results were reviewed by two radiologists, who were blinded to the clinical findings, for the presence of root avulsions and pseudocysts. Interobserver agreement was assessed by calculating κ values. RESULTS CT myelographic results showed root avulsions in at least one level in 66 (56%) of 118 patients born in the cephalic position and in six (100%) of six patients born in the breech position. Levels C7 and C8 showed the most root avulsions, even if not expected from clinical examination results. A large number of root avulsions showed pseudocysts (73 [68%] of 107 levels in patients born in the cephalic position and 11 [73%] of 15 levels in patients born in the breech position). CONCLUSION CT myelographic results showed root avulsions in more than half of patients with OBPL. Root avulsions were even detected at levels that were not expected at clinical examination. Because root avulsions require specific reconstructive techniques, CT myelography is recommended for every preoperative patient with OBPL.

Severe Obstetric Brachial Plexus Palsies Can Be Identified at One Month of Age

Objective To establish whether severe obstetric brachial plexus palsy (OBPP) can be identified reliably at or before three months of age. Methods Severe OBPP was defined as neurotmesis or avulsion of spinal nerves C5 and C6 irrespective of additional C7-T1 lesions, assessed during surgery and confirmed by histopathological examination. We first prospectively studied a derivation group of 48 infants with OBPP with a minimal follow-up of two years. Ten dichotomous items concerning active clinical joint movement and needle electromyography of the deltoid, biceps and triceps muscles were gathered at one week, one month and three months of age. Predictors for a severe lesion were identified using a two-step forward logistic regression analysis. The results were validated in two independent cohorts of OBPP infants of 60 and 13 infants. Results Prediction of severe OBPP at one month of age was better than at one week and at three months. The presence of elbow extension, elbow flexion and of motor unit potentials in the biceps muscle correctly predicted whether lesions were mild or severe in 93.6% of infants in the derivation group (sensitivity 1.0, specificity 0.88), in 88.3% in the first validation group (sensitivity 0.97, specificity 0.76) and in 84.6% in the second group (sensitivity of 1.0, specificity 0.66). Interpretation Infants with OBPP with severe lesions can be identified at one month of age by testing elbow extension, elbow flexion and recording motor unit potentials (MUPs) in the biceps muscle. The decision rule implies that children without active elbow extension at one month should be referred to a specialized center, while children with active elbow extension as well as active flexion should not. When there is active elbow extension, but no active elbow flexion an EMG is needed; absence of MUPs in the biceps muscle is an indication for referral.

Nerve surgery for neonatal brachial plexus palsy.

Neonatal brachial plexus palsies may cause lifelong limitations to function of the upper limb. Early nerve reconstructive surgery may be indicated in selected cases. An overview is given of our current understanding of this type of nerve lesion in the developing child. The neuropathology of the injury is presented to provide a background for the understanding of its natural history, as well as for the rationale and methods for nerve surgical treatment. The assessment of upper limb function and the range of severity of the lesions at the very young age are outlined. Decision-making regarding surgical selection and determination of the appropriate procedures is presented, as are the outcomes. Improved function can be obtained with surgical repair.

The Evidence for Nerve Repair in Obstetric Brachial Plexus Palsy Revisited

Strong scientific validation for nerve reconstructive surgery in infants with Obstetric Brachial Plexus Palsy is lacking, as no randomized trial comparing surgical reconstruction versus conservative treatment has been performed. A systematic review of the literature was performed to identify studies that compare nerve reconstruction to conservative treatment, including neurolysis. Nine papers were identified that directly compared the two treatment modalities. Eight of these were classified as level 4 evidence and one as level 5 evidence. All nine papers were evaluated in detail to describe strong and weak points in the methodology, and the outcomes from all studies were presented. Pooling of data was not possible due to differences in patient selection for surgery and outcome measures. The general consensus is that nerve reconstruction is indicated when the result of nerve surgery is assumedly better than the expected natural recovery, when spontaneous recovery is absent or severely delayed. The papers differed in methodology on how the cut-off point to select infants for nerve reconstructive surgical therapy should be determined. The justification for nerve reconstruction is further discussed.

Results of end-to-side nerve coaptation in severe obstetric brachial plexus lesions.

OBJECTIVEOptions for nerve repair are limited in brachial plexus lesions with multiple root avulsions because an insufficient number of proximal nerve stumps are available to serve as lead-out for nerve grafts. End-to-side nerve repair might be an alternative surgical technique for repair of such severe lesions. In this technique, an epineurial window is created in a healthy nerve, and the distal stump of the injured nerve is coapted to this site. Inconsistent results of end-to-side nerve repairs in traumatic nerve lesions in adults have been reported in small series. This article evaluates the results of end-to-side nerve repair in obstetric brachial plexus lesions and reviews the literature. METHODSA retrospective analysis was performed of 20 end-to-side repairs in 12 infants. Evaluation of functional recovery of the target muscle was performed after at least 2 years of follow up (mean, 33 mo). RESULTSFive repairs failed (25%). Seven times (35%) good function (Medical Research Council at least 3) of the target muscle occurred in addition to eight partial recoveries (40%). In the majority of patients, however, the observed recovery cannot be exclusively attributed to the end-to-side repair. The reinnervation may be based on axonal outgrowth through grafted or neurolyzed adjacent nerves. It seems likely that recovery was solely based on the end-to-side repair in only two patients. No deficits occurred in donor nerve function. CONCLUSIONThis study does not convincingly show that the end-to-side nerve repair in infants with an obstetric brachial plexus lesion is effective. Its use cannot be recommended as standard therapy.