Functional scoring system for obstetric brachial plexus palsy

Correlation between age, muscle architecture, and muscle strength in children with Erb’s palsy

Background

Muscle weakness is a widespread problem in children with Erb’s palsy as it can cause changes in muscle architecture parameters, which can be detected by ultrasonography. This study was conducted to determine the relation between age, muscle architecture, and muscle strength in children with Erb’s palsy. A total of 40 children with Erb’s palsy from both sexes aged 1–2.5 years were included in this study. Muscle thickness and pennation angle were measured by ultrasonography, and muscle strength was measured using the active movement scale.

Results

A significant relation was found between age, muscle thickness, pennation angle, and muscle strength (P < 0.05). Moreover, a significant difference was found in muscle architecture parameters during relaxation and contraction in both study groups and in each study group (P < 0.05).

Conclusion

Muscle weakness in children with Erb’s palsy has an effect on muscle architecture parameters, and these parameters also increase with age.

[Compensatory and adaptive mechanisms in children with congenital multiple arthrogryposis in the absence of active flexion in the elbow joint]

Arthrogryposis is one of the most severe congenital orthopedic diseases, characterized by multiple joint contractures, hypoplasia or aplasia of the skeletal muscles of the extremities, as well as severe motor disorders. The use of compensatory strategies allows patients to improve the ability to self-care.

OBJECTIVE

To study the compensatory strategies in children with arthrogryposis with absent of active flexion in the elbow joint and estimate their dynamic after surgical treatment.

MATERIAL AND METHODS

We performed a clinical examination of 236 patients with arthrogryposis with deformities of the upper extremities due to arthrogryposis at the age of 10 months to 16 years. The examination was carried out before the operation, as well as at various times (from 1 month to 8 years) after. In 87 cases (67 patients), restoration of active elbow flexion was performed by transposition of latissimus dorsii or pectoralis major to the biceps position. The activity of the muscles involved that most commonly used in compensatory strategies (synergy of m. biceps brachii and m. deltoideus or m.biceps brachii and m. quadriceps femoris) in 10 patients (from 3 to 10 y.o.), was evaluated before and after (from 2 months to 2 years) surgery by surface electromyography.

RESULTS

It was found that children's compensatory strategies are formed at the age of 6 months to 1 y.o.6 months after surgery, the using of compensatory strategies becomes more rare, and 12-18 months after surgery, when the strength of the forearm muscles was 4 points, they were not used at all.

CONCLUSIONS

Compensatory strategies in children with the absence of active and preservation of passive flexion in the elbow joint are diverse. They depend on the amplitude of passive and active movements in the shoulder, the function of the hand and deformities of the lower extremities. These strategies in children with arthrogryposis are unstable and completely disappear when active movements in the elbow joint are restored in the functional range.

The Effects of Virtual Reality on Upper Extremity in Patients with Obstetric Brachial Plexus Injury

The present study aimed to examine the effects of playing Nintendo Wii games on upper extremity functions compared with conventional physiotherapy, in children with obstetric brachial plexus injury (OBPI). Twenty-two patients with brachial plexus injuries were enrolled. The patients were divided into two groups by simple randomization. The control group (conventional physiotherapy group [CTG]: n = 11) received conventional physiotherapy for 6 weeks (40 minutes per day, for 4 days per week). The study group, called Nintendo Wii group (NWG; n = 11), received conventional physiotherapy as well as tennis, baseball, and boxing games with Nintendo Wii on days when there was no physical therapy. The upper extremity range of motion (ROM) was evaluated using a digital goniometer, motor function was assessed using the Active Movement Scale (AMS), and shoulder functions were assessed with the Mallet Scoring System (MSS). Virtual reality treatment had a positive effect on shoulder flexion, forearm pronation, wrist flexion, ROM, and functionality (p < 0.05). There was a significant improvement in shoulder abduction and shoulder external rotation in the CTG (p < 0.05). There was no significant difference in the MSS values of either groups (p > 0.05). As per the AMS, in the NWG, the shoulder internal rotation increased significantly (p < 0.05). Nintendo Wii treatment used in addition to conventional physiotherapy may be effective in increasing upper extremity functions in children with OBPI.

Feasibility and Challenges of Performing Magnetoencephalography Experiments in Children With Arthrogryposis Multiplex Congenita

Arthrogryposis multiplex congenita (AMC) has recently drawn substantial attention from researchers and clinicians. New effective surgical and physiotherapeutic methods have been developed to improve the quality of life of patients with AMC. While it is clear that all these interventions should strongly rely on the plastic reorganization of the central nervous system, almost no studies have investigated this topic. The present study demonstrates the feasibility of using magnetoencephalography (MEG) to investigate brain activity in young AMC patients. We also outlined the general challenges and limitations of electrophysiological investigations on patients with arthrogryposis. We conducted MEG recordings using a 306-channel Elekta Neuromag VectorView system during a cued motor task performance in four patients with arthrogryposis, five normally developed children, and five control adults. Following the voice command of the experimenter, each subject was asked to bring their hand toward their mouth to imitate the self-feeding process. Two patients had latissimus dorsi transferred to the biceps brachii position, one patient had a pectoralis major transferred to the biceps brachii position, and one patient had no elbow flexion restoration surgery before the MEG investigation. Three patients who had undergone autotransplantation prior to the MEG investigation demonstrated activation in the sensorimotor area contralateral to the elbow flexion movement similar to the healthy controls. One patient who was recorded before the surgery demonstrated subjectively weak distributed bilateral activation during both left and right elbow flexion. Visual inspection of MEG data suggested that neural activity associated with motor performance was less pronounced and more widely distributed across the cortical areas of patients than of healthy control subjects. In general, our results could serve as a proof of principle in terms of the application of MEG in studies on cortical activity in patients with AMC. Reported trends might be consistent with the idea that prolonged motor deficits are associated with more difficult neuronal recruitment and the spatial heterogeneity of neuronal sources, most likely reflecting compensatory neuronal mechanisms. On the practical side, MEG could be a valuable technique for investigating the neurodynamics of patients with AMC as a function of postoperative abilitation.

Restoration of elbow active flexion via latissimus dorsii transfer in patients with arthrogryposis

Background. Severe hypoplasia (or aplasia) of the biceps brachii is a primary cause of restriction in activities of daily living in patients with arthrogryposis. Aim. To estimate the possibility of restoring elbow active flexion via a latissimus dorsii transfer in patients with arthrogryposis. Materials and methods. From 2011 to 2018, we restored active flexion of the elbow via a latissimus dorsi transfer to the biceps brachii in 30 patients with arthrogryposis (44 upper limbs). We used different regimes including clinical examinations, EMG donor and recipient sites, and CT of the chest wall and shoulder. Results. The mean age of the patients was 4.0 ± 2.4 years, and the follow-up period was 3.2 ± 1.9 months. Follow-up results were available for 26 patients (30 upper limbs). The active postoperative elbow motion was 90.5 ± 14.9°. Elbow extension limitation occurred in 51% of cases (12.8 ± 4.3°) without any problems in activities of daily living. In total, 55.6% of patients had good results, 33.3% had satisfactory results, and 11.1% had poor results. Discussion. Our latissimus dorsi transfer results were comparable with those of other authors. Transposition of the latissimus dorsi to the biceps brachii restores sufficient flexion of the elbow without severe elbow flexion contractures. Conclusions. We suggest pedicle monopolar latissimus dorsi transfer as a reliable therapeutic option to restore active elbow flexion in patients with arthrogryposis having passive elbow flexion of 90° or higher before operation and donor muscle strain grade 4 or higher.

Development of a set of activities to evaluate the arm and hand function in children with obstetric brachial plexus lesion

Objective: To develop an observational instrument that can be used to evaluate the quality of arm and hand skills in daily functional activities in children with obstetric brachial plexus lesion (OBPL). A set of functional activities was constructed and standardized, and the intra-observer reliability of the assessment of this set of activities was studied.

Setting: Department of Occupational Therapy and Department of Rehabilitation Medicine, VU University Medical Centre.

Subjects: Twenty-six children with OBPL in the age range of 4 -6 years.

Interventions: The children were asked to perform 47 bimanual activities, which were recorded on videotape.

Main measures: The videotapes were scored twice by the same occupational therapist.

Results: The percentage of agreement in scoring ‘hand-use’, ‘speed’ and ‘assistance’ was over 80% for a substantial number of activities, indicating a strong agreement. However, in scoring ‘deviations in movements and body posture’ the percentage of agreement was insufficient in most activities.

Conclusions: This set of activities has good potential for assessment of the performance of functional activities in children with OBPL. This study, however, showed a number of difficulties in observing and scoring the activities that have to be considered when developing a standardized video observation.

Primary Nerve Repair for Obstetrical Brachial Plexus Injury: A Meta-Analysis

BACKGROUND

Nerve repair may be effective in improving function following obstetrical brachial plexus injury. No previous review has directly compared nerve repair to nonoperative management for similar patients, and no previous analysis has been adequately powered to determine whether nerve repair reduces impairment.

METHODS

Electronic databases were searched (MEDLINE, Embase, CINAHL, and Cochrane Central). Eligible studies were randomized controlled trials, observational studies, and case series (n > 9); included patients younger than 2 years undergoing nerve repair or nonoperative management of obstetrical brachial plexus injury; and reported functional impairment. Two reviewers independently screened articles using objective a priori criteria. Bias was assessed for each study. Overall quality of evidence was evaluated for each outcome.

RESULTS

Among nine cohort studies including 222 patients, nerve repair significantly reduced functional impairment compared with nonoperative management (relative risk, 0.58; 95 percent CI, 0.43 to 0.79; p < 0.001; I = 0 percent; absolute risk reduction, 19 percent; number needed to treat, six). Findings are consistent with comparison of similar patients from case series. With operative management, no deaths were reported; major adverse events were reported in 1.5 percent, and minor adverse events were reported in 5.0 percent of cases. Among demographic (all severities) samples managed nonoperatively, residual impairment remains in 27 percent (19 to 36 percent).

CONCLUSIONS

Nerve repair reduces functional impairment in obstetrical brachial plexus injury. Nonoperative management in patients with a deficit at 3 months of age leads to a high proportion of functional impairment. Mortality is not a common risk of modern pediatric microsurgical nerve repair. Residual impairment with nonoperative management is underestimated in the reported literature.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Utility of delayed surgical repair of neonatal brachial plexus palsy

OBJECT

Neonatal brachial plexus palsy (NBPP) represents a significant health problem with potentially devastating consequences. The most common form of NBPP involves the upper trunk roots. Currently, primary surgical repair is performed if clinical improvement is lacking. There has been increasing interest in "early" surgical repair of NBPPs, occurring within 3-6 months of life. However, early treatment recommendations ignore spontaneous recovery in cases of Erb's palsy. This study was undertaken to evaluate the optimal timing of surgical repair in this group with respect to quality of life.

METHODS

The authors formulated a decision analytical model to compare 4 treatment strategies (no repair or repair at 3, 6, or 12 months of life) for infants with persistent NBPPs. The model derives data from a critical review of published studies and projects health-related quality of life and quality-adjusted life years over a lifetime.

RESULTS

When evaluating the quality of life of infants with NBPP, improved outcomes are seen with delayed surgical repair at 12 months, compared with no repair or repair at early and intermediate time points, at 3 and 6 months, respectively. ANOVA showed that the differences among the 4 groups are highly significant (F = 8369; p < 0.0001). Pairwise post hoc comparisons revealed that there are highly significant differences between each pair of strategies (p < 0.0001). Meta-regression showed no evidence of improved outcomes with more recent treatment dates, compared with older ones, for either nonsurgical or for surgical treatment (p = 0.767 and p = 0.865, respectively).

CONCLUSIONS

These data support a delayed approach of primary surgical reconstruction to optimize quality of life. Early surgery for NBPPs may be an overly aggressive strategy for infants who would otherwise demonstrate spontaneous recovery of function by 12 months. A randomized, controlled trial would be necessary to fully elucidate the natural history of NBPP and determine the optimal time point for surgical intervention.

An obstetric brachial plexus data sheet

BACKGROUND

Several reputed obstetric brachial plexus clinics use their own protocols and indications for surgery. This study is to present and explain the obstetric brachial plexus data sheet used at our institution.

METHODS

The data sheet is composed of 5 main parts: (1) the basic database which includes the name, age, type and side of palsy, maternal history, birth history and other complications of the traumatic delivery; (2) motor assessment of the limb; (3) preoperative investigations; (4) description of intraoperative brachial plexus findings and type of nerve procedure performed; and (5) secondary surgery to the shoulder, elbow, forearm, wrist and hand.

RESULTS

The data sheet was found useful in documenting the assessment and events in infants and older children.

CONCLUSION

An obstetric brachial plexus data sheet is presented and it may be modified and used by other centers.

Lack of effectiveness of primary conservative management for infants with brachial plexus birth palsy

PURPOSE

Brachial plexus birth palsy (BPBP) is the most common peripheral nerve injury in children (prevalence <5.1 per 1000 live births) and conservative management is routinely used to manage them. We have previously systematically reviewed studies investigating primary conservative management, published between 1992 and 2002, and found these to be inconclusive. The aim of this review was to update our previous systematic review to include studies published between 2002 and 2008, synthesise the data thus obtained with that of our previous review and create an up-to-date body of evidence for conservative management of infants with BPBP.

PROCEDURES

Fifteen databases were searched systematically for quantitative studies (randomised controlled trials, comparative studies, case series), published in English between January 2002 and June 2008 inclusive. Studies were excluded if they investigated infants who, in their first two years of life, underwent microsurgical repair of the brachial plexus, surgical management of secondary deformities or received other treatments traditionally delivered by surgeons, such as Botulinum toxin injections. The eligibility of each study identified from the database searches was evaluated against the inclusion criteria by two independent reviewers. These studies were then critically appraised for level of evidence using the National Health and Medical Research Council of Australia Hierarchy of Evidence and methodological quality using the Critical Review Form - Quantitative Studies. Data pertaining to the demographic characteristics of study participants, treatments received, main results and outcome measures used were also extracted. Where any disagreement between reviewers occurred, consensus was reached by discussion. Data from the recently published studies were narratively synthesised and then combined with the data gained from our previous systematic review to create a body of evidence on primary conservative management for BPBP infants.

RESULTS

Four publications, representing three studies (one comparative study, two case series), were sourced. Methodological quality scores of these studies ranged from 6 to 12 (maximum =16). The current body of evidence (publications from 1992 to 2008) therefore comprises 11 studies, four using a comparative design and seven using a case series design. Six of the 11 studies were classified as being of "poor" methodological quality (score <8). Conservative management mainly consisted of exercise therapy, although splinting, massage and dynamic traction were also used. All studies lacked a clear definition of conservative management sufficient to allow replication of the treatment in a clinical setting. A variety of outcome measures were used, limiting comparability of the studies. Data from the three case studies suggests that conservative management may be more effective in infants with upper and middle plexus injuries compared with total plexus palsy. However, the different outcome measures used and lack of comparison groups limit the strength of this finding.

CONCLUSIONS

The body of evidence investigating the use of primary conservative management of infants with BPBP remains inconclusive. The studies published to date are limited in number, level of evidence and methodological quality. Further, a variety of outcome instruments, with limited psychometric properties, have been used to investigate management techniques which do not mirror those of contemporary clinical practice.

An economic analysis of the timing of microsurgical reconstruction in brachial plexus birth palsy

BACKGROUND

The role and timing of microsurgical reconstruction of the brachial plexus in infants who have no signs of biceps recovery within the first six months of life is controversial. The purpose of the present study was to create an economic model to compare microsurgical treatment at three as opposed to six months in patients with brachial plexus birth palsy who had no return of biceps function at three months.

METHODS

A cost-minimization study was performed with use of a decision-analysis model. Natural history, success, and tendon transfer and osteotomy rates were estimated from the literature. Costs were estimated from a single center.

RESULTS

The literature on patients without nerve root avulsion supports an 80% rate of biceps recovery between three and six months of age. On the basis of this value, microsurgical intervention at three months was more expensive than microsurgical intervention at six months. Microsurgical intervention at three months cost more than twice as much as intervention at six months. Sensitivity analysis revealed that when the rate of biceps recovery was 40% and surgery at three months was three times more successful than surgery at six months, then both treatments had equal costs.

CONCLUSIONS

It is unlikely that microsurgical intervention at three months for the treatment of rupture injuries of the brachial plexus will be successful enough to produce overall cost savings. While our results should not be used to dictate policy decisions as they are not definitive and remain contingent on future studies, it is still reasonable to consider economic factors and quality-of-life outcomes in brachial plexus birth palsy treatment strategies and future research.

Comparison of visual and objective quantification of elbow and shoulder movement in children with obstetric brachial plexus palsy

BACKGROUND

The Active Movement Scale is a frequently used outcome measure for children with obstetric brachial plexus palsy (OBPP). Clinicians observe upper limb movements while the child is playing and quantify them on an 8 point scale. This scale has acceptable reliability however it is not known whether it accurately depicts the movements observed. In this study, therapist-rated Active Movement Scale grades were compared with objectively-quantified range of elbow flexion and extension and shoulder abduction and flexion in children with OBPP. These movements were chosen as they primarily assess the C5, C6 and C7 nerve roots, the most frequently involved in OBPP. Objective quantification of elbow and shoulder movements was undertaken by two-dimensional motion analysis, using the v-scope.

METHODS

Young children diagnosed with OBPP were recruited from the Royal Children's Hospital (Melbourne, Australia) Brachial Plexus registry. They participated in one measurement session where an experienced paediatric physiotherapist facilitated maximal elbow flexion and extension, shoulder abduction and extension through play, and quantified them on the Active Movement Scale. Two-dimensional motion analysis captured the same movements in degrees, which were then converted into Active Movement Score grades using normative reference data. The agreement between the objectively-quantified and therapist-rated grades was determined using percentage agreement and Kappa statistics.

RESULTS

Thirty children with OBPP participated in the study. All were able to perform elbow and shoulder movements against gravity. Active Movement Score grades ranged from 5 to 7. Two-dimensional motion analysis revealed that full range of movement at the elbow and shoulder was rarely achieved. There was moderate percentage agreement between the objectively-quantified and therapist-rated methods of movement assessment however the therapist frequently over-estimated the range of movement, particularly at the elbow. When adjusted for chance, agreement was equal to chance.

CONCLUSION

Visual estimates of elbow and shoulder movement in children with OBPP may not provide true estimates of motion. Future work is required to develop accurate, clinically-acceptable methods of quantifying upper limb active movements. Since few children attained full range of motion, elbow and shoulder movement should be monitored and maintained over time to reduce disability later in life.

Interobserver reliability of the Mallet score

The interobserver reliability of the Mallet score for active shoulder function was assessed by three experienced observers in a group of 30 children with an obstetric brachial plexus lesion (mean age 7.1 years, range 4.5-10 years). Interobserver reliability, measured using weighted kappa, was good. Kappa varied between 0.37 and 0.84 and differed between the different aspects of the Mallet score and different pairs of observers. In decreasing order, mean weighted kappa was 0.75 for abduction, 0.73 for hand to neck, 0.67 for hand to spine, 0.6 for external rotation and 0.53 for hand to mouth.

Prognostic relevance of risk factors for obstetrical brachial plexopathy

We did a case-control study to verify if the birthweight, forceps delivery or perinatal asphyxia have any significant effect on the prognosis of obstetrical brachial plexopathy. Group A was composed of 25 infants who completely recovered at the age of 6 months. Group B was composed of 21 infants who were still not able to remove a blindfold from the face with the affected limb in the sitting position at the age of 12 months. There was no statistical difference of the median birthweight or median first minute Apgar score between the groups. There was also no relation between birthweight higher than 4000g, first minute Apgar score lower than 6 or forceps delivery with a poor prognosis.

Pediatric Evaluation of Disability Inventory: its application to children with obstetric brachial plexus palsy

PURPOSE

A standardized method of measurement of self-care ability in children with obstetric brachial plexus palsy (OBPP) has not been universally adopted. A study was conducted to determine if the Pediatric Evaluation of Disability Inventory (PEDI) was able to discriminate between the self-care ability of children with OBPP and their peers and distinguish between those with differing severities of OBPP.

METHODS

The PEDI self-care domain results for 45 children with OBPP (30 without hand impairment, 15 with hand impairment) were reviewed retrospectively.

RESULTS

The group performance of children without hand impairment was within 1 SD above the mean. The group performance of children with hand impairment was more than 2 SDs below the mean. The difference between the 2 groups was statistically significant.

CONCLUSIONS

In this study children without hand impairment did not have a self-care activity limitation as measured by the PEDI. A deficit in self-care ability was found in those with hand impairment. The PEDI was able to differentiate between the performances of reported self-care activities of children with differing severities of OBPP; however, it was unable to discriminate between those without hand impairment and their peers.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic, Level II.

Effectiveness of primary conservative management for infants with obstetric brachial plexus palsy

BACKGROUND

Obstetric brachial plexus palsy, a complication of childbirth, occurs in 1-3 per 1000 live births internationally. Traction and/or compression of the brachial plexus is thought to be the primary mechanism of injury and this may occur in utero, during the descent through the birth canal or during delivery. This results in a spectrum of injuries that vary in severity, extent of damage and functional use of the affected upper limb. Most infants receive treatment, such as conservative management (physiotherapy, occupational therapy) or surgery; however, there is controversy regarding the most appropriate form of management. To date, no synthesised evidence is available regarding the effectiveness of primary conservative management for obstetric brachial plexus palsy.

OBJECTIVES

The objective of this review was to systematically assess the literature and present the best available evidence that investigated the effectiveness of primary conservative management for infants with obstetric brachial plexus palsy.

SEARCH STRATEGY

A systematic literature search was performed using 14 databases: TRIP, MEDLINE, CINAHL, AMED, Web of Science, Proquest 5000, Evidence Based Medicine Reviews, Expanded Academic ASAP, Meditext, Science Direct, Physiotherapy Evidence Database, Proquest Digital Dissertations, Open Archives Initiative Search Engine, Australian Digital Thesis Program. Those studies that were reported in English and published over the last decade (July 1992 to June 2003) were included in this review.

SELECTION CRITERIA

Quantitative studies that investigated the effectiveness of primary conservative management for infants with obstetric brachial plexus palsy were eligible for inclusion in this review. This excluded studies that solely investigated the effect of primary surgery for these infants, management of secondary deformities and the investigation of the effects of pharmacological agents, such as botulinum toxin.

DATA COLLECTION AND ANALYSIS

Two independent reviewers assessed the eligibility of each study for inclusion into the review, the study design used and its methodological quality. Where any disagreement occurred, consensus was reached by discussion. Studies were assessed for clinical homogeneity by considering populations, interventions and outcomes. Where heterogeneity was present, synthesis was undertaken in a narrative format.

RESULTS

Eight studies were included in the review. Most were ranked low on the Hierarchy of Evidence (no randomised controlled trials were found), and had only fair methodological quality. Conservative management was variable and could consist of active or passive exercise, splints or traction. All studies lacked a clear description of what constituted conservative management, which would not allow the treatment to be replicated in the clinical setting. A variety of outcome instruments were used, none of which had evidence of validity, reliability or sensitivity to detect change. Furthermore, less severely affected infants were selected to receive conservative management. Therefore, it is difficult to draw conclusions regarding the effectiveness of conservative management for infants with obstetric brachial plexus palsy.

CONCLUSIONS

There is scant, inconclusive evidence regarding the effectiveness of primary conservative intervention for infants with obstetric brachial plexus palsy. Further research should be directed to develop outcome instruments with sound psychometric properties for infants with obstetric brachial plexus palsy and their families. These outcome instruments should then be used in well-designed comparative studies.

Motor conduction studies for prognostic assessment of obstetrical plexopathy

Early prognostic assessment of obstetrical brachial plexopathies (OBP) would facilitate rational selection of infants for brachial plexus surgery. We performed bilateral motor nerve conduction studies (MNCS) of axillary, musculocutaneous, radial, median, and ulnar nerves in 33 babies (age 10-60 days) with OBP in order to compare the amplitude of compound muscle action potentials (CMAPs). All babies were followed up until 6 months of age and the outcome was classified according to muscle strength and arm function. A CMAP amplitude reduction of more than 90%, compared to the unaffected side, predicted severe weakness of the corresponding root level (p < 0.01). Our results indicate that MNCS are a useful tool for very early prognostic assessment of OBP.

Assessment of the motor power in older children with obstetric brachial plexus palsy

The King Saud University (KSU) muscle grading system used for assessing the upper limb in older children with obstetric brachial plexus palsy is presented and compared to other muscle grading systems.

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.