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© 1999 The Journal of Bone and Joint Surgery, Inc. Comparison of the Natural History, the Outcome of Microsurgical Repair, and the Outcome of Operative Reconstruction in Brachial Plexus Birth Palsy* , BOSTON, MASSACHUSETTSInvestigation performed at Children's Hospital, Harvard Medical School, Boston
Background: The purposes of this study were to document the natural history of brachial plexus birth palsy, in relation to the recovery of biceps function, in the first six months of life; to assess the outcome after microsurgical repair of the brachial plexus in patients who had no recovery of biceps function at six months; and to compare the results of transfer of the latissimus dorsi and teres major tendons with the results of derotation osteotomy of the humerus and to compare the results of the tendon transfers and the osteotomy with the natural history of the disorder. Methods: Sixty-six patients (sixty-seven lesions) who had brachial plexus birth palsy were seen for an initial evaluation when they were less than three months old. The time of recovery of biceps function was recorded for each month of life for six months from the date of birth. The patients were divided into groups according to the month of life during which recovery of biceps strength was noted. A physical examination and an assessment with use of the functional criteria of Mallet were performed each month. Microsurgical repair of the brachial plexus was performed in six infants who had no evidence of biceps function within the first six months of life. Another group of twenty-seven patients were referred for evaluation of chronic neuropathy after they were six months old. A transfer of the latissimus dorsi and teres major tendons to the rotator cuff was performed in nine of these patients and a derotation osteotomy of the humerus was performed in seven because of an internal rotation contracture or functional weakness of the external rotators of the shoulder. Results: Twenty-two infants had recovery of biceps function within the first three months of life and had normal function at the time of the latest evaluation. Infants who had recovery of biceps function during the fourth, fifth, or sixth month of life later had significantly worse function, according to the criteria described by Mallet, than those who had had recovery in the first three months (p < 0.005). The clinical results for the six patients who had had microsurgical repair six months after birth were significantly better (p < 0.04) than those for the fifteen patients who had had recovery of biceps function in the fifth month of life. However, the results for the patients who had had repair of the brachial plexus were not found to be better than those for the eleven patients who had had recovery of biceps function in the fourth month of life. The improvement in function, as assessed with use of the Mallet criteria, after tendon transfer (p < 0.001) and humeral osteotomy (p < 0.0001) was significant. Conclusions: The present study confirms the observation of Gilbert and Tassin that it is rare for infants who have recovery of biceps function after the age of three months to have complete neurological recovery. Microsurgical repair was effective in improving function in the small subgroup of patients who had no evidence of recovery of biceps function within the first six months of life.
The natural history of brachial plexus birth palsy is largely unknown, as there are few studies in which infants who had this condition were followed from birth to recovery or to maturity7,15. Several of the published studies were retrospective and included only a small number of patients because many were lost to follow-up1,10,19. Other studies included only patients who had been referred to a specialist because of a residual neurological deficit, which introduced a pre-selection bias in the patient population19,21. The authors of a few papers concluded that infants who have evidence of some neurological recovery in all muscle groups within the first or second month of life will have complete recovery10,15,17,19. The role of microsurgical reconstruction of the brachial plexus in infants who have no signs of recovery within the first six months of life is controversial. Current recommendations for management consist of microsurgical reconstruction of the brachial plexus at the age of three months, if there is no evidence of recovery of biceps function7,13,16-18, or just observation or physical therapy19. The purposes of the present study were (1) to assess the natural history of brachial plexus birth palsy in the first six months of life and to determine the reliability of using return of biceps function to predict the long-term outcome, (2) to assess the results of microsurgical repair of the brachial plexus in patients who have no evidence of recovery of biceps function within the first six months of life, and (3) to compare the results of transfer of the latissimus dorsi and teres major tendons with those of derotation osteotomy of the humerus, as well as to compare the results of each of these procedures with the natural history of brachial plexus birth palsy.
Between January 1989 and December 1995, I evaluated ninety-three patients (ninety-four lesions) who had been referred at birth because of a brachial plexus palsy or who had a residual neurological deficit from a brachial plexus birth palsy. Sixty-six patients (sixty-seven lesions) were evaluated within the first three months of life. A database was created to record the birth history, the results of the initial musculoskeletal and neurological examinations, and the radiographic findings as documented in the neonatal medical records. At each follow-up visit, I recorded muscle function, the passive and active ranges of motion, and the presence of any glenohumeral instability or dislocation. The timing of recovery of biceps function in the first six months of life was recorded by me for forty-six patients (forty-seven lesions), and it was noted from hospital and office records for twenty patients. For analysis of the outcome, the patients were divided into groups according to the month during which recovery of biceps function was first noted. Eight patients had recovery within one month after birth. One patient, who had bilateral involvement, had bilateral recovery during the second month of life. Twelve patients had recovery during the third month; eleven, during the fourth month; fifteen, during the fifth month; and thirteen, during the sixth month. Six patients had no evidence of recovery at six months, and they were managed with microsurgical repair. For the purpose of data analysis, the patient who had recovery of biceps function during the second month was included in the group of patients who had recovery during the third month. The patients' functional status was classified according to the system of Mallet14, which includes the functional parameters of global abduction, global external rotation, the ability to bring the hand to the neck and to the mouth, and internal rotation. These parameters were assessed and were recorded for each patient at each visit17, and the findings were used to categorize the functional status into one of five classes. Class 1 indicates the absence of function. Class 2 indicates an inability to bring the hand to the neck and less than 30 degrees of global abduction, less than 0 degrees of external rotation, a marked trumpet sign (abduction of the shoulder accompanied by simultaneous flexion of the elbow) when bringing the hand to the mouth, and no internal rotation. Class 3 indicates 30 to 90 degrees of global abduction, 0 to 20 degrees of external rotation, difficulty in bringing the hand to the neck, a partial trumpet sign when bringing the hand to the mouth, and internal rotation to the first sacral vertebra. Class 4 indicates ease in bringing the hand to the neck and more than 90 degrees of global abduction, more than 20 degrees of external rotation, less than 40 degrees of abduction when bringing the hand to the mouth, and internal rotation to the twelfth thoracic vertebra. Class 5 implies normal function. It can be difficult to assess and to grade individual muscles in infants and young children. The Mallet functional assessment gives the examiner information about the absence of function, partial function against gravity, and normal function against gravity. Each parameter helps in the assessment of a composite movement and of the muscles that facilitate and perform the action being tested. Specifically, global abduction is used to assess the function of the deltoid, supraspinatus, serratus anterior, and infraspinatus muscles. Global external rotation is used to assess the function of the supraspinatus, infraspinatus, and teres minor muscles. The action of bringing the hand to the mouth is used to assess the function of the biceps, brachialis, coracobrachialis, pectoralis major, pectoralis minor, latissimus dorsi, and deltoid muscles. The action of bringing the hand to the neck is used to assess the function of the deltoid, supraspinatus, serratus anterior, pectoralis major, biceps, brachialis, and coracobrachialis muscles. The classification system of Narakas, which is used after a child is three weeks old, was employed to divide the patients into four groups according to the level of neurological involvement17. Patients in group 1 have a classic Erb palsy with weakness of shoulder abduction and external rotation, elbow flexion, and forearm supination (involvement of the fifth and sixth cervical nerve roots). Patients in group 2 have the same findings as those in group 1, as well as weakness of elbow and wrist extension (involvement of the fifth, sixth, and seventh cervical nerve roots). Patients in group 3 have the same findings as those in group 2, as well as weakness of finger extension (involvement of the fifth cervical through first thoracic nerve roots). Patients in group 4 have a flail arm with or without a Horner syndrome (involvement of the entire brachial plexus). The classification systems of Mallet and Narakas necessitate a careful physical examination of the patient. For newborns and infants, this requires patience and close observation of either spontaneous motion of the shoulder, elbow, wrist, and hand or movement of the extremity in response to stimulation by a parent or the clinician. Pertinent information about an older child can be obtained by observing the child at play. The return of biceps function was assessed by checking for a palpable contraction and the ability of the infant to move the extremity against gravity. Provocative tests were used to stimulate neonatal reflexes (the Moro reflex and asymmetrical tonic neck reflexes) to produce abduction and forward elevation of the shoulder, flexion of the elbow, and movements of the wrist and digits. At each follow-up visit, the active and passive ranges of motion, muscle strength, and the functional parameters of the Mallet classification system were documented for each subgroup7,17. The patients were also grouped according to the level of the residual neurological deficit. Patients who had involvement of the fifth and sixth cervical nerve roots had functional deficits of the deltoid, supraspinatus, infraspinatus, and biceps muscles, which resulted in weakness of abduction and external rotation of the shoulder, flexion of the elbow, and supination of the forearm. Patients who had involvement of the fifth, sixth, and seventh cervical nerve roots had the same deficits and weakness as the group that had involvement of the fifth and sixth cervical nerve roots. They also had involvement of the triceps, extensor carpi radialis longus and brevis, and extensor carpi ulnaris muscles, which resulted in weakness of elbow and wrist extension. Patients who had involvement of the eighth cervical and first thoracic nerve roots had residual weakness of the intrinsic muscles of the hand and of the flexor digitorum profundus and superficialis, flexor carpi radialis, and flexor carpi ulnaris muscles, with alteration in wrist and finger flexion. Patients who had involvement of all of the roots from the fifth cervical to the first thoracic level had weakness of all of the previously mentioned muscles and functions. Statistical comparisons were made among the Mallet scores of the different subgroups with use of the SPSS statistical software package (SPSS, Chicago, Illinois). Both analysis of variance and multiple analysis of variance were performed to explore the relationship between the timing of recovery of biceps function and the outcome as defined by the Mallet grade for each parameter. At the time of this review, all sixty-six patients were at least two years old and had been followed for an average of three years (range, two to eleven years). The patients who had recovery of normal function (the subgroup who had return of biceps function within the first two months of life) were discharged from care when they were two years old. The other patients continued to be evaluated at regular intervals. The medical records of twenty-seven patients who were more than six months old and who had been referred for evaluation of a chronic neuropathy were examined for information similar to that obtained for the patients who were studied prospectively. These patients were previously under the care of other members of the same pediatric orthopaedic surgery department. Details of the neurological examination, when available, were recorded retrospectively. These twenty-seven patients had not been evaluated by me in the first six months of life and did not have documentation of the timing of biceps recovery; thus, they were excluded from the analysis of neurological recovery. Nine of these patients had tendon transfers and seven had an osteotomy of the humerus.
Microsurgical Repair
Tendon Transfers and Osteotomy of the Humerus Seven of the sixteen patients who had severe functional limitations and evidence, on the imaging study, of a deformity of the humeral head, posterior glenohumeral subluxation, and glenoid hypoplasia had a derotation osteotomy of the humerus11,20. The average age at the time of the operation was nine years (range, three to thirteen years). Preoperatively, there was residual weakness of muscles innervated by the fifth and sixth cervical nerve roots in two patients; those innervated by the fifth, sixth, and seventh cervical nerve roots in three; and those innervated by the eighth cervical and first thoracic nerve roots in two. The preoperative and postoperative clinical evaluations included all of the parameters that were assessed for the prospective series. At the time of this review, all sixteen patients had been followed for more than two years postoperatively. Statistical comparisons were made between this group and the natural history and microsurgical groups at the time of the initial visit and at the latest follow-up evaluation.
Natural History Groups
Recovery During First Month
Recovery During Second or Third Month
Recovery During Fourth Month
Recovery During Fifth Month
Recovery During Sixth Month
Recovery During Fourth, Fifth, or Sixth Month
Group Managed with Microsurgical Repair
Group Managed with Tendon Transfer to the Rotator Cuff According to the classification system of Mallet, the average preoperative value was 2.9 for global abduction, 2.0 for global external rotation, 2.1 for the ability to bring the hand to the neck, and 2.1 for the ability to bring the hand to the mouth. Preoperative global abduction was class 2 in one patient and class 3 in eight. Preoperative global external rotation was class 2 in all nine patients. The ability to bring the hand to the neck was class 2 for eight patients and class 3 for one preoperatively. The ability to bring the hand to the mouth was class 1 for one patient, class 2 for seven, and class 4 for one preoperatively (Table II). The average preoperative passive external rotation at 90 degrees of shoulder abduction was -11 degrees (range, -40 to 25 degrees) on the affected side and 28 degrees (range, 20 to 40 degrees) on the normal side. At the time of follow-up at 2.4 years (range, two to four years) postoperatively, the average value was 3.9 for global abduction, 4.0 for global external rotation, 4.0 for the ability to bring the hand to the neck, and 4.0 for the ability to bring the hand to the mouth. Postoperative global abduction was class 3 in one of these patients and class 4 in the remaining eight, and postoperative global external rotation was class 4 in all nine patients. The ability to bring the hand to the neck and the ability to bring the hand to the mouth were also class 4 for all nine patients postoperatively (Table II). The average passive external rotation at 90 degrees of shoulder abduction was 19 degrees (range, 10 to 40 degrees) on the affected side and 28 degrees (range, 20 to 40 degrees) on the normal side. There was significant postoperative improvement in all of the measured parameters (p < 0.0005).
Three of the nine patients were known to have recovery of biceps function within six months after the operation, and the values for the functional parameters for these three patients were equivalent to those for the tendon-transfer group as a whole. The preoperative status of the nine patients who had a tendon transfer was statistically similar to that of the natural history subgroup that had evidence of recovery of biceps function during the sixth month. The biceps function after the transfers, as assessed according to the Mallet classes, was statistically equivalent to the function in the natural history subgroup that had recovery of function during the first, second, or third month of life.
Group Managed with Derotation Osteotomy of the Humerus
Comparison Among Subgroups According to the criteria used by Mallet, abduction (p < 0.001), external rotation (p < 0.0001), the ability to bring the hand to the mouth (p < 0.0001), and the ability to bring the hand to the neck (p < 0.0001) improved significantly after the tendon transfer. Similarly, abduction (p < 0.0001), external rotation (p < 0.0001), the ability to bring the hand to the mouth (p < 0.0001), and the ability to bring the hand to the neck (p < 0.0001) improved significantly after the derotation osteotomy of the humerus. In both groups, the functional status improved from being statistically equivalent to the group that recovered biceps function at six months to being equivalent to the group that recovered biceps function at three months.
The present study substantiates the conclusions of other studies that recovery of neurological function within one month after birth will result in normal neurological function. Greenwald et al.11 reported that thirty-six (95 percent) of thirty-eight newborn infants had complete recovery from a brachial plexus birth palsy and that twenty-five (66 percent) had it in the first week of life and thirty-five (92 percent) had it in the first three months of life. However, these conclusions were based on only thirty-eight of their original sixty-one patients, as twenty-three patients were lost to follow-up. Most reports in the orthopaedic, plastic surgical, neurosurgical, and microsurgical literature have presented findings in patients more than three months old who had a persistent neurological deficit1,2,13,15,21. The authors of these studies were less optimistic than Greenwald et al. about the chance of full recovery, although they concurred that recovery in the first four to six weeks of life leads to normal neurological function1,7,15. Gilbert and Meyer8 originally recommended microsurgical repair in patients who had no evidence of recovery of biceps function within six months after birth. They subsequently modified their statement and recommended repair if there was no recovery within three months. Unfortunately, the exact definition of recovery of biceps function has not been well delineated. In addition, I am not aware of any comparative studies of the results of repair based on the age of the patient at the time of repair. Michelow et al.15 recommended microsurgical repair if there was incomplete recovery when the infant was between nine and twelve months old. They recommended the use of a composite score of shoulder abduction, elbow flexion, and wrist, finger, and thumb extension rather than recovery of biceps function alone to predict a poor outcome and as a selection criterion for microsurgical repair. Regrettably, there is still a lack of consensus on the exact indications for microsurgical reconstruction of the brachial plexus in a patient who has birth palsy1-3,5,7-9,13-18. Concerns include the wish to avoid unnecessary operations and the fear that performing an operation either too early or too late will make the final outcome worse. Other authors have advocated late reconstruction of the glenohumeral joint with transfer of the latissimus dorsi and teres major tendons4,12 or a derotation osteotomy of the humerus11 for patients who have limited function. The present study supports the data of Michelow et al.15, who evaluated sixty-six patients; Gilbert and Meyer8, who evaluated 100 patients; and Benson et al.1, who evaluated 173 patients. Those authors reported that most infants who have involvement of the upper trunk and involvement of the fifth, sixth, and seventh cervical nerve roots have a worse prognosis than do those with involvement of the fifth and sixth cervical nerve roots. Failure to recover extension of the wrist, fingers, and thumb, in combination with failure to recover biceps function within three months after birth, indicates a worse prognosis1,7,9,15. In the current study, greater involvement of the eighth cervical and first thoracic nerve roots, in comparison with involvement of the fifth, sixth, and seventh cervical nerve roots, indicated a poorer prognosis. The presence of a Horner syndrome also indicated a poor prognosis3,6,15. Five of the six patients who had no evidence of biceps recovery within six months had a Horner syndrome (p < 0.0005). The other patients who had a Horner syndrome included four patients who had a greater degree of involvement of the eighth cervical and first thoracic nerve roots and one patient, who was four years old at the latest evaluation, who had evidence of recovery of biceps function in the sixth month but still had very poor function. The present study confirms the observation by Gilbert and Tassin7 that it is rare for infants who have recovery of biceps function after they are three months old to have complete neurological recovery. None of the thirty-nine patients in the present study who had recovery of biceps function during the fourth, fifth, or sixth month after birth had full recovery according to the Mallet classification. Furthermore, only one of the twelve patients who had had recovery of biceps function during the third month after birth had a normal Mallet score. Glenohumeral motion was limited in the patients who had had recovery of biceps function after the age of two months. Compared with the contralateral shoulder, passive external rotation was permanently limited (p < 0.0005) and winging of the scapula was present (p < 0.005) to compensate for the lack of passive glenohumeral rotation. The decrease in global abduction, global external rotation, the ability to bring the hand to the mouth, and the ability to bring the hand to the neck was significantly greater (p < 0.0005) in the patients who had had recovery of biceps function during the fourth, fifth, or sixth month than in patients who had had recovery of biceps function within the first three months of life. In addition, function decreased with an increase in the delay until recovery in the group of patients who had had recovery during the fourth, fifth, or sixth month. Microsurgical repair improved function in the small subgroup of patients who had no evidence of recovery of biceps function within the first six months of life. A repair would have been performed in an additional thirty-nine of the sixty-six patients if failure of recovery of biceps function within three months had been used as the indication for microsurgical repair of the brachial plexus. It is not known whether these patients would have done better or worse or remained at the same functional level after microsurgical repair. Gilbert and Whitaker9 as well as Boome and Kaye2 reported the results of microsurgical repair in patients who had had no recovery of biceps function within the first three months of life. Their findings were similar to the long-term Mallet scores for the patients in the present study who had recovery of biceps function between the third and sixth months of life without microsurgical repair. I recognize the difficulty of comparing the patients in the current study with those in other reports. Also, the Mallet classification may not be the best measure of functional outcome. The score can be affected by many factors, such as the strength of multiple muscles, the active and passive ranges of motion of each joint, osseous deformity, the cooperativeness of the child, and the patience and skill of the examiner. Even though the classification system of Mallet is used frequently, it has not been validated for precision and accuracy. In the current study, a tendon transfer (as described by L'Episcopo and modified by Hoffer et al.12) or a derotation osteotomy of the humerus greatly improved function in patients who had a residual brachial plexopathy. On the basis of the results of the present study, I am currently performing microsurgical repair in infants who have a flail arm and a Horner syndrome at the age of three months and in infants who have had no return of biceps function by the age of five months. I am also performing secondary reconstructive procedures in all children who have an internal rotation contracture of the shoulder, weakness of external rotation, and poor Mallet scores. A tendon transfer is performed in young patients who have only minor glenohumeral deformity, as seen on imaging studies, whereas an osteotomy of the humerus is performed in older patients who have severe glenohumeral deformity. In addition, I continue to prospectively study the natural history of the disorder, the results of microsurgical repair, and the results of secondary reconstructive procedures in these patients. A future prospective, multicenter study would be ideal to determine whether microsurgical intervention at three months in infants with no recovery of biceps function will lead to better function than will microsurgery at six months or spontaneous recovery augmented by secondary reconstructive procedures.
NOTE: The author is indebted to Jodi Vasen, Ph.D., for the statistical analysis.
*No benefits in any form have been received or will be recieved from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
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