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Abstract & Commentary
Source: Anand P, Birch R. Brain. 2002;125:113-122.
Despite improvement in perinatal care, the incidence of perinatal brachial plexus palsy (PBPP) has not declined in recent years (Dodds S, Wolfe S. Curr Opin Pediatr. 2000;12:40-47). The incidence of such injuries is approximately 0.1% in infants with birthweights < 4000 gm, but approximately 0.3% in infants weighing > 4500 gm at birth (Rouse DJ, et al. JAMA. 1996;276: 1480-1486). Thus, a large hospital can expect to see several cases of PBPP annually. In addition to macrosomia, additional risk factors for PBPP include shoulder dystocia, forceps or vacuum- assisted delivery, breech delivery, prolonged labor, and a previous birth complicated by PBPP. Although the older literature uses the terms "Erb’s palsy" and "Klumpke paralysis" to refer to upper and lower cervical PBPP, respectively, recent recommendations have suggested assessing PBPP on a 4-level scale of increasing severity (van Ouwerkerk, et al. Childs Nerv Syst. 2000;16:638-644).
Group 1 lesions involve lesions of the C5 or C6 roots or superior trunk with paralysis of shoulder abduction, elbow flexion, and forearm supination. Finger motion is normal. Spontaneous recovery rate is approximately 90%.
Group 2 lesions include Group 1 lesions with the additional involvement of C7 roots or medial trunk. In this case, there is paralysis of the extensors but not flexors of the fingers. Spontaneous recovery rate is approximately 65%.
Group 3 lesions add involvement of finger flexors, so that there is essentially no hand motion. Horner’s sign is absent. Spontaneous recovery rate is probably somewhat less than 50%.
Group 4 lesions present as a flail arm with Horner’s sign, indicating complete plexus lesion. There is no spontaneous recovery. This group also includes another variant ("dominant C7" paralysis) in which there is selective failure of shoulder adduction and elbow extension.
Unless a Group 4 lesion is clearly present at birth, the natural history of high spontaneous recovery of the lower grade lesions mandates conservative follow-up for a period of time following birth. Several authors recommend that if no recovery has occurred spontaneously by 3 months, then electrophysiological evaluation should be performed and if avulsion is confirmed, surgical repair be considered. This surgical repair is complex but is discussed in detail in this article.
The long-term outcome of sensory function in severe brachial palsy is unknown. Anand and Birch examined 24 patients who sustained severe (defined as either Group 3 or Group 4) injury at birth. These patients were examined at age 3-23 years, and 20/24 patients surgically repaired, the majority before 1 year of age. Remarkably, and in contrast to adults, none of these patients reported limb pain. This was true even in patients that had not been surgically repaired. All 4 of the nonoperated patients had persistent anesthesia to all sensory modalities in the injured arm and hand, but 18/20 (90%) of operated patients had at least some recovery of sensation, and in 3 it was complete. All patients could accurately localize pain, suggesting that plasticity had occurred, preserving original topographic organization. Interestingly, there was no clear correlation between interval between time of injury (birth) and the time of surgical repair, up to at least 35 months and return of sensory function; motor function is clearly better restored the earlier the operation is performed.
This paper beautifully illustrates the differences between nerve root avulsion in the developing and adult nervous systems. Whereas the recovery of sensory function is poor and persistence of chronic pain high in the adult, the situation is totally different in the young child. This paper also suggests that the nature of sensory nerve recovery changes after 3 years of age. Further studies are needed to define the temporal window where recovery begins to resemble the adult pattern. Presumably, molecular mechanisms underlie these dramatic differences. —Rosario Trifiletti
Dr. Trifiletti, Assistant Professor of Neurology & Pediatrics, New York Presbyterian Hospital-Cornell Campus, is Assistant Editor of Neurology Alert.