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Commentary and Perspective   |    
Commentary on an Article by Marybeth Ezaki, MD, et al.: “OnabotulinumtoxinA Injection as an Adjunct in the Treatment of Posterior Shoulder Subluxation in Neonatal Brachial Plexus Palsy”
Michael L. Pearl, MD
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The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

Copyright © 2010 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2010 Sep 15;92(12):e17 1-2. doi: 10.2106/JBJS.J.00938
The main article is available here
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Dr. Ezaki and coauthors bring to the orthopaedic literature the most comprehensive and convincing experience to date demonstrating a role for Botox (onabotulinumtoxinA) injection in the treatment of early internal rotation contractures secondary to birth brachial plexus palsy. The authors are to be congratulated for pushing forward a treatment protocol that was aimed at, and seems to have achieved, a reduced need for more extensive surgical procedures on their patients. What we learn from this study is that Botox injection into the internal rotator muscles of the shoulder and immobilization of the shoulder in a spica cast in external rotation decreases the severity of internal rotation contractures and possibly resultant humeral head and glenoid dysplasia in some children with birth brachial plexus palsy. What remains unclear is whether casting alone might be beneficial and how beneficial this would be. There are also many unanswered questions regarding which children are the best candidates for this intervention in terms of age, severity of contracture and deformity, etc. For those who do not respond to this treatment regimen, might we be expending resources and treatment opportunities that might have been better utilized by other procedures?
One section of this article that merits clarification is the discussion of humeral head subluxations and dislocations. It is misleading to conceptualize the glenohumeral dysplasia that results from these contractures as the humeral head leaving the confines of a well-formed socket. As they stated, "Subluxation is the term used if there is some contact between … the glenoid and the humeral head. Dislocation refers to … the humeral head posterior to … the glenoid and the posterior aspect of the labrum." The dysplasia from birth brachial plexus palsy results in abnormal glenoid and humeral shapes that are almost always in contact with each other, except in the most severe cases. The glenoid becomes convex (a pseudoglenoid), and although the humeral head is posterior to the scapular plane, it is not a true dislocation1,2. In this context, subluxation also takes on a different meaning, as does the concept of achieving a reduction. For children with this condition, if we can achieve external rotation of >45° with the arm at the side, we "reduce" the shoulder in that we better align the humeral head with the scapula. What happens at the joint is variable. Depending on the age of the patient, this maneuver likely results in immediate plastic deformation of pliable articular surfaces or reduction of the humeral head on the anterior aspect of the convex glenoid with the hope of eventual remodeling, or some combination of the two3-6.
The information from this study is likely to alter the treatment practice of various medical centers differently, depending on their present protocol for managing children with birth brachial plexus palsy. In my practice, where children with fixed contractures associated with glenohumeral deformity are treated with an arthroscopic release typically at fifteen months of age, Botox injection with casting has its primary role in children less than one year old with loss of passive shoulder external rotation to =30° with the arm at the side. For somewhat older children (but usually still less than two years old) who have internal rotation contractures evolving under our supervision despite home stretching and therapy, Botox injection has also been useful to convince all involved that the most conservative measures have been exhausted. In contrast to the authors’ protocol, we also inject the latissimus dorsi but follow their recommendation of a maximum total dose of 10 U/kg. Our early experience to date has been encouraging, but there have been at least as many failures with contracture recurrence requiring surgical release.
It bears mention that the off-label use of Botox as described here differs from its use for spasticity or other unwanted cholinergic mediated physiologic responses. For birth brachial plexus palsy, we inject the child's relatively normal musculature to improve muscular balance. Safety issues are an even greater concern as we paralyze the normal muscles of these growing children. While there is no evidence that a single treatment will permanently damage these normal muscles, some of the children in this series received two treatments. Given the three-month duration of action of Botox, one can imagine scenarios in which patients with an incomplete response are recommended to undergo multiple injections—a treatment approach that should be discouraged until we have more information.
Pearl  ML;  Edgerton  BW. Glenoid deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am.  1998;80:659-67.[PubMed]
 
Pearl  ML;  Edgerton  BW;  Kon  DS;  Darakjian  AB;  Kosco  AE;  Kazimiroff  PB;  Burchette  RJ. Comparison of arthroscopic findings with magnetic resonance imaging and arthrography in children with glenohumeral deformities secondary to brachial plexus birth palsy. J Bone Joint Surg Am.  2003;85:890-8.[PubMed]
 
Pedowitz  DI;  Gibson  B;  Williams  GR;  Kozin  SH. Arthroscopic treatment of posterior glenohumeral joint subluxation resulting from brachial plexus birth palsy. J Shoulder Elbow Surg.  2007;16:6-13.[PubMed][CrossRef]
 
Pearl  ML;  Edgerton  BW;  Kazimiroff  PA;  Burchette  RJ;  Wong  K. Arthroscopic release and latissimus dorsi transfer for shoulder internal rotation contractures and glenohumeral deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am.  2006;88:564-74.[PubMed]
 
Waters  PM;  Bae  DS. The early effects of tendon transfers and open capsulorrhaphy on glenohumeral deformity in brachial plexus birth palsy. J Bone Joint Surg Am.  2008;90:2171-9.[PubMed]
 
Pearl  ML. Shoulder problems in children with brachial plexus birth palsy: evaluation and management. J Am Acad Orthop Surg.  2009;17:242-54.[PubMed]
 

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References

Pearl  ML;  Edgerton  BW. Glenoid deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am.  1998;80:659-67.[PubMed]
 
Pearl  ML;  Edgerton  BW;  Kon  DS;  Darakjian  AB;  Kosco  AE;  Kazimiroff  PB;  Burchette  RJ. Comparison of arthroscopic findings with magnetic resonance imaging and arthrography in children with glenohumeral deformities secondary to brachial plexus birth palsy. J Bone Joint Surg Am.  2003;85:890-8.[PubMed]
 
Pedowitz  DI;  Gibson  B;  Williams  GR;  Kozin  SH. Arthroscopic treatment of posterior glenohumeral joint subluxation resulting from brachial plexus birth palsy. J Shoulder Elbow Surg.  2007;16:6-13.[PubMed][CrossRef]
 
Pearl  ML;  Edgerton  BW;  Kazimiroff  PA;  Burchette  RJ;  Wong  K. Arthroscopic release and latissimus dorsi transfer for shoulder internal rotation contractures and glenohumeral deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am.  2006;88:564-74.[PubMed]
 
Waters  PM;  Bae  DS. The early effects of tendon transfers and open capsulorrhaphy on glenohumeral deformity in brachial plexus birth palsy. J Bone Joint Surg Am.  2008;90:2171-9.[PubMed]
 
Pearl  ML. Shoulder problems in children with brachial plexus birth palsy: evaluation and management. J Am Acad Orthop Surg.  2009;17:242-54.[PubMed]
 
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