An MRI study on the relations between muscle atrophy, shoulder function and glenohumeral deformity in shoulders of children with obstetric brachial plexus injury^[*]

Abstract

Background A substantial number of children with an obstetric brachial plexus lesion (OBPL) will develop internal rotation adduction contractures of the shoulder, posterior humeral head subluxations and glenohumeral deformities. Their active shoulder function is generally limited and a recent study showed that their shoulder muscles were atrophic. This study focuses on the role of shoulder muscles in glenohumeral deformation and function.

Methods This is a prospective study on 24 children with unilateral OBPL, who had internal rotation contractures of the shoulder (mean age 3.3 years, range 14.7 months to 7.3 years). Using MR imaging from both shoulders the following parameters were assessed: glenoid form, glenoscapular angle, subluxation of the humeral head, thickness and segmental volume of the subscapularis, infraspinatus and deltoid muscles. Shoulder function was assessed measuring passive external rotation of the shoulder and using the Mallet score for active function. Statistical tests used are t-tests, Spearman’s rho, Pearsons r and logistic regression.

Results The affected shoulders showed significantly reduced muscle sizes, increased glenoid retroversion and posterior subluxation. Mean muscle size compared to the normal side was: subscapularis 51%, infraspinatus 61% and deltoid 76%. Glenoid form was related to infraspinatus muscle atrophy. Subluxation was related to both infraspinatus and subscapularis atrophy. There was no relation between atrophy of muscles and passive external rotation. Muscle atrophy was not related to the Mallet score or its dimensions.

Conclusion Muscle atrophy was more severe in the subscapularis muscle than in infraspinatus and deltoid. As the muscle ratios are not related to passive external rotation nor to active function of the shoulder, there must be other muscle properties influencing shoulder function.

^*This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

• References

• 1 Evans-Jones G, Kay SP, Weindling AM, Cranny G, Ward A, Bradshaw A. Congenital brachial palsy: incidence, causes, and outcome in the United Kingdom and Republic of Ireland. Arch Dis Child Fetal Neonatal Ed. 2003; 88 (3) 185-189 10.1136/fn.88.3.F185
• 2 Hoeksma AF, Ter Steeg AM, Dijkstra P, Nelissen RG, Beelen A, de Jong BA. Shoulder contracture and osseous deformity in obstetrical brachial plexus injuries. J Bone Joint Surg Am 2003; 85-A: 316-322 12571311
• 3 Pearl ML, Edgerton BW, Kon DS, Darakjian AB, Kosco AE, Kazimiroff PB. 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-A: 890-898 12728041
• 4 Dahlin LB, Erichs K, Andersson C, Thornqvist C, Backman C, Duppe H. Incidence of early posterior shoulder dislocation in brachial plexus birth palsy. J Brachial Plex Peripher Nerve Inj 2007; 2: 24 2225400 18081937 10.1186/1749-7221-2-24
• 5 Birch R. Birth lesions of the brachial plexus. In: Birch R, Bonney G, Wynn Parry CB. Surgical disorders of the peripheral nerves. Churchill Livingstone; London: 1998: 209-233
• 6 Waters PM, Smith GR, Jaramillo D. Glenohumeral deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am 1998; 80: 668-677 9611027
• 7 Poyhia TH, Nietosvaara YA, Remes VM, Kirjavainen MO, Peltonen JI, Lamminen AE. MRI of rotator cuff muscle atrophy in relation to glenohumeral joint incongruence in brachial plexus birth injury. Pediatr Radiol 2005; 35: 402-409 10.1007/s00247-004-1377-3 15635469
• 8 Einarsson F, Hultgren T, Ljung BO, Runesson E, Friden J. Subscapularis muscle mechanics in children with obstetric brachial plexus palsy. J Hand Surg Eur Vol 2008; 33: 507-512 10.1177/1753193408090764 18687840
• 9 van der Sluijs JA, van Ouwerkerk WJ, de Gast A, Wuisman PI, Nollet F, Manoliu RA. Deformities of the shoulder in infants younger than 12 months with an obstetric lesion of the brachial plexus. J Bone Joint Surg Br 2001; 83: 551-555 10.1302/0301-620X.83B4.11205 11380130
• 10 Mallet J. [Obstetrical paralysis of the brachial plexus. II. Therapeutics. Treatment of sequelae. Priority for the treatment of the shoulder. Method for the expression of results]. Rev Chir Orthop Reparatrice Appar Mot 1972; 58 Suppl 1: 166-168
• 11 van Ouwerkerk WJ, Sluijs JAvan der, Nollet F, Barkhof F, Slooff AC. Management of obstetric brachial plexus lesions: state of the art and future developments. Childs Nerv Syst 2000; 16: 638-644 10.1007/s003810000319 11151713
• 12 Narakas AO. Obstetrical brachial plexus injuries. In: Lamb D. The Paralysed Hand. Churchill Livingstone; Edinburgh: 1987: 116-135
• 13 Ward SR, Hentzen ER, Smallwood LH, Eastlack RK, Burns KA, Fithian DC. Rotator cuff muscle architecture: implications for glenohumeral stability. Clin Orthop Relat Res 2006; 448: 157-163 10.1097/01.blo.0000194680.94882.d3 16826111
• 14 Friedman RJ, Hawthorne KB, Genez BM. The use of computerized tomography in the measurement of glenoid version. J Bone Joint Surg Am 1992; 74: 1032-1037 1522089
• 15 Kamath S, Venkatanarasimha N, Walsh MA, Hughes PM. MRI appearance of muscle denervation. Skeletal Radiol 2008; 37: 397-404 10.1007/s00256-007-0409-0 18360752
• 16 Terzis JK, Vekris MD, Okajima S, Soucacos PN. Shoulder deformities in obstetric brachial plexus paralysis: a computed tomography study. J Pediatr Orthop 2003; 23: 254-260 10.1097/00004694-200303000-00023 12604961
• 17 Nath RK, Paizi M. Scapular deformity in obstetric brachial plexus palsy: a new finding. Surg Radiol Anat 2007; 29: 133-140 1820760 17262175 10.1007/s00276-006-0173-1
• 18 Petersilge CA, Pathria MN, Gentili A, Recht MP, Resnick D. Denervation hypertrophy of muscle: MR features. J Comput Assist Tomogr 1995; 19: 596-600 10.1097/00004728-199507000-00017 7622691
• 19 Williams PE, Goldspink G. Changes in sarcomere length and physiological properties in immobilized muscle. J Anat 1978; 127: 459-468 1235732 744744
• 20 Kozin SH. Correlation between external rotation of the glenohumeral joint and deformity after brachial plexus birth palsy. J Pediatr Orthop 2004; 24: 189-193 15076606