Congenital and acquired atrophy of the shoulder girdle muscles in a patient with Sprengel's deformity.

INTRODUCTION Sprengel’s deformity is a congenital anomaly of the shoulder girdle which results in elevation of the scapula (congenital high scapula) and limitation of movement of the shoulder. Sprengel’s deformity is the most common congenital malformation of the shoulder girdle, with a male to female ratio of 3:1. It is frequently associated with cervical spine malformations, absent or hypoplastic periscapular musculature, and abnormalities in the cervicothoracic vertebrae or thoracic rib cage: absent or fused ribs, chest wall asymmetry, Klippel-Feil syndrome, cervical ribs, congenital scoliosis, and cervical spina bifida. The hallmark of Sprengel’s deformity is shoulder asymmetry with restriction of shoulder abduction. The elevation of the scapula is accompanied by its rotation to various positions. Clinically, the affected scapula is usually elevated 2 to 10 cm, adducted, and its inferior pole is medially rotated. The left side is more commonly affected but may sometimes be bilateral, in which case it is more functionally disabling, although it is cosmetically much more acceptable. No satisfactory explanation exists regarding the pathogenesis of Sprengel’s deformity. It is thought to be the consequence of teratogenic exogenous or endogenous harmful agent affecting mesenchymal tissue in the fourth to fifth week of embryogenesis. There may be hereditary forms. There is underdevelopment and degeneration of the shoulder girdle muscles and creation of abnormal omovertebral fibrous, cartilaginous or osseous connection, such as the presence of an omovertebral bone seen in approximately one-third of patients. The hypoplastic scapula is usually tethered to the spine and posterior ribs by tight bands or by the omovertebral bone, which restricts scapular movements, and therefore abduction of the arm. The diagnosis of Sprengel’s deformity is based on clinical examination and radiological findings. It is uncommon to identify an adult with untreated Sprengel’s deformity, like the patient who presented here. Most patients with Sprengel’s deformity receive surgical treatment as children or adolescents. Adult patients with childhood polio, an acquired cause of weakness of the shoulder girdle, may present later in life with symptoms and signs of thoracic outlet syndrome with worsening of the weakness. The accompanying pain and sensory symptoms such as tingling and “numbness” would mitigate against a diagnosis of post polio syndrome in these patients.