Erb's Palsy

Introduction

Obstetric paralysis is currently reported at 0.4 to 2.5 per 1000 live births. In 90% of cases, birth has been difficult and traumatic. The injury is classified as upper plexus (Erb's & Duchenne), whole plexus, and lower plexus (Klumpke's). Of these, Erb's palsy is the commonest. The muscles most frequently paralyzed are the Supra and Infraspinatus due to fixity and the resultant injury of the Suprascapular nerve. Other muscles innervated by the C5 and C6 roots may be affected.

The clinical findings are variable. Initially, the newborn lies with the extremity limp and no demonstrable muscle contraction. Diffuse upper limb swelling may occur and epiphyseal separations around the shoulder girdle are frequently associated. The involvement of the dorsal scapular or anterior thoracic nerve indicates a poor prognosis.

A severe injury presents with characteristic deformities. The shoulder is maintained flexed, internally rotated, and mildly abducted. Active abduction is not possible. A severe internal rotation contracture develops and the humeral head may subluxate or dislocate posteriorly. Change in the configuration of the humeral head may occur. Deformities of the elbow and the forearm manifest as pronation contracture of the forearm dislocated radial head and bowing of the ulnar shaft. The wrist is maintained in palmar flexion. With the extension of the injury to the C7, there is paralysis of the elbow, wrist, and finger extensors and a resultant flexion attitude of the fingers and the thumb.

The aim of treatment in the initial stages of this paralysis should be to prevent contractures of muscles and joints while awaiting neurological recovery. A home exercise treatment plan should be taught to parents with an emphasis on gentle passive exercises to maintain a full range of motion in all upper extremity joints. The exercises should be carried out for 3 to 5 minutes every time a diaper is changed. The services of a skilled pediatric physiotherapist and a play therapist are essential. During the first year, the baby should be assessed neurologically every month and any developing contracture must be treated by aggressive physiotherapy and splintage. Thereafter examinations can be carried out less frequently. A minimal injury responds well to conservative treatment and spontaneous recovery occurs up to 18 months. A residual disability may be slight. Infraclavicular brachial plexus injuries carry a better prognosis than supraclavicular lesions. Surgical exploration is carried out when there is no return of power after 3 months in a whole plexus injury. Operative intervention is also indicated if there is non-progression of recovery and the lesion is determined as postganglionic involving the upper trunk. Preganglionic lesions may be explored if the lowest 2 roots are involved to determine the status of the upper roots. Excision of neuromas in continuity or neurolysis, when indicated may be beneficial. Patients over three years of age presenting with contractures are candidates for surgical correction of their deformity after preliminary physiotherapy and splintage. There are many surgical procedures based on the works of Fairbanks, Sever, Steindler, and others. These involve releasing of tight structures namely the pectoralis major, subscapularis, anterior joint capsule, Latissimus Dorsi, and Teres major and muscle transfers to augment external rotation at the shoulder. A previously dislocated shoulder is surgically treated by reduction and posterior bony buttressing. Other operations described are the humeral rotational osteotomy, pronator release in the forearm, rotational osteotomy of radius and ulna and excision of the radial head. However, even after the most carefully planned surgery, motion and muscle control remain significantly weak.