Pediatric orthopaedic cases 22

  Case 22                             

 

You are called to the newborn nursery to evaluate a 1-day-old girl who has not moved her right arm since birth. She was the product of spontaneous vaginal delivery at 41 weeks’ gestation. The mother’s pregnancy was complicated by gestational diabetes mellitus. Birth weight was 10 lb 2 oz (4,590 g). The delivery was complicated by shoulder dystocia lasting 1 minute, and the vacuum suction was used to facilitate delivery. The newborn girl now holds her arm in an extended and internally rotated position, with no active movement of the right upper extremity. She does not seem to respond to touch on that arm. She moves her left arm and both legs normally. There is no ecchymosis or swelling to suggest a fracture.

Your diagnosis is:

1. Cerebral palsy

2. Brachial plexus birth palsy

3. Congenital muscular torticollis

4. Arthrogryposis multiplex congenita

 

Discussion

The correct answer is (B). Prenatal risk factors for brachial plexus birth palsy include preeclampsia and gestational diabetes. Perinatal risk factors include macrosomia, shoulder dystocia, and the use of devices such as forceps and vacuum suction for delivery.

The differential diagnosis includes pseudoparalysis due to a fracture of the clavicle or humerus sustained during the birth practice. If local swelling or bruising suggests a fracture, x-rays should be obtained.

Upper extremity monoplegic type cerebral palsy can be mistaken for a brachial plexus birth palsy. Risk factors for cerebral palsy include prematurity and low birth weight.

Congenital muscular torticollis is due to a shortening or overactivity of the sternocleidomastoid muscle. The head is laterally tilted towards the affected muscle and rotated away from it.

Arthrogryposis multiplex congenital, or amyoplasia, is a condition of multiple congenital joint contractures. Hypoplasia of muscles leads to decreased joint

movement in utero. Usually both arms and both legs are involved, with the arms generally positioned in shoulder internal rotation, elbow extension, wrist flexion, and a thumb-in-palm deformity.

You notice that the newborn has ptosis of the eyelid on the same side as the paralyzed arm. On closer inspection, you also notice that the pupil is smaller than the contralateral side (miosis). You recognize that these signs, along with anhydrosis and enopthalmos, are known together as Horner’s syndrome.

 

Horner’s syndrome is a concomitant injury to the prognosis for this infant’s brachial plexus recovery:

1. Facial nerve, favorable

2. Facial nerve, unfavorable

3. Cervical sympathetic chain, favorable

4. Cervical sympathetic chain, unfavorable

 

Discussion

  , and denotes a   

The correct answer is (D). Horner’s syndrome arises from injury to the cervical sympathetic chain. Because the cervical sympathetic chain is in very close proximity to the spinal cord, Horner’s syndrome is pathognomonic for a brachial plexus injury that consists of a nerve root avulsion from the spinal cord. Birth injuries to the brachial plexus can occur along a continuum of severity (Fig. 10–40), of which nerve root avulsion is the most severe type.

 

 

 

Figure 10–40

 

Injury to the facial nerve is also possible during a difficult delivery. This would cause paralysis of the voluntary facial muscles, with facial drooping, on the affected side. There is no known prognostic value of a concomitant facial nerve injury.

You follow the patient’s recovery as an outpatient over the next few months. At the age of 6 months, you notice that her Horner’s syndrome has resolved. She can now move her fingers and wrist spontaneously, and she is able to internally rotate her shoulder. However, she still does not bend her elbow actively against gravity (AMS score of 3) and cannot elevate her shoulder in either forward flexion or abduction beyond 30 degrees even with gravity eliminated (AMS score of 2 for each).

Based on these physical examination findings, your next course of action is:

1. Schedule for exploration of the brachial plexus with microsurgical reconstruction

2. Schedule for Botox injections into her triceps and pectoralis major

3. Begin functional electrical stimulation therapy

4. Continue regular observation

5.  

Discussion

The correct answer is (A). Exact indications for microsurgical exploration and reconstruction of the brachial plexus are controversial in brachial plexus birth palsy. However, it is commonly agreed that for infants who do not recover the ability to flex the elbow against gravity by the age of 6 months, the course of their recovery will be improved by microsurgical treatment. The AMS or Active Movement Scale measures the active motion of 15 different movements of the upper extremity on a 0–7 scale, based on how much movement the child can produce with gravity eliminated (scores 0–4) or against gravity (scores 5–7).

Botox injections can be used as an adjunctive treatment in brachial plexus birth palsy, generally to assist in the treatment of secondary joint contractures.

On her preoperative examination, you notice that the passive range of motion of her shoulder has decreased from your prior examination. Specifically, it is difficult to passively externally rotate her shoulder while her arm is adducted to her side. You obtain an ultrasound of the shoulder, shown in Figure 10–41.

 

 

 

Figure 10–41 (Courtesy of Dr. Andrea Bauer)

 

The * in Figure 10–41 demonstrates:

1. The ossific nucleus of the humeral head, which is well-reduced in the glenoid

2. The ossific nucleus of the humeral head, which is posteriorly dislocated to the glenoid

3. The ossific nucleus of the humeral head, which is anteriorly dislocated to the glenoid

4. The ossific nucleus of the humeral head, which is superiorly dislocated to the glenoid

Discussion

The correct answer is (B). Ultrasound is a safe and reliable method of detecting glenohumeral dysplasia in infants with brachial plexus birth palsy. Through mechanisms that are still not completely understood, infants with brachial plexus birth palsy are at risk for developing glenohumeral dysplasia. The characteristic positioning is that of glenoid flattening and retroversion along with a flattened and posteriorly dislocated humeral head. Figure 10–42 demonstrates this positioning on ultrasound, this time with labels.

 

 

 

Figure 10–42

 

Objectives: Did you learn...?

 

The differential diagnosis of neonatal brachial plexus birth palsy?

 

The definition of a Horner’s syndrome and its prognostic value in brachial plexus birth palsy?

 

Indications for microsurgical repair for infants with brachial plexus birth palsy?

 

How to use ultrasound to evaluate for glenohumeral dysplasia in an infant with brachial plexus birth palsy?