Introduction
What is Birth Palsy?
Causes
Diagnosis and Management
Surgical treatment
The Brachial Plexus is the joining of cervical nerve trunks located between the cervical spine and the clavicle. It provides innervation to the upper limbs. It is formed by the combination and division of the 5 pairs of nerve roots, the C5, C6, C7, C8 and T1. There are 17 peripheral nerves emerge from the plexus, providing the motor control and sensory reception of the upper limbs from the shoulder to the finger tips.
Birth Palsy is describing the paralysis of the upper limb due to injury to the Brachial Plexus at birth. There are Upper Plexus Palsy (Erb’s Palsy) and Total Plexus Palsy (Global Palsy). Incidence of Birth Palsy is reported as 0.1 to 2.5 per 1000 live birth. It usually involves one side of the body, more often the right. In Upper Plexus Palsy, the hand and finger movements are spared, only the shoulder and the elbow are affected: there is limited active movement of the shoulder and elbow flexion. The upper limb tends to lie close to the body, the forearm and hand rotated to the back. The baby cannot raise the shoulder or open the arms. Total Plexus Palsy is more serious, affecting the whole upper limb, and occasionally, affects the sympathetic innervation of the ipsilateral eye, presenting as Horner syndrome with drooping of the upper eyelid and constriction of the pupil. Other common concomitant injury are fracture clavicle, fracture humerus, phrenic nerve palsy, congenital muscular torticollis and hemiparesis. Fortunately, most of the Birth Palsy are transient and can recover without much residual symptoms. Only a small portion of them would end up with permanent partial or complete upper limb paralysis.
Most of the Birth Palsy is related to difficult labour, about 93-96% is with shoulder dystocia. When the shoulder of the baby is caught in the birth canal during delivery, doctors or midwifes might need to pull the head and neck out while assisting the passage of the body to avoid asphyxia. Excessive pulling on the neck might have tense up the brachial plexus and its nerve branches, producing different degrees of nerve tissue damage. Excessive tension might rupture the nerve tissues, resulting in permanent nerve injury. About 1.5% of Birth Palsy might be found in babies delivered in Caserean Section.
Risk factors of Birth Palsy:
1. Previous history of labour with shoulder dystocia
2. Overweight Foetus: The chance of shoulder dystocia is about 1.7% for foetus over 4000 gm.; and is about 20%, if it is over 4500 gm
3. Overweight mother
4. Mother with diabetes mellitus of pregnancy.
5. Eclampsia of pregnancy
6. Prolonged labour
7. Prematurity
It is usually not difficult to observe that the active movement of the affected upper limb is limited, the diagnosis of birth palsy is among the possible causes such as fracture of the clavicle and fracture of the right humerus. The prognosis of fracture in neonates should be good and usually would heal without much sequale. However, if the paucity of active movement of shoulder and elbow persist more than one to two weeks, one should be alert and a detail examination of the brachial plexus is mandatory.
Although about 90% of the Upper Brachial Plexus Palsy will recover in about 3 to 6 months, assessment of the progress may be difficult in neonates. Referral to an experienced paediatrician and orthopaedic surgeon for continuous assessment and follow up. Timely intervention in form of physiotherapy or surgical exploration might be necessary should there be any complication or arrest in recovery.
As the optimal time for surgical exploration and nerve surgery is in the first 6 months, it is difficult to decide on the necessity of surgical intervention. If the nerves are ruptured, delay repair will only lead to progressive muscle wasting, so much that any subsequent nerve surgery may not be able to revive the muscle bulk. On the other hand, an injured but continuous nerve trunk, especially the upper plexus, may repair by itself if left alone, imprudent surgery may affect its natural recovery. Furthermore, prolonged surgery in a 3 to 6 month child carries a higher risk. Recent reports in the medical literature tend to agree on surgical exploration and nerve repair in 3 months if there is no return of the elbow flexion for upper brachial plexus palsy. For total brachial plexus injury, surgical exploration and nerve repair procedures would probably be indicated in most cases.
Nerve repair and reconstruction are complicated microsurgical procedures to be done by experienced hand surgeons, paediatric neurosurgeons with anaesthetists specialized in paediatric anaesthesia. It may require taking nerve grafts from non-essential areas to bridge up nerve defects and gaps.
Post-operative rehabilitation with physiotherapy and occupational therapy are essential. The repaired or grafted nerve trunks have to be protected from tension and yet all the joints, especially the shoulder, need to be exercised and the surrounding muscles stimulated with active exercises to prevent muscle atrophy.
If for various reasons, primary nerve reconstruction surgery had not been offered in the first 9 months, or the return of nerve function after surgery is short of satisfaction, patient might consider secondary reconstruction.
Ruptured nerves can regenerate and may reach the wrong innervation, resulting in un-coordinated, non- synergic movements affecting the shoulder, elbow and forearm movement. Other surgical options such as peri-articular muscle release, muscle transfer and osteotomy etc. may be necessary at different stage.
Dr. CHOI, Kai-yiu