The brachial plexus nerve is the main nerve innervating the upper extremity and can be divided into three segments: root, trunk, and bundle, each of which has branches innervating the corresponding muscles. The brachial plexus nerve travels between the clavicle and the first rib when it is fixed to the rib by the sternoclavicular fascia, and then passes under the rostral process of the humerus. The main causes of injury during delivery are obstructed shoulder delivery in cephalic position, misjudgment of fetal position, incorrect technique in brachial delivery or difficulty in delivering the posterior head, and strong pulling on the fetal shoulder and neck. The clinical manifestations vary according to the location of the injury, but the most common is superior palsy, with the typical manifestations being: the affected limb hanging loosely on the side of the body, unable to do activities such as abduction, external rotation and elbow flexion. Neonatal brachial plexus palsy can cause incalculable damage to individuals, families and society. Prevention is very important. Before delivery, we should estimate the weight of the fetus, identify the signals of breech delivery, master the indications of cesarean section and the delivery mechanism of cephalic and breech position, deliver the baby in a tense but not in a hurry, and correctly adopt various methods of handling breech delivery to ensure the safety of mother and baby. Neonatal brachial plexus palsy, also known as neonatal birth injury, is caused by excessive pulling of the fetal shoulder and neck during delivery.
1.Application of the anatomy of the brachial plexus nerve
1.1 Segmentation of the brachial plexus nerve, the brachial plexus nerve is the main nerve innervating the upper limbs, consisting of the 5th, 6th, 7th, 8th cervical nerve and the anterior branch of the 1st thoracic nerve combined, which can be divided into 3 segments: root, stem and bundle. The cervical 5 and 6 form the superior trunk, the cervical 7 extends into the middle trunk, and the cervical 8 and thoracic 1 form the inferior trunk. Each segment has branches to innervate the corresponding muscles. The axillary nerve, median nerve, musculocutaneous nerve, ulnar nerve, and radial nerve innervate the deltoid, pronator teres, biceps brachii, piriformis, and triceps brachii muscles, respectively. The interosseous muscle of the hand distributes the ulnar nerve, the cutaneous nerve of the back of the hand distributes the ulnar and radial nerves, and the cutaneous nerve of the palm distributes the ulnar and median nerves. Based on the paralysis of these muscles, the site and degree of brachial plexus paralysis can be indirectly determined.
1.2 The course of the brachial plexus nerve, the nerve roots of the brachial plexus nerve exit the intervertebral foramen of the cervical vertebrae and penetrate between the anterior and middle oblique muscles to divide into three trunks of the brachial plexus. When the brachial plexus nerve travels between the clavicle and the first rib, it is fixed to the first rib together with the axillary artery by the sternoclavicular fascia and then passes under the rostral process of the humerus. When the distance between the first rib and the rostral process is widened by external force, the brachial plexus nerve is damaged by strong pulling.
2, causes of brachial plexus nerve palsy
2.1 Cephalic delivery
(1) Shoulder obstructed labor: mostly seen in huge babies, due to the difficulty of delivering the shoulder and the use of strong pressure on the front shoulder method, so that the fetal head and neck try to pull in the direction of the opposite shoulder, so that the upper stem of the brachial plexus is in a state of tension, resulting in upper stem injury, which is the main cause of brachial plexus nerve paralysis.
(2) Fetal orientation error: the fetal head is mistakenly turned to the opposite side when the fetal head is rotated, resulting in the separation of the fetal head and shoulder in the opposite direction, which widens the distance between the first rib and the rostral process and causes brachial plexus palsy.
2.2 Breech delivery
(1) Incorrect delivery of the breech causes the breech to be delivered in an abducted manner, resulting in tension of the lower trunk of the brachial plexus nerve, which causes damage to the lower trunk and paralysis.
(2) Difficulty in delivery of the posterior head and strong pulling of the fetal shoulder and neck may cause complete paralysis of the brachial plexus nerve.
3. Clinical manifestations and typing of brachial plexus palsy
3.1 Upper trunk palsy typically shows that the upper limb is loosely suspended on the side of the body, the shoulder joint is internally rotated, the elbow joint is elongated, the forearm is rotated to the front, and the affected limb cannot do abduction and external rotation and elbow flexion.
3.2 Lower stem palsy, also known as forearm or stem-arm palsy, is less common. It mainly affects the ulnar nerve and median nerve, manifesting as partial or complete loss of wrist flexion and extension of the little finger.
3.3 The whole brachial plexus palsy consists of three trunks of the brachial plexus are injured, resulting in total motor and sensory paralysis of the affected limb. If the injury is close to the intervertebral foramen, Horner’s syndrome may appear, i.e., no sweating on the affected side, ptosis, protrusion of the eye fissure, small pupil, and sensory impairment in the ulnar nerve distribution.
4.Prevention
The main causes of brachial plexus palsy are obstructed shoulder delivery and breech delivery, and incorrect delivery method is also a factor that cannot be ignored.
4.1.1 Prenatal prediction of obstructed shoulder delivery is estimated to be 3%-12% for fetal weight ≥4000g [calculation method: uterine height (cm) × abdominal circumference (cm) +200] and 8.4%-14.6% for those above 4500g. 4.8cm is prone to difficult shoulder delivery and cesarean delivery should be recommended.
4.1.2 Prediction of obstructed shoulder delivery during labor
(1) Prolongation of the second stage of labor and failure of median forceps;
(2) Retraction of the fetal neck after delivery of the fetal head. (2) Retraction of the fetal neck after delivery of the head.
4.1.3 Handling of obstructed shoulder delivery When the factors of obstructed shoulder delivery are present before delivery and the signals of obstructed shoulder delivery appear during delivery, the midwife must be calm and handle the obstructed shoulder delivery correctly.
①Cesarean section should be performed if the possibility of shoulder obstructed labor is predicted before delivery.
②Vaginal delivery:
a. Flexion of thigh method: Let the mother bend her legs upward as much as possible against her abdomen, and hold her knees with both hands to reduce the pelvic tilt so that the front shoulder embedded above the pubic symphysis can be released naturally.
b.Pressure on the front shoulder method: apply pressure to the front shoulder of the fetus above the pubic symphysis to help the delivery of the embedded front shoulder.
c. Shoulder rotation method: Show the middle two fingers into the vagina and press against the back shoulder of the fetus and rotate the back shoulder to the side, the assistant will help to rotate the fetal head in the same direction and deliver the fetus when the back shoulder gradually rotates to the front shoulder.
d. The method of delivering the back shoulder by pulling out the back arm first: put your hand into the vagina along the sacrum, push the back upper limb and arm of the fetus, slide the fetus out of the vagina along the fetal chest and face and deliver the back shoulder and back upper limb of the fetus.
e. If the above methods are not effective, the fetal clavicle can be cut and the soft tissue can be sutured after delivery and the clavicle can be healed.
4.2 If breech delivery has been clearly diagnosed before delivery, in principle, cesarean section should be performed to end the delivery. If it is difficult to come out of the head after vaginal delivery, do not pull violently, and use the forceps to assist delivery after breech delivery, and general forceps can also be used instead. Lift the fetal trunk to reveal the perineum, put the left lobe and right lobe forceps into the fetal ventral side in turn, and pull downward and outward after intercourse.
4.3 Improve the quality of obstetrics and insist on the correct delivery to clarify the fetal orientation and determine the direction of the fetal back before delivery to avoid turning the fetal head to the opposite side by mistake during delivery; when assisting the delivery of the fetal buttocks in breech delivery, make sure that the fetal arms are delivered in a “cat wash” manner
Brachial plexus nerve injury in newborns
It is caused by excessive pulling on the head or arm during delivery, and can be classified according to the location of damage:
1, upper arm type (erb paralysis) c5,c6 nerve root innervated muscles are involved. The affected limb is drooping and inward, the shoulder is internally rotated, the elbow is rotated forward, the wrist and finger joints are flexed, and the embrace reflex is asymmetrical.
2, lower arm type (klumpke) paresis) c8 to t1 nerve root involvement, wrist flexor and hand muscle weakness, weak grip reflex.
The whole arm type is rare and has the above two types of symptoms. In the case of cervical sympathetic nerve damage, the upper eyelid droops, the pupil narrows, and homer syndrome appears.
Children with brachial plexus injury need to rest their shoulders and avoid traction, and most of them can recover in 2 to 3 weeks. Parents should be instructed to give the child passive activities to abduct the shoulder, rotate the arm backward, and extend the wrist. EMG should be reviewed periodically to determine the extent of injury and to estimate the prognosis. If the injury is still ineffective after more than 6 months, an abduction brace should be applied to prevent shoulder contracture, and in severe cases, nerve bundle anastomosis can be considered.
Diagnosis and treatment of neonatal brachial plexus nerve injury
Direct trauma such as stab wounds, contusions, and fractures of the clavicle and first rib can cause brachial plexus injury. Indirect trauma can be seen with forceful pulling of the upper limb, excessive head and neck bending, etc.
Indirect trauma is seen when the upper limb is pulled, the head and neck are bent to the opposite side excessively or the shoulder is pressed down strongly, such as heavy blows or birth injuries.
A. Clinical manifestations and diagnosis
(a) Complete brachial plexus injury motor disorders are manifested as total paralysis of the hand, forearm and upper arm muscles. Sensory changes are the loss of sensation in the hand, forearm and part of the upper arm. Injury at the proximal intervertebral foramen of cervical 8 and thoracic 1 may present with (Horner)’s syndrome.
(B) upper brachial plexus injury (Erb-Duchence type) This type is more common and is caused by injury to the cervical 5-6 nerve root at Erb’s point. This point is proximal to the suprascapular nerve and distal to the long thoracic and dorsal scapular nerves. The anterior serratus and rhomboid muscles are not affected. It is mostly caused by trauma that separates the head and shoulder, subacromial shoulder pressure or birth injury.
Motor: deltoid, teres minor, supraspinatus, infraspinatus and pectoralis major clavicularis are paralyzed, and the upper limbs are internally rotated due to the action of the latissimus dorsi and pectoralis major sternalis. The biceps and brachioradialis were paralyzed, the anterior brachialis was weakened, and the elbow joint was straightened due to the action of the triceps. The posterior rotator and anterior rotator roundus are paralyzed, and the forearm is rotated anteriorly due to the action of the anterior rotator muscle. The radial wrist extensors are paralyzed and the hand is deflected to the ulnar side. Sensation: sensation is not affected in the case of injury to the anterior branch of cervical 5. If cervical 6 is involved, numbness of the upper arm and lateral forearm is present. No Horner’s syndrome.
(C) lower brachial plexus injury (Klumpke type) is mainly cervical 8 thoracic 1 nerve root injury, mostly caused by excessive lifting or extension of the upper limb and excessive pulling of the trunk during arm position delivery. The main symptom is paralysis of the inner hand muscles with claw-like deformity. In the case of injury to the lower trunk of the brachial plexus, the flexors and extensors of the fingers are paralyzed. There is numbness of the ulnar side of the hand and forearm and a small area of numbness on the medial side of the upper arm. Horner’s syndrome may be present.
(D) Ancillary diagnostic methods The diagnosis of brachial plexus nerve injury mainly relies on medical history and clinical examination and X-ray radiography. Electrophysiological examination can help the localization and diagnosis of brachial plexus nerve injury.
1, electromyography examination of the posterior branch of the spinal nerve of the brachial plexus innervates the deep posterior cervical muscles. Therefore, the deepest posterior cervical muscles examined by EMG are the transverse spinal and intertransverse muscles. Where EMG shows denervated fiber fibrillation potentials, it indicates motor nerve fiber injury to the posterior branch of the spinal nerve, which is an intraspinal brachial plexus injury; where it shows no normal potentials, it indicates extraspinal brachial plexus injury; where there is active movement of any muscle innervated by the nerve root, i.e., it shows active muscle contraction potentials, it indicates incomplete nerve root injury.
Nerve injury generally degenerates significantly after three weeks, when electromyography is performed and denervated fiber fibrillation potentials are found. Therefore, electromyography
Electromyography should be performed at three weeks of injury, and rechecked at three-month intervals to observe any recovery of nerve function.
2, histamine flush test is mainly used to determine the site of brachial plexus strain injury, which can be divided into preganglionic and postganglionic injury. The signs of motor and sensory paralysis are the same in both types, but the axon reflex can be lost in postganglionic injury (extraforaminal nerve root injury) (negative), and the axon reflex may be present in preganglionic injury (intraforaminal nerve root injury) (positive). Methods: Intradermal injection with 1:1000 histamine phosphate is positive for a series of triple reactions.
(1) Immediate erythema of 10 mm in diameter.
(2) The appearance of an erythema of 20-40 mm around the erythema after half a minute.
(3) Wind masses appeared at the injection site. After peripheral nerve injury, only skin flushing without series of triadic reactions is observed. This method diagnoses brachial plexus nerve injury, positive mostly for preganglionic injury, negative mostly for postganglionic injury.
Second, treatment only a few patients with incomplete injury in 3 months to obtain satisfactory recovery, generally in 1 to 2 years constantly progress. When the upper brachial plexus injury, because the function of the hand is still good, so the effect of treatment recovery is better. In the case of lower brachial plexus injury, the function of the hand is more heavily involved and recovery is poor. Recovery from a complete brachial plexus injury is poor.
Brachial plexus injury caused by birth injury has symptoms such as swelling and pressure pain in the supraclavicular region and impaired arm movement in the early stage. A brace can be applied to keep the affected shoulder at 90° of abduction and 90° of elbow flexion to relax the nerve for recovery. Passive movement of the affected shoulder and elbow joint is performed several times a day.
In cases of partial brachial plexus injury, nerve release can often be performed to obtain some progress after the nerve function has stopped recovering. If necessary, nerve anastomosis is possible. To facilitate visualization, it is sometimes necessary to sever the clavicle. If there is a nerve defect, elevation of the affected shoulder with the head tilted to the affected side can help to perform nerve suturing and postoperative immobilization in a cast.
In upper brachial plexus injuries, if the shoulder muscles do not recover, shoulder fusion may be performed.
If the flexor muscles do not recover, elbow flexor plication can be performed using the forearm muscles or the pectoralis major muscle to improve function. Shoulder fusion should be performed after 14 to 15 years of age.
If the brachial plexus is completely injured and there is no sign of recovery, and the injury is within the intervertebral foramen, or if the injury cannot be repaired by surgical exploration, mid-arm amputation and shoulder fusion with a prosthesis can be considered as appropriate.
In recent years, great progress has been made in the treatment of brachial plexus radicular avulsion injury. The repair of axillary nerve, musculocutaneous nerve, median nerve, etc., using methods such as healthy cervical 7 nerve root transfer, phrenic nerve transfer, cervical plexus motor branch, paying nerve, intercostal nerve transfer, etc., have achieved certain efficacy, supplemented by muscle or musculocutaneous office transplantation, etc., so that the limb that has completely lost function has regained part of its function.