Obstetrical Brachial Plexus Injuries

Question 1

What is the cause of obstetrical brachial plexus palsy?

Answer 1

Traction injury to the brachial plexus during the birth process

Question 2

What is the estimated incidence of obstetrical brachial plexus palsy?

Answer 2

0.2% to 4% of live births globally, with higher incidence in underdeveloped countries with poor obstetrical care.

Question 3

What is the rate of spontaneous recovery?

Answer 3

Most patients will show some degree of spontaneous recovery within 1 month, and near full recovery within
3 months due to the short distance required for nerve regeneration to reach the target muscles and faster nerve regeneration rate in infants. The majority of patients recover spontaneously (>90%) due to the relatively minor degree of injury.

Question 4

What maternal factors may be associated with obstetrical brachial plexus palsy?

Answer 4

1. diabetes
2. preeclampsia
3. pong duration of labor
4. history of delivery problems with earlier pregnancies

Question 5

What fetal factors may be associated with obstetrical brachial plexus palsy?

Answer 5

1. large fetus for gestational age
2. history of humeral fracture or clavicle fracture during birth

Question 6

What factors during birth may be associated with obstetrical brachial plexus palsy?

Answer 6

1. difficult arm or head extraction in breech deliveries
2. shoulder dystocia in vertex deliveries
3. forceps or vacuum use during delivery

Question 7

Where are the common locations for obstetric brachial plexus injuries?

Answer 7

Obstetric brachial plexus palsy usually involves the upper trunk (C5-6), although sometimes there may be an additional injury to C7. Occasionally, the entire plexus may be involved (C5-T1).

Question 8

What are the different types of brachial plexus lesions

Answer 8

1. stretch
2. rupture (postganglionic)
3. avulsion (preganglionic)
   The dorsal root ganglion is adjacent to the spinal cord and contains the sensory nerve cell body. The motor nerve cell body is located within the spinal cord.
   Avulsion results in preganglionic nerve discontinuity, which has poor prognosis. Stretch results in no discontinuity of the nerve.
   Rupture results in postganglionic nerve discontinuity.

Question 9

What physical or radiological findings would suggest preganglionic lesions?

Answer 9

1. Horner syndrome (sympathetic chain)
2. elevated hemidiaphragm (phrenic nerve)
3. winged scapula (long thoracic nerve)

Question 10

What are the signs of Horner syndrome

Answer 10

1. ptosis
2. miosis
3. anhidrosis

Question 11

What is the significance of Horner syndrome in a patient being evaluated for brachial plexus injury?

Answer 11

The presence of Horner syndrome indicates disruption of sympathetic fibers proximal to where the preganglionic
fibers arise and suggests severe brachial plexus avulsion injury.

Question 12

What is the significance of Horner syndrome in a patient being evaluated for brachial plexus injury?

Answer 12

The presence of Horner syndrome indicates disruption of sympathetic fibers proximal to where the preganglionic
fibers arise and suggests severe brachial plexus avulsion injury.

Question 13

What is the significance of phrenic nerve palsy in a patient being evaluated for brachial plexus injury?

Answer 13

The presence of phrenic nerve palsy suggests severe avulsion injury of the upper trunk.
It also eliminates phrenic nerve as a potential donor nerve for neurotization.

Question 14

What tests and studies can be ordered to evaluate obstetric brachial plexus injury?

Answer 14

1. CXR (to look for elevated hemidiaphragm as an indication of ipsilateral phrenic nerve palsy) 2. MRI (to evaluate for avulsion of the nerve roots from the spinal cord)
2. EMG/NCS (to assess the function of each nerve and the muscles it innervates)

Question 15

What is the most reliable method of assessing the level and severity of obstetric brachial plexus injury?

Answer 15

Physical examination to assess motor and sensory function. EMG/NCS may be helpful but lacks accuracy.

Question 16

What is Erb palsy?

Answer 16

Obstetric brachial plexus palsy involving the upper trunk.

Question 17

What is Klumpke palsy?

Answer 17

Obstetric brachial plexus palsy involving the lower trunk.

Question 18

Where is Erb point?

Answer 18

Point where C5 and C6 merge to form upper trunk.

Question 19

What is the typical posture of Erb palsy

Answer 19

The features of upper plexus palsy (“waiter’s tip” position) involving C5, C6, ±C7 are: 1. shoulder adduction and internal rotation
2. elbow extension
3. forearm pronation
4. wrist flexion
5. finger flexion

Question 20

What is the modified Mallet classification system used for?

Answer 20

It is used to assess and document the recovery of upper trunk function in obstetric brachial plexus palsy (see Figure 39-4). However, it cannot be used to assess forearm/wrist/hand function.

Question 21

What is the main goal of physical therapy in obstetric brachial plexus palsy patients?

Answer 21

To maintain passive range of motion/prevent stiffness and contracture of the affected joints.

Question 22

What is the most common indication for surgery in obstetric brachial plexus palsy patients?

Answer 22

Absence of elbow flexion (biceps function) by 3 to 4 months of age.

Question 23

What are contraindications for surgery in obstetric brachial plexus palsy patients?

Answer 23

Patients with continual improvement in functional recovery are not candidates for surgery. However, the function of each nerve must be evaluated separately. For example, recovery of hand function without recovery of shoulder/elbow function is still an indication for upper plexus (shoulder/elbow function) reconstruction surgery, but not lower plexus (hand function).

Question 24

What are the common primary surgical treatments for obstetric brachial plexus palsy?

Answer 24

1. neurolysis
2. neurotization
   a. nerve grafting b. nerve transfer

Question 25

What are sources for nerve grafting in brachial plexus reconstruction?

Answer 25

1. sural nerve 2. cervical plexus 3. lateral antebrachial cutaneous nerve

Question 26

In avulsion injuries, innervation must be provided by alternative sources. This can be accomplished from remaining roots (intraplexal neurotization) or donor nerve outside the plexus (extraplexal neurotization). What are the options for extraplexal neurotization?

Answer 26

1. spinal accessory nerve 2. intercostal nerves 3. contralateral C7 root

Question 27

What are the common secondary surgical reconstructions for obstetric brachial plexus palsy?

Answer 27

1. joint release 2. tendon transfer 3. muscle transfer (eg, free gracilis muscle transfer)

Question 28

What is the hierarchy of obstetric brachial plexus palsy reconstruction?

Answer 28

1. Restores elbow function. 2. Restores shoulder function. 3. Restores wrist/hand function.

Question 29

What secondary surgical procedures are used to correct internal rotation contracture of the shoulder due to obstetric brachial plexus injury?

Answer 29

1. Early release of the subscapularis muscle/subscapularis tendon lengthening. 2. Anterior release of the pectoralis major tendon and transfer of the latissimus dorsi/teres major tendon (conjoined tendon). 3. Humeral derotational osteotomy (if advanced glenohumeral joint deformity).

Question 30

What secondary surgical procedure is used to improve wrist extension after brachial plexus reconstruction?

Answer 30

Tendon transfer.