Obstetrical Brachial Plexus Injuries Flashcards
What is the cause of obstetrical brachial plexus palsy?
Traction injury to the brachial plexus during the birth process
What is the estimated incidence of obstetrical brachial plexus palsy?
0.2% to 4% of live births globally, with higher incidence in underdeveloped countries with poor obstetrical care.
What is the rate of spontaneous recovery?
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.
What maternal factors may be associated with obstetrical brachial plexus palsy?
- diabetes
- preeclampsia
- pong duration of labor
- history of delivery problems with earlier pregnancies
What fetal factors may be associated with obstetrical brachial plexus palsy?
- large fetus for gestational age
- history of humeral fracture or clavicle fracture during birth
What factors during birth may be associated with obstetrical brachial plexus palsy?
- difficult arm or head extraction in breech deliveries
- shoulder dystocia in vertex deliveries
- forceps or vacuum use during delivery
Where are the common locations for obstetric brachial plexus injuries?
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).
What are the different types of brachial plexus lesions
- stretch
- rupture (postganglionic)
- 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.
What physical or radiological findings would suggest preganglionic lesions?
- Horner syndrome (sympathetic chain)
- elevated hemidiaphragm (phrenic nerve)
- winged scapula (long thoracic nerve)
What are the signs of Horner syndrome
- ptosis
- miosis
- anhidrosis
What is the significance of Horner syndrome in a patient being evaluated for brachial plexus injury?
The presence of Horner syndrome indicates disruption of sympathetic fibers proximal to where the preganglionic
fibers arise and suggests severe brachial plexus avulsion injury.
What is the significance of Horner syndrome in a patient being evaluated for brachial plexus injury?
The presence of Horner syndrome indicates disruption of sympathetic fibers proximal to where the preganglionic
fibers arise and suggests severe brachial plexus avulsion injury.
What is the significance of phrenic nerve palsy in a patient being evaluated for brachial plexus injury?
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.
What tests and studies can be ordered to evaluate obstetric brachial plexus injury?
- 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)
- EMG/NCS (to assess the function of each nerve and the muscles it innervates)
What is the most reliable method of assessing the level and severity of obstetric brachial plexus injury?
Physical examination to assess motor and sensory function. EMG/NCS may be helpful but lacks accuracy.
What is Erb palsy?
Obstetric brachial plexus palsy involving the upper trunk.
What is Klumpke palsy?
Obstetric brachial plexus palsy involving the lower trunk.
Where is Erb point?
Point where C5 and C6 merge to form upper trunk.
What is the typical posture of Erb palsy
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
What is the modified Mallet classification system used for?
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.
What is the main goal of physical therapy in obstetric brachial plexus palsy patients?
To maintain passive range of motion/prevent stiffness and contracture of the affected joints.
What is the most common indication for surgery in obstetric brachial plexus palsy patients?
Absence of elbow flexion (biceps function) by 3 to 4 months of age.
What are contraindications for surgery in obstetric brachial plexus palsy patients?
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).
What are the common primary surgical treatments for obstetric brachial plexus palsy?
- neurolysis
- neurotization
a. nerve grafting b. nerve transfer
