31 - brachial plexus trauma

Question 1

The brachial plexus is formed from the dorsal or ventral branches of the spinal cord segments?

Answer 1

ventral

Question 2

Which SC segments form the brachial plexus?

Answer 2

C6-T2

Question 3

in how many % of dogs do C5 spinal cord segments, it spinal nerve root and spinal nerve also contrite to the brachial plexus?

Answer 3

24%

Question 4

what structure do nerve roots lack that make them especially susceptible to traction?

Answer 4

nerve roots don’t have an epineurium

Question 5

In partial injury is the caudal or cranial portion more commonly affected?

Answer 5

caudal

Question 6

Axons orientate where?

Answer 6

neuronal cell bodies in gray matter of the SC.

Question 7

Each axon is surrounded by ?

Answer 7

Endoneurium

Question 8

endometrium is made of?

Answer 8

collagen fibrils, fibroblasts and vascular tissue

Question 9

groups of axons are surrounded by ?

Answer 9

perineurium

Question 10

perineurium is made of

Answer 10

collagen and elastic fibres

Question 11

connective tissue surrounding entire nerve is? and is made of?

Answer 11

epineurium.

connective tissue and collagen fibrils

Question 12

dorsal spinal nerve root provides?

Answer 12

sensory input in to SC via a spinal ganglion,

Question 13

ventral nerve root is for?

Answer 13

motor function and autonomic innervation

Question 14

dorsal and ventral nerve roots lie within the ….? and form together to form a ….? that lies within the ….?

Answer 14

vertebral canal
specific spinal nerve
intervertebral foramen

Question 15

which mater are the dorsal and ventral spinal roots surrounded by near to the spinal cord?

Answer 15

the Pia mater and inner layer arachnoid membrane.

Question 16

what happens the meninges as spinal ganglia becomes the spinal nerve

Answer 16

cont as epineurium

Question 17

what structures do nerves pass from being branches of the spinal roots to reaching the brachial plexus?

Answer 17

inter-transverse musculature, scalenus muscle and axillary space

Question 18

List the named nerves that are branches of the brachial plexus x 13

Answer 18

brachiocephalic
suprascapular
subscapular
axillary
musculocutaneous
radial
median
ulnar
dorsal thoracic
lateral thoracic
long thoracic
pectoral 
muscular

BSS AMRMU TTTPM

Question 19

brachial plexus injury is morally caused by what direction f movement/.

Answer 19

abduction and caudal displacement

Question 20

where are spinal nerve roots weakest? why ?

Answer 20

intradural

lack epineurium

Question 21

when can you see psi.ateral pelvic limb ataxia.plegia.paresus?

Answer 21

if injury is sever enough to damage spinal cord

Question 22

are ventral or dorsal a roots more susceptible to this kind of trauma?

Answer 22

ventral (motor) but both may be affected

Question 23

neuropraxia is?

Answer 23

Neurapraxia is the mildest form of nerve injury. It consists of loss of conduction without associated changes in axonal structure.
reversibel, improve in hours to 6 weeks

Question 24

axonotmesis?

Answer 24

The axons and their myelin sheath are damaged in this kind of injury, but the endoneurium, perineurium and epineurium remain intact.
recovery normally good bu t can take weeks

Question 25

neurotmesis?

Answer 25

axons, myelin sheath and digress of endometrium, perineurium and epineurium are disrupted.

Question 26

what are the 3 different classes of brachial plexus injury? and what SC segments/nerves are involved in each ?

Answer 26

1. cranial brachial plexus injury. C5/6 - C7 brachiocephalicus, supra scapular, subscaputlar, axillary, musculocutaneous
2. caudal C8- T2. radial, medial, ulnar
3. total avulsion

Question 27

which nerve is most commonly affected in cases of brachial plexus injury > what is its main role

Answer 27

1. radial nerve in 94% cases

2. elbow extensor therefore weight bearing.

Question 28

why do dogs with caudal brachia plexus injury display horners

Answer 28

pre ganglion fibres from T1 project on ascending sympathetic innervation of the eye

Question 29

what reflex is lost with injury to c8/t1 and which nerve is implicated?

Answer 29

cutaneous trunci, lateral thoracic nerve.

Question 30

clinical signs seen with cranial brachial plexus injury?

Answer 30

minimal, los shoulder movement and elbow flexion.

Question 31

clinical signs seen with caudal brachial plexus injury

Answer 31

leg may be flexed (as axillary, suprascapluar, musculocutaneous still inactivity) but unable to weight bear as no elbow extension (radial nerve)

Question 32

what neurodiagnostic may help with diagnosis?

Answer 32

1. electromyography
2. nerve conduction velocity
3. Evoked potentials and assessment of sensory nerve

Question 33

what MRI changes might you see with brachial plexus injury?

Answer 33

Can identify 1.incomplete root injuries, intraforaminal root avulsion, root avulsion from the SC.

2. preganglioninc injury may appear as contralateral displacement of the SC, SC oedema, myelomalacia, syringomyelia, foal ares of haemosiderin deposition (T@w hypo intense)
3. post ganglionic injuries - stretch injury with nerve disruption – swollen nerve isointense in T1w and hyper intense on t2w.

Question 34

What surgical options exist for brachial plexus injury?

Answer 34

1. Neurotization (for example use lateral thoracic nerve and suture to the musculocutaneus)
2. reimplantation

Question 35

what are the major surgical complications with brachial plexus nerve injury?

Answer 35

1. neurologic deterioration (can get significant ipsilateral and poss bilateral PL dysfunction)
2. cutaneuosu trauma and self mutilation

Question 36

how long should we give brachial plexus injury before assigning a grave prognosis

Answer 36

4- 6 weeks