chapter 7 - peripheral nerve injuries Flashcards
4 causes of nerve injuries and examples for each
- laceration - follow fracture, stab or surgical injury
- traction - ie brachial plexus injury, displaced fractures
- ischaemia -intraneural injection or compartment syndrome
- compression - carpal tunnel syndrome. blind use of artery forceps in a wound may crush a nerve
3 grades of nerve injuries and what they mean
- neuropraxia = complete motor loss; incomplete sensory loss
- axonotmesis = motor and sensory loss complete
- neurotmesis = complete division of all nerve elements
which grades present with complete recovery post nerve injury?
neuropraxia and axonotmesis
which grade of nerve injury requires surgical repair?
neurotmesis
what happens when a nerve is cut?
- nerve dies distally to the site of injury and schwann cells are left behind
- axon regrowth from injury site to distal stump
- regenerating axons produce 4-6 sprouts which grow distally towards a motor or sensory end point
- the first axon to reach the destination becomes the definitive axon and the others die
why do proximal muscles recover better than distal after a nerve injury?
proximal muscles receive the first axons
approach to diagnose a peripheral nerve injury
est cause of nerve injury
est degree of injury
est site of injury
est type of injury
examination to aid diagnosis of peripheral nerve injury - 6 modalities
1 sensory motor reflexes sudomotor = sweating vasomotor trophic
if features of peripheral nerve injury are confusing, what should you suspect
- partial nerve injury
- proximal lesion affecting roots or cords of plexus
what is the aim of the pirmary treatment of upper limb nerve injuries?
to prevent oedema and sepsis which cause fibrosis in and around the nerve leading to poor recovery
what is the primary level treatment of upper limb nerve injuries?
- tetanus toxoid 0.5ml
- antibiotics for hight risk cases
- GA
- clean wound with copious lavage - remove foreign material and clots with forceps and wet gauze swabs
- debride wound but NOT under tourniquet or if patient is shocked
- secure haemostasis - pressure with tie, clip or fry- bipolar dithermy
- if nerves are visible - tack the ends together by the epineurium with 5/0 nylon
- if wihtin a reasonable time since injury- close wound with 5/0 nylon and not silk
- dress with dry non bulky gauze to allow as much movement as possible
why do you use nylon and not silk sutures on the hand?
silk increases local wound inflammation
who should perform a definitive nerve repair
only an experienced surgeon - even if that means it will be delayed
what are the 3 required conditions for primary nerve repair?
clean wound less than 12 hours old
uncrushed, un torn cleanly incised nerve
minimal gap after trimming - ie no tension
how should you protect the nerve repair post op
with a plaster of paris splint
how long should the injury be splinted -
a) major nerves
b) small digital nerves
a) 6 weeks
b) 4 weeks
when should you not consider primary repair - 6 situations
contaminated wounds more than 12 hours old
avulsions or crushing with torn nerve
multiple severances
large part of nerve mobilised by the injury
large gap
associated avascular necrosis
how do you prevent joint stiffness and swelling post op
early physio and OT
how long should you wait beofre you explore a closed nerve lesion and how do you manage the patients during that time
6 weeks to 3 months
dynamic splints indicated
what are the dynamic splints for the 3 nerves called
knuckle duster splint - median and ulnar palsy
cock up splint - radial palsy
after managing the wound and before surgery what must be done ?
actively elevate the limb to prevent oedema and avoid slings if possible
immediately on the day of the injury the patient should start with rehabilitation - what should he do
put all joints through full range of motion - every hour to reduce stiffness
after definitive surgery how should the patient be managed?
POP splint to protect tendon or nerve repair and allow maximum movement of the other joints
mobilisation by physio and OT
8 factors that influence the prognosis of nerve injury
1 severity of injury 2. persistence of compression by scar tissue 3 surgical technique 4 children > young adults > over 40 5 delay before repair 6 pure nerves > mixed nerves
best prognosis with which severity of nerve injury
neuropraxia
worst prognosis with which severity of nerve injury
neurotemsesis
what causes scar tissue
injury
oedema
sepsis
surgical trauma
how is a nerve compressed after arterial injury
false aneurysm
if compression of nerve persists what do you do?
microsurgical release of scar tissue
surgical decompression is indicated
what is neurolysis
surgical decompression
if you delay the repair by x months then it has an effect on recovery
6 months
how long can you delay the repair of the nerve - max
2 years
what are mixed nerves
sensory + motor
which type of injuries recover better and why?
distal better than proximal
- end plates have not degenerated and the nerve is more likely pure
which injuries have the best recovery
clean lacerations
after a nerve injury what may cause tenderness at a later astage
superficial neuromata
why would a patient presetn 3-4 weeks after a nerve injury?
pain free initially
presents when neuropraxia recovers
causes of pain following nerve injury
intra neural injections bullet injuries ischaemic injury intermitten compression - carpal tunnel traction injuries require spinal rootlets
how to manage pain after nerve injury
- analgesia - tramadol or daloxene + codis
- sedative - largactil 25-50 mg nocte
- antidepressant - melleril
- TENS
- microssurgical neurolysis
when will microsurgical neurolysis not work for pain after injury to nerve
pain after rootlet avulsions from the spinal cord
important sign of brachial plexus injuries
senseless limb in deep pressure sensation in the finger tips
how do elicit a brachial plexus injury sign?
squeeze firmly with finger and thumb on the base of the patients nail and slide it towards the tip
if continuity remains post brachial plexus injury- what will the patient feel
mild burning in finger tip
what does a response to the pressure on the finger tip tell you?
the small fibers are present and functioning
how long do you wait before exploring the nerve after a brachial plexus injury and what do you do during that time?
test small fibers in finger tips at intervals for 6-8 weeks
what do you do if deep pressure sense returns after a brachial plexus injury before surgery
delay surgery and wait longer 3-5 months
how do you determine the level of the lesion in a brachial plexus injury
neurological exam
which lesions can be seen with CT myelogram
avulsion of the roots from the spinal cord - cannot be salvaged with surgery
treatment of major nerve injuries? 1 general; 5 specific
- refer for evaluation external neurolysis internal neurolysis nerve grafts neurotisations shoulder arthrodesis
type of nerve damage with direct sharp injury?
neurotmesis
clinical of direct shapr injury to nerve
sensation and function absent distally
treatment of direct sharp injury to nerve
repair asap
what can neck or shoulder traction cause and when do they occur
cervical root avulsions
after motorcycle accidents
which nerves are affected in a dislocated shoulder resulting in traction
axillary nerve
musculocutaneous nerve or distal plexus
what type of nerve injury does traction cause
mixed nerve injury
neuropraxia to neurotmesis
what limits injury after traction and where
perineural and intraneural fibrosis
minimally injured part of the nerve
how to treat traction injury
splint and watch for 3-6 months
if no progress consider surgery
what is a common injury that occurs at birth during delivery and may follow cpd
brachical plexus injury
in neonates with birth trauma during delivery which nerves roots are commonly affected and what is it called
c5 c6 nerve roots - erbs palsy
paralysis of arm and elbow
which nerve roots are involved in erbs palsy
c5 c6
after a brachial plexus injury what should the mum do to the baby and how often
abduction and external rotation of the childs shoulder
6 times a day to avoid stiff shoulders
after brachial plexus injury at birth which muscles should recover and in what time period
deltoid and biceps function
3 months
what to do after 3 m if function has not returned
consider surgery
what surgery is needed for brachical plexus injury in neonata
nerve grafts to bridge gap between injured nerve and well nerve
tendon transfers
when are tendon transfers indicated post brachial plexus injury in a neonate ie at what age
18m till 5 years
how does vascular compression by a false aneurysm present
progressive paralysis of the limb starting hours, days or a week later
which vessels are commonly involved in vascular compression by a false aneurysm
subclavian and axillary artery
complication of vascular compression by false aneurysm
brachial plexus injury
how to treat vascular compresion by false aneurysm
surgical control of aneurysm
internal neurolysis
4 nerve entrapment syndromes of upper limb
above shoulder - cervical spondylosis or TOS
median nerve
ulnar nerve
radial nerve
entrapment syndromes above the shoudler
cervical root foramina in spondylosis
TOS or cervical rib entrament of lower roots of brachial plexus
median nerve entrapment syndrome?
carpal tunnel
anterior interosseus sundrome - deep branch to thumb and index long flexor passes beneath superficialis arcade
ulnar nerve entrapment?
cubital tunnel syndrome - elbow injiry
guyons canal at wrist next to pisiform
ulnar nerve palsy signs
wasting of first web space
clawing of fingers
hyperextension of mpj and flexion at ipj
radial nerve entrapment -causes
local injury - entrapped at spiral groove of humerus
supinator syndrome around nexk of radius related to local injury or muscle hypertrophy
entrapment of nerves in the lower limbs- 5 conditions
meralgia paraethetica = lateral cutaneous nerve
lateral popliteal nerve entrapment
tarsal tunnel syndrome
plantar digital nerve neuritis= mortons metatarsalgia
piriformis syndrome
how does entrapement of lateral cutaneous nerve of thigh present
paraesthesia over lateral thigh
recent weight gain
cause of latearl popliteal nerve entrapment
anomalous ligaments at neck of fibula
mechanism of plantar digital nerve neuritis
digital nerve to toes is compressed against intermetatarsal ligament of sole
piriformis syndrome compresses which nerve
sciatic nerve
