Peripheral nerve injuries Flashcards
Epineurium
Surrounds spinal nerve
Perineurium
Surrounds fascicle
Endineurium
Surrounds myelinated neuron
General
Dendrites receive signal
CNS fibres do not regenerate- slow clean up, enviro not optimal
PNS fibres regenerate- fast clean up (macrophages), schwann cells assist
If cell body is damaged cell can’t regenerate
If axon is damaged reservation can occur, 1mm a day
Sensory- muscle to CNS
Motor- CNS to muscle
Transient iscaemia
Acute nerve compression
15 mins numbness + tingling
30 mins loss of P sensibility
45 muscle weakness
Relief of compression –> recovery + no nerve damage
Iscaemia aetiology
Brief blood clot in brain
Blockage of artery to heart
Iscaemia presentation
Weakness, numbness, paralysis in face, arm or leg- typically on one side of body
Slurred or garbled speech or difficulty understanding others
Blindness in one or both eyes or double vision
Vertigo, loss of balance/coordination
Neuropraxia
Reversible physiological nerve conduction block
Loss of some types of sensations + power
Spontaneous recovery after few weeks/days
May be due to mechanical compression which cause segmental demyelination
E.g. radial nerve compression (wrist drop)
Symptoms of neuropraxia
Weakness
P
Touch sensitivity
Loss of sensation
Tingling, numbness
Neuropraxia diagnosis
Difficult to diagnose
Commonly underreported
Nerve conduction tests to find out exact location of block along nerve
Neuropraxia management
Usually heals on its own
Brace, cast, splints can manage P
Axontemesis
More severe form of nerve injury seen in closed fractures, dislocations, obstetric palsies
Loss of conduction but nerve is in continuity + neural tube intact
Axon regeneration starts within hours of nerve damage
Schwaan cells
Demyelination + axon loss
Neuron can regrow
Axonotmesis diagnosis
Nerve conduction velocity test
Electromyography performed after 3-4 weeks shows signs of denervation and fibrillations
Neurotmesis
Originally meant severance of nerve
Now understood that severe injury may occur without nerve division
Wallarin degeneration and repair takes place but results are poor due to endometrial tube destruction, distal end not regenerated
Resultant scarring may occur
Demyelination + axon loss + damage to endineurium (can have fair growth), perineurium (poor growth), epineurium (no growth)
Wallarin degeneration
Results when nerve fibres is cut or crushed, in which part of axon separates from neuron cell body
Degenerates distal to injury
Occurs 7-21 days post injury
Double crush phenomenon
Upton + McComa (1973) proposed that idc near enough is impaired at one located it makes Px more susceptible to toner entrapments along side CNS
Damage to brachial plexus
Commonly injured by traction
Not commonly injured by clavicle fractures
Obstetric brachial plexus- Erbs Palsy
Difficult birth- baby position, paralysis can be partial or complete, most invalid root is C5
Nerves involved- supra scapular, musculocutaneous, axillary
Signs of Erbs palsy
Loss of sensations in arms, paralysis + atrophy of deltoid, biceps and brachialis
Stunted growth of affected arm
Impaired muscular, nervous and circulatory development
Obstetric BPI- Klumpkes palsy
Difficult birth- neuropraxia or scarring
Lower plus lesion C8-T1
Frequently associated with pre-ganglion injury + Horner’s syndrome (constricted pupil)
Klumpkes palsy physical exam
Deficit of small muscles of hand- claw hand
Management goals of Klumpkes palsy
Paralysis may recover completely , improve or remain unaltered
Long thoracic nerve
Branch from brachial plexus (C5, 6 + 7)
In pectoral region on surface of serrates anterior just behind mid axillary line
Clinical features of long thoracic damage
Aching or weakness with arm movements, winging of scapula
Accessory nerve
Superficial- easily injured by trauma/surgery (e.g. whiplash)
Asymmetry of shoulders + weakness of abduction
Suprascapular nerve
Injured in clavicle or scapular fractures
Shoulder weakness (abd, ext rot)
May present as orator cuff disease or cervical spondylosis
Axillary nerve
Shoulder weakness
Deltoid wasting
Abduction still maintained by supraspinatous
Radial nerve
Commonly injured at elbow, upper arm or axilla
Radial nerve lower lesion
Possibly due to dislocations at elbow or to local wound
Iatrogenic lesion of post interosseous nerve- occasionally seen post surgery to proximal radius
Result is weakness of metacarpopharyngeal –> hand clumsiness
Radial nerve high lesion
Occur with fractures of humerus
Obvious wrist drop
Sensory loss limited to superior radial nerve distribution
Radial nerve very high lesion
Shoulder surgery
Saturday night palsy (occurs from prolonged direct pressure to radial nerve- e.g. resting on chair)
Triceps paralysed/reflex absent
Treatment depends upon open or closed injuries
Ulnar nerve
Common via elbow/wrist
Open wounds may damage at any level
Guyon’s canal syndrome
Entrapment of ulnar nerve in cubital tunnel
Ulnar nerve high lesion
Elbow damage
Ulnar neuritis cubital tunnel syndrome (compression of ulnar nerve at level of elbow)
Ulnar nerve low lesions
Claw hand deformity
Unexplained lesions
Treatment of ulnar nerve damage
Suture (of open wounds), passive/active exercises
IF unsuccessful, hand function compromised severely
Median nerve
Most injured ear wrist or high forearm
Median nerve low lesion
Carpal dislocation
Loss of abd of thumb, sensory loss over radial three and a half digits
Median nerve high lesions
Forearm fracture/elbow dislocation- clinically the same but long flexors of the thumb, index and middle fingers paralysed/radial wrist flexor + forearm promotors lost
‘Pointing sign’ due to damage of index + middle finger
Treatment of median nerve damage
Suture, nerve grafting/wrist splinted in flexion to avoid tension
Severe disability follows non-recovery
Femoral nerve
Usually injured via traction or pressure preoperatively (around surgery)
Loss of quad action, deep tendon reflexes and numbness of ant thigh and medial leg
Sciatic nerve
Complete division rare except gun shot wound
Traction lesion
Post total hip replacement
Clinical features of sciatic damage
Complete lesion- hamstring and all below knee paralysed, drop foot, sensory loss below knee
Sometimes only deep part affected ]Complications- tropic ulcers/foot drop
Treatment of sciatic damage
Suture, traction
Generally poor prognosis
Amputation
Clinical features of ulnar nerve damage
Numbness + tingling in ulnar half of ring/pinky finger
May be related to specific postures
Initial stages may be difficult to see
Management of ulnar nerve damage
Conservative measures
Night slinging
Surgical release in advancing cases with intrinsic wasting
Guyon’s canal compression
Symptoms may be motor, sensory or both
Ganglion from triquetrohamate Jt
Ulnar artery aneurysm
Fractured hook of hamate
Iscaemia findings
Physical exam and test vision
Eye movements, speech, language
