Peripheral Nerve Injuries

Sunderland 1

• neuropraxia

• ionic block; possible segmental demyelination

• full recovery potential

Sunderland II

• axonotmesis

• axon severed; endonuerial tube intact

• full recovery potential

Sunderland III

• axonotmesis

• endoneurial tube torn

• slow; incomplete recovery potential

Sunderland IV

• Axonotmesis

• only epineurium intact

  • neuroma-in-continuity

Sunderland V

• neurotmesis

• loss of continuity

• no potential to recover

Sunderland VI

• neurotmesis

• combination of above

• unpredictable recovery potential

Wallerian degeneration

• distal to the injury

• breakdown of myelin

• disintegration of axons

Neuronal regeneration

• 1 to 3mm per day

• axonal sprouting

• can be complicated

  • Take a measurement from point of injury to nerve root to know where nerve is in process of regeneration

Variables that can affect healing of peripheral nerve injury

• age of patient

• type and intensity of original injury

• need for and/or timeliness of repair

• surgical techniques used

Sequence of sensory return for peripheral nerve injury

1. pain

2. vibration of 30Hz

3. moving touch (moving 2PD)

4. constant touch

5. Vibration of 256Hz

Radial nerve sensation branches

1. Brachial cutaneous branches

2. antebrachial branch

3. Superficial sensory branch

Brachial cutaneous branches sensations

posterior arm and lateral forearm

Antebrachial branch sensations

posterior forearm

Superficial sensory branch sensations

lateral 2/3 dorsal hand, dorsal thumb, proximal dorsal aspects index, long, and half of walk

Triceps innervation

Radial

Anconeus innervation

radial

Brachioradialis innervation

radial

Extensor carpi radialis longus innervation

radial

extensor carpi radialis brevis innervation

radials

supinator innervation

radial

extensor digitorum innervation

radial

extensor digiti minimi innervation

radial

extensor carpi ulnaris

radial

abductor pollicis longus innervation

radial

extensor pollicis longus innervation

radial

extensor pollicis brevis

radial

extensor indicis proprius innervation

radial

Radial nerve function

• elbow extension

• wrist extension

• MCP extension

• Thumb extension and radial abduction

• Essential for tenodesis action (grasp-release of normal hand)

Axilla “Crutch Palsy”

• no sparing of muscle function

  • motor and sensory loss

Mid-humerus “saturday night palsy”

• triceps spared

  • motor and sensory loss

How to check functionality of radial nerve

extend wrist to radial side and provide resistance

Elbow “posterior interosseous nerve palsy”

• brachioradialis and radial wrist extensors spared

• motor involvement: lack extension ulnar wrist and digits

  • sensation spared

“Radial tunnel syndrome”

Pain sensation

Wrist “superficial radial nerve palsy”

• sensory involvment only

• itching

Lesions of the radial nerve

• motor palsy has significant functional impacts

  • decreased grasp and release

  • instability at wrist limits hand flexion

  • loss of thumb function

• sensory loss to dorsal radial hand not debilitating

Median nerve sensation

• palmar cutaneous branch

• volar hand: thumb, index, long, and radial ring

  • dorsal hand: 20 to 35% of terminal ends thumb, index, long, and radial ring

Pronator teres innervation

median nerve

flexor carpi radialis innervation

median

palmaris longus innervation

median

flexor digitorum superficialis

median

flexor digitorum innervation

median and ulnar

flexor pollicis longus innervation

median

pronator quadratus

median

abductor pollicis brevis

median

flexor pollicis brevis (superficial head) innervation

medianop

opponens pollicis innervaation

mediani

index lumbrical innervation

median

middle digit lumbrical innervation

median

How can you test lumbrical function?

Flex at MCP, abduct fingers

function of median nerve

• forearm pronation

• radial wrist flexion

• thumb, index, and long digit flexion

• thumb palmar abduction and opposition

• positions hand for function

• allows precision pinch

• sensory impairment makes fine motor coordination impossible

Elbow “pronator syndrome”

• pain syndrome

  • sometimes sensory issues

elbow “anterior interosseous syndrome”

• paralysis of FPL and 2 FDP

• forearm pain

• A OK sign

Wrist “carpal tunnel syndrome”

• nocturnal pain

• altered sensibility

• thenar weakness: if there is atrophy, management of condition is going to be more challenging

Lesions of the Median Nerve

• deformity

• loss of precision pinch and thumb opposition

• loss of sensibility at fingertips

• functional deficits in fine motor

  • complaints of numbness, pain, and dropping objects

How does a median nerve lesion progress?

• proximal median nerve lesion (hand of benediction) → when patient tries to make fist

• Distal median nerve lesion (median claw) → when patient tries to extend fingers

ulnar nerve sensation

• dorsal cutaneous branch

• superficial sensory branch

• ulnar hand (dorsal and volar)

  • ulnar aspect of ring and all of small finger (dorsal and volar)

Flexor carpi ulnaris innervation

ulnar nerve

abductor digiti minimi innervation

ulnar

opponens digiti minimi innervation

ulnar

flexor digiti minimi innervation

ulnar

3rd/4th lumbricals innervation

ulnar

palmar interossei innervation

ulnar

dorsal interossei innervation

ulnar

flexor pollicis brevis (deep head)

ulnar

adductor pollicis innervation

ulnar

Ulnar nerve function

• Strong wrist flexion and ulnar deviation

• power grip from ulnar two digits

• tip and lateral pinch

  • hypothenar muscles and interossei allow the hand to cup an object → 4th and 5th CMC joints are extremely important

Elbow cubital tunnel syndrome

• pain medial elbow

• weakness all ulnar innervation muscles → loss of grip strength

• weak clawing of 4th/5th digits

  • dorsal and volar dysthesia “abnormal sensation” (burning, prickling, or aching feeling”

If there is a high ulnar lesion, what is the resulting hand deformity?

Mild hand deformity

If there is a low ulnar lesion, what is the resulting hand deformity?

significant hand deformity?

Wrist “Guyon’s Canal Compression”

• pain

• intrinsic muscle weakness

• stronger clawing of 4th/5th digits → closer to the paw, worse the claw

• abnormal sensation volar surface only → spared to dorsal surface

Lesions of the Ulnar Nerve

• balance between intrinsic and extrinsic muscles lost

• flattening of arches

• claw hand deformity

• wasting of interosseous, thenar adductor, and hypothenar eminence

• loss of tip and lateral pinch and grip strength

• impaired in-hand manipulation and gauging force to hold objects

• sensory losses not severely disabling

Limited PROM

Joint

Limited AROM

musculotendinous tightness

Radial nerve peripheral nerve assessment

• elbow extension

• wrist extension

• thumb extension

median peripheral nerve assessment

• thumb opposition

• thumb palmar

• abduction

Ulnar peripheral nerve assessment

• MCP abduction/adduction

  • thumb adduction

Nerve compression tests

monofilaments, vibration, provocative tests, NCVs, EMGs

Nerve lacerations

tinel’s sign, monofilaments, moving two-point discrimination, static two-point discrimination, NCVs/EMGs

Sensory screening

monofilaments, static two-point discrimination

Treatment of CTS

• neutral wrist orthosis

• therapeutic exercise

• activity modification

  • education

Treatment of Cubital TS

• anterior elbow conformer 30 to 40 flexion for nights/rest

• therapeutic exercises

• activity modifications

• education

Treatment of PIN

• wrist extension orthosis and/or dynamic MCP extension assist device

• therapeutic exercises

• activity modification

  • education

Treatment for peripheral nerve injuries

• pain relief

• education

• focused exercises

• motor retrainin

• desensitization

• sensory re-education

Radial nerve injury orthoses

• static MCP extension orthosis

  • dynamic MCP extension assist orthosis

Median nerve injury orthosis

• hand based orthosis to position thumb in opposition and abduction

  • important to maintain first web space

ulnar nerve injury orthosis

• hand based orthosis to prevent MCP hyperextension and allow IP extension for digits 4 and 5