Peripheral Nerve Injury

Peripheral Nerves

Peripheral Nerves

Connect information to the central nervous system

Efferent

Motor fibers

Afferent

Sensory fibers

Interneurons

Connect neurons within a specific region of the CNS responsible for reflexes

Nodes of Ranvier

Constrictions separating successive segments of myelin

Nerve impulses leap

Farther apart = faster conductions

Traumatic Injury can cause injury due to

• Mechanical damages

• Thermal damages

• Chemical damages

• Ischemic damages

Wallerian Degeneration

Axon distal to the injury degenerates due to nerve fiber being cut, crushed, or compressed

Bands of Bunger

Formed by Schwann Cells, guide growth factors

Schwann Cells and Macrophages

Clear the debris to assist with growth

Which degrees of nerve injury are reversible?

1st and 2nd Degree

Which degrees of nerve injury are non-reversible?

3rd/4th and 5th degrees

1st Degree of Reversible of Nerve Injury (Neuropraxia)

Interruption of conduction; short recovery time

Ex: Carpal Tunnel

2nd Degree of Nerve Injury (Axonotmesis)

Loss of continuity of the axon; Wallerian degeneration; Preservations of endo-, peri-, and epineurium

3rd/4th Degree of Nerve Injury (Neurotmesis)

Loss of continuity; Some loss of continuity of epineurium and perineurium; may or may not be disrupted

5th Degree of nerve Injury (Transection)

Severe Neurotmesis; gross loss of continuity

Treatment for Neurapraxia

Observation and education

Treatment for Axonotmesis

Surgical intervention may be required; education

Treatment for Neurotmesis

Loss of nerve trunk → surgical intervention is neccessary

Goal of surgical repair

Tension free and end to end repair

Surgical repair

• May be microscopic immediate repair, within 24 hours

• Delayed repair 3-5 days

• Delayed repair with nerve graft

Autograph

Harvested from the patient’s own body, but from another location:

• Medial antebrachial cutaneous nerve (<8 cm)

• Sural nerve (up to 30cm)

• Posterior interosseous nerve: distal digital nerve (<2cm)

Limitations of Autographs

• Requires 2nd surgery site to harvest tissue

• Mismatch of donor nerve size

• Fascicular inconsistencies

Allograft

Tissue from another individual

Limitations for Allograft

• Risk of infection & tumor formation

• Immune rejections

• Risk of cross contamination

• Secondary infection

• Limited supply

Xenograft

Graft attained from a member of a specifies other than the recipient

Limitations of Xenograft

• Risk of cross-species disease transmission

• Requires immuno-suppressive drugs

• Risk of infection and tumor-formation

Nerve Conduits

• Serves as an artificial means of guiding axonal regrowth for nerve generation

• Preserves extra-cellular matrix for mechanical guidance for regenerating axons

Early Vasomotor distal observations of nerve injury

Skin rosy

Late Vasomotor distal observations of nerve injury

Skin mottled or splotchy

Early Sudomotor distal observations of nerve injury

Dry skin

Late Sudomotor distal observations of nerve injury

Dry or overly moist skin

Pilomotor observations

Goose flesh or goosebumps. This is absent for early and late nerve injury

Early Tropic distal observations of nerve injury

• Fingernails blemish

• Longer & fine hair growth

• Skin soft & smooth

• Slight atrophy

Later Tropic distal observations of nerve injury

• Curved

• Longer & fine hair growth

• Skin smooth/non-elasticAtrophy at finger pulps (tips)

Test for pain/temp sensory return

Sharp/dull, temp

Test for vibration (30cps) sensory return

Tuning fork (30 cps)

Test for moving touch sensory return

Moving light touch

Test for constant touch sensory return

Semmes Weinstein

Test for vibration (256 cps) sensory return

Tuning fork (250 cps)

Ten Test

• Screen for large A-Beta fibers (testing moving fibers)

• Touch contra-lateral unaffected digit to identify normal sensation. Touch same area on the involved side and have pt rate the normal sensation compared to contra-lateral side.

Primary goals for direct intervention

• Prevent rupture after surgical repair with orthosis fabrication and client education. Control edema and scarring, maintain motion safely. Promote healing

• Work on sensory return and desensitization. Work on strengthening avoiding fatigue when MMT is 3/5 or less

Additional treatment consideration

•Hypertrophic scarring

•Decrease pain

•Increase prehension skills

•Increase ADL & work skills

•Instruct patient and family in rehab process.

•Psychological adjustment

•Prevocational & vocational assessment

Acute Phase of Treatment Post-Surgical Nerve

• Orthosis to protect nerve repair

• Maintain AROM in uninvolved joints

• Scar management

Recovery Phase of Treatment Post-Surgical Nerve

• Orthosis to maintain webspace to be worn nocturnally

• Digit motion combined with wrist motion

• NEuromuscular Re-education

• Desensitization

• Sensory Re-education

Orthosis Fabrication for Median Nerve

Fabrication of wrist based, and thumb included to maintain webspace orthosis

Orthosis Fabrication for Ulnar Nerve

Fabrication of wrist orthosis in neutral and MCP joints of ring and little in 70 deg. flexion

Orthosis Fabrication for Radial Nerve

Depends on location of repair, possibly a resting hand orthosis (unusual)

Length of Acute (Protection) phase of post-surgical repair

0-4 weeks

Sensory Re-Education: Silent Phase (Early)

Return of vibration 30 Hertz and beginning to identify moving touch

Sensory Re-Education: Silent Phase (Early) Activities/Procedures

• Imagery

• Mirror Box

• Laminated cards with verbs to be read throughout the day

Sensory Re-Education: Late Phase

• Identifies 250 cps

• Nerve is beginning to innervate

Sensory RE-Education: Late Phase Activities/Procedures

• Introduce traditional sensory training identifying objects

  • Rice bins

  • Textures

  • Shapes

  • Tracing items with digits

What kind of activities would you use in the Advanced late Phase of Sensory Re-Education?

Proprioceptive Activities, such as gentle oscillations, light ball toss or scarf juggling

What may occur in early or late phase?

Hypersensitivity

Desensitization Massage Interventions

• Self Massage every 2 hours

• Grade up: massage with soft brush and progress to electric toothbrush with vibration

Desensitization Texture Interventions

• Rub area with textures 4-6 times daily for 3-5 minutes

• Textures should be bearable, but uncomfortable

• Start soft and grade up as area adapts

Desensitization Immersion Interventions

• Immerse area with varying textures within a container

• Ex: dry lentils, rice, macaroni, dried beans, etc.

Key exercise for motor retraining Median Nerve Injury

Hold hand so thumb in a palmar opposition position and try to maintain. Try to mimic the perimeter of a jar lid

Key exercise for motor retraining Ulnar Nerve Injury

Finger abduction and adduction. Hand palm down on a flat service abd & adduction of fingers. Use powder on a board to reduce friction

Radial Nerve Injury

• Wrist drop

• Loss of:

  • Extension of wrist

  • Extension of fingers

  • Thumb abduction

  • Thumb extension

  • Supination of forearm (weak)

Splint for radial nerve injury

Focus on wrist extension for functional grasp

Key exercise for motor retraining Radial Nerve Injury

Extension of wrist, fingers and thumb. When retraining, finger intrinsic substitution (lumbricals) can be a problem. Use coban to isolate the extensor digitorum.

Median Nerve Injury

Ape Hand Deformity

Atrophy of Thenar muscles

Splint for Median Nerve Injury

Focus on thumb in functional position

Special tests to use to assess integrity of Median nerve

• Phalen’s Test

• Tinen’s Test

Ulnar Nerve Injury

• Claw Hand

• Loss:

  • Functional grip is weak, loss of power grip

  • Weakness of wrist flexion

  • Loss of little and ring finger DIP flexion

  • Partial loss of Palmar pinch

  • Weakness of MP adduction and abduction

  • Difficulty making an O

  • Functional loss of writing grip

  • Loss of thumb adduction

Splint for Ulnar Nerve injury

Focus on 4th and 5th digit flexion for increased function

Special test to assess integrity of Ulnar Nerve

Froment’s Sign

Froment’s Sign

When patient attempts to pinch with the thumb and index finger, the long flexor of the thumb is used to substitute for thumb adductor, resulting in flexion of thumb at the IP joint