1. PERIPHERAL NERVE INJURIES
ALI AL-OMARI, MD
ASS. PROFESSOR
ORTHOPAEDICS AND SPINE SURGERY
FACULTY OF MEDICINE
JORDAN UNIVERSITY OF SCIENCE AND TECHNOLOGY

2. Structure of a nerve epineural sheath: surrounds peripheral nerve
Epineurium
surrounds a group of fascicles to form peripheral nerve
functions to cushion fascicles against external pressure
Perineurium
connective tissue covering individual fascicles
primary source of tensile strength and elasticity of a peripheral nerve 
provides extension of the blood-brain barrier
provides a connective tissue sheath around each nerve fascicle

3. Fascicles
a group of axons and surrounding endoneurium
Endoneurium
fibrous tissue covering axons
participates in the formation of Schwann cell tube
Myelin
made by Schwann cells
functions to increase conduction velocity
Neuron cell
cell body - the metabolic center that makes up < 10% of cell mass
axon - primary conducting vehicle
dendrites - thin branching processes that receive input from surrounding nerve cells

4. Nerve fiber types Fiber Type Diameter (uM) Myelination Speed Example A
10-20
heavy
fast
touch B
< 3
moderate
medium
ANS C
< 1.3
none
slow
pain

5. Pathology of nerve injuries
Mechanisms:
Ischaemia:
15 min numbness and tingling
30 min loss of pain
45 min muscle weakness
Relief of ischemia intense parasthesia for 5 min “pins and needles” sensation restored within 30 seconds muscle power after 10 mins
Stretching:
8% affect microcirculation
15%  disrupt axons
Examples: Stingers, suprascapular nerve stretching, peroneal nerve after valgus correction in total knee replacement.

6. Pathology of nerve injuries
3) Compression/crush:
Local deformation local ischemia increase vascular permeability endoneural edema axon compression poor axonal transport and nerve dysfunction.
fibroblasts invade if compression persists scar impairs fascicular gliding
30 mmHg parasthesia (increase latencies)
60 mmHg complete conduction block.
4) Laceration:
Better than compression injuries
Ends retract nerve stop producing neurotransmitters nerve start to product proteins of axon regeneration.

7. Pathology of nerve injuries
Regeneration after transection:
From proximal to distal
Neural sheet intact or repaired
Distal segment undergoes Wallerian degeneration (axoplasm and myelin are degraded distally by phagocytes).
Existing Schwann cells proliferate and line up on basement membrane.
Lee et al. reviewed peripheral never injury and repair. They commented that Wallerian degeneration is initiated 48 to 96 hours after transection. The Schwann cells then align themselves longitudinally, creating columns of cells called Büngner bands. At the tip of the regenerating axon is the growth cone. 
Proximal budding (occurs after 1 month delay) leads to sprouting axons that migrate at 1mm/day to connect to the distal tube.

8. Pathology of nerve injuries
Factors affect recovery:
Age (most important)
Level of injury (distal vs proximal) 2nd most important.
Mechanism of injury (sharp vs crush)
Repair timing (time limit for repair 18 months).
NOTE: PAIN IS FIRST INDICATOR TO RETURN OF FUNCTION

9. Radiculopathy Weakness in muscles supplied by the nerve root (myotome)
Process affecting the nerve root, most commonly by a herniated disc
Weakness in muscles supplied by the nerve root (myotome)
Sensory loss in the area of the skin supplied by the nerve root (dermatome)

10. Mononeuropathy Weakness in muscles supplied by the nerve
Dysfunction of a single peripheral nerve
Weakness in muscles supplied by the nerve
Sensory loss in the area of the skin supplied by the cutaneous branches of the nerve

11. Polyneuropathy Symetrical dysfunction of peripheral nerves Sensory
Motor
Metabolic, DM, viral ….

12. Polyneuritis Multiplex
Asymetrical involvement of several peripheral nerves
Metabolic, viral…

13. Plexopathy Trunk lesion Cord lesion
Can refer to involvement of the entire plexus, or parts of the plexus
Trunk lesion
Cord lesion
Distribution of weakness and numbness depends upon the part of the plexus affected

14. Neuroma
Sprouting of nerve fibers aimlessly resulting in pain and sensitivity to touch along its distribution

15. Double-crush phenomenon
Blockage of axonal transport at one point makes the entire axon more susceptible to compression elsewhere.
Cervical radiculopathy or proximal nerve entrapment may coexist with distal nerve compression in double-crush syndrome.
Outcome of surgical decompression may be disappointing unless all points of compression are addressed.
Logical to start with less complex distal releases first.

16. Causes Of Neuropathy
Metabolic
Toxic
Viral
Compression
trauma

17. Classifications Seddon classification: Neurapraxia Axonotmesis
Mild nerve stretch or contusion
Focal conduction block
No wallerian degeneration
Disruption of myelin sheath
Epineurium, perineurium, endoneurium intact
Prognosis excellent, recovery expected
Axonotmesis
Incomplete nerve injury
Wallerian degeneration distal to injury
Disruption of axons
Sequential loss of axon, endoneurium, perineurium (Sunderland class 2, 3, and 4)
May develop neuroma-in-continuity
Recovery unpredictable

18. Neurotmesis
Complete nerve injury
Focal conduction block
Wallerian degeneration distal to injury
Disruption of all layers, including epineurium
Proximal nerve end forms neuroma
Distal end forms glioma
Worst prognosis

19. Classifications Sunderland classification 1st degree 2nd degree
same as neurapraxia
2nd degree
same as axonotmesis
3rd degree 
injury with endoneurial scarring
most variable degree of ultimate recovery
4th degree
nerve in continuity but at the level of injury there is complete scarring across the nerve)
5th degree
same as neurotmesis

20. Classifications

21. Classifications

22. Clinical features
Nerve injuries are easily missed if associated with fractures and dislocations.
Always test for nerve injuries in any significant trauma, pre- and post- operation or manipulation.
Full neurological exam (abnormal gaits, weakness in specific muscle group, change in sensibility)
If nerve injuries is diagnosed look for accompanying vascular injuries.
OPEN WOUND  EARLY EXPLORATION.

23. Clinical features Tinel’s sign:
Level, type and degree of damage.
Low energy neurapraxia
High energy axonotmesis or neurotmesis.
In doubtful case, wait and see to role out complete transection.
Time of recovery!!!
Tinel’s sign:
Peripheral tingling provoked by percussion the nerve at site of injury.
Sensitive spot progress distally in regenerating nerve.

24. Clinical features Electrodiagnostic tests: EMG (Electromyography)
NCV (LATANCIES MORE IMPORTANT THAN VELOSITY)

25. Principles of Localization
Certain sites are prone to nerve entrapments/injuries
Nerve opposing bone
Ulnar nerve at the elbow
Closed spaces
Carpal tunnel
Adjacent structures
Median nerve at the elbow, adjacent to the brachial artery

29. Principles of localization, cont
Order in which branches arise
Movements at specific joints
Single nerve
Elbow extension
Radial
Multiple nerves
Elbow flexion
Musculocutaneous

33. Typical deformities : Wrist drop ---- radial nerve injury
Claw hand ---- ulnar nerve injury
Foot drop ---- common peroneal nerve injury
Ape thumb ---- median nerve injury
Winging of scapula ---- long thoracic nerve injury
Pointing index ---- median nerve injury

38. Factors Affecting Recovery
In favor
Younger age
Type of injury
More distal injury
Time of repair: first 3 weeks
Pure motor or sensory

39. Treatment Nonoperative Operative observation with sequential EMG
indications
neuropraxia (1st degree)
axonotmesis (2nd degree)
Operative
surgical repair
neurotomesis (3rd degree)

40. Treatment
Open wound early exploration and primary repair with 10-0 epineural repair, if large defect more than 2.5 cm despite of mobilization autograft (sural, saphenous, lateral antebrachial, etc) vs allograft (collagen conduits) physiotherapy.
Close wound  wait and see failure of recovery within time frame (good care for paralyzed part and dynamic splint) delayed repair with resection of proximal neuroma and distal glioma.

41. Treatment Direct muscular neurotization Epineural Repair
insert proximal nerve stump into affected muscle belly
results in less than normal function but is indicated in certain cases
Epineural Repair
primary repair of the epineurium in a tension free fashion
first resect proximal neuroma and distal glioma
it is critical to properly align nerve ends during repair to maximize potential of recovery

42. Treatment Fasicular repair indications
three indications exist for grouped fascicular repair
median nerve in distal third of forearm
ulnar nerve in distal third of forearm
sciatic nerve in thigh
technique
similar to epineural repair, but in addition repair the perineural sheaths (individual fascicles are approximated under a microscope)
outcomes
no improved results have been demonstrated over epineural repair
Nerve grafting
autologous graft
remains the gold standard of repair for segmental defects > 5cm is autologous nerve grafting 
allograft
the only synthetic graft which shows equal results to autologous nerve grafting is a collagen conduit
collagen conduits allow for nutrient exchange and accessibility of neurotrophic factors to the axonal growth zone during regeneration

43. COMPRESSION NEUROPATHies OF THE UPPER LIMB

44. Entrapment neuropathy is caused by the direct pressure on a single nerve.
Symptoms & signs depend on which nerve is affected.
Earliest symptoms to occur: tingling & neuropathic pain.
Followed by reduced sensation or complete numbness
Muscle weakness is noticed later, followed by muscle atrophy.

45. Pathophysiology COMPRESSION VENOUS OBSTRUCTION + ISCHEMIA
ANOXIC SEGMENT
NEURAL EDEMA & DILATATION OF SMALL VESSELS
EXACERBATION OF ORIGINAL COMPRESSION
CONT OF VICIOUS CYCLE
PERSISTENT EDEMA + ANOXIA/
HYPOXIA
FIBROSIS
IMPAIRMENT OF SUPPLY
DEFICIENCY OF VITAL NUTRIENTS
FUNCTIONAL IMPAIRMENT
PERMANENT IMPAIRMENT OF FUNCTION IF LEFT UNTREATED

46. MEDIAN NERVE CARPAL TUNNEL SYNDROME ANTERIOR INTEROSSEOUS SYNDROME
3 important compression neuropathies from distal to proximal
CARPAL TUNNEL SYNDROME
ANTERIOR INTEROSSEOUS SYNDROME
PRONATOR SYNDROME

47. CARPAL TUNNEL SYNDROME
Results from compression of the median nerve within the carpal tunnel.
Most common compression neuropathy in the upper limb.
ANATOMY
- Cylindrical cavity connecting the volar forearm with the palm.
- Floor: transverse arch of carpal bones
- Medially: hook of hamate, triquetrum & pisiform
- Laterally: scaphoid, trapezium & fibro osseous flexor carpi radialis sheath.
- Roof: proximally flexor retinaculum, transverse carpal ligament over the wrist and aponeurosis between thenar & hypothenar muscles distally.

48. CONTENTS:
Tendons of flexor digitorum superficialis & profundus in a common sheath
Tendon of flexor pollicus longus in an independent sheath
Median nerve

49. ETIOLOGY: DECREASE IN SIZE OF CARPAL TUNNEL
Bony abnormalities of the carpal bones
Acromegaly
INCREASE IN CONTENTS OF CANAL
Forearm & wrist fractures (colle’s, scaphoid)
Dislocations & subluxations (scaphoid rotary subluxation, lunate volar dislocation)
Post traumatic arthritis (osteophytes)
Aberrant muscles (lumbricals, palmaris longus, palmaris profundus)
Local tumours (neuroma, lipoma, ganglion, cysts, multiple myeloma)
Persistent medial artery
Hyrertrophic synovium
Hematoma (hemophilia, anti coagulation therapy, trauma)

50. EXTERNAL FORCES DM Alcoholism Double crush syndrome
NEUROPATHIC CONDITIONS DM
Alcoholism
Double crush syndrome
Exposure to industrial solvents
INFLAMMATORY CONDITIONS
Rheumatoid arthritis
Gout
Non specific tenosynovitis
Infections
EXTERNAL FORCES
Vibration
Direct pressure

51. Thyroid disorders (esp. hypothyroidism) Renal failure
ALTERATIONS OF FLUID BALANCE
Pregnancy
Menopause
Eclampsia
Thyroid disorders (esp. hypothyroidism)
Renal failure
Long term hemodialysis
Raynaud’s disease
Obesity

52. Clinical Features
Paresthesias and pain (often at night) in volar aspect of radial 3½ digits (thumb, index, long and radial half of ring)
Large sensory fibers (light touch, vibration) are affected before small fibers (pain and temperature)
Pain usually wake up patient from sleep
Weakness, loss of fine motor control, and abnormal two- point discriminationare later findings.
Thenar atrophy may be present in severe denervation

53. CLINICAL FEATURES:
SIGNS : Tinel's sign, thenar atrophy, sensory changes in the distribution of median nerve
Tinel’s sign: percussing the
median nerve at the wrist.
Phalen’s test:
Patient places elbow on table,
forearm vertical with wrist flexed.
Numbness & Tingling in median nerve
distribution occurs in 60 seconds in + ve cases.
Reverse Phalen’s test:
Sustained extension of the wrist may also
aggravate the symptoms. Not a reliable test.

54. TOURNIQUET TEST:
Inflating a BP cuff on the arm to a pressure above systolic pressure will initiate symptoms (paraesthesia & numbness).
DURKAN’S TEST:
Application of direct pressure on the carpal tunnel with either pressure manometer or by thumb of the examiner for 30 seconds will produce the symptoms.
SENSORY TESTS
Weber’s 2 point discrimination test:
Test is positive in about one-third cases.
Semmes - Weinstein monofilaments:
Monofilaments of increasing diameters are touched to palmar side of the digit until the patient can tell which digit is touched.

55. INVESTIGATIONS: Electro diagnostic studies:
Most reliable confirmatory test.
Conduction time & latency for both sensory & motor conduction is determined.
CT & MRI:
If mass is suspected within the carpal tunnel
LABORATORY TESTS: specific cause is suspected
Renal & thyroid function, RA factor, ESR, Anti nuclear antibody, uric acid, blood sugars.
Radiographs: Wrist AP, Lateral, Carpal tunnel views. Useful in detecting congenital anomalies, fractures, Calcific deposits or tumours of carpal bones.
TREATMENT:
NON OPERATIVE
OPERATIVE

56. NON OPERATIVE: OPERATIVE: Activity modification NSAID’S Splinting
Treating the underlying disease
Local steroid injections
OPERATIVE:
OPEN CARPAL TUNNEL RELEASE
ENDOSCOPIC CARPAL TUNNEL RELEASE

57. OPEN CARPAL TUNNEL RELEASE:
Incision & deeper dissection are performed ulnar to the longitudinal plane between the ulnar border of the ring finger & a point along the wrist crease noted by flexing the ring finger against the palm.
Transverse carpal ligament is divided proximally to distally.

58. COMPLICATIONS:
Incomplete division of transverse
carpal ligament.
Division of palmar cutaneous branch or
motor branch of median nerve.
Injury to superficial palmar vascular arch.
Reflex sympathetic dystrophy.
Palmar hematoma
Loss of grip strength.

59. Co existent ulnar tunnel release. Limited wrist & finger extension.
ENDOSCOPIC CARPAL TUNNEL RELEASE
Emerging technology for open decompression of the carpal tunnel.
CONTRAINDICATIONS:
Co existent ulnar tunnel release.
Limited wrist & finger extension.
Tenosynovitis
Previous surgery

60. ANTERIOR INTEROSSEOUS SYNDROME
Anterior interosseous branch of the median nerve supplies the flexor digitorum profundus to the index finger, flexor pollicis longus & pronator quadratus.
Provides sensation to the volar aspect of carpus.
POTENTIAL SITES OF COMPRESSION:
Fibrous bands of the flexor digitorum superficialis
Fibrous bands of the deep or superficial heads of the pronator teres.
LESS COMMMON CAUSES
Anomalous muscles
Enlarged / thrombosed vessels
Tumours
Enlarged bursae

61. Weakness of flexion in the IP joint of the thumb.
CLINICAL FEATURES:
Weakness of flexion in the IP joint of the thumb.
Weakness of flexion in the DIP joint of index finger.
No sensory loss
Pain is exacerbated by exercise & relieved by rest.
Number of cases occur due to a viral neuropathy.
TREATMENT
INITIALLY: CONSERVATIVE
SURGICAL: INDICATIONS
No resolution of symptoms
Severe symptoms
SURGICAL EXPLORATION: Identification & division of the offending structure.

63. PRONATOR SYNDROME Below lacertus fibrosus
Anatomical sites of compression:
Below lacertus fibrosus
Between the 2 heads of pronator teres

64. Numbness in the distribution of the median nerve.
CLINICAL FEATURES
Ache or discomfort in the forearm associated with weakness or clumsiness of the hand.
Numbness in the distribution of the median nerve.
Night pain is not common.
Phalen’s test & Tinel's sign: negative
Difficult to demonstrate electrophysiological abnormality.

65. Possible sites checked Appropriate release is done.
TREATMENT
CONSERVATIVE:
NSAID’S
Splinting with the elbow at 90 degrees, slight forearm pronation & wrist flexion.
SURGICAL:
Exploration of distal 5 to 8 cm of the course of the median nerve in the arm combined with its course in the upper forearm.
Possible sites checked
Appropriate release is done.

66. ULNAR NERVE At the elbow (cubital tunnel syndrome)
Ulnar nerve gets entrapped at 2 common sites:
At the elbow (cubital tunnel syndrome)
Guyon’s canal (ulnar tunnel syndrome)

67. CUBITAL TUNNEL SYNDROME
Second commonest nerve entrapment of the upper limb
ANATOMY: CUBITAL TUNNEL
Starts at the groove between the olecranon & the medial epicondyle.
Tunnel is formed by a fibrous arch connecting the 2 heads of the flexor carpi ulnaris & lies just distal to the medial epicondyle.

68. Tight fascial band over the cubital tunnel. Medial head of triceps
CAUSES OF ENTRAPMENT
ARCADE OF STRUTHER’S: Formed by superficial muscle fibres of the medial head of triceps attaching to the medial epicondyle ridge by a thickened condensation of fascia.
Tight fascial band over the cubital tunnel.
Medial head of triceps
Aponeurosis of flexor carpi ulnaris
Recurrent subluxation of ulnar nerve, results in neuritis.
Osteophytic spurs
Cubitus valgus following supra condylar fracture.

69. Hand weakness & clumsiness
CLINICAL FEATURES
Numbness involving the little finger & the ulnar half of the ring finger.
Hand weakness & clumsiness
Tenderness over the ulnar nerve at the elbow.
Tinel’s sign is positive: exacerbation of paraesthesia’s with light percussion over the ulnar nerve.
Advanced cases : clawing of the ring & little fingers

70. TREATMENT NON OPERATIVE: Early stages Activity modification
Immobilization of the elbow in 30 degrees of extension, followed by periods of mobilization with elbow padding.
SURGICAL:
Decompression of the nerve by dividing of the basic offending structure.
Anterior transposition of the ulnar nerve
Medial epicondylectomy

71. ULNAR TUNNEL SYNDROME
Ulnar nerve is compressed as it passes through GUYON’S canal in the wrist.
Less common than entrapment of the ulnar nerve at the elbow.

72. Medial wall : pisiform & pisiohamate ligament.
ANATOMY: GUYON’S CANAL
ROOF: composed of palmar carpal ligament blending into the FCU tendon attaching to the pisiform & the pisiohamate ligaments.
Medial wall : pisiform & pisiohamate ligament.
Lateral wall: hook of hamate & some fibres of the transverse carpal ligament.
Ulnar nerve enters guyon’s canal accompanied by ulnar A & Ulnar V.
Guyon’s canal lies in the space between flexor retinaculum & volar carpal ligaments.

73. The anatomy of distal ulnar tunnel is divided into 3 zones.
Zone 1:proximal to the bifurcation of the ulnar nerve & consists of both sensory & motor fibres of the nerve.
Zone 2: represents the motor branch of the ulnar N distal to the bifurcation.
Zone 3: represents the sensory branches of the ulnar nerve beyond its bifurcation.

74. Clinical presentations:
ZONE 1 LESIONS : Mixed sensory & motor loss.
ZONE 2 LESIONS : Isolated motor deficit.
ZONE 3 LESIONS : Isolated ulnar N sensory loss.
Common Causes in zone 1 & 2: ganglions, fractures of the hook of hamate.
Zone 3: ulnar artery thrombosis
OTHER CAUSES:
Malunited fracture of fourth/fifth metacarpal.
Anomalous muscles
Occupational trauma

75. INVESTIGATIONS
X RAY : Oblique/carpal tunnel views
Delineate bony anatomy to diagnose hook of hamate fractures.
MRI: Ganglia, space occupying lesions
TREATMENT
Operative release of the canal by reflecting the FCU, pisiform & pisiohamate ligament ulnarly.
Distal deep fascia of the forearm below the wrist crease should be released.
Resection of any space occupying lesion
Treatment of hook of hamate fractures.

76. RADIAL NERVE PROPER RADIAL NERVE PALSY “SATURDAY NIGHT PALSY”
POSTERIOR INTEROSSEOUS NERVE SYNDROME
RADIAL TUNNEL SYNDROME
WARTENBERG’S SYNDROME

77. Proper radial nerve
Rarely compressed by lateral head of triceps, typically compromised in setting of humerus trauma or related surgical approaches
“Saturday night palsy”—Intoxicated patient passes out with arm hanging over chair, wakes up with wrist drop.
Clinical findings include weakness of proper radial nerve–innervated muscles such as triceps, brachioradialis, and ECRL plus muscles innervated by the PIN.
Sensory deficits may be present in distribution of superficial sensory branch.
EMG may be helpful.
May be initially observed but may be explored if no significant recovery after 3 months

78. Posterior interosseous nerve compression syndrome
PIN is a branch of the radial nerve that provides motor innervation to the extensor compartment
Symptoms include lateral elbow pain and distal muscle weakness.
Radial deviation with active wrist extension because ECRL innervated by proper radial nerve more proximally.
PIN innervates the ECRB, supinator, EIP, ECU, extensor digitorum communis (EDC), extensor digiti minimi, APL, EPB, and EPL.
Patients may also have dorsal wrist pain, where the terminal nerve fibers provide sensory innervation to the dorsal wrist capsule.
Terminal branch is located on the floor of the fourth extensor compartment.
EMG may be helpful.

79. Anatomic sites of compression include
Fascial band at the radial head
Recurrent leash of Henry
Edge of the ECRB
Arcade of Frohse (the most common site, proximal edge of the supinator)
Distal edge of the supinator

80. Unusual causes include chronic radial head dislocation, Monteggia fracture- dislocation, radiocapitellar rheumatoid synovitis, and space-occupying elbow mass (e.g., lipoma)
PIN palsy is differentiated from extensor tendon rupture by a normal wrist tenodesis test.
Nonoperative treatment includes activity modification, splinting, and NSAIDs.
Operative intervention warranted if no recovery by 3 months
Surgical decompression of anatomic sites of compression provides good to excellent results for 85% of patients.

81. RADIAL TUNNEL SYNDROME
Characterized by lateral elbow and radial forearm pain without motor or sensory dysfunction
Provocative tests include resisted long-finger extension (positive if resistance reproduces pain at the radial tunnel) and resisted supination
Lateral epicondylitis coexists in a small percentage of patients.
The point of maximum point tenderness is anterior and distal to the lateral epicondyle.

82. Despite affecting the same nerve (PIN) and sites of compression,electrodiagnostic tests are typically normal.
Prolonged nonoperative treatment for up to 1 year with activity modification, splints, NSAIDs, and local modalities.
Success of surgical decompression less predictable than for PIN syndrome, with good to excellent results in only 50% to 80% after prolonged postoperativerecovery

83. Wartenberg syndrome
Compressive neuropathy of superficial sensory branch of the radial nerve
Compressed between brachioradialis and ECRL with forearm pronation (by a scissor-like action between the tendons)
Symptoms include pain, numbness, and paresthesias over the dorsoradial hand.
Provocative tests include forceful forearm pronation for 60 seconds and a Tinel sign over the nerve.
Initially treated by activity modification, splinting, and NSAIDs
Surgical decompression warranted if 6-month trial of nonoperative treatment fails.

85. Education is not the learning of facts, But the training of the mind to think

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