Basics of radial nerve anatomy, diagnosis and treatment of radial nerve injury

1. RADIAL NERVE PALSY
Dr. Shibu B
Consultant Physiatrist
Poovanthi Rehabilitation Institute, Poovanthi, Tamil
Nadu

2. ANATOMY OF RADIAL NERVE
• Originates as the terminal branch of the
posterior cord of the brachial plexus:
– Roots from C5, 6, 7, 8, & T1
– Largest branch of brachial plexus
– Mixed nerve

4. Course of Radial Nerve (RN) in the arm
In the axilla, RN lies
anterior to subscapularis,
teres major and LD
• Sensory supply:
Posterior cutaneous
nerve of arm
RN leaves the axilla via
the triangular space
• Motor
supply:
long head of
Triceps
It then comes to lie along
spiral groove on
posterior aspect of
humeral shaft along with
arteria profunda brachii
• Motor: medial and lateral
heads of triceps, Anconeus
• Sensory: posterior
cutaneous nerve of forearm,
lower lateral cutaneous
nerve of arm

5. RN leaves the spiral
groove  piercing the
lateral intermuscular
septum anterior
compartment of the
arm, 10-12 cm above the
lateral epicondyle
• Motor supply:
Brachialis (lateral part) , BR, ECRL
Anterior to lateral
epicondyle, RN divides
into its terminal branches
• Terminal branches:
Posterior Interosseous
Nerve (PIN) and Dorsal
or Superficial radial
sensory nerve
Here it lies b/w
brachialis and BR

6. BR
ECRL
Dorsal Radial Sensory
Nerve
Dorsal digital nerves
Radial styloid
8 cm
Dorsal radial nerve
courses through the
forearm immediately
deep to the BR
Emerges b/w tendons
of BR and ECRL ≈ 8 cm
proximal to radial
styloid, to become
subcutaneous
Crosses the anatomical
snuffbox b/w EPB and
EPL, dividing into
multiple branches to
supply sensation to
hand
Course of Radial Nerve (RN) in the
forearm

7. Deep terminal branch →
Posterior interosseous
nerve (PIN)
Supinator
EIP
EDC and EDM
ECU
ECRB
Superficial terminal branch
Radial Nerve Proper
EPL
EPB
APL
PIN reaches the back of
forearm by passing b/w
the superficial and deep
heads of the Supinator to
supply all extensor
compartment muscles
PIN ends by supplying
carpal joint sensation

8. Sensory Supply of Radial Nerve

10. Seddon Classification of Nerve Injury

13. Causes of Radial Nerve Injury
• Axilla
– Crutch palsy/crutch neuropathy
– Aneurysm of axillary vessels
• Arm/Spiral groove
– # shaft of humerus
– Prolonged pressure ( Saturday night
palsy/honeymooner’s palsy
– Deep muscular injections
– Excess callous formations from old fracture
– Prolonged tourniquet application

14. Causes of Radial Nerve Injury
• Elbow
– Dislocation of elbow
– # neck of radius
– Enlarged bursae
– Rheumatoid synovitis of elbow
– Surgical excision of radial head

15. Features of RN Lesion in Spiral groove
Inability to extend the wrist
Inability to extend the fingers at
the MCP joints
Inability to extend and radially
abduct the thumb
Weakness of grip strength and
sensory loss over superficial radial
nerve distribution and occassionally
posterior cutaneous nerve of forearm
WRIST DROP
Triceps intact

16. Features of RN Lesion in Axilla
• Crutch palsy / Crutch neuropathy
• Wrist drop
• Weakness of all muscles including triceps
• Absent triceps jerk
• Numbness in area of superficial radial nerve,
posterior cutaneous nerve of forearm and
occasionally arm

17. Posterior Interosseous Syndrome
• D/t compression of PIN in the radial tunnel
• Most common causes include:
– Radial subluxation
– # Proximal radius
– Prolonged or repeated pronation-supination
– Tumours like glioma , lipoma

19. Clinical Features of PIN
• Normal supination and radial wrist extension
• Attempted wrist extension  radial deviation
of wrist
• Weakness of finger and thumb extension
• Pain : 5- 8 cm distal to lateral epicondyle
• No sensory loss

20. Superficial Radial Nerve Lesion
• Cheirargia paresthetica / Wartenberg syndrome/
handcuff neuropathy
• D/t compression of Superficial radial nerve as it
emerges b/w ECRL and BR, 8 cm proximal to
radial styloid
• Cause: Tight fitting watches/bracelets/bands
• Pain or dyesthesia over radial dorsum of hand

21. Diagnosis
• History
– Mechanism of injury (e.g. sharp penetrating vs.
blunt trauma)
– Timing of injury
– Loss of motor and sensory function
– Presence of pain
– Interval recovery of function in patients
presenting late

22. Diagnosis
• Physical Examination
– Assessment of motor function
– Assessment of sensory function
• Specific sensory testing
• Tinels sign
– Assessment of involved joints
• Tests
– Electodiagnostic test
• Nerve Conduction Studies
• EMG

23. Electrodiagnostic Studies
• Documentation of injury
• Location of insult
• Severity of injury
• Recovery pattern
• Prognosis
• Pathology
• Selection of optimal muscles for tendon transfer
procedures

25. Sequence of events in nerve
compression
Focal demyelination
Axonal damage at the
compression site
Further axonal loss
Axonal sprouting producing
collateral re-innervation
Remyelination following
decompression
▪↑Latency
▪↓Nerve conduction velocity
Associated Electrodiagnostic
findings
▪↓SNAP
▪↓CMAP
▪↑Insertional activity
▪Fibrillation potentials and
fasciculations
▪’Giant’ MUPs
▪Normalization of NCV
▪Loss of ‘giant’ MUPs

26. Treatment of Radial Nerve Palsy
• Avoid or modify aggravating activities
• Treatment of underlying cause
• Resting splints/ orthosis
• Anti inflammatory medications
• Corticosteroid injections
• Physical modalities : Electrical stimulation
• Exercises: Radial nerve glide
• Surgery

27. Splinting in Radial Nerve Palsy
• Extensor muscles weakened  overstretching
• Function of orthosis
– Prevent overstretching of extensor muscles
– Prevent deformity at wrist joint
– Maximise functional use of hand
• Types
– Static : Cock up splint
– Dynamic : Dynamic cock up , Oppenheimer splint

28. Splinting in Radial Nerve Palsy
• Static Cock up splints
disadvantage
– Do not address absent finger ext
– Grasp and release need
assistance
– Cover palmar sensibility

29. Dynamic Radial Nerve Palsy Splint

30. Electrical Stimulation
• Faradic type current :
– Neuropraxia
– Early Axonotmesis
– Muscle re education after tendon transfer
– Parameter settings
• Freq : 35-80 pps
• Duration : 150-200 microseconds
• Treatment time : 10-20 min every 2-3 hrs when awake
• Interrupted direct current used in denervated
muscle

31. Motor Points

32. Radial Nerve Glide Exercises

33. Surgery
• Indications
– Sharp injury for exploration & repair
– Blunt injury for suturing nerve ends for late repair
– No recovery after 8-10 weeks
– Failed conservative treatment for 3 months
• Procedures
– Exploration
– Neurorhaphy
– Nerve grafting
– Tendon transfer

34. Exploration

35. Nerve Repair
• Neurorhaphy
– Cutting the damaged nerve endings and suturing
– Indicated when nerve ends can be approximated
without tension
• Nerve grafting
– critical nerve gap is > 8cm (radial nerve in midarm)
– Sural nerve : most commonly used

36. Tendon Transfer
• Indication : No functional recovery after 1 year
• Current protocol of tendon transfer ( Brandt)
– Pronator teres ECRB
– Flexor carpi ulnaris  Extensor Digitorum Communis
– Palmaris longus  Extensor Pollicis Longus

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