PLASTIC SURGERY

1. Radial
Nerve
Palsy
Clinical
features &
Diagnosis
Dr Subhakanta Mohapatra
IPGME&R,Kolkata.INDIA

2. Anatomy

3. Radial Nerve
• Largest branch of the brachial plexus
• Arises from the posterior cord of the
brachial plexus (C5–8)
• Mixed nerve

4. Course of Radial Nerve (RN) in the arm
• Sensory supply:
In the axilla, RN lies
Posterior cutaneous
anterior to subscapularis,
nerve of arm
teres major and LD
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 then leaves the spiral groove
by piercing the lateral
intermuscular septum to enter
the anterior compartment of the
arm, 10-12 cm above the lateral
epicondyle
• Motor supply: Brachialis (lateral
part), BR, ECRL
Here it lies b/w brachialis and
BR
• Terminal branches:
Posterior Interosseous
Anterior to lateral epicondyle, RN
Nerve (PIN) and Dorsal
divides into its terminal branches
or Superficial radial
sensory nerve

6. Radial nerve (C5, 6, 7 , 8, T1)
exiting axilla via the
triangular space
Triceps brachii
Radial nerve in the spiral
groove (posterior aspect of
humeral shaft)
Posterior cutaneous nerve of
arm
Lower lateral cutaneous
nerve of arm
Lateral intermuscular
septum
Brachialis (lateral part)
ECRL (last branch of radial
nerve proper)
Brachioradialis (BR)
Posterior cutaneous nerve of
forearm
Anconeus

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

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

9. Cutaneous innervation from radial nerve
Lower lateral cutaneous
nerve of arm
Posterior cutaneous nerve
of arm
Gives sensibility to the dorsum
of the hand over the radial twothirds, the dorsum of the
thumb, and the index, long, and
half of the ring finger proximal
to the distal interphalangeal
joint.
Posterior cutaneous nerve
of forearm
Dorsal radial sensory nerve

10. Clinical Features

11. Functional motor deficit
Inability to extend the wrist (in
case of injury at level of PIN, wrist
extension is weak with radial
deviation since ECRL innervation
is intact)
Inability to extend and radially
abduct the thumb
Weakness of grip strength d/t loss
of mechanical advantage that
wrist extension provides for grasp
and power grip
Inability to extend the fingers at
the MCP joints

12. Sensory Loss
Unlike the median and ulnar
nerves, sensory loss following
radial nerve injury is not
functionally disabling unless the
patient develops a painful
neuroma
Area of sensory loss in
radial nerve injury in the
axilla
The Lateral cutaneous nerve of
forearm has a significant
overlap pattern with the
Superficial radial sensory nerve
Autonomous sensory zone for
radial nerve → dorsum of 1st
webspace

13. Radial Nerve
Compression
Syndromes

14. Wartenberg’s syndrome
• Aka: Cheiralgia paresthetica
• D/t compression of Superficial radial nerve as it
emerges b/w ECRL and BR, 8 cm proximal to radial
styloid

15. presence of motor weakness
suggests a more proximal site of
compression
isolated pain or paresthesias
over the dorsoradial aspect of
the hand
preceding history of trauma to
the area (i.e., handcuffs,
forearm fracture)
Clinical features
Differentiating Wartenberg’s
syndrome from de Quervain’s
tenosynovitis
In WS, pain is exacerbated by pronation, while in DQT pain
is elicited with changes in thumb and wrist position
DQT - normal sensation in the dorso-radial hand
DQT - pain on percussion over the 1st extensor
compartment
Also seen in patients who use
forearms in pronated position
for extended periods → in
pronation, the tendons of BR
and ECRL approximate and may
compress the nerve
A Tinel’s sign over the
superficial sensory radial nerve
is the most common exam
finding
Electrodiagnostic testing is of
limited value in Wartenberg’s
syndrome

16. Posterior interosseous nerve (PIN) syndrome
• D/t compression of PIN in the radial tunnel
• Most common causes include:
Tumors such as lipomas, ganglia
Rheumatoid synovitis
Septic arthritis
Vasculitis

17. PIN
BR
arcade of Fröhse
The radial tunnel is a 5 cm space
bounded by:
Dorsally: capsule of the
radiocapitellar joint
Volarly: the BR
Laterally: the ECRL and ECRB
muscles
Medially: the biceps tendon and
brachialis muscles
Supinator
ECRL
Within radial tunnel, there are 5
potential sites of compression:
fibrous bands to the
radiocapitellar joint between the
brachialis and BR
the recurrent radial vessels (leash
of Henry)
the proximal edge of the ECRB
the proximal edge of the
Supinator (arcade of Fröhse)
the distal edge of the Supinator

18. Diagnosis
loss of finger and thumb extension
Weak wrist extension with radial deviation
(since ECRL innervation is intact)
Intact passive tenodesis effect
(rules out extensor tendon rupture)
EMG testing is helpful to confirm the diagnosis and
monitor motor recovery

19. Radial Tunnel syndrome
• Similar to PIN syndrome, it is also d/t compression of
PIN in the radial tunnel
• Not considered a true compression neuropathy by
some

20. Radial Tunnel Syndrome is a clinical diagnosis
Pain at ECRB origin
with resistance of
middle finger
extension
Tenderness over
radial tunnel
(lateral proximal
forearm, 3-4 cm distal
to lateral epicondyle
over the mobile wad)
Pain with resisted
forearm supination
↑ Pain on combined
elbow extension,
forearm pronation,
and wrist flexion
Radial Tunnel
Syndrome

21. Proximal Radial nerve compression
• Compression of the radial nerve proximal to the elbow is
uncommon
• Causes:
Fibrous arch from the lateral head of triceps
After strenuous muscular activity
Bony exostosis of humerus
Injury in spiral groove:
# shaft humerus
‘Saturday night palsy’ (neuropraxia)
Post injection palsy (chemical neurotmesis)
• Patients present with variable degrees of radial nerve
dysfunction

22. Diagnosis

23. 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

24. Physical
Examination
Individual muscles innervated by the
nerve are tested to determine what is
functioning and what is not:
Helps to determine the level of injury
Guides future surgical planning
Assessment of motor function
Assessment of sensory function
Elicitation of Tinel’s sign
Specific sensory testing
Assessment of involved joints
Each joint is taken through its passive
range of motion to assess for
suppleness → presence of fixed joint
contractures in delayed presentations
is associated with poor treatment
outcomes

25. Specific sensory tests
Test
Perception
Main receptor
Comments
Static 2 point
discrimination (2PD)
Tactile
Merkel cell
Evaluates sensory
receptor innervation
density
Normal distance: 6mm
Moving 2PD
Tactile
Meissner corpuscle
Tuning fork (250 Hz)
Vibration
Pacinian corpuscle
Tuning fork (30 Hz)
Vibration
Meissner
Semmes-Weinstein
monofilament test
Pressure
Merkel
Ten test (moving light
touch)
Pressure
Merkel
Cold-heat test
Temperature
Free nerve endings
Normal distance: 3mm
Reliability comparable
to monofilament test
•Changes in Vibration and Pressure thresholds are seen in early nerve compression but are unreliable for
evaluating nerve lacerations
•Changes in sensory receptor innervation density (2PD) are seen in chronic nerve compression but are reliable for
evaluating nerve lacerations

26. Electrodiagnostic
testing
Electromyography (EMG)
Helpful in arriving at a diagnosis
in presence of atypical
presentations or equivocal clinical
findings
Nerve conduction studies
(NCS)
Limitations of EDT:
Evaluates only large myelinated
fibres → smaller axons conveying
pain and temperature are not
assessed
Changes in unmyelinated nerve
fibres, which are the first to be
affected in nerve compressions,
are not evaluated
Performing the test before 3-6
weeks post injury can give
inaccurate results
Very proximal or distal nerve
injuries are difficult to assess
Unreliable assessment of multilevel injuries
Examiner dependant

27. Nerve conduction studies (NCS)
2 electrodes are placed along the course of the
nerve. The first electrode stimulates the nerve to
fire, and the second electrode records the
generated action potential
Amplitude
• represents the size of the
response
• proportional to the number
of depolarizing axons in the
nerve
Latency
• the delay in response
following stimulation
Sensory nerve action potential
(SNAP)
• Response obtained when
the recording electrodes is
placed proximally along the
sensory nerve, toward the
spinal cord
Conduction velocity
Compound motor action
potential (CMAP)
• Response obtained when
the recording electrodes is
placed distally at the target
muscle

28. Electromyography (EMG)
Insertional activity
Fibrillation potentials
Fasciculations
Motor unit potentials
(MUPs)
• Activity observed when a needle
electrode is inserted into the muscle
• Seen when the muscle is at rest
• Absent in normal muscles
• Generated by the muscle during a
voluntary contraction
• Evaluates the integrity of neuromuscular junction

29. 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
Associated Electrodiagnostic
findings
↑Latency
↓Nerve conduction velocity
↓SNAP
↓CMAP
↑Insertional activity
Fibrillation potentials and
fasciculations
’Giant’ MUPs
Normalization of NCV
Loss of ‘giant’ MUPs