Radial nerve entrapment

Presented by : Dr Yash Oza
Moderator : Dr Pradip Patil

Radial Nerve
e
• Largest branch of the brachial plexus
• Arises from the posterior cord of the brachial plexus (C5–T1)
• Mixed nerve
Anatomy

Course of Radial Nerve
• The Axilla
• The Axilla to the Spiral Groove
• The Spiral Groove to the Supinator Muscle
• Branches
• The Posterior Interosseous Nerve
• The Superficial Sensory Radial Nerve

• The Axilla
• Radial nerve in the distal axilla.
• The radial nerve lies superficial to
three muscles
• (from proximal to distal):
1. the subscapularis
2. the latissimus dorsi tendon
3. the teres major
• The radial nerve enters the arm
anterior to the long head of the
triceps.
• It soon dives into a cleft between the
long triceps head and the medial
triceps head.
• Within this cleft, the nerve runs
toward the spiral groove.

• The Axilla to the Spiral Groove
• The radial nerve passes down the spiral
groove between the origins of the lateral
and medial heads of the triceps.
• It remains in contact with the humerus
and is covered by the lateral head of the
triceps.
• Then it pierces the lateral intermuscular
septum, about halfway down the arm.

• The Spiral Groove to the Supinator
Muscle
• Upon entering the flexor compartment at
midarmlevel, the radial nerve runs under
three muscles, which sequentially arcade
over the nerve.
• This anatomical arrangement has been
referred to as the radial tunnel.
• ECRB loops over it; that may predispose
the radial nerve to irritation.
• Distal to the elbow joint, the radial nerve
bifurcates into the,
1. posterior interosseous and
2. superficial sensory radial nerves.
And enter supinator muscle.

• The supinator has a deep and a superficial head.
• The superficial head forms a pocket, into which the posterior
interosseous nerve descends. The edge of this pocket can be fibrous
and is termed the arcade of Fröhse.
• The superficial sensory radial nerve remains superficial to both heads
of the supinator.

• The Posterior Interosseous Nerve
• After emerging from between the two heads of the supinator muscle,
the PIN lies between extensor digitorum communis the abductor
pollicis longus.
• It then ramifies into a large number of unnamed branches, which are
often called the cauda equina of the forearm.
• It gives of muscular branches to following muscle.
• PIN Deep Group:
• Abductor Pollicis longus
• Extensor pollicis longus
• Extensor pollicis brevis
• Extensor indicis
• PIN Superficial Group
• Extensor carpi Ulnaris
• Extensor digitorum communis
• Extensor digiti minimi

• The Superficial Sensory Radial Nerve
• It remains deep to the brachioradialis muscle until 2/3rd of the way down the
forearm.
• In the lower 1/3rd it becomes superficial when the BR and ECRL form their
tendons.
• Then nerve passes to the dorsal aspect of the wrist, branches upon the
dorsolateral aspect of the hand, and remains superficial to the extensor
retinaculum.
• The superficial sensory radial nerve usually has four or more terminal sensory
branches.
Dorsal digital nerves ECRL
Dorsal Radial Sensory BR
Nerve
8 cm
Radial styloid

Lower lateral cutaneous
nerve of arm
Posterior cutaneous
nerve of arm
Posterior cutaneous
nerve of forearm
Dorsal radial sensory
nerve
dorsum of the hand over the
radial two-thirds, the dorsum
of the thumb, and the index,
middle finger proximal to the
distal interphalangeal joint.
Cutaneous innervation from radial nerve

MOTOR
Innervation Of
Radial Nerve

MOTOR Innervation Of Radial Nerve
Radial nerve
Innervated muscle
Triceps brachii
Brachioradialis
Extensor carpi radialis longus
Extensor carpi radialis brevis

Radial nerve
Innervated muscle
Triceps brachii
Brachioradialis
Extensor carpi radialis longus
Extensor carpi radialis brevis

PIN
Supinator
Extensor carpi ulnaris
Extensor digitorum
Extensor digiti minimi
Abductor pollicis longus
Extensor pollicis longus
Extensor pollicis brevis
Extensor indicis

PIN
Supinator
Extensor carpi ulnaris
Extensor digitorum
Extensor digiti minimi
Abductor pollicis longus
Extensor pollicis longus
Extensor pollicis brevis
Extensor indicis
EPB – Resistance applied
at prox phalanx
EPL – Resistance applied
at distal phalanx

Radial Nerve Entrapment
• Entrapment neuropathies refer to isolated nerve injury occurring at
specific location where a nerve is mechanically constricted in a
fibrous/ fibro osseous tunnel
• Mechanism is : Compression, constriction, angulation or streatching
• Common cause :
• External : cast brace, tourniquet
• Internal : Bony callous, ganglion, tumours, fibrous tissue, normal or abberent
muscle
• Compression may be acute or intermittent or continuous.

Pathophysiology of entrapment
• Nerve is surrounded by loose connective tissue called adventia
nevosum – it is regional vascular bundle in nerve circumference
• Normally, Movement of extremity slightly alters this vascular
circulation
• Stretch or traction beyond certain limit will affect this circulation and
obstruction to outflow.
• Create positive pressure to endoneurium
• Leading to intrafascicular edema & nerve damage
• It’s termed as miniature closed compartment syndrome
• Histologically – segmental demyelination & remyelination seen
It is type of a Neuropraxia

• General condition that may predispose to Neuropathy
• DM
• GB Syndrome
• Double crush hypothesis – nerves are more susceptible to
compression if fibers are damaged proximally
• Tomoculous Neuropathy – a hereditary pressure sensitive neuropathy
. d/t abnormal myelination

Radial Entrapment
• Common site
A) Axialla :
• Crutch palsy – d/t pressure with
ill- adjusted crutches whithout
proper handgrip
• Aneurism of axillary vessels
B) Shoulder
• # - D/L of upper humerus &
attempt to their reduction
C) Radial Groove :
• # shaft Humerus
• Prolonged application of
tourniquet
• Ill-applied cast
• Saturday Night Palsy &
Honeymoon palsy
• Excessive callus of an old fracture
• Infection & Iatrogenic

D) B/w Spiral groove & Lat.
Epicondyle
• # Shaft Humerus
• # Supracondylar humerus
• # lateral condyle
• Cubitus vulgus deformity
E)Elbow :
• Dislocation
• # neck of radius
• Enlarged burase
• RA Elbow
• Radial head excision surgery
• Radial tunnel syndrome/ PIN
syndrome
F) Forearm
• Cheiralagia Parasthetica /
Wartnberg Disease

Saturday night palsy :
• radial nerve compression in the arm resulting from direct pressure
against a firm object.
Honeymoon Palsy :
• When bed partner’s head compresses radial nerve while resting in
crook of partner’s arm
Radial tunnel syndrome :
• Entrapment of PIN in in radial tunnel
Cheiralagia Parasthetica / Wartnberg Disease:
• compression of Superficial radial nerve as it emerges b/w ECRL
and BR, 8 cm proximal to radial styloid

Type Location Motor Sensory
Very High Above spiral
groove
Total Palsy Post Cut.N. of
Arm spared
High B/w Spiral
groove & Lat
Epicondyle
Triceps spared
BR involevd
Lower Lat.CN of
Arm & Post.CN of
Forearm (+/-?)
(both emerges from
spiral groove)
Low At Elbow Elbow, Wrist
extensor spared
Lost over dorsum
of 1st web space
PIN - Elbow, Wrist
extensor spared
Spared
Type of Radial nerve injuries according to location

Clinical Features
• Sign & Symptoms – according to the level of involvement
MOTOR :
• Clumpsiness, weakness, wasting or fasciculation of muscle
• Paralysis, loss of tone, atrophy, areflexia, insensitivity to compression
SENSORY :
• Numbness, paresthesia, tingling, prickling, burning over affected
area
AUTONOMIC :
• Atrophy, ulcer, skin changes, hyperesthesia

•TINEL SIGN :
• Gentle percussion by finger hammer from distal to
proximal direction along the course of nerve gives
transient tingling sensation in distribution of nerve
• Sensation should persist for several seconds

Diagnosis
• History taking
• Motor- sensory examination
• Electrophysiological studies – EMG & NCV
• CT scan
• MRI

Lower lateral cutaneous
nerve of arm
Posterior cutaneous
nerve of arm
Posterior cutaneous
nerve of forearm
Dorsal radial sensory
nerve
Cutaneous innervation from radial nerve

EMG
• Indicates that the muscle is innervated or not
• But gives no specific indication as to the level of injury to nerve
• Denervated muscle show sharp positive consistent waves.
• This waves will last until the muscle has become reinvervated or
fibrotic.

NSC
• In nerve conduction velocity studies there will be slowed conduction
time at a specific point along the course of the nerve

• Use of Electrodiagnostic Testing
1. Documentation of injury
2. Location of insult
3. Severity of injury
4. Recovery pattern
5. Prognosis
6. Objective data for impairment documentation
7. Pathology
8. Selection of optimal muscles for tendon transfer
procedure

CT scan & MRI
• Used to identify causative factor & site for nerve compression by an
anatomical object.
• Not always indicated.

Treatment
• Most of entrapment injuries are managed conservatively with good
to excellent result.
• Important function to be regained are
1. Wrist extension
2. Metacarpophalangeal joint extension
3. Thumb Extension

 SPLINTS
 NSAIDS
 Ultrasound Therapy
 Gradual rehabilitation programme
 Removal external offending compression
 Steroid injection
Conservative Treatment

 SPLINTS
 full passive range of motion in all joints of
the wrist and hand and prevention of
contractures, including that of the thumb-
index
 wrist drop can be treated successfully by
splints
 Barkhalter has observed that grip strength
may be increased by 3 to 5 times by simply
stabilizing the wrist with splints
 Many types of splints have been
described & Each patient individual
need should be addressed
Conservative Treatment

 EMG studies every 4 week is indicated during conservative treatment
 If clinical or EMG evidence of recovery ensues within 12 weeks of onset
surgical exploration is most likely not indicated

 When a nerve deficit follows blunt or closed trauma,
and no clinical or electrical evidence of regeneration
has occurred after an appropriate time, exploration of
the nerve is indicated.
 If no sign of recovery seen after 12 weeks of
conservative therapy,
 Surgical exploration & Neurolysis with release of all
possible offending structure is needed
Surgical Exploration

 It provides internal splint.
 It restores the power quickly and effectively
Advantages are:
 It works as a substitute during nerve regrowth and
largely eliminates an external splint
 Subsequently the transfer aids the newly innervated
and weak wrist extensor
 It continues to act as a substitute in case nerve
regeneration is poor or absent
Tendon Transplant

 Tendon transfers work to correct:
 instability
 imbalance
 lack of co-ordination
 restore function by redistributing remaining
muscular forces

 Tendon transplant in radial nerve palsy
needs to be provided with
(1) wrist extension.
(2) finger (metacarpophalangeal [MP] joint) extension.
(3) a combination of thumb extension and abduction.

Radial nerve compression syndromes

Wartenberg’s syndrome / Cheiralgia paresthetica
• compression of Superficial radial nerve as it emerges b/w ECRL
and BR, 8 cm proximal to radial styloid
Dorsal digital nerves ECRL
Dorsal Radial Sensory BR
Nerve
8 cm
Radial styloid

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

Finkelsetein sign
Palmar flexion & ulnar deviation increases the sympopms
Treatment
- Removal of encircling structure ( Wristwatch, Handcuff)
- Local Inj.of steroid
- Exploration & Neurolysis

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

The radial tunnel is a 5cm space
bounded by:
▪Dorsally: capsule ofthe
radiocapitellar joint
▪Volarly: the BR
▪Laterally: the ECRL and ECRB
muscles
▪Medially: the biceps tendon and
brachialis muscles
Within radial tunnel, there are5
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 ofFröhse)
▪the distal edge of theSupinator
BR
arcade of Fröhse
Supinator
ECRL
PIN

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

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

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

Radial nerve entrapment

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