Radial nerve compression Flashcards
Define PIN compression syndrome?
Compressive neuropathy of PIN effective the muscular supply of the forearm EXTENSOR compartment

What is the epidemiology of PIN compression syndrome?
- 3 per 100,000 people pa
- More common in
- manual labourers
- males
- bodybuilders
Describe the aetiology of PIN compresison syndrome?
- Trauma- fracture/dislocation monteggia/radial head fr
- Microtrauma- repitive pronosupination movements
- Space filling lesions- ganglions/lipomas
- Inflammation - rheumatoid synovitis
- Iatragenic- surgery
Describe the pathoanatomy of PIN compression syndrome?
- 5 potential sites of compression= FLEAS
-
Fibrous tissue ant to radiocapitellar joint
- between brachialis/brachioradialis
-
Leash of Henry
- recurrent radial vessels fan out across PIN at level of radial necl
-
Extensor carpi radialis brevis edge
- mediporx edge of ECRb
-
Arcade of Frohse
- prox edge of superficial portion of Supinator
-
Supinator Muscle edge
- Distal edge of supinator muscle

Decribe the anatomy of PIN?
- Branch of radial nerve
- Provides motor innervation EXTENSOR compartment
Course
- Passes between 2 heads of supinator muscle
- Direct contact with radial neck
- Passes over Abductor pollicis longus to reach interosseous membrane
- transverses along posterior interossesous membrane

What does PIN supply?
Common extensors
- ECRB
- EDC
- EDM
- ECU
Deep Extensors
- Supinator
- Abductor pollicis longus
- Extensor pollicis brevus
- Extensor pollicis longus
- Extensor incidis proprius
Sensory
- sensory fibres to dorsal wrist capsule- by terminal branch
- Located on floor of 4th EXTENSOR COMPARTMENT

What are the symptoms and signs of PIN compression syndrome?
Symptoms
- Insidous onset
- Pain in forearm & wrist- location depends on site of compression
- Weakness with finger, wrist and thumb movements
Signs
- Chronic compression- muscle atrophy
- Weakness- finger metacarpal extension
- Wrist extension weakness
- inability to extend wrist in neutral/ulna deviation.
- Wrist will extend with RADIAL deviation due to intact ERCL ( radial N) and absent ECU ( PIN)
-
Provocation test
- RESISTED SUPINATION- Increase Pain
- Normal Tenodesis effect - Ra ext tendons won’t
Are any investigations helpful in PIN compression syndrome?
- Yes MRI- maybe helpful to deliniate the soft tissue mass responsible for compression
- EMG- may be helpful to identify level of compresion adn rule out differential diagnosis of neuropathy
What is the DDX of forearm pain and weakness?
- PIN compression syndrome
- Brachial plexus compression
- Cervical spine nerve compression
- Peripheral neuropathy
Describe the TX of PIN compression syndrome?
Non operative
- Rest, activity modification, stretch, splinting, NSAIDS
-
Cortiosteriod injection if compressive mass ruled out and isolated tenderness distal to lateral epicondyle
- single injection 3-4 cm to lat epicondyle at site of compression
Operative
- Surgical decompression
- symptoms >3mo of non op tx
- compressive mass detected on investigations
- Outcomes variable- spontaneous recovery of motor function seen in 75-97% of non traumatic cases
- may continue to improve for up to 18 mo
Describe the technique for surgical decompression of PIN syndrome?
Approach
- Anterolateral to elbow most common
- Release first..
- Fibrous band connecting Brachialis and brachioradialis
- leash of Henry
- Fibrous edge of ERCB
- Radial tunnel inc arcade of Frosche and distal supinator
Name the complications of PIN compression syndrome?
- Muscle fibrosis of PIN innervated muscles -> tendon transfer procedures to establish funciton
- Chronic Pain
What is the last muscle to recover in PIN compression syndrome?
- Extensor indicis Proprius
What is radial tunnel syndrome?
- A compressive neuropathy of PIN with PAIN ONLY
- No motor or sensory dysfunction
Describe the pathophysiology of radial tunnel syndrome?
involves the same sites as PIN compression syndrome
- Fibrous band between Brachialis and brachoradialis, anterior to radiocapitellar joint
- Leash of Henry- radial recurrent vessels
- ECRB medial border
- Arcade of Frohse prox edge of supinator- most frequent site of entrapment
- Supinator distal border edge

Can you describe any associated conditions of radial tunnel syndrome?
- Lateral Epicondylitis
- RTS is difficult to distinguish from lateral epicondylitis and coexts in 5% pts
Describe the anatomy of the radial tunnel?
- 5cm in length
- Extends from level of radiocapitellar joint extending distally past the proximal edge of supinator
- Boundaries
- lateral
- Brachioradialis
- ECRB
- ECRL
- medial
- Biceps tendon
- Brachialis
- Floor
- capsule of radiocapitellar joint
- lateral
Describe the signs and symptoms of radial tunnel syndrome?
Symptoms
- Deep aching pain in DORSAL RADIAL PROXIMAL forearm
- From lateral elbow to wrist
- increased during forearm rotation/lifting
- muscle weakness due to pain
Signs
- Tenderness over wad in supinator arch
- Max tenderness 3-5cm distal to Lat epicondyle
- Resisted long finger extension->pain at tunnel
- Resisted supination ( elbow/wrist in extension)
- Passive pronation-> pain
- Radial tunel injection test- positive= PIN palsy, PAIN relief
Investigations in radial tunnel syndrome?
- MRI usually negative
-
EMG- inconclusive as PIN carries Group IV fibres- (C fibres, nioception) and small myelinated Group IIA afferent fibres( temperature)
- Pressure on these nerves causes pain
- these fibres can’t be evaluated by EMG
- large myelinated PIN fibres remain normal so EMG normal
- Diagnostic injection into area of local tenderness
What is the DDX of lateral forearm pain?
- Radial tunnel syndrome- tenderness 305cm distal to lat epi
- Lateral epicondylitis- tenderness directly over Lat epicondyle
- Cervical radiculopathy C6-7
What is Tx of the radial tunnel syndrome?
Non operative
- Activity modification, temporary splinting, nsaids
- Corticosteriods
70% improvement at 6 weeks
60% painfree at 2 years
Operative
- Radial tunnel release
- Disappointing outcomes only 50-90% gd-ex recovery
- delayed max recovery up to 9-18 months
- lower success in concomitant lat epicondylitis, multiple entrapment neuropathies and workers compensation
Describe the technique for radial tunnel release?
Approach
- Dorsal approach to PIN
- 3 planes have been described
- between ERCB and EDC
- Between brachioradialis and ERCL
- Transmuscular brachioradialis spliting
- Anterior approach to PIN
- Between brachioradilis and biceps
- Release
- fibroud bands superificial to radiocapitellar joint
- arcade of Frohse
- distal edge of supinator
- Outcomes= success rate decompression 70-90%
What is Wartenberg’s syndrome?
- Compressive neuropathy of Superficial radial nerve
- aka Cheiralgia paresthetica
- Sensory manifestation only
- no motor deficit
What is the epidemiology of Wartenberg’s syndrome?
- Rare
- Female : Male 4:1
- Age 20-70 years



