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Radial nerve compression Flashcards

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1
Q

Define PIN compression syndrome?

A

Compressive neuropathy of PIN effective the muscular supply of the forearm EXTENSOR compartment

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2
Q

What is the epidemiology of PIN compression syndrome?

A
  • 3 per 100,000 people pa
  • More common in
    • manual labourers
    • males
    • bodybuilders
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3
Q

Describe the aetiology of PIN compresison syndrome?

A
  • Trauma- fracture/dislocation monteggia/radial head fr
  • Microtrauma- repitive pronosupination movements
  • Space filling lesions- ganglions/lipomas
  • Inflammation - rheumatoid synovitis
  • Iatragenic- surgery
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4
Q

Describe the pathoanatomy of PIN compression syndrome?

A
  • 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
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5
Q

Decribe the anatomy of PIN?

A
  • 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
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6
Q

What does PIN supply?

A

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
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7
Q

What are the symptoms and signs of PIN compression syndrome?

A

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
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8
Q

Are any investigations helpful in PIN compression syndrome?

A
  • 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
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9
Q

What is the DDX of forearm pain and weakness?

A
  • PIN compression syndrome
  • Brachial plexus compression
  • Cervical spine nerve compression
  • Peripheral neuropathy
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10
Q

Describe the TX of PIN compression syndrome?

A

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
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11
Q

Describe the technique for surgical decompression of PIN syndrome?

A

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
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12
Q

Name the complications of PIN compression syndrome?

A
  • Muscle fibrosis of PIN innervated muscles -> tendon transfer procedures to establish funciton
  • Chronic Pain
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13
Q

What is the last muscle to recover in PIN compression syndrome?

A
  • Extensor indicis Proprius
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14
Q

What is radial tunnel syndrome?

A
  • A compressive neuropathy of PIN with PAIN ONLY
  • No motor or sensory dysfunction
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15
Q

Describe the pathophysiology of radial tunnel syndrome?

A

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
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16
Q

Can you describe any associated conditions of radial tunnel syndrome?

Study These Flashcards
A
  • Lateral Epicondylitis
  • RTS is difficult to distinguish from lateral epicondylitis and coexts in 5% pts
17
Q

Describe the anatomy of the radial tunnel?

Study These Flashcards
A
  • 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
18
Q

Describe the signs and symptoms of radial tunnel syndrome?

Study These Flashcards
A

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
19
Q

Investigations in radial tunnel syndrome?

Study These Flashcards
A
  • 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
20
Q

What is the DDX of lateral forearm pain?

Study These Flashcards
A
  • Radial tunnel syndrome- tenderness 305cm distal to lat epi
  • Lateral epicondylitis- tenderness directly over Lat epicondyle
  • Cervical radiculopathy C6-7
21
Q

What is Tx of the radial tunnel syndrome?

Study These Flashcards
A

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
22
Q

Describe the technique for radial tunnel release?

Study These Flashcards
A

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%
23
Q

What is Wartenberg’s syndrome?

Study These Flashcards
A
  • Compressive neuropathy of Superficial radial nerve
  • aka Cheiralgia paresthetica
  • Sensory manifestation only
  • no motor deficit
24
Q

What is the epidemiology of Wartenberg’s syndrome?

Study These Flashcards
A
  • Rare
  • Female : Male 4:1
  • Age 20-70 years
25
Describe the pathoanatomy of Wartenberg's syndrome?
* Superficial radial nerve compressed by **SCISSORING action of Brachioradialis & ERCL tendons** during forearm **PRONATION** * **also fascial bands** at its exit site in subcutaneous tissue
26
Name any associated conditions with Wartenberg's syndrome?
* De Quervain's Disease in 20-50%
27
What is the prognosis of Wartenberg's syndrome?
* **Spontaneous resolution** is common * **74% success** after _surgical decompression_
28
Describe the course of the superificial radial nerve?
* Arises from the bifircation of the radial nerve in the proximal forearm * travels **DEEP** to **brachioradialis** in forearm * emerges from **BETWEEN Brachioradialis & ERCL 9cm Proximal to RADIAL STYLOID** * **Bifurcates** proximal to wrist * **dorsal branch lies 1-3cm radial to lister's tubercle** * supplied 1st /2nd web space * palmar branch passes **2cm of 1st dorsal compartment directly over EPL**- supplies dorsolat thumb
29
Describe the Signs and symptoms of Warternberg's syndrome?
Hx * maybe of trauma- forearm fracture * handcuffs * tight wrist band/ wrist watch , bracelet or pop Symptoms * **ILL defined pain** over **DORSALRADIAL hand**- no watch!! * **Paresthesia** over **dorsalradial hand** * **Numbness** * **worse w repetitive wrist flexion/ulnar deviation** * **no motor weakness** _​Signs_ * **Tinel's signover superficial sensory radial nerve** * **Wrist flexion, ulnar deviation & pronation for 1 min** * **Finklestein test** Investigaitons limited- emg limited, diagnostic wrist block
30
What is the DDX of ill-defined forearm pain and parathesia?
* **De Quervain's Tenosynovitis**- Pain not aggrevated by wrist pronation * **Lateral antebrachial cutaneous nerve neuritis-** positive tinels over LACN mistaken for SSR nerve * **Intersection syndrome-** dorsoradial swelling, crepitus on wrist flexion/extension * **Wartenberg's syndrome**
31
Describe the tx of Wartenberg's syndrome?
_Non operative_ * **Rest, activity modification, nsaids, wrist splints** * **Corticosteriod injections** - linited evidence _Operative_ * **Surgical decompresion**- symptoms **\>6 months**
32
Describe the surgical decompression technique?
Approach * longitudinal incision volar to Tinsel's sign * to _avoid Lateral antebrachial cutaneous nerve_ * to avoid _tethering of incision scar over sup radial Nerve_ * Neurolysis * Release fascia betwen **Brachioradialis and ERCL**
33
What are the complications of Wartenberg's syndrome?
* Failed Decompression * Persistent Pain and numbness * wound dehiscence * Infection
34
35
Describe the course of the radial nerve?
* Arises **posterior cord brachial plexus C5-8 roots** * descends **anteriorly to Subscapularis, teres major, lat dorsi** * continues **lateral and posterior to run in spiral groove of proximal humerus** * passes beneath **LATERAL head of TRICEPS to PIERCE LATERAL INTERMUSCULAR SEPTUM as it courses from POST to ANT** compartments * IN cubital fossa - emits muscular branches to **BRACHIALIS, BRACHIORADIALIS, ERCL.** * Then divides into **PIN** and **SENSORY RADIAL NERVE** * Level of **RADIOHUMERAL joint PIN enters radial tunnel.**

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