Median Neuropathies Flashcards Preview

Hands FRCS > Median Neuropathies > Flashcards

Flashcards in Median Neuropathies Deck (33):
1

Define Carpal Tunnel syndrome?

Most common compressive neuropathy of median nerve at the wrist

A image thumb
2

Describe the aetiology of Carpal Tunnel syndrome?

  • Pathologic Inflammed Synovium most common cause of idopathic CTS

3

What is the epidemiology of CTS?

  • 0.1-1% general population effected

  • Risk factors

    • Female 



    • obesity 





    • Pregnancy 







    • Hypothyroidism 









    • RA
       
    • advanced age


    • Chronic kidney failure 




    • Smoking 






    • ETOH excess 








    • Repitive motion activities 










    • Mucopolysaccharidosis 












    • Mucoliposis 

 

 

4

Describe the pathophysiology of CTS?

  • Mechanism- precipitation to repititive motions and vibrations
    • cyclists, tennis, throwing
  • Compression maybe due to
    • repetitive motions in patients with normal anatomy
    • Space occupying lesions- e.g. gout/ synovial sarcoma/lipma/ganglions

5

Name associated conditions with CTS?

  • Diabetes Mellitis
  • Hypothyroidism
  • RA
  • Pregnancy
  • Amyloidosis

6

What is the prognosis of CTS?

Good prognostic indicatiors are

  • Night symptoms
  • Short incisions
  • relief of symptoms with steriod injections
  • Not improved when incomplete release of transeverse carpal ligament is discovered

 

 

7

What is the anatomy of the carpal tunnel?

Defined by

  • Scaphoid tubercle and trapezium radially
  • hook of hamate and pisiform ulnarly
  • Transverse carpal ligament -roof
  • proximal carpal row distally - floor
  • narrowest at Hook of HAMATE

Contains

  • 9 flexor tendons- FDP/FDS/ FPL
  • 1 nerve- Median
  • FPL most radial structure

 

A image thumb
8

Name the branches of the median nerve?

  • Palmar cutaneous branch of median n- between PL & FCR at wrist flexion crease
  • Recurrent motor branch of median nerve
    • ​50% Extraligamentous w recurrent innervation
    • 30% Subligamentous with recurrent innervation
    • 20% Transligamentous with recurrent innervation
    • Cut transverse ligament far ULNAR to avoid cutting nerve if transligamentous

A image thumb
9

Can you describe the signs and symtpoms of carpal tunnel?

Symptoms

  • Numness and tingling in radial 3 1/2 digits
  • clumsiness
  • Pain and parathesia that awaken pt at night
  • self administered hand digram= 76 % carpal tunnel

O/E

  • Thenar atrophy
  • Durkan's compression test- most sensitive dx- pressing thumbs over carpal tunnel and pressure hold for 30 seconds- onset of pain & parathesia within 30s= +ve
  • http://www.orthobullets.com/video/view?id=12
  • Phalen's test- Wrist flexion with elbow extended for 60sec= + symptoms
  • http://www.orthobullets.com/video/view?id=13
  • Tinels test- tapping nerve over volar carpal tunnel
  • Semmes- Weinstein testing- most sensitive sensoy test for detecting ealry carpal tunnel syndrome, measures single nerev fiber innervating a receptor/gr of receptors
  • Innervation density test- statis adn moving 2 point discrimination. Measure mutiple overlapping of diff sensory units and complex cortical integration. Gd at testing functional nerve regeneration after n injury

 

A image thumb
10

What investigations are helpful in CTS diagnosis?

EMG and NCV

not needed to establish diagnosis as this is clinical

  • NCV
  • Demyelination-> Increase latencies= slowing NCV
    • distal sensory >3.2ms, motor >4.3 ms
    • decrease condition velocities, V<52m/sec abn
  • ​EMG
    • Test the electrical activity of individual muscle fibres and motor units
    • Details insertional/ sponataneous activity
    • Increase insertional activity
    • Sharp waves
    • Fibrillations
    • Fasciculations
    • Complex repetitive discharges

 

 

11

What is neve histology characterised by?

  • Oedema
  • Fibrosis
  • Vascular sclerosis
  • Scattered lymphocytes
  • Amyloid deposits shown with special stains in some cases

12

Describe the Tx of CTS?

Non operative

  • Night splints, NSAIDs, Activity modifications
  • night splints gd for nocturnal symptoms, activity modification- neutral position as extension increases carpal tunnel pressure and symptoms
  • Steriod Injection- 80% transient improvement- 22% symptom free at 1 yr. Failure to improve post injection= poor prognostic sign

Operative

  • Carpal Tunnel Release-open vs arthroscopic failed Consx Tx/Acute radius Fracture, temporarily improvement w steriod -pt gd outome with surgey
    • Pinch strength return in 6 weeks
    • Grip strength expected to return to 100% preop levels by 12 weeks
  • ​Revision for CTS for incomplete release
    • Failure to improve post primary surgery
    • Incomplete release most common cause
    • Outcomes= only 25% will have complete relief after revision CTR, 50% some relief, 25% no relief

13

Describe the technique for CTS release?

  • Antibiotics not required for elective pts
  • Guyon's canal doesn't need release as decompressed by carpal tunnel release
  • Tourniquet
  • Local anaesthetic
  • Incision= inline with 3rd webspace 3-4cm in palm
  • thru skin, fat, down to transverse carpal ligament
  • Be aware of recurrent branch of median nerve may cross TCL
  • Cut TCL under direct vision then see median nerve
  • Put macdonalds uner neath distal to fat - distal palmar artery branch close 
  • Release proximal over tendon first then thru tendon
  •  

 

14

Describe the complications of open CT decompression?

  • Incomplete release
  • Damage to recurrent branch of median nerve-> thenar muscle atrophy

15

what are the advantages of arthropscopic ct release?

  • Accelerated rehabiliation
  • Long term results same as Open
  • Incomplete division of transverse carpal ligament

16

Define AIN compression neuropathy?

  • Compressive neuropathy of the AIN that results in
  • Motor Deficit only
  • No sensory loss 

 

17

Describe the anatomy course of AIN?

  • Terminal branch of median nerve
  • AIN arises from median n approx 4cm distal to medial epicondyle where it passes into the anterior interosseous membrane to sites of innervation

AIN 3 letters supplies 3 muscles 'OK sign"

  • Supplies
    • FDP to Index and middle finger
    • FPL
    • Pronator quadratus

A image thumb
18

Dsecribe the pathoanatomy of AIN compression?

Potential sites of entrapment

  • Tendinous edge of deep head of PRONATOR TERES- most common area
  • FDS arcade
  • Edge of lacertus fibrosus
  • Accessory head of Gantzer's muscle

A image thumb
19

What are the signs and symptoms of AIN compression?

Symptoms

  • Motor deficit only
  • No pain

​Signs

  • Complete palsy of all 4 muscles innervated by AIN
  • Weakness of grip and strength esp at thumb= unable to make an OK sign- test FPL/FDP
  • Pronator quadratus weakness- weak resisted pronation w elbow maximally flexed
  • Distinguigh FPL attritutio rupture (RA) by passively flexing and extending wrist to confirm tenodesis effect in intact tendon

 

A image thumb
20

What if a patient has incomplete palsies of the muscles supplied by AIN on examination?

This is abnormal as normally all 4 effected

so think weird anatomy/ Martin-Gruber anastomies

  •  15% population axons of AIN may cross over to innervate other muscle groups and so present differently

21

Names associated conditions with AIN compression neuropathy?

  • Parsonage- Turner Syndrome
    • Bilateral AIN caused by Viral Brachial neuritis
    • be sucipious if motor loss Preceded by INTENSE SHOULDER PAIN/ VIRAL Prodrome

22

What investigations are helpful in diagnosis of AIN compression?

EMG

  • may rule out more proximal lesions
  • May reveal abnormalities to FPL,FDP index and middle finger and pronator quadratus

23

Describe the TX of AIN compression?

Non operative

  • Observation, rest , splinting in elbow 90o flexion 8-12 wks
    • Majority imporve with Consx

Operative

  • Surgical decompression of AIN - if non op fails
  • 75% success rate with surgery

 

24

Define pronator syndrome?

Compressive neurology of median nerve at elbow

25

What is the epidemiology of pronator syndrome?

  • More common in women
  • more common 5th decade
  • ssociated with well developed forearm muscles= weight lifters 

26

Describe the pathoanatomy of pronator syndrome?

5 potential sites of compression= SLAP F

  • Supracondylar process- residual osseous structure on distal humerus = 1% 
  • Ligament of Struthers
    • travels tip of supracondylar process to medial epicondyle
    • can-> ulnar/median nerve neuropathies
  • Bicipital aponeurosis ( Lacertus fibrosis)
  • Between ulnar/radial heads Pronator teres
  • FDS aponeurotic arch

A image thumb
27

Name any associated conditions with pronator syndrome?

  • Medial Epicondylitis

28

What are the signs and symptoms of pronator syndrome?

Symptoms- motor and sensory!

  • parathesia to thumb, index and middle finger & radial 1/2 ring
  • Acting pain over proximal forearm
  • Sensory distrubance over distribution of PALMAR Cutaneous branch of median nerve ( palm of hand) which arises 4-5 cm proximal to carpal tunnel
  • NO of night pain

O/E

Provocations tests specific for sites of compression

  • Positive Tinels in PROXIMAL forearm, but NO tinels sign at WRIST/ symptoms with wrist flexion
  • Resisted elbow flexion w supination forearm= BICIPITAL APONEUROSIS compression
  • Resisted forearm pronation w elbow extended= 2 heads of PT compression
  • resisted contraction of FDS to middle finger= FDS fibrous arch
  • coexisting medial epicondylitis

 

29

What investigations are useful in Pronator syndrome?

Elbow films mandatory- ? supracondylar process

A image thumb
30

Describe the tx of Pronator syndrome?

Non operative

  • Rest, splinting and nsaids for 3-6 months
    •  mild/moderate pain
    • splint should avoid forearm rotation

Operative

  • Surgical Decompression of median nerve
    • When consx fails after 3-6months
    • Decompression of nerve at 5 possible sites
    • outcomes variable 80% relief of symptoms

31

Describe the course of the median nerve?

  • Origin- medial and lateral cords of brachial plexus C5-T1 roots
  • Anterior compartment of arm
    • Anteromedial to humerus
    • runs with BRACHIAL arrtery ( lat on upper arm/medial at elbow)
    • No branches in arm
  • Forearm
    • enters foerarm between pronator teres & biceps tendon
    • Travels between FDS and FDP
    • Emerges between FDS & FPL
  • Hand
    • Enters via Carpal tunnel along with FDS/FDP & FPL
  • terminal Branches
  • Anterior interosseous nerve- Pronataor quadratus, FDP and FDS middle/index and FPL
  • Palmar cutaneous branch- sensation lat palm
  • Recurrent motor branch-thenar muscles
  • Digital cutaneous branch - senstation palmar radial 3 1/2 digits, index, long and ring dorsally

A image thumb
32

what does the median nerve innervate?

Superficial volar

  • Pronator teres
  • Flexor carpi radialis
  • Palmaris longus

Intermediate

  • Flexor digitorium superficialis- AIN

Deep 

  • Flexor digitorium profundus ( lateral)- AIN
  • Flexor pollicis longus- AIN
  • Pronator quadratus-AIN

Hand- recurrent branch 

  • 1st and 2nd lumbricals
  • Opponens pollicis
  • Abductor pollicis brevis
  • Flexor pollicis brevis

33