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Hand > Nerve Entrapment/Compression > Flashcards

Nerve Entrapment/Compression Flashcards

1
Q

Compression nerve injuries cause BLANK and damage by BLANK

A

Neuropraxia

Ischemia

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2
Q

Conduction velocity changes in peripheral nerve chronic compression syndromes is due to…..

A

Schwann cell proliferation and apoptosis

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3
Q

What are the 4 locations of median/AIN compression

A
  • Edge of Lacertus fibrosis (AIN)
    • Edge of pronator teres (AIN)
    • Ligament of Struthers (median) - fibrous band that runs from the supracondylar process on distal humerus to the medial epicondyle (underneath are Median N. And Brachial a.)
      • Causes high median neuropathy -> must address thumb opposition AND thumb IP flexion and IF DIP flexion (bc prior to branching of AIN)
        • Transfer for thumb opposition: EIP to APB
    • Carpal tunnel (median)
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4
Q

What are the 5 possible sites of PIN Compression? Which is MOST COMMON?

A
  • 5 Possible Sites: (listed proximal to distal)
    * Fibrous tissue anterior to radial capitellar joint
    * Leash of Henry (=recurrent radial vessels that fan out across PIN at radial neck)
    * ECRB edge
    * Arcade of Frohse - tendinous border of proximal supinator m.
    * MC site of spontaneous compression!!!
    * Distal supinator m. edge
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5
Q

What are the PE findings of PIN compression?

A
  • Physical Exam findings: this is a motor-only nerve
    * Weak finger and thumb extension
    * Will have some wrist extension but will be radial deviated b/c ECRL-only driven (since innervated by radial nerve before becomes PIN) and don’t have ECRB or ECU to balance
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6
Q

What are the 2 sites of Ulnar nerve compression?

A
  • Cubital tunnel

* Guyon canal (minus dorsal sensory branch!!…so don’t have numbness in dorsal ulnar distribution)

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7
Q

Electrodiagnostic studies for Carpal Tunnel - what are the values:

* Prolonged sensory latency: ?
* Prolonged motor latency: ?
* Nerve conduction velocity: ?
A
  • Prolonged sensory latency: > 3.5 ms
    • Prolonged motor latency: > 4.5 ms
    • Nerve conduction velocity < 52 m/s (less specific for severity of disease compared to the above)
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8
Q

What is the difference b/t endoscopic and open CTR?

A
  • Endoscopic has decreased postop pain and analgesic use
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9
Q
  • Outcome of surgery vs immobilization/steroid injection:
A
  • Surgery has better results at both 6 mo and 1 yr postop
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10
Q
  • Complication of CTR surgical release - nerve related and what will patient have trouble with?
A
  • Injury to the recurrent motor branch -> occurs due to radially based cut of the TCL and patient will have inability to oppose the thumb
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11
Q
  • After carpal tunnel release grip strength ~75% by 6 wks, returned to preop level by ? months, and increased from preop by ? months.
  • Rate of residual/persistent preop symptoms at 1 year is ??%
A
  • After carpal tunnel release grip strength ~75% by 6 wks, returned to preop level by 3 months, and increased from preop by 6 months.
  • Rate of residual/persistent preop symptoms at 1 year is 20%
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12
Q
  • Transverse carpal ligament attaches to…
A
  • Transverse carpal ligament attaches to the outer bones in the proximal and distal carpal row:
    * Scaphoid/trapezium and pisiform/hook of hamate
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13
Q

Cubital tunnel is made up of

A

Osborne’s Ligament and MCL

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14
Q

In situ vs transposition of ulnar nerve - when is each indicated and why?

A
  • In situ cubital tunnel release has been shown to achieve EQUAL clinical outcomes compared to transposition (either subQ or submuscular) AND has decreased postop complications as well (submuscular transposition found to be highest). 2018 OITE question
  • However, watch if questions gives you a kid and/or clear nerve instability - then do transposition. Stutz paper found that revision was more common in adolescent population after in situ decompression than subQ transposition (2017 OITE!)
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15
Q

pressure of nerve in cubital tunnel is least between ?? degrees of flexion.

A

pressure of nerve in cubital tunnel is least between 40-50 degrees of flexion.

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16
Q

Name 2 Exam findings of Ulnar Nerve injury

A
  • First sign = Wartenberg sign = small finger abduction due to unopposed pull of EDM (radial n) due to weak interossei
    • Late sign = Froment’s sign = thumb IP flexion (AIN) to compensate for inability to perform key pinch (adductor policis innervated by Ulnar n)
17
Q
  • Contents of Guyon canal =
A

Ulnar Nerve (has deep and superficial branches w/in the canal) and Artery

18
Q
  • Compression in Guyon Canal can be caused by what 4 things? And which is MC?
A
  • a ganglion cyst (MC)
    • Osteophytes
    • Ulnar a. Aneurysm
    • Chronic nonunion of hook of hamate
19
Q
  • Nerve injury order of loss and order of recovery (motor vs touch vs pain etc)
A
  • Motor -> proprioception -> light touch -> temp -> pain -> sympathetic activity
    • Recovery happens in reverse order
20
Q
  • Nerve transection caused by GSW should be repaired HOW LONG following injury to allow time for demarcation of damaged tissue (and also obviously after definitive fracture fixation has occurred if needed)
A

1-3 weeks

21
Q

Nerve repair: what should be used for
< 3 cm
> 3 cm
Digital nerve repair

A
  • Maximum length that can be bridged by nerve conduit (autologous - ie venous or arterial - or synthetic) when repairing a nerve gap -> < 3 cm…so recommend to use when < or = 2 cm gap
    • Nerve autograft is better and should be used for 3 cm gap or larger
  • Best options for digital nerve repair -> collagen conduit or autograft
22
Q
  • Nerve Repair Outcome Potential:
    • Excellent -
    • Moderate -
    • Poor -
    median, radial, peroneal, musculocutaneous, femoral, ulnar, tibial
A
  • Nerve Repair Outcome Potential:
    • Excellent - radial, musculocutaneous, femoral
    • Moderate - median, ulnar, tibial
    • Poor - peroneal
23
Q
  • Radial nerve injury - most consistently proposed tendon transfer is
A

to power wrist extension: PT -> ECRB

24
Q
  • PIN injury (chronic) -> need tendon transfers ->
A

FCR to EDC, and PL to EPL

* Don’t need wrist extensor bc still have ECRL which is supplied by the radial nerve

25
Q

Ulnar nerve injury (chronic) will lead to “Ulnar claw hand” which is due to…

    * In order to determine the tendon transfer needed must use  BLANK test...and describe it - what is negative or positive and what it means for tendon transfers
A
  • Bouvier test:
          * Block full MCP extension (so MCP partially flexed) and see if can extend PIPJ -> positive test =  “simple claw hand”
          * Only need tendon transfer to get MCP flexion (transfer onto A1 or A2 pulley or proximal phalanx
      * If cannot extend PIPJ -> negative test = “complex claw hand”
          * Will need a tendon transfer to get MCP flexion and PIP extension via insertion on lateral bands
26
Q

Martin-Gruber anastomosis

A
  • Martin-Gruber anastomosis -> motor connection between the median and ulnar nerves that occurs in the forearm. Such that a nerve injury to either the median or ulnar nerve would still show intact motor function to that nerve; but sensation to the injured nerve would be out (despite motor being intact)

To help remember - use the “M” in Martin for MEDIAN
and the “U” in GrUber for ULNAR

27
Q
  • Possible cause of cubital tunnel is presence of accessory muscle called…
A

ANCONEUS EPITROCHLEARIS - causes mass effect (only found at time of surgery in people who have it - seen in up to 30%!)

28
Q
  • Paresthesias near the incision during cubital tunnel release are due to injury of what nerve and what is it a branch of?
A

the medial antebrachial cutaneous nerve (which is a branch from the medial cord of brachial plexus)

29
Q

Radial Tunnel Syndrome:

  • Presentation:
  • Initial Treatment:

What PE finding can help differentiate radial tunnel from PIN compression?

A
  • Pain in dorsoradial forearm
    • Worsened with activities like using a screwdriver
    • Tenderness over radial head and mobile wad
    • Pain with resisted wrist and finger extension
    • *No tenderness over lateral epicondyle
      PT and activity modification

PIN is motor only - so no sensory deficits
With PIN compression will be able to extend wrist but there will be radial deviation due to ECRL being strong and innervated by radial nerve!

30
Q

Wartenberg Syndrome:
What nerve is compressed?
What are symptoms?
What causes compression?

A
  • Compression of superficial radial sensory nerve
  • No motor symptoms!
  • Caused by compression from scissoring action b/t brachioradialis and ECRL during forearm pronation
31
Q

What are 2 exam findings that help distinguish compression of the ulnar nerve at Guyon’s canal instead of more proximal?

A
  • Will not get numbness on dorsal ulnar nerve distribution of hand b/c the dorsal sensory branch exits proximal to Guyon canal! So is not affected!
  • Also the small and ring finger FDP (ulnar innervated) will not be effected bc is innervated proximal to Guyon canal
32
Q

Sites of ulnar nerve compression include…(5)

A 
Arcade of Struthers
Cubital tunnel/Osborne’s ligament
Medial intermuscular septum
FCU aponeurosis
Guyon’s canal

Hand (6 decks)

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