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Joe's Test Class > Ch 5 - EDX: Upper Limb Mononeuropathy > Flashcards

Ch 5 - EDX: Upper Limb Mononeuropathy Flashcards

1
Q

Describe the pathway of the median nerve in the upper arm.

A

Runs medial to the axillary artery, down the humerus and runs under the ligament of Struthers (LOS) at the medial epicondyle

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2
Q

What does the median nerve innervate in the forearm?

A 
– Pronator teres (PT)
– FCR
– Palmaris longus
– Flexor digitorum superficialis (FDS)
– Palmar cutaneous branch
– The AIN branches from the median nerve to innervate (four Ps):
■ Flexor pollicis longus (FPL)
■ Flexor digitorum profundus (FDP 1 and 2)
■ Pronator quadratus (PQ)
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3
Q

What does the median nerve innervate in the hand?

A 
Through the carpal tunnel “LOAF” muscles:
– Lumbricals (1, 2)
– Opponens pollicis
– Abductor pollicis brevis
– Flexor pollicis brevis (superficial)
– (Digital cutaneous branches)
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4
Q

What nerve and artery can be injured under the Ligament of Struthers (LOS)?

A

Median nerve and Brachial artery

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5
Q

What is the clinical presentation of nerve injury at the Ligament of Struthers?

A

Involvement of ALL median innervated muscles and loss of:

  • Grip strength/ Benediction sign (FDS, FDP)
  • Wrist flexion (FCR)
  • Dull, aching in distal forearm
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6
Q

What is the bicipital aponeurosis?

A

Antebrachial fascia attaching biceps to the ulna

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7
Q

How can the median nerve be injured at the bicipital aponeurosis?

A

Entrapment or hematoma
compression resulting from an arterial blood gas or
venipuncture

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8
Q

What is pronator teres syndrome?

A

Median nerve compression between the heads of the PT muscle or the bridging fascial band of the FDS muscle

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9
Q

What is the clinical presentation of pronator teres syndrome?

A

All median innervated muscles EXCEPT PT involved
Dull ache of the proximal forearm exacerbated by forceful pronation (PT) or finger flexion (FDS). Forearm and hand muscles easily fatigued.

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10
Q

What is affected in AIN syndrome?

A

FPL, PQ, FDP 1, 2 weakness

The FPL is 1st muscle affected

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11
Q

What is the etiology of AIN syndrome?

A

Idiopathic process
Fracture of the forearm
Lacerations
Compression

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12
Q

What is the clinical presentation of AIN syndrome?

A

Pure motor syndrome
ABN “OK” sign
Difficulty forming a fist

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13
Q

What are the contents of the carpal tunnel?

A 
Superficial layer
-4 FDS tendons
-1 FPL tendon
-Median nerve
-(FCR is outside the carpal tunnel)
Deep layer
-4 FDP tendons
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14
Q

What are different etiologies of carpal tunnel syndrome?

A

Inc canal volume: thyroid dz, CHF, renal failure, mass (tumor, hematoma), pregnancy (at 6 months and resolves postpartum).
Dec canal volume: fracture, arthritis, rheumatoid tenosynovitis.
Double crush syndrome: DM, cervical radiculopathy, TOS

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15
Q

Why are sensory NCS more sensitive than motor studies?

A
  • Larger distribution of the large myelinated fibers, which are more susceptible to compression/ ischemia. - Antidromic studies produce larger amp
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16
Q

How does a demyelinating lesion in CTS present on EDX?

A

Slowing and prolongation of the distal motor and sensory latencies

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17
Q

How does a conduction block or axonal loss in CTS present on EDX?

A

Prolongation of the distal motor and sensory latencies

Dec distal CMAP and SNAP amp

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18
Q

How does CTS differ from peripheral neuropathy on EDX?

A

CTS: max slowing across the wrist

Peripheral neuropathy: distal segment more ABN

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19
Q

Describe EDX of mild CTS.

A

SNAP: Prolonged latency
CMAP: Normal
EMG: Normal

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20
Q

Describe EDX of moderate CTS.

A

SNAP: Prolonged latency, dec amp
CMAP: Prolonged latency
EMG: Normal

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21
Q

Describe EDX of severe CTS.

A

SNAP: absent
CMAP: Prolonged latency, dec amp
EMG: ABN activity

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22
Q

Describe the orthotic for mild CTS treatment.

A

Hand splint 0 to 30° neutral to extension

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23
Q

What are surgical indications for CTS?

A

Muscle atrophy
Severe pain
Severe median nerve damage
Profound muscle atrophy

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24
Q

What are indications of poor prognosis with CTS?

A 
Sx > 10 mo
Constant paresthesias
\+ Phalen’s test < 10 sec
Weakness, atrophy
Prolonged latency on NCS
ABN spontaneous activity
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25
Q

What is Martin-Gruber anastomosis?

A

AIN branch of the median nerve anastamose

w/ the ulnar nerve or proximal median nerve cross over to the ulnar nerve

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26
Q

What does Martin-Gruber anastomosis innervate?

A

ADP, ADM, and MC 1st DI muscles

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27
Q

How is Martin-Gruber anastomosis diagnosed on EDX?

A

Initial + deflection in CMAP and inc median amp at elbow but not at wrist
Artificially fast conduction velocity

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28
Q

What is a Riche-Cannieu anastomosis?

A

Connection of the recurrent branch of the median nerve in the hand to the deep motor branch of the ulnar nerve

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29
Q

What does Riche-Cannieu anastomosis produce?

A

All ulnar innervated hand

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30
Q

How is Riche-Cannieu anastomosis diagnosed on EDX?

A

Recording over the APB, CMAP waveform is absent w/ median nerve stim but present with ulnar nerve stim

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31
Q

Describe the pathway of the ulnar nerve in the upper arm

A

Medial surface of the medial head of the triceps, runs w/in
Arcade of Struthers (AOS), continues posteriorly in a sulcus b/w the medial epicondyle and olecranon called the retrocondylar groove

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32
Q

What is the Arcade of Struthers (AOS)?

A

Fascial band in the medial arm that connects the brachialis to the triceps brachii

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33
Q

What does the ulnar nerve innervate in the forearm?

A 
Flexor carpi ulnaris (FCU)
FDP
Palmar ulnar cutaneous nerve
Dorsal ulnar cutaneous (DUC) nerve
Dorsal digital nerves
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34
Q

Why is the dorsal ulnar cutaneous nerve normal in ulnar neuropathies at the wrist?

A

Does not travel through Guyon’s canal (arising 5–8 cm more

proximally)

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35
Q

Describe how the ulnar nerve branches and what it innervates in the hand.

A 
Superficial sensory branch
Hypothenar branch
– Opponens digiti quinti
– Abductor digiti quinti
– Flexor digiti quinti
Deep motor branch
– Palmaris brevis
– 4 Dorsal interossei—(“DAB”: Abduction)
– 3 Palmar interossei—(“PAD”: Adduction)
– 2 Lumbricals
– 1 Adductor pollicis
– 1/2 Flexor pollicis brevis (deep head)
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36
Q

What is the clinical presentation of ulnar compression under Arcade of Struthers?

A

ALL ulnar innervated muscles
Radial deviation w/ wrist flexion
ABN ulnar sensation
Ulnar claw hand

37
Q

Describe ulnar claw hand.

A

Hand at rest, an unopposed pull of EDC causes partial finger flexion of the fourth and fifth PIP and DIP joint due to
extension of the MCP

38
Q

What is a positive Froment’s sign?

A

Inability to hold piece of paper with thumb and index finger due to adductor pollicis
weakness so pt substitutes FPL

39
Q

What is a positive Wartenberg’s sign?

A 
Inability to adduct the
fifth digit (interossei weakness)
40
Q

What is a tardy ulnar nerve palsy?

A

Ulnar neuropathy mos to yrs after a distal humeral fx d/t bone overgrowth, scar formation or inc carrying angle at elbow

41
Q

What is the etiology of cubital tunnel syndrome?

A

Compression beneath the proximal edge of the FCU aponeurosis or arcuate ligament

42
Q

What elbow angle should NCS done for accurate results?

A

90° to 110° elbow
flexion to avoid underestimation of actual nerve length, thus causing false
+ findings

43
Q

When evaluating for cubital tunnel syndrome what is a benefit of recording at FDI instead of ADM?

A

FDI may show earlier abnormalities due to those nerve fascicles
being more prone to injury at the elbow

44
Q

What can cause ulnar amp decrease above and below the elbow?

A

Martin-Gruber anastomosis

45
Q

How can you check for Martin-Gruber anastomosis when evaluating the ulnar nerve with EDX?

A

Stim median nerve at the elbow will provide a waveform with an amp equal to what is considered “missing” from the ulnar nerve stim

46
Q

What happens to CMAP in cubital tunnel syndrome?

A

~10 to 15 ms drop of CV across the elbow or a drop of amp of 20%

47
Q

What is seen on EMG in cubital tunnel syndrome?

A

ABN activity in ulnar nerve hand intrinsics > forearm muscles

48
Q

What is the most reliable muscle to test with EMG for cubital tunnel syndrome?

A

FDP has more fascicles that pass through the cubital tunnel and reliable than FCU

49
Q

What is a Type I Shea classification?

A

Involvement of the deep ulnar branch, hypothenar, and sensory

50
Q

What is a Type II Shea classification?

A

Involvement of deep ulnar motor branches

51
Q

What is a Type III Shea classification?

A

Involvement of the superficial ulnar sensory branch

52
Q

How can the ulnar nerve be injured at Guyon’s canal?

A

Cyclist’s palsy
Wrist ganglions
RA

53
Q

What is the clinical presentation of ulnar injury at Guyon’s canal?

A

Painless wasting of the first DI
Claw hand (lumbrical
weakness)
FDP remains intact, causing marked finger flexion

54
Q

Describe which SNAP’s are ABN in ulnar injury at Guyon’s canal.

A
  • DUC nerve spared

- SNAP to 5th digit ABN

55
Q

Describe the Radial nerve course in the upper arm

A

Located posterior to the axillary artery.

Descends b/w the long and medial heads of the triceps muscle toward the spiral groove.

56
Q

Which muscles are innervated by the Radial nerve ABOVE the spiral groove?

A

Triceps brachii
Anconeus
Posterior cutaneous nerve
Lower lateral cutaneous nerve

57
Q

Which muscles are innervated by the Radial nerve BELOW the spiral groove?

A

Brachioradialis (BR)
Extensor carpi radialis longus (ECR-L)
Posterior cutaneous nerve of forearm

58
Q

Describe the course of the Radial nerve 10 cm proximal to the lateral epicondyle of the humerus.

A

Pierces the lateral intermuscular septum and enters the anterior compartment of the arm. Continues distally b/w the brachioradialis and brachialis

59
Q

What does the Radial nerve split into at the lateral epicondyle?

A 
Motor (posterior interosseus nerve [PIN]) 
Sensory branch (superficial radial nerve)
60
Q

Which muscles do the PIN innervate?

A 
– Extensor carpi radialis brevis (ECR-B)
– Supinator
– Extensor digitorum communis (EDC)
– Extensor digiti minimi (EDM)
– Extensor carpi ulnaris (ECU)
– Abductor pollicis longus (APL)
– Extensor pollicis longus (EPL)
– Extensor pollicis brevis (EPB)
– Extensor indicis proprius (EIP)
61
Q

What is the clinical presentation of crutch palsy?

A

Weakness in all radial nerve innervated muscles, including the triceps brachii. Sensation may be decreased over the posterior arm and forearm

62
Q

What are etiologies of Radial nerve injury at the spiral groove?

A

Prolonged arm position over back of chair or person’s head.

Humerus fracture at spiral groove

63
Q

Which muscles are spared in Radial nerve spiral groove injury?

A

Triceps brachii and Anconeus

64
Q

What is the clinical presentation of Radial nerve spiral groove injury?

A

Weakness in EF, supination, wrist drop and finger extension. Sensory deficits in dorsal aspect of hand and posterior forearm

65
Q

What is Radial tunnel syndrome?

A

Radial nerve or PIN can be entrapped b/w the brachialis and BR

66
Q

How are Radial tunnel syndrome symptoms reproduced?

A

Resisted extension of the 3rd digit during elbow extension
Resisted supination
Palpation of the radial head

67
Q

What are etiologies of PIN syndrome?

A 
Compression of the
nerve at the Arcade of Frohse of the supinator
Lipoma
Ganglion cyst
Synovitis from RA
Monteggia fx
68
Q

What is a Monteggia fracture?

A

Fracture of the proximal 1/3 of the ulna and dislocation of the radial head

69
Q

What is the etiology of a Monteggia fracture?

A

FOOSH w/ the forearm locked in full pronation

70
Q

What is the clinical presentation of PIN syndrome?

A

Pseudo claw-hand deformity may be demonstrated (finger extensor weakness). Radial deviation is noted with wrist extension (ECU weakness) and sensation is spared

71
Q

What is Cheiralgia paresthetica?

A

Superficial radial neuropathy or Wristwatch syndrome

72
Q

What is the clinical presentation of Superficial radial neuropathy?

A

Pure sensory syndrome on the dorsal radial aspect of the hand

73
Q

How can symptoms of Superficial radial neuropathy be exacerbated?

A

Palmar and ulnar wrist flexion or forced pronation

74
Q

Describe the course of the musculocutaneous nerve in the arm.

A

Passes along the medial aspect of the

humerus and continues anterior to the antecubital fossa, lateral to the biceps tendon

75
Q

What does the musculocutaneous nerve innervate?

A

– Coracobrachialis
– Biceps brachii
– Brachialis
–Lateral antebrachial cutaneous nerve

76
Q

What are etiologies of musculocutaneous injury?

A

Entrapment from the coracobrachialis Gunshot wounds
Shoulder dislocation
Phlebotomy

77
Q

What is the clinical presentation of musculocutaneous injury?

A

EF weakness
ABN sensation over lateral forearm
Coracocbrachialis usually spared

78
Q

What are the borders of the quadrangular space?

A

Humerus
Long head of triceps
Teres minor
Teres major

79
Q

Describe the course of the axillary nerve.

A

Runs through the quadrangular space

80
Q

What are etiologies of Axillary neuropathy?

A

Traction or compression from a shoulder dislocation
Humeral
head fracture
Improper axillary crutch use

81
Q

What is the clinical presentation of Axillary neuropathy?

A 
Shoulder flexion and abduction weakness (deltoid)
ER weakness (teres minor)
ABN sensation of lateral shoulder
82
Q

Describe the course of the Suprascapular nerve.

A

Passes posterior triangle of the neck, runs beneath trapezius to superior scapula through suprascapular notch then around spinoglenoid notch

83
Q

What is the MC nerve involved in neuralgic amyotrophy?

A

Suprascapular nerve

84
Q

What are etiologies of suprascapular neuropathy?

A 
Forced scapular protraction
Penetrating wounds
Improper crutch use
Traction rotatorcuff rupture
Erb’s palsy
Spinoglenoid ganglions
Hematoma
Suprascapular or spinoglenoid notch entrapment
Paralabral cyst
Overhead activities
85
Q

What is the clinical presentation of suprascapular neuropathy?

A

Weakness in abduction (SS) and external rotation (IS) of the glenohumeral joint

86
Q

Describe the course of the long thoracic nerve.

A

Runs distally along the thoracic wall to innervate the serratus anterior

87
Q

What is weak/injured in medial scapula winging?

A

Serratus anterior weakness

Long thoracic nerve injury

88
Q

What is weak/injured in lateral scapula winging?

A

Tapezius weakness

Spinal accessory nerve injury

89
Q

What are etiologies of long thoracic nerve injury?

A

Fall
MVA
Sports activities
Shoulder bags

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