1. Peripheral Nerve Injuries of the Upper Limb
Stacy Rudnicki, MD
Associate Professor of Neurology

2. Aids to the Examination of the Peripheral Nervous System
WB Saunders, publishers

3. Definitions

4. Radiculopathy
Process affecting the nerve root, most commonly by a herniated disc
Weakness in muscles supplied by the nerve root (myotome)
Sensory loss in the area of the skin supplied by the nerve root (dermatome)

6. Mononeuropathy Dysfunction of a single peripheral nerve
Weakness in muscles supplied by the nerve
Sensory loss in the area of the skin supplied by the cutaneous branches of the nerve

7. Brachial Plexopathy
Can refer to involvement of the entire plexus, or parts of the plexus
Trunk lesion
Cord lesion
Distribution of weakness and numbness depends upon the part of the plexus affected

8. Sensory Supply to the Arm
Because fibers from different nerve roots come together and then split apart in the plexus
A dermatome may include areas of the skin supplied by different peripheral nerves
Example: C6
A single nerve may supply sensation to skin covered by more than one dermatome
Example: median nerve

9. Sensory Supply to the Arm
Because of the pattern of root contribution to the plexus:
An upper trunk lesion has sensory loss in the combined C5,6 dermatomes
A middle trunk lesion has sensory loss in the C7 dermatome
A lower trunk lesion has sensory loss in the combined C8T1 dermatomes

11. Principles of Localization
Certain sites are prone to nerve entrapments/injuries
Nerve opposing bone
Ulnar nerve at the elbow
Closed spaces
Carpal tunnel
Adjacent structures
Median nerve at the elbow, adjacent to the brachial artery

12. Principles of localization, cont
Order in which branches arise
Movements at specific joints
Single nerve
Elbow extension
Radial
Multiple nerves
Elbow flexion
Musculocutaneous
Thumb
Multiple different movement accomplished by multiple muscles innervated by the median, ulnar, and radial nerves

13. Additional Helpful Hints
All muscles within the hand (intrinsic hand muscles)
Are innervated by C8T1 nerve roots
Are innervated by the lower trunk
Are innervated by the medial cord
All ulnar innervated muscles
Are innervated by the C8T1 nerve roots
All axillary and musculocutanious innervated muscles
Are innervated by C5,6 nerve roots
Are innervated by the upper trunk

14. Additional Helpful Hints, cont
Muscles inserting onto the humerus (and so related to movements of the arm) are primarily C5,6
Infraspinatus
Supraspinatus
Deltoid
Teres minor
Teres major (Plus C7)
Pectoralis Major (plus C7)
Latissimus is C6,7,8

15. Work Back from the Exam What muscles are weak?
What innervates the muscle?
Peripheral nerve
Part of plexus
Cord
Trunk
Nerve roots
Where is the sensory loss? Does it best follow the pattern of
A dermatome
A single nerve
A cord or trunk of the plexus

17. Case 1
A 34 yo woman, currently 28 weeks pregnant, complains of numbness in her fingers
She finds that it is more difficult to manipulate small objects
She is awakened at night be tingling and pain in her hand which seems to spare her little finger

18. Case 1, continued On exam she has:
Mild weakness of thumb abduction and opposition
Decreased pin prick on the palmar aspect of the thumb, index, middle and lateral aspect of the ring finger
No evidence of loss of muscle bulk in the hand

19. Case 1, continued
Finding Muscle Nerve Plexus Root Thumb Abd APB Median Lower trunk C8T1 Medial cord Thumb opp OP Median Lower trunk C8T1 Sensory loss Median

20. Finding Muscle Nerve Plexus Root
Thumb Abd APB Median Lower trunk C8T1
Medial cord
Thumb opp OP Median Lower trunk C8T1
Sensory loss Median

21. Why isn’t this the medial cord, lower trunk, or C8T1 nerve roots?

22. Why isn’t this the medial cord, lower trunk, or C8T1 nerve roots?
All should also involve ulnar innervated muscles

23. Why aren’t the other median innervated muscles involved?

24. Median Nerve

25. Carpal tunnel syndrome (median neuropathy at the wrist)
Case 1, continued
Final Diagnosis
Carpal tunnel syndrome
(median neuropathy at the wrist)

27. Case 2
A 38 yo woman was the restrained passenger in a car struck head on
She braced her hands on the dashboard immediately prior to impact
She suffered bilateral fractures of the humerus at the spiral (radial) groove
She complains of diffuse aches in her arms and neck and weakness in her arms

28. Case 2, cont On exam she has:
Bilateral wrist and finger drop (ie profound weakness of wrist and finger extension at the MCPs)
Weakness of thumb extension
Weakness of supination
Weakness of elbow flexion with forearm held so that thumb is toward shoulder, but not with hand held in supination
Remainder of strength exam is normal

29. Sensory Loss

30. Case 2, cont Finding Muscle PN Plexus* Root
Wr drop ECR, ECU Radial POST C C5,6,7,8
Fing drop EDC,EI Radial POST C C7, C8
Elb flx BR Radial POST C C5,C6
Th Ext EPL, EPB Radial Post C C7,8
Sens Radial

31. Finding Muscle PN Plexus* Root
Wr drop ECR, ECU Radial POST C C5,6,7,8
Fing drop EDC,EI Radial POST C C7, C8
Elb flx BR Radial POST C C5,C6
Sens Radial

32. What isn’t involved? If it is a Posterior Cord lesion Radial Nerve
Axillary nerve
Deltoid – arm abduction
Teres Minor – lateral rotation of arm
Radial Nerve
Why is the Triceps spared?

33. Triceps, long head
Triceps, lateral head Triceps, med hd
Brachioradialis
ECRL
ECRB Superficial
Supinator Radial sens
Ext Digit
Abd Pol Longus Post Interosseous
Ext Pol Longus
Ext Pol Br
Ext Indicies

34. Sensory loss in a high radial nerve lesion (Signficant variability b/w patients)

35. Final Diagnosis
Bilateral radial nerve palsies at the spiral (radial) groove related to fractures

37. Case 3
A 25 year old man gets involved in a fist fight and the police arrest him
When he is released on bail, he goes to see his doctor because he has numbness in the hand
On exam he had
a number of scratches and bruises on both arms
normal strength
sensory loss on the dorsum of the hand

38. Patient’s sensory loss

39. Case 3, cont
Finding PN PLEXUS Root
Sens Loss Sup Sens <C6
Rad

40. Triceps, long head
Triceps, lateral head Triceps, med hd
Brachioradialis
ECRL
ECRB Superficial
Supinator Radial sens
Ext Digit
Abd Pol Longus Post Interosseous
Ext Pol Longus
Ext Pol Br
Ext Indicies

41. Superficial radial neuropathy secondary to handcuffs
Final Diagnosis
Superficial radial neuropathy secondary to handcuffs

43. Case 4
15 yo football player is hit be another player, with the helmet striking him in the axilla
On getting up, he is aware of shoulder weakness and pain and is taken to the ER

44. Case 4, cont On exam he has: Normal elbow flexion
Normal elbow extension
Normal shoulder adduction
Ability to initiate shoulder abduction, but he cannot raise his arm more than 15 degrees
Mild weakness of external (lateral) rotation of the arm
A patch of sensory loss over his upper arm

45. Case 4, sensory loss

46. Case 4, cont Finding Muscle PN Plexus Root
Abd>15 Deltoid Axillary Post C C5,6
Ext Rot T. Minor Axillary Post C C5,6
Infrasp Suprascap UT C5,6
Sens Axillary <C5

47. Case 4, continued Finding Muscle PN Plexus Root
Abd>15 Deltoid Axillary Post C C5,6
Ext Rot T. Minor Axillary Post C C5,6
Infrasp Suprascap C5,6
Sens Axillary <C5

48. Pattern of sensory loss
Case 4, cont
If it’s at the posterior cord
Radial innervated muscles should be affected
But elbow extension is spared
If it’s C5,6
Other C5,6 muscles should be affected
But elbow flexion, initiation of arm abduction spared
Pattern of sensory loss

49. Case 4, Final diagnosis
Axillary Neuropathy

51. Case 5
A 55 yo hospital worker comes to see you with a 2 week history of pain in her neck, which radiates into her shoulder, and upper arm
Symptoms began when she tried to help restrain a combative patient

52. Case 5, cont On exam she she: Weakness of shoulder abduction
Weakness of elbow flexion
Mild weakness of pronation
Sensory loss in her lateral forearm and thumb both posteriorly and anteriorly

53. Case 5, continued Finding Muscle PN Plexus Root
Arm Abd Deltoid Axillary PC C5,6
Elb Flex BC, Brach Musc LC C5,6
BR Radial PC C5,6
Pronation PT Median M & LC C6,7
Sens C6

54. Finding Muscle PN Plexus Root
Arm Abd Deltoid Axillary PC C5,6
Elb Flex BC, Brach Musc LC C5,6
BR Radial PC C5,6
Pronation PT Median M & LC C6,7
Sens C6

55. C6 Radiculopathy secondary to a
Case 5, Final Diagnosis
C6 Radiculopathy secondary to a
herniated disc

57. Case 6
40 yo woman comes to see you because she has noticed weakness and numbness in her right hand
This started 2 months ago and is slowly worsening
She is otherwise healthy, and rides her bike at lease 40 miles per week

58. Case 6, continued On exam she has:
Atrophy of the interosseous muscles of the right hand
Mild weakness of abducting and adducting the fingers
Normal thumb abduction, opposition and extension
Normal wrist flexion in both a radial and ulnar direction

59. Sensory Loss

60. Case 6 continued Finding Muscle PN Plexus Root
Fing Add Palm Int Ulnar MC C8,T1
Fing Abd Dors Int Ulnar MC C8T1
Sens Loss Ulnar <C8

61. Case 6 continued Finding Muscle PN Plexus Root
Fing Add Palm Int Ulnar MC C8,T1
Fing Abd Dors Int Ulnar MC C8T1
Sens Loss Ulnar MC <C8

62. Case 6 continued If it’s the C8 nerve root, or medial cord
other muscles affected should include:
APB and Opponens pollicus (median)
EPL and EPB (radial)
But these muscles are spare
more extensive sensory changes should be found

63. Ulnar nerve lesion Why is wrist flexion spared?
Why does the sensory loss not include more of the dorsum of the hand?

64. Ulnar sensory loss in an ulnar lesion proximal to the midforearm

65. Ulnar nerve Elbow Flexor carpi ulnaris Flex Dig Prof III/IV
Dorsal uln cut
Wrist
Adductor Pollicus Abductor
Flex Pollicus Br Opponens Digiti Minimi
Flexor
Dorsal/palmar
Interosseous
3rd/4th lumbricals

66. Ulnar neuropathy at the wrist
Case 5, final diagnosis
Ulnar neuropathy at the wrist

68. Case 7
This 38 yo man fell off a ladder and acutely noted weakness in his right arm
He suffered a fracture of his right clavicle
He c/o pain in the shoulder

69. Case 7, cont His exam shows:
Weakness of initiating abduction of his right arm
If you raise his right arm to 90 degrees, he is unable to maintain it
With his arm at his side, he is unable to externally rotate his arm
Weakess of elbow flexion
Numbness of the lateral arm and forearm

70. Case 7, cont Finding Muscle Root Plexus Nerve
1 sh abd Supraspinatus C5,6 UT Suprascap
2 sh abd Deltoid C5, UT Axillary
Post Cord
Ext rot Infraspinatus C5, UT Suprascap
Teres minor C5, UT, PC Axillary
Elbow flexion Biceps C5,6 UT, LC Musc
BR C5, UT, PC Radial
Sensory C5 & UT Axillary &
LC & PC Musc

71. Case 7, cont Finding Muscle Root Plexus Nerve
1 sh abd Supraspinatus C5,6 UT Suprascap
2 sh abd Deltoid C5, UT Axillary
Post Cord
Ext rot Infraspinatus C5, UT Suprascap
Teres minor C5, UT, PC Axillary
Elbow flexion Biceps C5,6 UT, LC Musc
BR C5, UT, PC Radial
Sensory C5 & UT Axillary &
LC & PC Musc

72. Case 7, cont
Difficult to distinguish based on exam alone if this is upper trunk or C5 and C6 radiculopathies
Brachial plexopathies may occur with fractures of the clavicle
Radiculopathies are unusual without neck pain
Preservation of the function of serratus anterior muscle makes root less likely
Further studies (EMG) can help localize b/w root and trunk

74. Upper trunk plexopathy
Case 7, cont
Final diagnosis:
Upper trunk plexopathy

75. Don’t Forget to Vote!