Nerve Injury of Upper Limb

Peripheral Nerve Injuries of the Upper
Limb
Stacy Rudnicki, MD
Associate Professor of Neurology
Definitions
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)
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
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
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
– A single nerve may supply sensation to skin
covered by more than one dermatome
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
Dermatomes of the Posterior Arm
Dermatomes of the Anterior Arm
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
Principles of localization, cont
• Order in which branches arise
• Movements at specific joints
– Single nerve
• Elbow extension
– Radial
– Multiple nerves
• Elbow flexion
– Musculocutaneous
– Radial
Case 1
• 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
Case 1, cont
• On exam she has:

– Bilateral wrist and finger drop (ie profound weakness of
wrist and finger extension at the MCPs)
– 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
– She has numbness in the posterior forearm extending into
dorsum of hand into thumb and proximal index finger
Case 1, cont
• FINDING MUSCLE ROOT PLEXUS PN
WR DROP ECR, ECU C7, C8 POST C RADIAL MT,

LT
FING DRP EDC,EI C7, C8 POST C RADIAL MT, LT
ELB FLX BR C5,C6 POST C RADIAL UT
SENS ---- C6 LAT C RADIAL

UT
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
Sensory loss in a high radial nerve lesion
(Signficant variability b/w patients)
Final Diagnosis
Bilateral radial nerve palsies at the spiral (radial)

groove related to fractures
Case 2
• 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
Patient’s sensory loss
Case 2, cont
FINDING ROOT PLEXUS PN

SENS LOSS < C6 < LAT CORD SUP
RAD
SENS
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
Final Diagnosis
Superficial radial neuropathy secondary to

handcuffs
Case 3
• 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
Case 3, 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
Case 3, sensory loss
Case 3, cont
FINDING MUSCLE ROOT PLEXUS PN
Abd>15 Deltoid C5,6 Post C Axillary
UT
Ext Rot T. Minor C5,6 Post C Axillary
Infrasp C5,6 UT Suprascap
Sens ------- <C5 <POST C Axillary
<UT
C5
C6
C7
C8
T1
Case 3, cont
• If it’s at the posterior cord
– Radial innervated muscles should be
affected
• But elbow extension is spared
• If it’s at the upper trunk
– Musculocutaneous innervated muscles
should be affected
• But elbow flexion is spared
• Pattern of sensory loss
Case 3, Final diagnosis
Axillary Neuropathy in the Axilla

Case 4
• A 55 yo hospital worker comes to see you with a

2 week history of pain in her neck, shoulder,
and upper arm
• Symptoms began when she tried to help
restrain a combative patient
Case 4, 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
Case 4, cont
ARM DELTOID C5,6 POST C, UT AXIL

ABD Suprasp SUPRASC
ELB FLX BC, BRACH C5,6 MED C, UT MUSC
BR POST C, UT RAD
PRON PT C6,7 LAT C MED
SENS ------ C6 LAT C, UT MULT

Case 4, Final Diagnosis
C6 Radiculopathy secondary to a
herniated disc
Case 5
• 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
Case 5, cont
• 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, abduction and adduction
Case 5, sensory loss
CASE 5, cont
FING AD PALM C8T1 MED C, LT ULNAR

INT
FING DORSAL C8T1 MED C, LT ULNAR
ABD INT
Sens loss ---- <C8 LT/Med Cd Uln
Case 5, cont
• If it’s the lower trunk, C8/T1, or medial cord

other muscles affected should include:
– APB and Opponens pollicus (median)
– EPL and EPB (radial)
• Can it be localized further to a specific

site of the ulnar nerve?
Ulnar sensory loss in an ulnar lesion
proximal to the midforearm
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
Case 5, final diagnosis
Ulnar neuropathy at the wrist

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Peripheral Nerve Injuries of the Upper

• Process affecting the nerve root, most

• Dysfunction of a single peripheral nerve

• Can refer to involvement of the entire plexus,

• Because fibers from different nerve roots come

• Because of the pattern of root contribution to

• Certain sites are prone to nerve

• A 38 yo woman was the restrained passenger in

• On exam she has:

WR DROP ECR, ECU C7, C8 POST C RADIAL MT,

FING DRP EDC,EI C7, C8 POST C RADIAL MT, LT

ELB FLX BR C5,C6 POST C RADIAL UT

SENS ---- C6 LAT C RADIAL

Bilateral radial nerve palsies at the spiral (radial)

• A 25 year old man gets involved in a fist fight and

FINDING ROOT PLEXUS PN

Superficial radial neuropathy secondary to

• 15 yo football player is hit be another player,

Axillary Neuropathy in the Axilla

• A 55 yo hospital worker comes to see you with a

• On exam she she:

FINDING MUSCLE ROOT PLEXUS PN

ARM DELTOID C5,6 POST C, UT AXIL

SENS ------ C6 LAT C, UT MULT

• 40 yo woman comes to see you because she has

• On exam she has:

FING AD PALM C8T1 MED C, LT ULNAR

• If it’s the lower trunk, C8/T1, or medial cord

• Can it be localized further to a specific

Flex Dig Prof III/IV

Ulnar neuropathy at the wrist

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