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 P N

WR DROP ECR, ECU C7, C8 POST C RADIAL

MT, LT

FING DRP EDC,EI C7, C8 POST C RADIALMT, LT

ELB FLX BR C5,C6 POST C RADIALUT

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 RADSENS

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, contFINDING 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 UTSuprascap

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

FINDING MUSCLE ROOT PLEXUS PN

ARMABD

DELTOIDSuprasp

C5,6 POST C, UT AXILSUPRASC

ELB FLX BC, BRACHBR

C5,6 MED C, UTPOST C, UT

MUSCRAD

PRON

SENS

PT

------

C6,7

C6

LAT C

LAT C, UT

MED

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

FINDING MUSCLE ROOT PLEXUS PN

FING AD PALMINT

C8T1 MED C, LT ULNAR

FINGABD

DORSALINT

C8T1 MED C, LT ULNAR

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 nerveElbow

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