peripheral nerve injuries of the upper limb stacy rudnicki, md associate professor of neurology
Post on 14-Dec-2015
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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• Example: C6
– A single nerve may supply sensation to skin covered by more than one dermatome• Example: median nerve
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
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
• Thumb
– Multiple different movement accomplished by multiple muscles innervated by the median, ulnar, and radial nerves
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
– Are innervated by the lower trunk
– Are innervated by the medial cord
• All axillary and musculocutanious innervated muscles
– Are innervated by C5,6 nerve roots
– Are innervated by the upper trunk
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
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
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
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
Case 1, continued
Finding Muscle Nerve Plexus Root
Thumb Abd APB Median Lower trunk C8T1
Medial cord
Thumb opp OP Median Lower trunk C8T1
Medial cord
Sensory loss Median --- ---
Finding Muscle Nerve Plexus Root
Thumb Abd APB Median Lower trunkC8T1
Medial cord
Thumb opp OP Median Lower trunkC8T1
Medial cord
Sensory loss ----- Median --- ---
Why isn’t this the medial cord, lower trunk, or C8T1 nerve roots?
• All should also involve ulnar innervated muscles
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
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
Case 2, cont
• Finding Muscle PN Plexus* RootWr 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 ExtEPL, EPB Radial Post C C7,8
Sens ---- Radial --- ---
• 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 --- ---
What isn’t involved?
• If it is a Posterior Cord lesion– Axillary nerve
• Deltoid – arm abduction
• Teres Minor – lateral rotation of arm
• Radial Nerve– Why is the Triceps spared?
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
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
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
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
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
Case 4, contFinding 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
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
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
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
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
Case 5, continued
Finding Muscle PN Plexus Root
Arm AbdDeltoid 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
Finding Muscle PN Plexus Root
Arm AbdDeltoid 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
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
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
Case 6 continued
Finding Muscle PN Plexus Root
Fing Add Palm Int Ulnar MCC8,T1
Fing Abd Dors Int Ulnar MCC8T1
Sens Loss ---- Ulnar --- <C8
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
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
Ulnar nerve lesion
• Why is wrist flexion spared?• Why does the sensory loss not include more of
the dorsum of the hand?
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 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
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
Case 7, cont
Finding Muscle Root Plexus Nerve
1 sh abd Supraspinatus C5,6 UT Suprascap
2 sh abd Deltoid C5,6 UT Axillary
Post Cord
Ext rot Infraspinatus C5,6 UT Suprascap
Teres minor C5,6 UT, PC Axillary
Elbow flexion Biceps C5,6 UT, LC Musc
BR C5,6 UT, PC Radial
Sensory C5 & 6 UT Axillary &
LC & PC Musc
Case 7, cont
Finding Muscle Root Plexus Nerve
1 sh abd Supraspinatus C5,6 UT Suprascap
2 sh abd Deltoid C5,6 UT Axillary
Post Cord
Ext rot Infraspinatus C5,6 UT Suprascap
Teres minor C5,6 UT, PC Axillary
Elbow flexion Biceps C5,6 UT, LC Musc
BR C5,6 UT, PC Radial
Sensory C5 & 6 UT Axillary &
LC & PC Musc
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
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