Peripheral Nerve Injuries of the Upper Limb

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Peripheral Nerve Injuries of the Upper Limb

• Stacy Rudnicki, MD
• Associate Professor of Neurology

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Definitions
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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)

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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

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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

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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

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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

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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

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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

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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

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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

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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

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Case 1, cont

• FINDING MUSCLE ROOT PLEXUS P N
• WR DROP ECR, ECU C5,6,7,8 POST C RADIAL UT,
  MT, LT
• FING DRP EDC,EI C7, C8 POST C RADIAL MT,
  LT
• ELB FLX BR C5,C6 POST C RADIAL UT
• SENS ---- C6 Post C RADIAL
• UT

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• 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

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

• Bilateral radial nerve palsies at the spiral
  (radial) groove related to fractures

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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

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Patients sensory loss
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Case 2, cont

• FINDING ROOT PLEXUS PN
• SENS LOSS lt C6 lt Post CORD SUP
  RAD SENS

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• 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

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Final Diagnosis

• Superficial radial neuropathy secondary to
  handcuffs

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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

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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

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Case 3, sensory loss
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Case 3, cont

• FINDING MUSCLE ROOT PLEXUS PN
• Abdgt15 Deltoid C5,6 Post C Axillary
• UT
• Ext Rot T. Minor C5,6 Post C Axillary
• Infrasp C5,6 UT Suprascap
• Sens ------- ltC5 ltPOST C Axillary
• ltUT

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Case 3, cont

• If its at the posterior cord
• Radial innervated muscles should be affected
• But elbow extension is spared
• If its at the upper trunk
• Musculocutaneous innervated muscles should be
  affected
• But elbow flexion is spared
• Pattern of sensory loss

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Case 3, Final diagnosis

• Axillary Neuropathy

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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

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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

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Case 4, cont
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Case 4, Final Diagnosis

• C6 Radiculopathy secondary to a
• herniated disc

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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

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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

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Case 5, sensory loss
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CASE 5, cont
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Case 5, cont

• If its the lower trunk, C8/T1, or medial cord
  other muscles affected should include
• APB and Opponens pollicus (median)
• EPL and EPB (radial)
• But these muscles are spared

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Ulnar sensory loss in an ulnar lesion proximal to
the midforearm
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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

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Case 5, final diagnosis

• Ulnar neuropathy at the wrist

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Case 6

• 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

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Case 6, cont

• 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
• Normal reflexes
• No evidence of loss of muscle bulk in the hand

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Case 6, cont

• Finding Muscle Root Plexus Nerve
• Thumb Abd APB C8, T1 Lower trunk Median
• Medial cord
• Thumb opp OP C8T1 Lower trunk Median
• Medial cord
• Sensory loss C6, 7 UT LT Median
• Lateral cord

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Case 6, cont
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Case 6, cont

• Final Diagnosis
• Carpal tunnel syndrome
• (median neuropathy at the wrist)

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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

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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 turn
  his forearm back
• Weakess of elbow flexion
• Numbness of the lateral arm and forearm

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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

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Case 7, cont

• Since the suprascapular nerve is involved, must
  be at the level of the upper trunk or nerve root
• 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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Case 7, cont

• Final diagnosis
• Upper trunk plexopathy