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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Dermatomes of the Posterior Arm
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Dermatomes of the Anterior Arm
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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

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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 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

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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 LAT 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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• C5
• C6
• C7
• C8
• T1

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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 in the Axilla

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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)
• Can it be localized further to a specific site of
  the ulnar nerve?

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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