PNS: Ulnar and Radial Nerve Lesions

• Peripheral Nervous System (PNS): Ulnar and Radial Nerve Lesions
• Focus on understanding nerve pathways, identifying compression sites, developing, and implementing treatment plans.

Class Outline

• Review questions related to ulnar and radial nerve lesions
• Learn to accurately identify sensory areas innervated by the radial and ulnar nerves through sensory testing
• Includes a lecture covering key concepts
• Learn assessment techniques
• Treatments and homecare strategies for radial and ulnar nerve lesions

Radial Nerve

• Originates from the posterior cord of the brachial plexus
• Brachial plexus originates from (C5-T1) nerve roots
• Passes through the triangular interval/triceps hiatus.
• Courses with the triceps medial head, travels posterior axilla along spiral groove of the humerus.
• Moves anteriorly between the brachialis and brachioradialis muscles
• Runs beneath the ECRL and ECRB muscles
• Crosses the elbow lateral to the olecranon process
• Distal to the elbow, radial nerve divides into a posterior motor branch and a superficial sensory branch

Radial Nerve Motor Function

• Innervates the following muscles:
• Triceps brachii
• Anconeus
• Brachioradialis
• Extensor Carpi Radialis Longus (ECRL)
• Extensor Carpi Radialis Brevis (ECRB)
• Extensor Digitorum
• Extensor Carpi Ulnaris
• Extensor Digiti Minimi
• Abductor Pollicis Longus
• Extensor Indicis

Causes of Radial Nerve Lesions

• Can result from fractures of the humerus, especially at the spiral groove
• Fractures to the radius at the proximal 1/3 can cause “radial nerve palsy”
• Elbow dislocations can compress or damage the radial nerve
• Compression at the Arcade of Frohse or within the radial tunnel
• Prolonged pressure on the arm during surgery
• Crutch palsy, "Saturday night palsy", or "honeymoon palsy’ can occur
• Prolonged compression of the radial nerve at the axilla
• Nerve damage can cause neuropraxia or axonotmesis
• Wallerian degeneration is a process that can occur after nerve injury

Radial Nerve Lesions Signs & Symptoms

• Altered sensation in the radial nerve distribution
• Complete lesion presents with wrist drop
• Lesions proximal to the elbow affect sensory and motor branches
• Lesions distal to the elbow typically affect either sensory or motor function, but not both
• Possible signs and symptoms include:
• Muscle wasting
• Swelling on the dorsum of the hand
• Pain
• Paresthesia in the webbing between digits 1 & 2

Radial Nerve Palsy

• Commonly due to a fracture of the humerus
• Signs and symptoms include:
• Weakness or paralysis of wrist/finger extensors and forearm supinators resulting in wrist drop.
• Possible weakness of the triceps, depending on the location of the injury
• Paresthesia in the dorsum of the hand, lateral 3.5 digits, and lateral forearm

Saturday Night/Crutch/Honeymoon Palsy

• Occurs due to prolonged compression at the posterior axilla or spiral groove

• Commonly observed in cases with:

• An intoxicated person passes out with arm over the back of a chair or other surface

• Falling asleep with someone’s head resting on your arm

• Incorrect crutch use

• Signs and symptoms include:

  • Wrist drop
  • Possible weakness to triceps
  • Paresthesia in dorsum of the hand, lateral 3.5 digits and lateral forearm

• It can result in neuropraxia or axonotmesis depending on compression duration

Radial Tunnel Syndrome/Posterior Interosseous Nerve Syndrome

• Distal to the elbow, the radial nerve splits into:

• Superficial radial nerve (sensory)

• Posterior interosseous nerve aka PIN (motor)

• The PIN passes through the Arcade of Frohse in the supinator muscle

• The PIN travels posterior to the Arcade of Frohse within the Radial Tunnel

• Radial tunnel involved the following muscles:

  • Supinator
  • Brachioradialis
  • Extensor Carpi Radialis Longus (ECRL)
  • Extensor Carpi Radialis Brevis (ECRB)

• Compression can also occur in the radial tunnel during repetitive use of these muscles

• Signs and symptoms include:

  • Pain distal to the lateral condyle
  • Weakness/paralysis of wrist and finger extensors
  • Symptoms worsen with elbow extension and pronation

• Radial tunnel syndrome does not present any sensory deficits

Superficial Radial Nerve Syndrome/Wartenberg's Syndrome/Cheiralgia Paraesthetica

• Involves compression of the sensory branch
• Trauma is a cause of compression of the sensory branch
• Direct pressure on the nerve from watches and hand-cuffs
• Hypertoned or overused muscles like the brachioradialis and ECRL muscles
• Presents as:
  • Pain over distal radial forearm
  • Paresthesia in dorsal hand
  • No motor deficits

Radial Nerve Lesion Differential Diagnosis (DDx)

• Radiculopathy
• Brachial plexus injuries
• Other sites of compression along the radial path
• If pain is present, consider:
  • Lateral epicondylitis
  • DeQuervain's syndrome

Assessments: History

• Location(s) of symptoms
• When did the symptoms began?
• Nature of symptoms:
  • Intermittent/chronic/episodic?
  • Related patterns to posture, activity, or sleep?
• Quality of symptoms:
  • Is there pain?
  • Numbess, weakness, or tingling in the affected area?
  • Skin or temperature changes?

Assessments: Observation/Palpation/Movement

• Postural scan looks for a waiter's tip posture

• Palpate for:

  • Tenderness
  • Hypertonic musculature (HT mm)
  • Fascial restrictions.
  • Temperature changes/edema.

• Range of motion (ROM) assessment for shoulder, elbow, and wrist

• Manual muscle testing (MMTs) for weakness or imbalances:

  • Wrist extensors
  • Finger extensors
  • Abductor Pollicis

Assessments: Special Tests

• Deep Tendon Reflexes:

  • Triceps brachii
  • Brachioradialis muscles.

• Review Sensory assessment of the back of the hand, digits 1, 2, 3 ½ of 4, and web of thumb

• Upper Limb Tension Test (ULTT) 3 - Radial nerve neurodynamic testing

• Rule out other potential conditions through special tests:

  • Thoracic Outlet Syndrome tests
  • Finkelstein's test to assess for De Quervain's tenosynovitis
  • Lateral Epicondylitis tests

Ulnar Nerve Pathway

• Originates from the medial cord of the brachial plexus (C8-T1)
• Runs from the axilla to the medial aspect of the humerus
• Travels posteriorly to the medial epicondyle
• Courses through the forearm between the Flexor Carpi Ulnaris (FCU) and Flexor Digitorum Profundus (FDP) muscles
• Located beneath ECRL & ECRB
• Passes over the flexor retinaculum between the pisiform and hook of hamate
• Travels through Guyon's Canal/ulnar tunnel
• Terminates through the palm to digits 1, 4 and 5

Ulnar Nerve Motor Function

• Innervates the following muscles:
  • Flexor Carpi Ulnaris
  • Flexor Digitorum Profundus (to digits 4 & 5)
  • Abductor, flexor, and opponens digiti minimi (hypothenar group)
  • 3rd and 4th lumbricals
  • Palmar and dorsal interossei
  • Adductor pollicis
  • Flexor Pollicis brevis

Ulnar Nerve Lesions

• Claw Hand occurs in the following position:
  • Passive hand position.
  • Fifth metacarpophalangeal (MCP) joint: extended and abducted.
  • Fifth interphalangeal (IP) joint: flexed.
  • Fourth MCP joint: extended.
  • Fourth IP joint: flexed.

Claw Hand

• The passive hand position is due to ulnar damage at the wrist
• Hyperextension of the MCP joints of the ring and small fingers
• Flexion of the DIP joints of the same digits
• Wasting of hypothenar musculature

Ulnar Nerve Lesions

• Benediction Hand presentation:
  • Passive hand position
  • Loss of lumbrical function
  • Digits 4 & 5 IPs & DIPs flex unopposed

Ulnar Nerve Sensory Function

• Provides sensory innervation to:
  • Digits 5 and ½ of 4
  • Ulnar aspect of palm

Ulnar Nerve Complete Lesion:

- Presents a claw hand
- Loss of thumb adduction
- Muscle wasting in hypothenar and interosseous spaces
- Anhydrosis and vasomotor changes

Causes of Ulnar Nerve Lesions:

• Fractures of the medical epicondyle, forearm and Colles fracture
• Elbow dislocation
• Prolonged compression
• Repetitive use
• Trauma
• The nerve is most vulnerable at the elbow & wrist

Tardy Ulnar Palsy:

• A condition that develops post fracture, sometimes years later
• Characterized by callus formation and valgus deformity.
• Gradually stretches the nerve in the ulnar groove of the medial epicondyle

Cubital Tunnel Syndrome:

• Passage between heads of FCU and FDP.
• When the elbow is flexed it flattens the tunnel, putting pressure on the ulnar nerve

Ulnar Tunnel/Guyon's Tunnel Syndrome

• Formed by:
  • Pisiform
  • Hook of hamate
  • Volar carpal ligament
  • Transverse carpal ligament
• Contains:
  • Ulnar nerve
  • Ulnar artery
• Caused by:
  • Pressure on the hypothenar eminence
  • Cycling
  • Jackhammers or other heavy tools
  • Keyboard use
• Trauma that causes swelling
• Carpal Fracture
• Arthritis

Ulnar Nerve Lesion Differential Diagnosis DDx

• Radiculopathy

• Brachial plexus injuries

• Thoracic Outlet Syndrome (TOS)

• Other compression sites

• If pain is present:

  • Triangular Fibrocartilage Complex (TFCC) Injuries
  • Other conditions present in the ulnar nerve distal pathway like wrist and elbow strains/tendinopathies

Assessments: History

• Location(s) of symptoms.
• Onset
• Nature of symptoms:
  • Intermittent/chronic/episodic?
  • Related patterns to posture, activity, or sleep?
• Quality of symptoms:
  • Is there pain?
  • Numbess, weakness, or tingling in the affected area?
  • Skin or temperature changes?

Assessments: Observation/Palpation/Movement

• Postural scan for claw hand
• Palpate for:
  • Tenderness
  • Hypertonic musculature (HT mm)
  • Fascial restrictions.
• Palpate for temperature changes/edema/sweating
• Range of motion (ROM) assessment for elbow, wrist, fingers, and thumb
• Manual muscle testing (MMTs) for weakness or imbalances:
  • Flexor Carpi Ulnaris (FCU) assessment
  • Flexor Digitorum Profundus (FDP) assessment
  • Hypothenar group assessment
  • Interossei assessment
  • Adductor Pollicis (ADD P) and Flexor Pollicis Brevis (FPB)

Assessments: Special Tests

• Tinel's Test
  • Locate the ulnar nerve at the medial epicondyle
  • Determines the amount of regeneration
  • Tapping the nerve will elicit tingling
• Froment's Sign
  • tests the strength of the Adductor Pollicis muscle
  • Patient grasps paper between 1st and 2nd digit
  • Examiner tries to pull paper
  • Positive result where patient will flex their IP to recruit flexors to maintain grasp due to weakness in Adductor Pollicis (ADD P)
• Sensory Testing:
  • Assessment of Ulnar distribution
• Upper Limb Tension Test (ULTT 4) – Ulnar nerve neurodynamic testing

Treatment Goals: Regenerating Nerves

• Address the area Proximal to lesion or compensatory muscles
  • Reduce fascial restrictions
  • Manage edema
  • Reduce trigger points
  • Reduce muscle hypertonicity
• Manage edema
• Increase and maintain Range Of Motion & tissue health
• Support motor and sensory function
• Manage pain (reduce fear avoidance behavior)
• Promote relaxation

Treatment: Regenerating Nerves

• Segmental strokes proximal to lesion, perpendicular to the nerve to improve nerve regeneration

• Use blocking/stabilization proximal to the nerve to prevent tissue drag during treatment

• Flaccid tissue:

  • Light stroking
  • Compressions
  • The treatment of unaffected tissue should be toward but not on flaccid tissue

• Passive Range Of Motion:

  • Use movements that slacken/don't bias the affected nerve

• Stretching - passive/PNF/pin and stretch

• Positioning – neutral position using pillows to optimize tissue healing

• DO NOT provide traction to regenerating nerves

• DO NOT stretch denervated tissue/muscles

Homecare - Regenerating nerves

• Splinting/bracing
• Protect areas of decreased sensitivity using gloves
• Sensory Re-education:
  • Expose area to multiple kinds of stimulus texture
  • Exposure stimulus through tissue vibrations
  • Identify touch with eyes closed
  • Identify different objects with eyes closed
• Mild Hydrotherapy (Contraindicated if autonomic nerve symptoms)
• Neural Mobilizations
• ADL modifications
  • Canes or hand/ crutches
  • Based on compression site/symptoms