Ulnar Nerve Lesion

Question 1

The Path

Answer 1

Originates from the medial cord of the brachial plexus (C8-T1)

It follows along the posterior wall of the axilla, under the pectoralis muscle to the mid-upper arm (insertion of coracobrachialis)

It then travels along the medial triceps (superficial)

At the elbow, it goes posterior to the medial epicondyle of the humerus and medial to the olecranon process

The ulnar collateral ligament supports the nerve

If then follows a path between and deep to the head of the flexor carpi ulnaris muscle (can be a site of compression)

Continuing to the wrist about midway down the forearm there are two main sensory branches and this is where the dorsal branch emerges and supplies the extensor surface of the 4th digit to the IP joint

At the wrist, the ulnar nerve travels over the flexor retinaculum between the pisiform and the hook of the hamate and beneath the volar carpal ligament and palmaris brevis muscle (Guyon’s canal) (site of compression)

• The ulnar nerve divides into:

1. Superficial branch which is primarily sensory and travels deep to palmaris brevis and then divides further into the palmar digital branch which supplies the ulnar side of the 5th digit and another branch for the radial side of the little finger and the ulnar side of the 4th digit
2. The deep branch is primarily motor and travels with the ulnar artery, going deep between abductor and flexor digiti minimi. It then pierces the opponens digiti minimi before continuing radially beneath the tendons of the finger flexors to the adductor pollicis

Question 2

Muscles Innervated by the Ulnar Nerve

Answer 2

Flexor carpi ulnaris
Flexor digitorum profundus (medial half)
Hypothenar muscles
Abductor digiti minimi
Flexor digiti minimi
Opponens digiti minimi
3rd and 4th lumbricals
Palmar and dorsal interossei
Adductor pollicis
Flexor pollicis brevis (deep head)

Question 3

Causes of Lesions of the Ulnar Nerve

Answer 3

1. Fractures:

Of the medial condyle of the elbow, mid-forearm or wrist (Colles fracture)

2. Dislocations:

Of the elbow

3. Post-surgical complications

Due to unrelieved pressure from the arm hanging over the edge of a table or the arm positioned improperly while under anesthesia

4. Prolonged Compression

From resting the elbow on a hard surface, wearing too tight of a wrist band or handcuff, cycling

5. Repetitive Action

Causing excessive stress such as pitching a ball or repeated flexion and extension with machine work. May develop due to fibrosis at specific sites

6. Direct Trauma

Such as a contusion or laceration at the wrist or hand, which is often in combination with a median nerve lesion

7. Pathology

Such as leprosy, as the ulnar nerve is commonly involved

Question 4

Symptom Picture

Answer 4

Presentation of a complete ulnar nerve lesion is known as a claw hand

The 5th digit is hyperextended and abducted at the MCP joint as well as flexed at the IP joint

The 4th digit is hyperextended at the MCP joint with varying amounts of flexion at the IP joint

The hyperextension is due to the loss of some of the finger flexors which results in unopposed extensors pulling the fingers back

Flexion of the IP joints combined with extension of the MCP joints is from the loss of the 3rh and 4th lumbricals

There is slight adduction of the 5th digit with loss of function of the adductor digiti minimi

Froment’s sign is positive with ulnar nerve lesion. The client attempts to maintain a firm grip on an object held between the thumb and index finger. This is impossible with loss of the adductor pollicis function. The flexor pollicis longus (innervated by the median nerve) is recruited in order to hold the object better resulting in flexion at the terminal phalanx

Muscle wasting is most remarkable at the hypothenar eminence and in the interosseous spaces. It may be present at the ulnar side of the forearm if flexor carpi ulnaris and flexor digitorum profundus are affected by a nerve lesion

Altered sensation and vasomotor changes may occur

Question 5

Sensory Dysfunction as a Result of a Lesion

Answer 5

Altered sensation is experienced on the ulnar side of the hand, especially in the little finger and medial half of the ring finger, including the palmar and dorsal aspects of the hand. This extends from a point just above the head of the ulna to the ends of the digits

Anesthesia (area of isolated supply) occurs along the little finger to the wrist

Question 6

Sites of
impingement

Answer 6

• Elbow - cubital tunnel syndrome, compression due to fractures at medial epicondyle or sustained pressure &/or anomalies in the anconeus muscle; when one hits their ‘funny bone’, it is usually a sensation due to the compression of the ulnar nerve as it passes posterior to the medial epicondyle
• Signs and symptoms:
• weakness of wrist flexion (ulner side)
• Claw hand deformity with normal PROM
• Loss of sensation to medial 1% fingers
• Wrist - Tunnel of Guyon, defensive wounds from cuts, stalo wounds or other trauma, repeated impact from riding a bicycle without padded gloves
• Signs and symptoms:
• Bishops or claw hand deformity
• loss of sensation to medial 1 % fingers, with normal PROM

Question 7

Cubital
Tunnel
Syndrome

Answer 7

1. Defination: Increased pressure on ulnar nerve at the elbow (cubital tunnel or ulnar groove), leading to numbness, tingling. & pain in the 4th & Sth fingers
2. Acessment:

• Inspection: Excessive cubitus valgus, atrophy of intrinsic hand muscles, Possible ‘claw hand’ or ‘bishop’s hand’
• Palpation: Direct pressure over the cubital tunnel exaggerates symptoms or pain.
• Motion: AROM & PROM: may be somewhat decreased, full flexion may aggravate symptoms.
• RROM: may be weak for muscles supplied by the ulnar
  nerve.
• Neurovascular: Numbness & tingling over 4th &5th fingers
• Differential Diagnosis: Ulnar nerve contusion, Thoracie outlet syndrome or cervical radiculopathy, Dupuytrens contracture (fascial restrictions), Medial epiconaylitis.
  Uinar neuropathy at the wrist, compression at the tunnel ot Guyon.
• Special Test:

+ Elbow flexion test: full flexion of elbow, supination & extension of the wrist produce pain or paresthesia within one minute → ulnar neuropathy

+ Froment’s sign: weakness in pinching paper belween thumb & index finger jaction of adductor

+ Tinels st ebow &wrist Itap on nerve)

+ Pressure proyocation fest. exeminer applies prolonged pressure over ulner nerve

• Management:
  General Modification: Stop aggravating

3. Treatment:

• Do NOT aggravate symptom at site of compression
• Evaluate &treat the entire course of the nerve.
• Muscle stripping to the flexor carpi ulnaris, flexor carpi radialis, pronator teres muscles - reduce hypertonicity
• Consider fascial work to prevent scar tissue & adhesions, reduce inflammation, relieve muscle
  sension, improve sirculation of blood and lymph
  fluic to promote healing

+ Joint mobs: neck, upper back, elbow, wrist|careful not to compress or tacoonnervew

Homecare: Realize nerve tissue may take a long time to heal. Start with basic wrist, hand & elbow ROM exercises & stretching that does not aggravate Patient Education:
* Limit repetitive elbow flexion/extension activities.
Consider ergonomic evaluation of work environment & sleeping posicion.
Wear an elbow brace at night if the patient sleeps with e bows hoperflexed
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