Ulnar nerve injury

Malunited lateral condylar fracture REF: Apley 8^th ed p. 599

TARDY ULNAR NERVE PALSY:

• Seen after fracture of lateral condyle
• Late complication , may be seen years after the injury
• Motor loss occurs first followed by sensory changes
• Cubitus valgus deformity leads to stretching of medial structures including ulnar nerve

Adduction of thumb.

Injury to the Ulnar nerve

• Ulnar nerve is most commonly injured at the elbow, where it lies behind the medial epicondyle and at the wrist where it lies in front of flexor retinaculum.
• In high ulnar nerve injury at or proximal to elbow, all the muscles supplied by the ulnar nerve in the forearm and hand are paralyzed whereas in low ulnar nerve palsy, there is sparing of the forearm muscles (in flexor carpi ulnaris and flexor digitorum profundus). Sensory deficit are same in both high & low ulnar nerve injury.

Tuberculoid leprosy

All interossei muscles are innervated by deep branch of ulnar nerve.

Palmar interossei adduct thumb, index, ring and little finger to the middle finger. Dorsal interossei are abductors of index, middle and ring finger. So clumsiness of hand in this patient is due to weakness of interosseus muscle innervated by ulnar nerve.

• Flexor carpi ulnaris
• Flexor digitorum profundus III and IV
• Adductor pollicis
• Flexor pollicis brevis
• Palmar interossei
• Dorsal interossei
• Lumbricals III and IV
• Hypothenar muscles

• Paresthesia and dysesthesia in the small finger and ulnar portion of ring finger
• Hand weakness and clumsiness
• Positive Tinel’s sign: Exacerbation of paresthesias with light percussion over the ulnar nerve within the cubital tunnel.
• Clawing of ring and small finger
• Interosseus muscle wasting
• Froment’s sign: substituting thumb IP joint flexion for thumb adduction due to weakness of adductor pollicis muscle.

Claw hand or “main en griffe”, is an abnormal posture of hand with hyperextension at metacarpophlangeal joints (fifth, fourth and to a lesser extent third) and flexion at interphlangeal joints.

This results from ulnar nerve leisions above the elbow or injury to the lower part of brachial plexus, producing wasting and weakness of hypothenar muscles, interossei, and ulnar (medial) lumbricals, allowing the long finger extensors and flexor to act unopposed.

Ref: Essential Orthopedics by Maheshwari 3^rd Edition, Page 51; A Dictionary of Neurological Signs By Andrew J. Larner, 2010.

Options 1 (true)
The cutaneous branch of the radial nerve supply the skin over anatomical snuff box, as such radial nerve injury causes anaesthesia over anatomical snuff box.

The ulnar nerve is most vulnerable near the elbow where it curves posteriorly around the medial epicondyle. The chief motor disability from palsy is loss of the finer intrinsic motions of the hand. Inspection will show an abduction deformity of the little finger from paralysis of the interossei, interosseous muscle wasting, and partial claw hand from interphalangeal flexion deformities of the ring and little fingers.

This is a case of cubital tunnel syndrome, which is caused by compression or irritation of the ulnar nerve as it passes under the medial epicondyle before it branches to deep and superficial branches. Symptoms are usually tingling and numbness in the cutaneous distribution of the ulnar nerve. In severe cases, muscle weakness may be apparent, with atrophy of the hypothenar eminence.

• Hypothenar compartment
• Adductor pollicis
• Dorsal interossei
• Palmar interossei
• Medial lumbricals

• Palmaris brevis 
• Surrounding skin of the digit 5 and the medial side of digit 4

When the ulnar nerve is injured in the hand, there is a loss of the interossei and lumbricals 3 and 4, and clawing of digits 4 and 5 may become apparent due to an imbalance of the extrinsic and intrinsic muscles. Because the extrinsic extensors of the hand are not opposed by the intrinsic flexors of the hand, the metacarpophalangeal joint hyperextends and is unable to extend the proximal and distal interphalangeal joints. 

• The axillary nerve is related to the surgical neck of humerus and is damaged in fracture of the surgical neck and in anterior dislocation of the humeral head.
• The radial nerve is related to the posterior aspect of shaft at the spiral groove, hence it is injured in fracture of mid shaft of the humerus and also following careless injection into the triceps muscle.

A i.e. Radial nerve injury cause anaesthesia over anatomical snuff box; C i.e. Ulnar nerve injury cause claw hand; B i.e. Index finger anesthesia is caused by median nerve injury 

B. i.e. Oppenens polices

Ulnar nerve in hand supply-3^rd & 4″¹ lumbricals, interossei (pabnar & dorsal), adductor pollicis & hypothenar musclesQ.

A i.e. Weakness of thumb adduction; B i.e. Froment’s sign

Grip is weak in ulnar n. palsy due to paralysis of intrinsic muscles (all interossei, lateral two 3^rd & 4^th lumbricals, hypothenar & adductor pollicis muscles)Q.

In low ulnar n. palsy forearm muscles are spared but the clawing is moreQ (as compared to high ulnar n. palsy) this phenomenon is k/a ulnar paradox.

Sensory supply of ulnar n. is medial % fingersQ.

Abductor pollicis is supplied by median nerve.

Finger drop i.e. loss of extension of metacarpophalyngeal jointQ is seen in Radial & Posterior interosseous nerve palsy

C i.e. Fracture lateral condyle

 Mitch type I (Salter Harris type IV)

–    Less common type

–    Fracture running through the secondary ossification centre of capitullum and entering the joint lateral to capitulotrochlear groove Cause growth defectQ

Mitch type II (Salter Harris type II (?) IV (?))

– Commonest

– Fracture starting in metaphysis and running along the physis of lateral condyle into trochlear i.e. fracture extends medial to capitulotrochlear groove.

–  Make ulnar

– humeral (elbow) joint unstableQ.

* If the lateral condyle is left capsized nonunion is inevitableQ : with growth elbow becomes increasingly valgus and tardy ulnar nerve palsyQ is then likely to develop.

D i.e. Ulnar nerve is most commonly involved

• In few cases of # supracondylar humerus tardy ulnar nerve palsy may be seen. (Tachdjian – 2166)

Ans. is ‘b’ i.e., Start MDT for 6 month 

o This patient from Bihar where there is high prevalence of Leprosy, has involvement of skin (an erythematous, anaesthetized patch) and nerves (enlarged tender ulnar nerve) signifies Tuberculoid leprosy. “For treatment

puposes, the WHO classifies patients as paucibacillary or multibacillary. Previously, patients without demonstrable AFB in the dermis were classified as paucibacillary and those with AFB as multibacillary. Currently

owing to the perceived unreliability of skin smears in the field, patients are classified as multibacillary if they have six or more skin lesions and as paucibacillary if they have fewer”- Harrison 17th/1025

” Use of skin smears is no longer encouraged by the World Health Organization (WHO) and is often replaced by

mere counting of lesions, which, together with the lack of histopathology, may negatively affect decisions about chemotherapy, increase the potential for reactions, and worsen the ultimate prognosis”- Harrison 17’h/1025

o So, on clincial basis, this patient is suffering from Paucibacillary leprosy and should be treated by multidrug therapy (Dapson + rifampicin for 6 months).

Froment sign

• To perform the test, a patient is asked to hold an object, usually a flat object such as a piece of paper, between their thumb and index finger (pinch grip). The examiner then attempts to pull the object out of the subject’s hands.
• A normal individual will be able to maintain a hold on the object without difficulty.
• However, with ulnar nerve palsy, the patient will experience difficulty maintaining a hold and will compensate by flexing the FPL (flexor pollicis longus) of the thumb to maintain grip pressure causing a pinching effect.
• Clinically, this compensation manifests as flexion of the IP joint of the thumb (rather than extension, as would occur with correct use of the adductor pollicis).
• The compensation of the affected hand results in a weak pinch grip with the tips of the thumb and index finger, therefore, with the thumb in obvious flexion.
• FPL is normally innervated by the anterior interosseous branch of the median nerve.

Ans:C.)Claw Hand.

• An ulnar claw, also known as claw hand, or ‘Spinster’s Claw’ is an abnormal hand position that develops due to a problem with the ulnar nerve. A hand in ulnar claw position will have the 4th and 5th fingers extended at the metacarpophalangeal joints and flexed at the interphalangeal joints. The patients with this condition can make a full fist but when they extend their fingers, the hand posture is referred to as claw hand. The ring- and little finger can usually not fully extend at the PIP joint.
• This can be commonly confused with the “Hand of benediction”, which is caused by high (at elbow level) median nerve damage.

The metacarpophalangeal joints become hyperextended because of the paralysis of the lumbrical and interosseous muscles, which normally flex these joints.

Because the first and second lumbricals are not paralyzed (they are supplied by the median nerve), the hyperextension of the metacarpophalangeal joints is most prominent in the fourth and fifth fingers.

The interphalangeal joints are flexed, owing again to the paralysis of the lumbrical and interosseous muscles, which normally extend these joints through the extensor expansion.

The flexion deformity at the interphalangeal joints of the fourth and fifth fingers is obvious because the first and second lumbrical muscles of the index and middle fingers are not paralyzed.

In long-standing cases the hand will show hollowing between the metacarpal bones caused by wasting of the dorsal interosseous muscles

True/complete claw hand involving all the fingers is produced by a combined lesion of ulnar and median nerve

Ans. D: All of the above

• If the fracture line exits medial to the trochlear groove – no lateral buttress for the ulna & it may dislocate laterally (Milch II).
• If the fracture line exits lateral to the trochlear groove – ulna will be buttressed by the trochlea and will not dislocate (Milch I).

Treatment – open reduction internal fixation-must see inside the joint to judge the reduction (because it is cartilaginous!) Complications of lateral humeral condyle fractures include:

• Nonunion, usually from persistent cast treatment of mildly displaced fractures
• Cubitus valgus deformity-diminished growth at the lateral side of distal humerus epiphysis results in a cubitus valgus deformity which may result in tardy/late ulnar nerve palsy.
• Avascular necrosis is a complication of operative dissection.
• Cubitus varus of a mild degree is fairly common, even after nonoperative treatment.
• Spur formation at the metaphyseal site of fracture is unusually frequent after lateral humeral condyle fractures, it is only a problem if it accompanies cubitus varus.
• Malunions can occur from faulty reduction or fixation, as they can with any fracture.
• Osteo-arthritis if improper reduction of articular surface.

Ans: C i.e. Clawing of fingers

Ans. B i.e. Ulnar nerve

When the ulnar nerve compression occurs at the elbow, it is called “cubital tunnel syndrome.”

Ans. A: Ulnar and median nerve

Claw hand deformity is manifested by flattening of the transverse metacarpal arch and longitudinal arches, with hyperextension of MCP joints and flexion of the PIP and DIP joints;

This deformity is produced by imbalance of the intrinsic & extrinsics:

i. Intrinsic muscles must be markedly weakened or paralyzed to produce claw deformity;

Long extensor muscles hyperextend the MCP joint, & long flexor muscles flex the PIP and DIP joints; weakness of the

long flexors (as in high palsy) actually decreases claw fingers;

In ulnar nerve palsy, only the medial two fingers develops clawing while all the four fingers develop clawing in combined median and ulnar nerve palsy.

Ans. A: Ulnar Nerve

The primary factor responsible for deformities in leprosy is involvement of peripheral nerves. Nerves which may be affected are:

1. Supra orbital n.
2. Facial n.
3. Great auricular n.
4. Supra clavicular n. (rare)
5. Radial n.
6. Ulnar n.
7. Radial cutaneous n.
8. Median n.
9. Femoral cutaneous n. (rare)
10. Lateral popliteal (common peroneal) n.
11. Superficial peroneal n.
12. Sural n.
13. Posterior tibial n.

The commonly affected nerves are (in order of their frequency of affection):

• Ulnar nerve at elbow
• Median nerve above the wrist
• Common peroneal nerve at the knee resulting in foot drop.

Ans. B: Ulnar Nerve

Certain lesions are commonly associated with fractures to specific areas of the humerus.

At the upper end, the surgical neck of the humerus and anatomical neck of humerus can both be involved, though fractures of the surgical neck are more common. The axillary nerve can be damaged in fractures of this type.

Mid-shaft fractures may damage the radial nerve, which traverses the lateral aspect of the humerus closely associated with the radial groove.

The median nerve is vulnerable to damage in the supracondylar area.

The ulnar nerve is vulnerable to damage near the medial epicondyle, around which it curves to enter the forearm.

Ans. B: Cubitus Valgus Deformity

A Shallow ulnar groove predisposes to ulnar nerve injury.

Inadequate fibrous arch or recurrent subluxation of ulnar nerve can lead to ‘Tardy ulnar nerve palsy’. Progressive deformity of cubitus valgus may precipitate this condition.

The nerve may be compressed if the fascial roof formed by flexor carpi ulnaris gets tightened resulting in numbness in the little finger and ulnar half of ring finger.

There is motor weakness of intrinsic muscles of the hand supplied by ulnar nerve.

The surgical treatment for this condition may be:

• Decompression of cubital tunnel, and/or
• Anterior transposition of ulnar nerve, or
• Medial epicondylectomy

Ans. B: Ulnar Nerve

I. Lesion at the elbow

• The term cubital tunnel syndrome is often used for ulnar nerve compression at the elbow.
• Total paralysis of the nerve, including those branches of the nerve serving the flexor digitorum profundus and flexor carpi ulnaris muscles, causes wasting along medial side of forearm.
• Paralysis of the nerve also leads to weakness of flexion of fourth and fifth fingers; if proximal portions of these fingers are held steady, patient is unable to flex terminal phalanges.
• With paralysis of hypothenar muscles, abduction of fifth finger is impossible.
• Paralysis of interossei and medial two lumbricals causes ‘claw hand’ deformity, mainly seen in the ulnar fingers.
• There may be wasting of hypothenar muscles, interossei and medial part of thenar eminence.
• Also there is weakness in movement of fingers and abduction to the extended thumb against the palm.
• There is sensory loss of the dorsal and palmar aspects of the medial side of the hand together with the medial one and a half fingers.
• With compression of the ulnar nerve, the ulnar nerve is often palpably enlarged in the ulnar groove and for a short distance proximal to the elbow.

II. Lesion at the wrist

• Cutaneous sensation of hand and fingers is often spared.
• If lesion is just proximal to the wrist, it causes impaired sensation on the palmar aspects of hand and the fourth and fifth fingers and muscle weakness, especially in the hypothenar eminence.

Adductor pollicis will be injured in ulnar nerve injuries so patient will hold the book by using the flexor pollicis longus (supplied by median nerve).This is the basis of book test/froment sign.

Positive Tinel’s sign on percussion over ulnar nerve at wrist (light percussion over the nerve causes a sensation of “pins and needles” in the distribution of the nerve, i.e. ulnar side of hand and fourth and fifth fingers). Positive Phalen’s test with paraesthesias in fourth and fifth fingers (patient holds their wrist in maximum flexion for 30-60 seconds

Ans. B: Ulnar Nerve

Ans. A: Ulnar Nerve Palsy

Ans:B.)Ulnar Nerve.

Fracture of medial condyle of humerus is shown in the image.

Ans. is ‘b’ i.e., Lateral condyle # humerus

Causes of tardy ulnar nerve palsy are : –

1. Malunited lateral condyle humerus fracture (cubitus valgus)
2. Displaced medial epicondyle humerus fracture
3. Cubitus varus deformity (due to supracondylar fracture humerus)
4. Elbow dislocation
5. Contusions of ulnar nerve
6. Shallow ulnar groove
7. Hypoplasia of humeral trochlea
8. Joint deformity after prolonged arthritis of elbow