Nerve Injuries of the Upper Limb Dr Zeenat

Nerve Injuries of the Upper Limb Dr. Zeenat Zaidi

Upper limb is supplied by branches of the brachial plexus, formed by the ventral rami of the spinal nerves C 5, 6, 7, 8, and T 1 the Since the spinal nerves are mixed nerves carrying sensory, motor and autonomic fibers, their injuries result in sensory, motor and autonomic disturbances

Symptoms & Signs of Peripheral Nerve Injury Depend on the site and extent of the lesion Motor changes: The innervated muscles become paralyzed. The reflexes in which the muscles participate are lost Sensory changes: Loss of cutaneous sensibility over the area exclusively supplied by the nerve Trophic changes: Due to interruption of postganglionic sympathetic fibers: n n There is loss of vascular control: the skin at first becomes red & hot. Later becomes blue and colder than normal. The nail growth becomes retarded The sweat glands cease to produce sweat and the skin becomes dry and scaly

Upper Limb Tendon Reflexes Biceps brachii reflex: C 5, 6 (flexion of elbow joint by tapping the tendon of biceps muscle) Triceps brachii reflex: C 6, 7, 8 (extension of elbow joint by tapping the tendon of triceps muscle) Supinator (brachioradialis) reflex: C 5, 6, 7 (supination of radioulnar joint by tapping the tendon of brachioradialis muscle)

A spinal nerve may get injured: 1. at the level of its roots within the vertebral canal 2. at the level of its passage through the intervertebral foramen 3. At any level in its peripheral course Injuries 1 & 2 may result due to: n Fracture of the vertebra n Narrowing of intervertebral foramina n Herniation of the intervertebral disc n Degeneration of the intervertebral disc

Brachial plexus injuries May involve the roots, trunks, divisions, cords & branches Supraclavicular injuries involve the roots and the trunks, infraclavicular injuries will affect the divisions and cords Result due to: n Compression n Traction n Stab wounds Symptoms depend on the site of injury & involvement of nerve fibers

Brachial plexus injuries Are of two types: n Upper lesions usually involving C 5 & C 6 n Lower lesions usually involving (C 8), T 1

Upper Lesions of the Brachial Plexus (Erb-Duchenne Palsy) • These are usually the result of traction & tearing of the 5 th and 6 th root of the brachial plexus • This may occur: • In infants during a difficult delivery • In adults following a fall on or a blow to the shoulder. • It involves the: • Nerve to sublavius • Suprascapular nerve • Axillary nerve • Musculocutaneous nerve

The muscles affected are: n Abductors (supraspinatus & deltoid) and lateral rotators (Infraspinatus &teres minor) of the shoulder n Subclavius, biceps, brachialis & coracobrachialis Thus: n The limb hangs limply by the side, and is medially rotated n The forearm is pronated and extended n There is loss of sensation down the lateral side of the arm & the forearm Another name for this lesion is 'porters tip'

Lower Lesions of the Brachial Plexus (Klumpke Palsy) These are usually caused by excessive abduction of the arm as a result of: n Someone clutching for an object when falling from a height n Difficult delivery in which baby’s upper limb is pulled excessively. n Result of malignant metastases from the lungs in the lower deep cervical lymph nodes n A cervical rib

Usually the lowest root (T 1) of the brachial plexus is involved The fibers from this segment of the spinal cord supply the small muscles of the hand (interossei and lumbricals). Paralysis and wasting of small muscles of hand occurs There is also sensory loss along the medial side of the forearm, hand medial 2 fingers Often associated with Horner’s syndrome (drooping of upper eyelid & constricted pupil) due to traction of sympathetic fibers

The hand has a clawed appearance due to: n Hyperextension of the metacarpophalangeal joints (the extensor digitorum is unopposed by the lumbricals and interossei and extends the metacarpophalangeal joints). n Flexion of the interphalangeal joints (the flexor digitorum superficialis and profundus are unopposed by the lumbricals and interossei, the middle and terminal phalanges are flexed).

Long Thoracic Nerve Lesion (Nerve to Serratus Anterior) This nerve may be injured by: n Blows or pressure in the posterior triangle of the neck n During a radical mastectomy surgical procedure. The serratus anterior muscle: n Pulls the medial border of the scapula to the posterior thoracic wall and stabilizes it there. n Rotates scapula during the abduction of arm above a right angle

The patient shows difficulty in raising the arm above the head If patient is asked to push against a wall, the medial border of the scapula will be pushed away from the thoracic wall and protrude like a wing, on the side of the lesion. 'winged scapula'.

Axillary Nerve Lesion Axillary nerve may get injured: n Due to downward dislocation of humeral head in shoulder dislocation n Fracture of the surgical neck of humerus Deltoid and teres minor muscles become paralyzed Abduction of the shoulder is impaired. The paralyzed deltoid wastes rapidly (loss of rounded contour of the shoulder) Loss of sensation over the lower half of deltoid muscle

Radial Nerve The radial nerve is commonly damaged: n in the axilla n in the radial groove n Injury to the deep branch (in the supinator tunnel) n Injury to the superficial branch

Radial Nerve Injury in the Axilla In the axilla the nerve may be injured by: n Pressure of the upper end of badly fitting crutch pressing up in to the armpit (crutch palsy) n The drunkard falling asleep with his arm over the back of a chair (saturday night palsy). n Fractures or dislocations of the upper end of the humerus

Motor: Triceps, anconeus and long extensor of the wrist are paralysed. The patient is unable to extend the elbow joint, wrist joint and fingers. “Wrist drop” or flexion of the wrist occurs as a result of the unopposed flexor muscles of the wrist. This is a very disabling injury, since a person can't flex the fingers strongly for gripping an object with the wrist fully flexed. The brachioradialis and supinator muscles are paralyzed, but supination can still be performed due to intact biceps brachii.

Sensory: Due to the overlap of sensory innervation by adjacent median & ulnar nerves, the area of total anaesthesia is relatively small, overlying the first dorsal interosseous muscle (between the 1 st and 2 nd metacarpal bones)

Radial Nerve Injury in the Radial Groove The most common lesion of the radial nerve resulting because of the: n Fracture of the shaft of humerus n Callus formation n Pressure on the back of the arm on the edge of the operating table in an unconscious patient n Prolonged application of tourniquet.

The injury to radial nerve occurs most commonly in the distal part of the groove beyond the origin of the nerve to the triceps & anconeus (so that extension of the elbow is possible), and beyond the origin of the cutaneous nerves Motor : The long extensors of the forearm are paralyzed and this will result in a "wrist drop". Sensory: Loss of sensation from small area overlying the first dorsal interosseous muscle

Injury to the Deep Branch of the Radial Nerve It may be damaged in fractures of the proximal end of the radius or during dislocation of the radial head. Motor: . n n Intact forearm extension and flexion with intact hand extension. Only weakness of finger extensors. Nerve supply to the supinator and extensor carpi radialis longus will be undamaged and because the later muscle is powerful it will keep the wrist joint extended and wrist drop will not occur. Sensory: There will be no sensory loss since this is a motor nerve.

Injury to the Superficial Branch of the Radial Nerve It may be damaged as a result of stab injury, or pressure from handcuffs & tight bangles Motor: There will be no motor loss since this is a sensory nerve. Sensory: There is a small loss of sensation over the dorsal surface of the hand the dorsal surfaces of the roots of the lateral three fingers

Median Nerve Lesions Injury of median nerve at different levels cause different syndromes. The most serious disability of median nerve injuries is the: n Loss of opposition of the thumb. The delicate pincerlike action is not possible n Loss of sensation from the thumb and lateral 2½ fingers & lateral ⅔ of the palm

Median Nerve Lesions Median nerve can be damaged: n In the elbow region n At the wrist above the flexor retinaculum n In the carpal tunnel

Median Nerve Lesion in the Elbow Region Damaged in supracondylar fracture of humerus Muscles affected are: n Pronator muscles of the forearm n All long flexors of the wrist and fingers except flexor carpi ulnaris and medial half of flexor digitorum profundus

Motor: Loss of pronation. Hand is kept in supine position Wrist shows weak flexion, and ulnar deviation No flexion possible on the interphalangeal joints of the index and middle fingers Weak flexion of ring and little finger Thumb is adducted and laterally rotated, with loss of flexion of terminal phalanx and loss of opposition Wasting of thenar eminence Hand looks flattened and “apelike”, and presents an inability to flex the three most radial digits when asked to make a fist.

Sensory: Loss of sensation from: n The radial side of the palm n Palmer aspect of the lateral 3½ fingers n Distal part of the dorsal surface of the lateral 3½ fingers Trophic Changes: n n n Dry and scaly skin Easily cracking nails Atrophy of the pulp of the fingers

Median Nerve Lesion at the Wrist Often injured by penetrating wounds (stab wounds or broken glass) of the forearm Motor: Thenar muscles are paralyzed and atrophy in time so that thenar eminence becomes flattened. Opposition and abduction of thumb are lost, and thumb and lateral two fingers are arrested in adduction and hyperextension position. “Apelike hand” Sensory & trophic changes are the same as in the elbow region injuries

Carpal Tunnel Syndrome Compression of median nerve in the carpal tunnel Motor: Weak motor function of thumb, index & middle finger Sensory: Burning pain or ‘pins and needles’ along the distribution of median nerve to lateral 3½ fingers No sensory changes over the palm as the palmer cutaneous branch is given before the median nerve enters the carpal tunnel

Ulnar Nerve Lesion Ulnar nerve can be damaged: n At the elbow, where it lies behind the medial epicondyle n At the wrist, where it lies with the ulnar artery superficial to the flexor retinaculum

Ulnar Nerve Lesion at the Elbow Often injured with fractures of the medial epicondyle Motor paralysis involves: n Flexor carpi ulnaris n Medial half of flexor digitorum profundus n Small muscles of the hands, except the muscles of thenar eminence and first two lumbricals. n Adductor pollicis Sensory loss over the anterior & posterior surfaces of the palm & medial one and half finger Trophic changes: because of loss of sympathetic control

Flexion of the wrist will result in abduction The thumb is abducted and extended with the distal phalanx flexed (difficulty in holding a piece of paper between thumb and index finger). The adduction and abduction of fingers is lost (difficulty in holding a piece of paper between fingers). The lateral two fingers are fully extended with a slight flexion of the distal phalanges. The medial two fingers are hyperextended at the metacarpophalangeal joints but flexed at the distal phalangeal joints.

Wasting of the hypothenar eminence The dorsum of the hand shows hollowing between the metacarpal bones The hand resembles a "claw" and is called a claw hand. The clawing becomes most obvious when the person is asked to straighten their fingers.

Ulnar Nerve Lesion at the Wrist Commonly occur due to cuts and stab wounds Motor: The small muscles of the hands are paralyzed, except the muscles of thenar eminence and first two lumbricals. The claw hand is more obvious as the flexor digitorum profundus is intact Sensory loss over the anterior surfaces of the palm and the anterior & posterior surfaces of the medial one and half finger. (The posterior surface of the hand is spared as the posterior cutaneous branch arises above the level of wrist)