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PERIPHERAL NERVE INJURYIES

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MHD BASHAR ALBOSHI Microscopic anatomy INTERNAL TOPOGRAPHY OF PERIPHERAL NERVES NEURONAL DEGENERATION AND REGENERATION: Phagocytosis Secondary or wallerian ... – PowerPoint PPT presentation

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Title: PERIPHERAL NERVE INJURYIES


1
PERIPHERAL NERVE INJURYIES
  • MHD BASHAR ALBOSHI

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  • Microscopic anatomy

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  • INTERNAL TOPOGRAPHY OF PERIPHERAL NERVES

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  • NEURONAL DEGENERATION AND REGENERATION
  • Phagocytosis
  • Secondary or wallerian degeneration
  • Primary or retrograde egeneration

7
  • CLASSIFICATION OF NERVE INJURIES ( Seddon1943)
  • Neurapraxia
  • Axonotmesis
  • neurotmesis
  • (Sunderland 1951) classification

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  • Etiology of peripheral nerve injuries
  • - Metabolic or collagen diseases
  • - Malignancies
  • -Endogenous or exogenous toxins
  • -Thermal
  • -Chemical
  • -Mechanical trauma

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  • Clinical diagnosis of nerve injuries
  • Highet Scale
  • 0 total paralysis.
  • 1- muscle flicker.
  • 2-muscle contraction.
  • 3- muscle contraction against gravity.
  • 4- muscle contraction against gravity and
    resistance.
  • 5-normal muscle contraction .

16
  • Diagnostic tests
  • Electrodiagnostic studies provide the clinician
    with a base of knowledge as follows
  • 1-Documentation of injury
  • Location of insult 2 -
  • 3-Severity of injury
  • 4-Recovery pattern
  • 5-Prognosis
  • 6-Objective data for impairment documentation
  • 7-Pathology
  • 8-Selection of optimal muscles for tendon
    transfer 9-procedures

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  • The most common electrodiagnostic methods used
    for the study of peripheral nerve injuries are
  • _at_- nerve conduction studies and
  • _at_-electromyography (EMG)

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  • Fig. 59-10 Diagram of EMG tracing depicting
    normal insertion activity, which also may be
    present immediately after denervation.

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  • Fig. 59-11 A, Diagram of EMG tracing
    demonstrating positive sharp wave consistent with
    denervation 10 to 14 days after injury. Rhythm is
    regular, amplitude is 100 to 400 uV, duration is
    5 to 150 msec, and rate is 2 to 40 Hz.
  • B, Diagram of EMG tracing demonstrating
    spontaneous denervation fibrillation potentials
    present within 14 to 18 days after injury. Rhythm
    is regular, amplitude is 50 to 1000 uV, duration
    is 0.5 to 2 msec, and rate is 2 to 30 Hz. 

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  • Tinel sign
  • A positive Tinel sign is presumptive evidence
    that regenerating axonal sprouts that have not
    obtained complete myelinization are progressing
    along the endoneurial tube.
  • _at_- neuropraxia(sunderland1) -------negative
    Tinel sign.
  • _at_- axonotmesis (sunderland2,3) -------positive
    Tinel sign.
  • (sunderland4-------- negative Tinel sign )
  • _at_- neurotmesis (sunderland 5) ------- negative
    Tinel sign.
  • Other diagnostic test
  • Sweat test.,skin resistance test, electrical
    stimulation

22
  • GENERAL CONSIDERATIONS OF TREATMENT.
  • FACTORS THAT INFLUENCE REGENERATION AFTER
    NEURORRHAPHY
  • 1-Age
  • 2-Gap Between Nerve Ends
  • 3-Delay Between Time of Injury and Repair
  • 4-Level of Injury 5-Condition of Nerve Ends

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  • TECHNIQUE OF NERVE REPAIR
  • Endoneurolysis (Internal Neurolysis
  • Partial Neurorrhaphy Neurorrhaphy and Nerve
    Grafting

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  • Methods of Closing Gaps Between Nerve Ends
  • Mobilization
  • Positioning of Extremity
  • Transposition
  • Bone Resection
  • Nerve Stretching and Bulb Suture
  • Nerve Grafting

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Techniques of Neurorrhaphy
  • Epineurial Neurorrhaphy

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  • Perineurial (Fascicular) Neurorrhaphy

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  • Interfascicular Nerve Grafting

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Brachial Plexus
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  • ETIOLOGY AND CLASSIFICATION OF BRACHIAL PLEXUS
    INJURIES
  • -birth,
  • -missiles,
  • - stab wounds,
  • - traction applied to the plexus during falls,
  • -vehicular accidents,
  • - sports activities,
  • -as well as radiation.

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  • Rupture of the axillary or subclavian artery
    occurs in 20 of patients.
  • Common associated injuries include
  • _at_fractures of the proximal humerus, the scapula,
    the ribs, the clavicle, and the transverse
    processes of the cervical vertebrae
  • _at_dislocation of the shoulder, the
    acromioclavicular, and the sternoclavicular
    joints.
  • _at_ A torn rotator cuff also has been described in
    conjunction with brachial plexus injury.

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Upper plexus injury (Erb)
  • involves the segments innervated by the C5 and C6
    nerve roots with or without dysfunction of the C7
    root.
  • -Typically the limb is extended at the elbow(the
    biceps, brachialis, and brachioradialis muscles)
  • -flaccid at the side of the trunk,
  • -Adducted (deltoid and supraspinatus muscles)
  • -internally rotated (infraspinatus and teres
    minor muscles, supinator muscle)

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Lower plexus injury (Klumpke)
  • can be diagnosed by finding segmental sensory and
    motor deficits involving C8 and T1 with or
    without C7 dysfunction.
  • _at_ The primary dysfunction is apparent in
  • -the intrinsic musculature of the hand along
    with paralysis of the wrist and finger flexors.
  • - The sensory deficit is along the medial aspect
    of the arm, forearm, and hand.
  • _at_Associated Horner syndrome should alert the
    examiner to the possibility of an avulsing injury
    of the lower plexus,
  • .

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Injuries to the upper or lower trunks
  • produce essentially the same sensory and motor
    deficits as do injuries to their respective rami,
    except for preservation of function of the long
    thoracic and dorsal scapular nerves in the upper
    trunks and absence of Horner syndrome in the
    lower trunks.

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Injuries of the lateral cord
  • deficits in the distribution of
  • -musculocutaneous nerve (paralysis of the
    biceps).
  • -lateral root of the median nerve (paralysis of
    the flexor carpi radialis and pronator teres).
  • -lateral pectoral nerve (clavicular head of the
    pectoralis major).
  • _at_Glenohumeral subluxation may result. This may be
    prevented by an aggressive program of
    rehabilitation of the remaining intact
    musculature.
  • _at_Sensory deficit can be detected over the
    anterolateral aspect of the forearm in the
    relatively small autonomous zone of the
    musculocutaneous nerve.

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Injuries of the posterior cord
  • deficits in the distribution of the following
    nerves -subscapular (paralysis of the
    subscapularis and teres major),
  • -thoracodorsal (paralysis of the latissimus
    dorsi).
  • - axillary (paralysis of the deltoid and teres
    minor),
  • -radial nerve (paralysis of extension of the
    elbow, wrist, and fingers).
  • _at_The disability consists mainly of inability to
    internally rotate the shoulder, elevate the limb,
    and extend the forearm and hand.
  • _at_ Sensory loss most often is apparent only in the
    autonomous zone of the axillary nerve overlying
    the deltoid muscle..

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Injuries of the medial cord
  • produce the motor deficit of
  • - a combined ulnar and median nerve lesion
    (except for the flexor carpi radialis and
    pronator teres) and
  • - extensive sensory loss along the medial aspect
    of the arm and hand

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TREATMENT OF BRACHIAL PLEXUS INJURIES
  • Open injuries exploration and primary repair can
    be attempted. Usually, however, injuries to
    adjacent vessels or to the mediastinal or
    thoracic viscera must be treated first, and thus
    repair of the plexus injury must be delayed.
  • _at_. Leffert emphasized the poor prognosis after
    lower trunk injuries but advised surgical
    exploration for sharp injuries of the upper and
    middle trunks.
  • _at_When an open injury has been caused by a
    low-velocity missile, early exploration is not
    indicated unless injuries to adjacent vessels or
    viscera make immediate treatment necessary.
  • _at_Consequently a period of observation is
    indicated because considerable function may
    return spontaneously
  • _at_Again electromyograms should be obtained 3 to 4
    weeks after injury to aid in determining the
    extent of denervation. Thereafter periodic
    examinations are indicated every 4 to 6 weeks
  • _at_When such examinations during a reasonable
    period of time reveal the absence of recovery or
    that any recovery has halted, exploration and
    neurorrhaphy, grafting, or neurolysis may be
    beneficial

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Surgical Goals
  • Surgical Goals The surgeon should have clear and
    reasonable surgical goals, which are in order of
    priority
  • (1) restoration of elbow flexion.
  • (2) restoration of shoulder abduction.
  • (3) restoration of sensation to the medial
    border of the forearm and hand.
  • _at_After brachial plexus repair and reconstruction,
    12 to 18 months are required to determine the
    extent of neural regeneration.
  • /

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  • . Tendon transfers about the shoulder that may be
    considered include
  • trapezius to deltoid transfer to improve
    abduction
  • -latissimus dorsi transfer to improve external
    rotation.
  • - Shoulder arthrodesis is helpful if active
    scapulothoracic motion is preserved and has been
    shown to improve elbow flexion by preventing
    uncontrolled internal rotation of the shoulder.
    The shoulder should be fused in only 20 to 30
    degrees of abduction because most of these
    patients..

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  • _at_Operations to restore elbow flexion include
    transfers of the latissimus dorsi, the pectoralis
    major, the triceps, the sternocleidomastoid, and
    the flexor-pronator mass).
  • - Marshall et al. reviewed 50 such transfers and
    found the latissimus dorsi and triceps transfers
    to be the most reliable. Restoration of elbow
    flexion is helpful to the patient even if the
    hand is functionless

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  • The long thoracic nerve arises from C5, C6, and
    C7 immediately after they emerge from the
    intervertebral foramina.

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  • . It traverses the neck posterior to the brachial
    plexus, continues distally along the lateral
    aspect of the thoracic wall, and innervates the
    serratus anterior muscle.

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  • injuries may result from
  • -either sharp or blunt trauma
  • - or from traction when the head is forced
    acutely away from the shoulder or when the
    shoulder is depressed, as when carrying heavy
    weights.
  • - Other causes include exposure to cold, viral
    infections, and placing patients in the
    Trendelenburg position with shoulder braces that
    compress the supraclavicular areas.

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  • Examination
  • -When the serratus anterior is paralyzed, the
    patient cannot fully flex the arm above the level
    of the shoulder anteriorly, and active abduction
    also may be restricted.
  • - When the patient attempts to exert forward
    pushing movements with the hands, "winging" of
    the scapula occurs and its vertebral border and
    inferior angle become unduly prominent.

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  • Treatment
  • When the nerve has been stretched rather than
    severed, it usually is enough to immobilize the
    shoulder girdle in extension with the arm against
    the chest.
  • Care should be taken to avoid contractures of the
    shoulder, elbow, and wrist while awaiting
    recovery.
  • -According to Sunderland, the nerve may recover
    after 3 to 12 months. If paralysis persists or if
    the nerve has been severed, the prognosis for
    recovery is poor, and a reconstructive operation
    may be indicated

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  • Arising from the upper trunk of the brachial
    plexus

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  • The only surgically significant nerve. This is
    the first important branch seen when the plexus
    is explored superior to the clavicle. This nerve
    proceeds distally, passing through the scapular
    notch to the posterior aspect of the scapula,
    where it supplies the supraspinatus muscle and,
    after proceeding around the lateral border of the
    scapular spine, supplies the infraspinatus
    muscle..

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  • The nerve may be injured by
  • -penetrating trauma in the posterior triangle of
    the neck
  • - cancer surgery in the same area,
  • - blunt or penetrating trauma in the
    supraclavicular region,
  • - fractures of the superolateral portion of the
    scapula, especially involving the region of the
    suprascapular notch,
  • - anterior dislocations of the shoulder joint
  • - entrapment in the suprascapular notch,
  • - space-occupying lesions such as a ganglion at
    the spinoglenoid notch.

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  • Examination -Pain in the shoulder and weakness of
    the shoulder girdle are common complaints.
  • Atrophy of both the supraspinatus and
    infraspinatus muscles may be seen if the nerve is
    injured at or proximal to the suprascapular
    notch.
  • - Atrophy of only the infraspinatus muscle
    suggests entrapment distal to the supraspinatus
    fossa, as may occur at the spinoglenoid notch.
  • _at_Electrodiagnostic studies are helpful in
    confirming the diagnosis

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  • The axillary nerve, composed of fibers from C5
    and C6, is a branch of the posterior cord of the
    brachial plexus.

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  • emerging inferior to the subscapular and
    thoracodorsal nerves at the level of the humeral
    head it then winds around the neck of the
    humerus

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  • , passing through the quadrangular space to
    supply the deltoid and teres minor muscles, , and
    the skin overlying the deltoid.
  • .

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  • This nerve commonly is injured by
  • -fractures or dislocations about the shoulder,
  • -penetrating wounds, and direct blows.
  • - Rarely, compression of the axillary nerve or
    one of its major branches may occur in the
    quadrilateral space and cause chronic pain and
    paresthesia aggravated by forward flexion or
    abduction and external rotation of the humerus

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  • Examination -Because a lesion of the axillary
    nerve sometimes does not cause anesthesia, the
    diagnosis must rest solely on the presence or
    absence of function in the deltoid muscle.
  • -Usually deltoid paralysis is easily detected by
    the inability to actively abduct the arm.
  • However, it is well documented that full
    abduction of the arm is possible in the presence
    of deltoid paralysis because of the action of the
    supraspinatus and because of rotation of the
    scapula. Therefore it is essential to observe and
    palpate the deltoid muscle for contraction during
    the examination.
  • - Electrical stimulation of the nerve in situ is
    easily accomplished by inserting the needles
    along the posterior border of the deltoid.
  • Treatment
  • -Transfer of the insertion of the trapezius is
    the most satisfactory operation for complete
    paralysis of the deltoid.
  • -Transfer of Deltoid Origin for Partial
    Paralysis.
  • .

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  • The musculocutaneous nerve, composed of fibers
    from C5 and C6, is a branch of the lateral cord
    of the brachial plexus

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  • muscles supplied by the musculocutaneous nerve
    are the biceps the brachialis and the
    coracobrachialis.

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  • It most commonly is injured by
  • -penetrating injuries
  • -occasionally by anterior dislocation of the
    shoulder or fractures of the humeral neck.
  • - When this nerve is injured in the axilla, the
    injury often is in conjunction with injuries to
    other components of the brachial plexus.

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  • Examination -The only muscle supplied by the
    musculocutaneous nerve that can be examined
    accurately is the biceps the brachialis and the
    coracobrachialis are difficult to palpate.
  • -Complete division of the nerve may be overlooked
    because the sensory loss may be ill defined and
    flexion of the elbow by the brachioradialis may
    be strong enough to mask biceps paralysis. In
    these instances it is essential to palpate the
    biceps while testing its function to identify
    specific muscle contractions
  • - Sensory examination is of no great value
    because complete anesthesia is rare. Division of
    this nerve may cause less disability than that of
    any other major nerve in the body, and for this
    reason, especially in older patients, suture
    occasionally is not even indicated.

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  • The radial nerve, a continuation of the posterior
    cord of the brachial plexus, consists of fibers
    from C6, C7, and C8 and sometimes T1..

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  • It is primarily a motor nerve that innervates the
    triceps, the supinators of the forearm, and the
    extensors of the wrist, fingers, and thumb.

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  • This nerve is injured most often by
  • -fractures of the humeral shaft.
  • -Gunshot wounds are the second most common cause
    of radial nerve injury.
  • Other causes include lacerations of the arm and
    proximal forearm,
  • - injection injuries,
  • - and prolonged local pressure.

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Entrapment syndromes of the radial nerve
  • -may develop when the nerve or one of its
    branches is compressed at some point along its
    course.
  • -Compression of the radial nerve in the arm may
    be caused by the fibrous arch of the lateral head
    of the triceps muscle.
  • -The posterior interosseous nerve may be
    compressed by the fibrous arcade of Frohse,
    fracture-dislocations or dislocations of the
    elbow, fractures of the forearm, Volkmann
    ischemic contracture, neoplasms, enlarged bursae,
    aneurysms, or rheumatoid synovitis of the elbow.
  • -According to Spinner, posterior interosseous
    nerve entrapment is of two types. In one type all
    the muscles supplied by the nerve are completely
    paralyzed these include the extensor digitorum
    communis, extensor indicis proprius, extensor
    digiti quinti, extensor carpi ulnaris, abductor
    pollicis longus, and extensor pollicis brevis. In
    the second type only one or a few of these
    muscles are paralyzed.

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radial tunnel syndrome
  • -entrapment of the posterior interosseous nerve
    cause chronic and refractory tennis elbow.
  • -can occur at four potentially compressive
    anatomical structures
    - the origin of the extensor carpi radialis
    brevis,
    -adhesions about the radial head,
    - the
    radial recurrent arterial fan,
    -and the
    arcade of Frohse as the posterior
    interosseous
    nerve enters the supinator.
  • _at_Lotem et al. found that when symptoms and signs
    of radial nerve entrapment in the arm develop
    only after muscular effort, spontaneous recovery
    can be anticipated.
  • _at_However, when entrapment is caused by other
    conditions, especially in the forearm, surgical
    exploration and decompression of the nerve
    usually are beneficial.
  • _at_Compression of the superficial radial nerve
    causes pain in the forearm and sensory impairment
    on the dorsum of the thumb. The nerve may be
    caught in scar tissue at the wrist after surgery
    or trauma.

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  • Examination The following muscles supplied by the
    radial nerve can be tested accurately because
    their bellies or tendons or both can be palpated
  • - the triceps brachii,
    - brachioradialis,
  • - extensors carpi radialis,
    -extensor digitorum
    communis, -extensor
    carpi ulnaris,
  • - abductor pollicis longus, and
  • - extensor pollicis longus.
  • _at_ Injury to this nerve results in inability to
    extend the elbow or supinate the forearm and in a
    typical wristdrop

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  • _at_The triceps is not seriously affected by
    injuries of the nerve at the level of the middle
    of the humerus or distally.
  • _at_ In injuries of the nerve at its bifurcation
    into the deep and superficial branches the
    brachioradialis and the extensor carpi radialis
    longus continue to function thus the arm can be
    supinated and the wrist can be extended..
  • _at_Sensory examination is relatively unimportant,
    even when the nerve is divided in the axilla,
    because usually there is no autonomous zone.

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  • The ulnar nerve is composed of fibers from C8 and
    T1 coming from the medial cord of the brachial
    plexus.

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  • Injuries
  • -When it is injured in the upper arm, other
    nerves or the brachial artery because of their
    proximity also may be injured.
  • -In the middle of the arm the ulnar nerve is
    relatively protected,.
  • -in the distal arm and at the elbow it often is
    injured by dislocations of the elbow and
    supracondylar and condylar fractures.
  • -The nerve is injured most commonly in the distal
    forearm and wrist in these locations it may be
    injured by gunshot wounds, lacerations,
    fractures, or dislocations.
  • - In civilian life lacerations cause most of the
    injuries at the wrist.
  • .

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Tardy ulnar nerve palsy
  • may develop after
  • malunited fractures of the lateral humeral
    condyle in children,
  • - displaced fractures of the medial humeral
    epicondyle,
  • -dislocations of the elbow,
  • - contusions of the nerve.
  • - In malunion of the lateral humeral condyle,
    cubitus valgus develops in this deformity the
    ulnar nerve is gradually stretched and can become
    incompletely paralyzed.
  • -also may develop in patients who have a shallow
    ulnar groove on the posterior aspect of the
    medial humeral epicondyle,.
  • - hypoplasia of the humeral trochlea, .
  • - an inadequate fibrous arch that normally keeps
    the nerve in the groove, resulting in recurrent
    subluxation or dislocation of the nerve..

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cubital tunnel syndrome
  • compression neuropathy of the ulnar nerve about
    the elbow with no antecedent trauma.
  • - As the ulnar nerve enters the cubital tunnel it
    is first bordered by the medial epicondyle
    anteriorly, then by the elbow joint laterally,
    and finally by the two heads of the flexor carpi
    ulnaris medially.
  • -In other areas the nerve may be compressed by
    ligaments, neoplasms, rheumatoid synovitis,
    aneurysms, vascular thromboses, or anomalous
    muscles.

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  • Postoperative ulnar nerve palsy
  • - may result from either direct pressure on the
    ulnar nerve at the elbow or prolonged flexion of
    the elbow during surgery.
  • - The ulnar nerve is especially vulnerable to
    compression when the forearm is allowed to rest
    in pronation.
  • -Alvine and Schurrer suggested that some patients
    may have a preexisting subclinical cubital tunnel
    syndrome that may predispose them to this
    complication.

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  • Examination -Interrupting the ulnar nerve
    proximal to the elbow is followed by paralysis
    of
  • - the flexor carpi ulnaris,
  • -the flexor profundus to the little and ring
    fingers,
  • -the lumbricals of the same fingers,
  • - all of the interossei,
  • - the adductor of the thumb,
  • - and all of the short muscles of the little
    finger. _at_Occasionally when a nerve is completely
    divided at this level, the intrinsic muscles of
    the hand function normally because of anomalous
    innervation of these muscles by the median nerve.
    In these instances the fibers that supply the
    intrinsic muscles may be incorporated in the
    median nerve down to the middle of the forearm
    where they leave the median nerve to join the
    ulnar nerve (Martin- Gruber anastomosis)..

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  • Complete division of the ulnar nerve at the wrist
  • usually causes paralysis of all ulnar-innervated
    intrinsic muscles unless an anatomical variation
    connects the median and ulnar nerves in the palm
    (Riche-Cannieu anastomosis). Usually when the
    nerve is divided at the wrist, only the opponens
    pollicis, the lateral or superficial head of the
    flexor pollicis brevis, and the lateral two
    lumbricals remain functional

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  • _at_In practice only three muscles
  • -the flexor carpi ulnaris,
  • - the abductor digiti quinti, and
  • - the first dorsal interosseuscan be
    tested accurately. The bellies or tendons (or
    both) of these muscles may be easily palpated or
    seen

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  • _at_Atrophy of the muscles supplied by the ulnar
    nerve and clawing of the little and ring fingers
    usually are confirmatory evidence of paralysis of
    the muscles supplied by this nerve.
  • _at_ However, if the nerve has been injured proximal
    to the elbow, clawing of these two fingers may be
    absent because the flexor digitorum profundus to
    the ring and little fingers also is denervated.
  • _at_The sensory examination usually is
    straightforward, although anatomical variations
    may cause confusing sensory findings. One need
    examine only the middle and distal phalanges of
    the little finger, which make up the autonomous
    zone of the ulnar nerve .
  • -Complete anesthesia to pinpricks in this area
    strongly suggests total division of the nerve.

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  • _at_In patients suspected of having cubital tunnel
    syndrome
  • -a positive percussion test over the ulnar nerve
    at the level of the medial epicondyle
  • - and a positive elbow flexion test are strongly
    suggestive of a significant compressive
    neuropathy.
  • -With the elbow fully flexed, the patient will
    complain of numbness and tingling in the small
    and ring fingers, often within 1 minute.
  • - Nerve conduction studies are helpful and should
    demonstrate slowing in the ulnar nerve velocities
    across the elbow, although normal velocities may
    be maintained during early involvement.
    Electromyography may demonstrate fibrillations in
    the ulnar innervated intrinsic muscles.

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  • The treatment for refractory tardy ulnar nerve
    palsy
  • - may require removal of the nerve from its
    groove, neurolysis if necessary, and anterior
    transposition of the nerve to the flexor surface
    of the elbow.
  • -Conservative treatment for this syndrome should
    be attempted before surgical treatment.
  • Patients are instructed to avoid prolonged elbow
    flexion in the workplace and are given elbow
    extension splints for sleeping. The splint should
    not be fitted with the forearm held in pronation
    because this may aggravate the symptoms.
  • - Towels or pillows secured about the elbow may
    adequately limit elbow flexion during sleep.
  • -Conservative treatment usually is attempted for
    a period of 3 months before surgical treatment is
    considered

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  • The surgical treatment of cubital tunnel syndrome
  • -includes simple decompression, medial
    epicondylectomy, and anterior transposition of
    the ulnar nerve either into a subcutaneous,
    intramuscular, or submuscular bed
  • . -For a moderate degree of compression the
    greatest number of excellent results and fewest
    recurrences were obtained with the submuscular
    technique. The anterior intramuscular technique
    yielded the fewest excellent results

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  • The median nerve, formed by the junction of the
    lateral and medial cords of the brachial plexus
    in the axilla, is composed of fibers from C6, C7,
    C8, and T1

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  • Median nerve injuries
  • -often result in painful neuromas and causalgia.
  • - From the sensory standpoint they are more
    disabling than injuries of the ulnar nerve
    because they involve the digits used in fine
    volitional activity.
  • -Median nerve injuries often are caused by
    lacerations, usually in the forearm or wrist.
  • Sunderland pointed out that in
  • - the upper arm the nerve can be injured by
    relatively superficial lacerations, excessively
    tight tourniquets, and humeral fractures, and
    when it is injured near the axilla, the ulnar and
    musculocutaneous nerves and the brachial artery
    also are commonly injured.
  • - In the arm the median nerve may be
    compressed by the ligament of Struthers.
  • -At the elbow the nerve may be injured in
    supracondylar fractures and posterior
    dislocations of the elbow.

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  • _at_Median nerve deficits, as seen in the pronator
    syndrome, may result from compression of the
    nerve at the pronator teres, the lacertus
    fibrosus, or the fibrous flexor digitorum
    sublimis arch or from anomalies including a
    hypertrophic pronator teres, a high origin of the
    pronator teres, fibrous bands within the pronator
    teres, the median nerve passing posterior to both
    heads of the pronator teres, or an accessory
    tendinous arch of the flexor carpi radialis
    arising from the ulna..

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  • _at_The anterior interosseous nerve may be injured
    in fractures and lacerations or may be compressed
    or entrapped by any of the following the
    tendinous origins of the flexor digitorum
    sublimis or the pronator teres, variant muscles
    such as the palmaris profundus and flexor carpi
    radialis brevis, tendons from the flexor
    digitorum sublimis to the flexor pollicis longus,
    an accessory head of the flexor pollicis longus
    (Gantzer muscles), an aberrant radial artery,
    thrombosis of the ulnar collateral vessels,
    enlargement of the bicipital bursa, or a Volkmann
    ischemic contracture.
  • _at_At the wrist the median nerve may be injured by
    fractures of the distal radius and by fractures
    and dislocations of the carpal bones.

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  • Examination The muscles of the forearm and hand
    supplied by the median nerve that can be tested
    with relative accuracy are
  • the pronator teres,
  • - flexor carpi radialis,
  • - flexor digitorum profundus (index),
  • - flexor pollicis longus,
  • - flexor digitorum sublimis,
  • -and abductor pollicis brevis.
  • _at_ Substitution movements caused by action of
    intact muscles may cause confusion during the
    examination.

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  • _at_ Usually if the forearm can be actively
    maintained in pronation against resistance, the
    pronator teres is intact.
  • _at_ If the wrist can be actively maintained in
    flexion and a contracting flexor carpi radialis
    is palpated, this muscle is intact.
  • _at_Similarly if the interphalangeal joint of the
    thumb can be maintained in flexion against
    resistance with the wrist in the neutral position
    and the thumb adducted, the flexor pollicis
    longus is functioning.
  • _at_ The flexor digitorum sublimis to each finger is
    examined separately while the remaining fingers
    are held in full passive extension.
  • _at_ Although opposition of the thumb can be
    difficult to confirm, if the thumb can be
    actively maintained in palmar abduction and a
    contracting abductor pollicis brevis is palpated,
    this muscle is functioning.
  • _at_The lumbricals cannot be discretely tested
    because they cannot be palpated and because their
    function may be confused with that of the
    interosseus muscles..

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  • According to Spinner, the anterior interosseous
    syndrome
  • -can cause varying signs and symptoms.
  • -Typically, the patient has pain in the proximal
    forearm lasting for several hours and is found to
    have weakness or paralysis of the flexor pollicis
    longus, the flexor digitorum profundus to the
    index and long fingers, and the pronator
    quadratus.
  • -When the patient attempts to pinch, active
    flexion of the distal phalanx of the index finger
    is impossible.

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  • Treatment
  • In patients who have symptoms of carpal tunnel
    syndrome and pronator teres syndrome,
  • particular attention should be paid to the nerve
    conduction studies during preoperative planning.
  • - If the nerve conduction test is positive for
    carpal tunnel syndrome, we agree in recommending
    carpal tunnel release in anticipation that the
    proximal symptoms will resolve.
  • -If the nerve conduction test is negative for
    carpal tunnel syndrome, we recommend proximal
    median nerve exploration and proximal
    decompression as the initial procedure of choice.
  • _at_. For the anterior interosseous syndrome. If the
    onset of paralysis has been spontaneous, the
    initial treatment is nonoperative. Surgical
    exploration is indicated in the absence of
    clinical or electromyographic improvement after
    12 weeks .

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PERIPHERAL NERVE INJURYIES
157
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    department of orthopedics in Damascus hospital,
    under the supervision of Dr. Bashar Mirali.
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Dr. Muayad Kadhim
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