Disorders of the Peripheral Nervous System Peripheral Nerve

Disorders of the Peripheral Nervous System

Peripheral Nerve Disorders n The spectrum of peripheral nerve disorders includes n n n Mononeuropathies (entrapment, trauma, etc) Mononeuritis multiplex (DM, vasculitis) Plexopathies (immune, neoplastic) Radiculopathies (discs, immune) Peripheral Neuropathies

Spinal Nerves Connective tissue coverings of spinal nerves: n Epineurium, perineurium and endoneurium: n Fascicles

Distribution of Spinal Nerves n n Spinal nerves branch and their braches are called rami: Posterior (dorsal) ramus Anterior (ventral) ramus Plexuses: a network of axons Anterior rami except T 1 -T 11 form plexuses. Copyright 2009, John Wiley & Sons, Inc.

Plexuses n n Ventral rami of spinal nerves join together & form a network- called plexus. 31 pairs; mixed nerves. n Cervical (C 1 -C 8), thoracic (T 1 -T 12), lumbar (L 1 -L 5), sacral (S 1 -S 5) and coccygeal There are 4 voluntary plexuses n n Cervical plexus: C 1 - C 4 Brachial plexus: C 4 -T 1 Lumbar plexus: L 1 - L 4 Sacral plexus: L 4 - S 5

Cervical Plexus n n Formed by the anterior rami of C 1 -C 5. Phrenic nerves- important nerves from the cervical plexuses.

Brachial plexus n n n Formed by the anterior rami of C 5 -C 8 & T 1. Supplies the shoulders and upper limbs. Roots → trunks → divisions → cords → nerves. Copyright 2009, John Wiley & Sons, Inc.

Brachial plexus Important nerves that arise from the brachial plexuses are n n n Axillary nerve Musculocutaneous nerve Radial nerve Median nerve Ulnar nerve Copyright 2009, John Wiley & Sons, Inc.

Brachial Plexus • Posterior Compartment—posterior cord • Anterior compartment—medial, lateral cords • Name of cord is relative to axillary artery

Brachial plexus organizes nerves out to muscles of upper limb n One posterior nerve n n Radial n. Three anterior nerves n n n Musculocutaneous n. Median n. Ulnar n.

Injuries to the Brachial Plexus n Upper primary trunk C 5, C 6 n n n Middle primary trunk (C 7) n n Ressembles radial nerve palsy, excepting the long supinator, which receives innervation from C 6 Lower primary trunk (C 8, D 1) n n n shoulder movement Flexion of the elbow Clinically resembles a median and cubital palsy Claude Bernard-Horner syndrome Complete

Injuries to the Brachial Plexus n n Erb-Duchenne palsy (waiter’s tip)- loss of sensation along the lateral side of the arm. Wrist drop- inability to extend the wrist and fingers. Copyright 2009, John Wiley & Sons, Inc.

n n n Median nerve palsy- numbness, tingling and pain in the palm and fingers. Ulnar nerve palsy- inability to abduct or adduct fingers Winged scapula- the arm cannot be abducted beyond the horizontal position.

Cutaneous Innvervation n n Test ulnar nerve at ulnar 5 th digit Test median nerve at tip of index finger

Cutaneous Innvervation n Test radial nerve at 1 st dorsal web space

Median nerve n Anatomy n n n n Derived from C 5 -T 1 Runs medial to axillary and brachial arteries Passes deep to bicipital aponeurosis and flexor muscle mass 80% passes between two heads of pronator teres Continues between FDS and FDP Emerges in forearm radial to superficialis tendons Passes under transverse carpal ligament

Median nerve n Superficial trunk supplies: Pronator teres n Flexor carpi radialis n PL n FDS index Deep trunk supplies (anterior interosseus nerve): n FDP to index and middle n FPL n Pronator quadratus n Sensation to radial carpal joint n n n 5 -6 cm proximal to anterior wrist crease n Palmar cutaneous branch n n n Innervates skin at base of palm Does not pass through carpal tunnel Beneath transverse carpal ligament n Recurrent motor branch n n Supplies thenar muscles, 1 st and 2 nd lumbricals Three proper digital nerves and two common digital nerves

n Axilla n n n n Supracondylar spurs & ligaments (Ligament of Struthers) Fracture n Humerus supracondylar: Children; Anterior interosseus distribution n n Elbow dislocation Injection injury Pronator teres syndrome (Pronator syndrome) Anterior interosseus syndrome Median neuropathy in forearm n Elbow n n Stab wounds: ± Brachial artery injury Sleep palsy: Near pectoralis major tendon Tourniquets Fracture: Humerus shaft Medial epicondylar n Upper arm n n Crutch compression Missle injury Anterior shoulder dislocation Lipoma or other neoplasm n Bleeding into flexor compartment Hemophiliacs; Anticoagulants; Brachial artery puncture A-V fistula for dialysis: Pain common; Onset days to weeks after surgery Carpal tunnel syndrome

Clinical testing of median nerve function

Median nerve n Anatomy of the carpal tunnel n Boundaries n n Roof (Volar): n Transverse carpal ligament Floor (Dorsal): n Volar ligaments and carpal bones Lateral wall (Radial): n Scaphoid tuberosity and trapezial crest Medial wall (Ulnar): n Pisiform and hook of the hamate

Median nerve n Carpal Tunnel Syndrome n Pain and paresthesias palmar radial hand n n n Worse at night Driving Exacerbated with repetitive forceful use Sensation of swelling Normal sensation in area of palmar cutaneous branch of median nerve Motor function n Late sign n Clumsiness n Thenar atrophy n Weak thumb abduction

Median nerve - Carpal Tunnel Syndrome n Provocative tests n Tinel’s sign n Compression test Phalen’s test n n n Production of paresthesias with percussion at the carpal tunnel entrance Symptoms with wrist flexion Reverse Phalen’s test Tourniquet test n Above systolic pressure n Sensory testing n early n n n Semmes-Weinstein monofilament Vibrometry Late n Two point discrimination

Median nerve - Carpal Tunnel Syndrome n Electrodiagnostic studies n Sensory and motor n n Diagnostic criteria n n False negative as high as 10 -20% Distal motor latency >4. 5 ms Distal sensory latency >3. 5 ms Asymmetry between hands n Motor > 1 ms, Sensory > 0. 5 Comparison to ulnar nerve n >0. 8 ms difference

Median nerve - Carpal Tunnel Syndrome n Treatment n Conservative n n Attempt in mild disease with intermittent paresthesias Splinting to prevent wrist flexion Systemic anti-inflammatory medications Steroid injection n n Controversial Transient relief in 80% 22% symptom free after 12 months Ergonomic adjustments Failure to respond n Surgical decompression

Median nerve - Carpal Tunnel Syndrome n Surgical technique n Open n n n Variety of skin incisions Incision between 3 rd and 4 th metacarpals Caution re: palmar cutaneous branch and recurrent motor branch Through palmar fascia Transection of transverse carpal ligament Endoscopic n Controversial

Median nerve - Carpal Tunnel Syndrome n Outcomes n n n 80% patients experience excellent or good results 10 -15% fair results 5 -10% poor results Pain relief IMMEDIATE Maximum recovery 6 -12 months after surgery Numbness n Weakness n

Ulnar nerve

Ulnar nerve n Anatomy n Continuation of medial cord of brachial plexus n n Axilla n n n C 8 and T 1 Lies deep to pectoralis minor Between axillary artery and vein Descends in arm medial to brachial artery between coracobrachialis and triceps

Ulnar nerve n Anatomy n n n Passes through medial intermuscular septum Lies in groove at medial head of triceps Fascial arch n Arcade of Struthers n n n Lies across nerve 70% patients 7 -10 cm proximal to medial epicondyle Passes posterior to medial epicondyle Cubital tunnel Passes between humeral and ulnar heads of FCU

Ulnar nerve n Anatomy n n n Small branches to elbow joint Innervates proximal FCU Dorsal sensory branch n n n 4 -6 cm proximal to wrist Outside of Guyon’s canal Nerve of Henle n Ulnar artery

Ulnar nerve n Anatomy n Guyon’s canal n n Triangular Roof n n Medial n n Superficial volar carpal ligament Pisiform Lateral n Hook of the hamate

Ulnar nerve n Anatomy n Hand n Deep (motor) branch n n n n Superficial (sensory) branch n n n Hypothenar eminence Midpalm Interossei Two ulnar lumbricals Adductor pollicis Deep head of FPB Radial carpal joint Ulnar aspect hand Palmar cutaneous branch of ulnar nerve absent when nerve of Henle present

n Elbow n Ulnar nerve lesions – possible causes n n n Axilla & Upper arm: Uncommon n Compression, external: Sleep; Crutches; Tourniquets Compression at Arcade of Struthers: Fascial plane in medial triceps muscle Mass: Aneurysm of brachioaxillary artery; Schwannoma n n Bony deformities - old fractures, arthritis, shallow ulnar groove Valgus deformity - congenital or 2 o to lateral epicondyle fracture Paget's disease Trauma: Acute, Chronic Anesthesia (pressure with elbow flexed) Soft tissue masses: In condylar groove or cubital tunnel Anconeus Epitrochlearis (anomalous muscle) Ulnar nerve prolapse n n n Leprosy Idiopathic Forearm n n Nerve rolls out of ulnar groove Predisposes to repetitive trauma Trauma Hematoma in forearm muscles: Hemophiliacs Dialysis shunts: Ischemia Wrist & Hand

Ulnar nerve - Ulnar tunnel syndrome n n Rare Entrapment of ulnar nerve in Guyon’s canal n n Numbness in ulnar two digits Sensation in dorsal sensory branch spared Pure motor, sensory or mixed Etiologic factors n n Use of “heel of hand” Space occupying lesions n Ganglia, bony, pseudoaneurysms n Presentation: n Pain in wrist n n Numbness Tingling Burning Provocative tests n Sustained hyperextension or flexion of wrist

Ulnar nerve - Ulnar tunnel syndrome n Physical Intrinsic weakness n Sensory testing n Fractures of hook of hamate n n Electrodiagnostic studies n Establish diagnosis

Ulnar nerve - Entrapment n Ulnar tunnel syndrome n Treatment n Conservative n n n Splint NSAIDs Surgical n n n Refractory to conservative care Documented anatomic lesions Release Guyon’s canal

Ulnar nerve - Entrapment n Cubital tunnel syndrome n n “Tardy ulnar palsy” Presentation: n n n 2 nd most common site Repetitive elbow flexion-extension Elbow pain Sensory disturbance in ulnar nerve distribution Weakness of ulnar intrinsics n n 1 st dorsal interosseus Adductor pollicis Key pinch strength Interosseus wasting

Ulnar nerve - Entrapment n Cubital tunnel syndrome n Physical Tinel’s at medial epicondyle n Subluxation of nerve n Snapping of triceps n Decreased pinch strength n Intrinsic atrophy n Weakness in small FDP and FCU n “wish sign” n n Crossing middle over index

Ulnar nerve - Entrapment n Cubital tunnel syndrome n Wartenberg’s sign Abducted habitus of small finger n Weak adduction by third palmar interosseus n n Froment’s sign Compensatory hyperflexion of thumb IP n Hyperextension thumb MP secondary to loss of adductor pollicis and FPB (deep head) n n Claw hand n MP hyperextension

Ulnar nerve - Entrapment n Cubital tunnel syndrome n Provocative tests n Elbow flexion test n n Increase in cubital tunnel pressure with flexion Aggravates symptoms

Ulnar nerve - Entrapment n Cubital tunnel syndrome n Electrodiagnostic studies Can confirm cubital tunnel n Conduction velocities useful n n Vary with elbow position Three segments: n Above elbow n Across elbow n Forearm Dip in CV across elbow with forearm recovery significant (>20%)

Ulnar nerve - Entrapment n Cubital tunnel syndrome n Treatment n Conservative management n n Splint NSAIDs Avoidance of elbow trauma Inappropriate to attempt if: n MUSCLE ATROPHY, WEAKNESS OR PERMANENT SENSORY CHANGES

Ulnar nerve - Entrapment n Cubital tunnel syndrome n Treatment n Surgical n Four approaches: 1. 2. 3. 4. n Simple decompression – fascial covering split Medial humeral epicondylectomy Anterior subcutaneous transposition Anterior submuscular transposition Latter two approaches most commonly used

Ulnar nerve - Entrapment n Cubital tunnel syndrome n Treatment n Surgical n Keypoints: n Protect medial antebrachial cutaneous nerve of forearm and its branches n Release Arcade of Struthers and Osborne’s ligament n Split FCU but protect motor nerve n Excise band between medial epicondyle and shaft of humerus n Hemostasis

Ulnar nerve - Entrapment n Cubital tunnel syndrome n Treatment n Surgical n Technique n Incision midway between olecranon and medial epicondyle n 8 cm proximal and 6 cm distal n Identification proximally and distal dissection n Cubital tunnel release n Protect articular sensory and FCU branches n Release of intermuscular septum

Ulnar nerve - Entrapment n Cubital tunnel syndrome n Outcomes n Minimal compression n n Excellent results in 90% Moderate compression n Excellent in 50%

Radial nerve n Anatomy n n n Arises from C 5 -T 1 (posterior cord) Descends around humerus in spiral radial groove beneath lateral head of triceps Emerges through lateral intermuscular septum n 10 -15 cm proximal to lateral epicondyle

Radial nerve n Anatomy n Travels: n Medial n n Lateral n n between brachialis and biceps tendon brachioradialis and ECRL, ECRB Supplies: n brachioradialis, ECRL, ECRB

Radial nerve n Anatomy n Divides at elbow into: n Superficial sensory division n Travels under brachioradialis Emerges at midforearm subcutaneously Deep motor branch n n n Posterior interosseus nerve Passes deep under fibrous proximal margin of supinator n Arcade of Froshe Innervation to extensors, sensory to wrist

Nervul radial • • • Posterior cord of bp motor: Extension and supination (posteroextern muscles in forearm and posterior muscler of the arm) Sensory: middle 1/3 of posterior forearm, lateral part of the dorsal hand first 3 fingers

Nervul radial

Nervul radial n Leziunea proximala completa duce la imposibilitatea n n n extensiei cotului (triceps), flexiei cotului cu antebratul in pozitie intermediara intre pronatie si supinatie (lungul supinator), supinatia antebratului, extensia degetelor si pumnului, extensia si abductia policelui in planul mainii n Daca leziunea afecteaza doar nervul interosos posterior, sunt lezate doar extensia degetelor (sindrom canalar, prin compresiunea nervului sub arcada fibroasa dintre cele doua capete ale scurtului supinator) n Amiotrofii Pierderea reflexului tricipital si stiloradial, disparitia corzii lungului supinator, atitudine in gat de lebada (membrul superior cu antebratul in semiflexie si pronatie, cu mana cazuta in hiperflexie si degete semiflectate) Nu sunt evidente tendoanele pe fata posterioara a maini, imposibilitatea “salutului militar” sau “juramantului”, semnul vipustii (imposibilitatea de a aseza marginea cubitala a mainii pe cusatura pantalonului), n n

Humerus Fractures

Radial nerve - Entrapment n Radial tunnel syndrome n Presentation Pain localized to tender extensor muscle mass n Radiates to wrist and dorsum hand n Worse with use of arm n Heaviness and fatigability n Often misdiagnosed as lateral epicondylitis n Involves both divisions of radial nerve n n Weakness with digital extension

Radial nerve - Entrapment n Radial tunnel syndrome n Physical examination n Tenderness over “mobile wad” n n Brachioradialis and radial wrist extensors Provocative tests Firm pressure over radial nerve at supinator muscle n Third finger test n n n Increased pain with resisted extension of long finger with elbow extended Resisted supination

Radial nerve - Entrapment n Radial tunnel syndrome n Electrodiagnostic studies n Usually normal

Radial nerve - Entrapment n Radial tunnel syndrome n Treatment n Conservative n n Rest from repetitive motions Splints Concurrent lateral epicondylitis n Steroid injection Spontaneous remission can occur in mild cases

Radial nerve - Entrapment n Radial tunnel syndrome n Treatment n Surgical n n Indicated in failed conservative treatment CRITICAL release of: n Arcade of Froshe n Vascular leash of Henry

Radial nerve - Entrapment n Posterior interosseus compression n Presentation n Aching pain n Similar to radial tunnel syndrome Weakness of digital extensors n No sensory disturbance n n Physical n Weakness of ECU, thumb and finger extensor, APL

Radial nerve - Entrapment n Posterior interosseus compression n Electrodiagnostic studies n Can be confirmatory

Radial nerve - Entrapment n Posterior interosseus compression n Treatment n Conservative n n n Splinting Systemic steroids (short course) Surgical n Indicated if no recovery after 3 months of conservative treatment

Radial nerve - Entrapment n Wartenberg’s syndrome n Presentation n Involvement of superficial sensory branch of radial nerve n n Dorsoradial aspect of the hand Emerges between brachioradialis and ECRL n Compressed by scissor like action with pronation Complaints of pain and paresthesias with forearm pronated n Differentiate n n de. Quervain’s tenosynovitis

Radial nerve - Entrapment n Wartenberg’s syndrome n Provocative tests n Forceful pronation of forearm against resistance n n n 30 -60 seconds Tightens brachioradialis across the nerve Diagnosis Electrodiagnostic studies n Local anaesthetic block n

Radial nerve - Entrapment n Wartenberg’s syndrome n Treatment n Conservative n n n Splinting NSAIDs Local steroid injection Changes in work activities Surgical n n Failed conservative treatment Release fascia of brachioradialis and ECRL

Lumbar Plexus n n n Formed by the anterior rami of L 1 -L 4. Supplies the anterolateral abdominal wall, external genitals, and part of the lower limbs. Femoral nerves, obturator nerves. Copyright 2009, John Wiley & Sons, Inc.

Sacral Plexus n n n Formed by the anterior rami of L 4 -L 5 and S 1 -S 4. Supplies the buttocks, perineum, and lower limbs. Gives rise to the largest nerve in the body- the sciatic nerve. Copyright 2009, John Wiley & Sons, Inc.

Distribution of Nerves from the Lumbar and Sacral Plexuses Copyright 2009, John Wiley & Sons, Inc.

Coccygeal Plexus n n Formed by the anterior rami of S 4 -S 5 and the coccygeal nerves. Supplies a small area of skin in the coccygeal region. Copyright 2009, John Wiley & Sons, Inc.

Dermatome n Dermatome is the area of the skin that provides sensory input to the CNS via one pair of spinal nerves or the trigeminal nerve. Copyright 2009, John Wiley & Sons, Inc.