Disorders of the Peripheral
Nervous System
Peripheral Nerve Disorders

The spectrum of peripheral nerve
disorders includes
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Mononeuropathies (entrapment, trauma, etc)
Mononeuritis multiplex (DM, vasculitis)
Plexopathies (immune, neoplastic)
Radiculopathies (discs, immune)
Peripheral Neuropathies
Spinal Nerves
Connective tissue coverings of spinal nerves:
 Epineurium, perineurium and endoneurium:
 Fascicles
Distribution of Spinal Nerves


Spinal nerves branch and their braches
are called rami:
Posterior (dorsal) ramus
Anterior (ventral) ramus
Plexuses: a network of axons
Anterior rami except T1-T11 form
plexuses.
Copyright 2009, John Wiley & Sons,
Inc.
Plexuses
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Ventral rami of spinal nerves join together &
form a network- called plexus.
31 pairs; mixed nerves.

Cervical (C1-C8), thoracic (T1-T12), lumbar (L1-L5),
sacral (S1-S5) and coccygeal
There are 4 voluntary plexuses

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Cervical plexus: C1- C4
Brachial plexus: C4-T1
Lumbar plexus: L1- L4
Sacral plexus: L4- S5
Cervical Plexus


Formed by the anterior rami of C1-C5.
Phrenic nerves- important nerves from the
cervical plexuses.
Brachial plexus



Formed by the
anterior rami of C5C8 & T1.
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
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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

One posterior nerve


Radial n.
Three anterior nerves

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Musculocutaneous n.
Median n.
Ulnar n.
Injuries to the Brachial Plexus

Upper primary trunk C5, C6
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Middle primary trunk (C7)

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Ressembles radial nerve palsy, excepting the long supinator,
which receives innervation from C6
Lower primary trunk (C8, D1)

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shoulder movement
Flexion of the elbow
Clinically resembles a median and cubital palsy
Claude Bernard-Horner syndrome
Complete
Injuries to the Brachial Plexus


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.

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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


Test ulnar nerve at
ulnar 5th digit
Test median nerve
at tip of index finger
Cutaneous Innvervation

Test radial
nerve at 1st
dorsal web
space
Median nerve

Anatomy
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Derived from C5-T1
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

Superficial trunk supplies:
Pronator teres
 Flexor carpi radialis
 PL
 FDS index
Deep trunk supplies (anterior
interosseus nerve):
 FDP to index and middle
 FPL
 Pronator quadratus
 Sensation to radial carpal joint


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5-6 cm proximal to anterior wrist crease

Palmar cutaneous branch
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Innervates skin at base of palm
Does not pass through carpal tunnel
Beneath transverse carpal ligament

Recurrent motor branch
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Supplies thenar muscles, 1st and 2nd
lumbricals
Three proper digital nerves and two
common digital nerves

Axilla
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Supracondylar spurs & ligaments
(Ligament of Struthers)
Fracture

Humerus supracondylar: Children;
Anterior interosseus distribution


Elbow dislocation
Injection injury
Pronator teres syndrome
(Pronator syndrome)
Anterior interosseus syndrome
Median neuropathy in forearm

Elbow


Stab wounds: ± Brachial artery injury
Sleep palsy: Near pectoralis major
tendon
Tourniquets
Fracture: Humerus shaft
Medial epicondylar

Upper arm

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Crutch compression
Missle injury
Anterior shoulder dislocation
Lipoma or other neoplasm

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

Anatomy of the carpal
tunnel

Boundaries

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Roof (Volar):
 Transverse carpal
ligament
Floor (Dorsal):
 Volar ligaments and
carpal bones
Lateral wall (Radial):
 Scaphoid tuberosity
and trapezial crest
Medial wall (Ulnar):
 Pisiform and hook of
the hamate
Median nerve

Carpal Tunnel Syndrome

Pain and paresthesias palmar
radial hand
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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

Late sign
 Clumsiness
 Thenar atrophy
 Weak thumb abduction
Median nerve - Carpal Tunnel
Syndrome

Provocative tests

Tinel’s sign

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Compression test
Phalen’s test

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Production of
paresthesias with
percussion at the carpal
tunnel entrance
Symptoms with wrist
flexion
Reverse Phalen’s test
Tourniquet test

Above systolic pressure

Sensory testing

early

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
Semmes-Weinstein
monofilament
Vibrometry
Late

Two point
discrimination
Median nerve - Carpal Tunnel
Syndrome

Electrodiagnostic studies

Sensory and motor

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Diagnostic criteria
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False negative as high as 10-20%
Distal motor latency >4.5 ms
Distal sensory latency >3.5 ms
Asymmetry between hands
 Motor > 1 ms, Sensory > 0.5
Comparison to ulnar nerve

>0.8 ms difference
Median nerve - Carpal Tunnel
Syndrome

Treatment

Conservative
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Attempt in mild disease with intermittent paresthesias
Splinting to prevent wrist flexion
Systemic anti-inflammatory medications
Steroid injection
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Controversial
Transient relief in 80%
22% symptom free after 12 months
Ergonomic adjustments
Failure to respond

Surgical decompression
Median nerve - Carpal Tunnel
Syndrome

Surgical technique
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Open
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Variety of skin incisions
Incision between 3rd and 4th
metacarpals
Caution re: palmar cutaneous branch
and recurrent motor branch
Through palmar fascia
Transection of transverse carpal
ligament
Endoscopic

Controversial
Median nerve - Carpal
Tunnel Syndrome

Outcomes
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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
 Weakness

Ulnar nerve
Ulnar nerve

Anatomy

Continuation of medial
cord of brachial plexus


Axilla
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
C8 and T1
Lies deep to pectoralis
minor
Between axillary artery
and vein
Descends in arm
medial to brachial artery
between
coracobrachialis and
triceps
Ulnar nerve

Anatomy

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Passes through medial intermuscular
septum
Lies in groove at medial head of triceps
Fascial arch

Arcade of Struthers
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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

Anatomy
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Small branches to
elbow joint
Innervates proximal
FCU
Dorsal sensory
branch
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4-6 cm proximal to
wrist
Outside of Guyon’s
canal
Nerve of Henle

Ulnar artery
Ulnar nerve

Anatomy

Guyon’s canal

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Triangular
Roof
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Medial
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Superficial volar
carpal ligament
Pisiform
Lateral

Hook of the
hamate
Ulnar nerve
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Anatomy

Hand

Deep (motor) branch
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Superficial (sensory) branch
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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

Elbow

Ulnar nerve lesions –
possible causes
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Axilla & Upper arm:
Uncommon
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Compression, external: Sleep;
Crutches; Tourniquets
Compression at Arcade of
Struthers: Fascial plane in
medial triceps muscle
Mass: Aneurysm of
brachioaxillary artery;
Schwannoma


Bony deformities - old fractures,
arthritis, shallow ulnar groove
Valgus deformity - congenital or
2o 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

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Leprosy
Idiopathic
Forearm
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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
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Rare
Entrapment of ulnar
nerve in Guyon’s canal
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Numbness in ulnar two
digits
Sensation in dorsal
sensory branch spared
Pure motor, sensory or
mixed
Etiologic factors
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Use of “heel of hand”
Space occupying lesions

Ganglia, bony,
pseudoaneurysms

Presentation:

Pain in wrist
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Numbness
Tingling
Burning
Provocative tests

Sustained
hyperextension or flexion
of wrist
Ulnar nerve - Ulnar tunnel
syndrome

Physical
Intrinsic
weakness
 Sensory testing
 Fractures of hook
of hamate


Electrodiagnostic
studies

Establish
diagnosis
Ulnar nerve - Entrapment

Ulnar tunnel syndrome
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Treatment
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Conservative
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Splint
NSAIDs
Surgical
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Refractory to conservative care
Documented anatomic lesions
Release Guyon’s canal
Ulnar nerve - Entrapment
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Cubital tunnel syndrome
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“Tardy ulnar palsy”
Presentation:
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2nd most common site
Repetitive elbow flexion-extension
Elbow pain
Sensory disturbance in ulnar nerve distribution
Weakness of ulnar intrinsics
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1st dorsal interosseus
Adductor pollicis
Key pinch strength
Interosseus wasting
Ulnar nerve - Entrapment

Cubital tunnel syndrome

Physical
Tinel’s at medial epicondyle
 Subluxation of nerve
 Snapping of triceps
 Decreased pinch strength
 Intrinsic atrophy
 Weakness in small FDP and FCU
 “wish sign”
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
Crossing middle over index
Ulnar nerve - Entrapment

Cubital tunnel syndrome

Wartenberg’s sign
Abducted habitus of small finger
 Weak adduction by third palmar interosseus


Froment’s sign
Compensatory hyperflexion of thumb IP
 Hyperextension thumb MP secondary to loss
of adductor pollicis and FPB (deep head)


Claw hand

MP hyperextension
Ulnar nerve - Entrapment

Cubital tunnel syndrome

Provocative tests

Elbow flexion test


Increase in cubital tunnel pressure with flexion
Aggravates symptoms
Ulnar nerve - Entrapment

Cubital tunnel syndrome

Electrodiagnostic studies
Can confirm cubital tunnel
 Conduction velocities useful

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Vary with elbow position
Three segments:
 Above elbow
 Across elbow
 Forearm
Dip in CV across elbow with forearm recovery
significant (>20%)
Ulnar nerve - Entrapment

Cubital tunnel syndrome

Treatment

Conservative management




Splint
NSAIDs
Avoidance of elbow trauma
Inappropriate to attempt if:
 MUSCLE ATROPHY, WEAKNESS OR
PERMANENT SENSORY CHANGES
Ulnar nerve - Entrapment

Cubital tunnel syndrome

Treatment

Surgical

Four approaches:
1.
2.
3.
4.

Simple decompression – fascial covering
split
Medial humeral epicondylectomy
Anterior subcutaneous transposition
Anterior submuscular transposition
Latter two approaches most commonly used
Ulnar nerve - Entrapment

Cubital tunnel syndrome

Treatment

Surgical

Keypoints:
 Protect medial antebrachial cutaneous nerve
of forearm and its branches
 Release Arcade of Struthers and Osborne’s
ligament
 Split FCU but protect motor nerve
 Excise band between medial epicondyle and
shaft of humerus
 Hemostasis
Ulnar nerve - Entrapment

Cubital tunnel syndrome

Treatment

Surgical

Technique
 Incision midway between olecranon and
medial epicondyle
 8 cm proximal and 6 cm distal
 Identification proximally and distal dissection
 Cubital tunnel release
 Protect articular sensory and FCU branches
 Release of intermuscular septum
Ulnar nerve - Entrapment

Cubital tunnel syndrome

Outcomes

Minimal compression


Excellent results in 90%
Moderate compression

Excellent in 50%
Radial nerve

Anatomy



Arises from C5-T1
(posterior cord)
Descends around humerus
in spiral radial groove
beneath lateral head of
triceps
Emerges through lateral
intermuscular septum

10-15 cm proximal to lateral
epicondyle
Radial nerve

Anatomy

Travels:

Medial


Lateral


between brachialis
and biceps tendon
brachioradialis and
ECRL, ECRB
Supplies:

brachioradialis, ECRL,
ECRB
Radial nerve

Anatomy

Divides at elbow into:

Superficial sensory division



Travels under brachioradialis
Emerges at midforearm subcutaneously
Deep motor branch



Posterior interosseus nerve
Passes deep under fibrous proximal margin of
supinator
 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 and first 3 fingers
Nervul radial
Nervul radial

Leziunea proximala completa duce la imposibilitatea





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

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)

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),


Humerus Fractures
Radial nerve - Entrapment

Radial tunnel syndrome

Presentation
Pain localized to tender extensor muscle
mass
 Radiates to wrist and dorsum hand
 Worse with use of arm
 Heaviness and fatigability
 Often misdiagnosed as lateral epicondylitis
 Involves both divisions of radial nerve


Weakness with digital extension
Radial nerve - Entrapment

Radial tunnel syndrome

Physical examination

Tenderness over “mobile wad”


Brachioradialis and radial wrist extensors
Provocative tests
Firm pressure over radial nerve at supinator
muscle
 Third finger test



Increased pain with resisted extension of long
finger with elbow extended
Resisted supination
Radial nerve - Entrapment

Radial tunnel syndrome

Electrodiagnostic studies

Usually normal
Radial nerve - Entrapment

Radial tunnel syndrome

Treatment

Conservative




Rest from repetitive motions
Splints
Concurrent lateral epicondylitis
 Steroid injection
Spontaneous remission can occur in mild cases
Radial nerve - Entrapment

Radial tunnel syndrome

Treatment

Surgical


Indicated in failed conservative treatment
CRITICAL release of:
 Arcade of Froshe
 Vascular leash of Henry
Radial nerve - Entrapment

Posterior interosseus compression

Presentation

Aching pain

Similar to radial tunnel syndrome
Weakness of digital extensors
 No sensory disturbance


Physical

Weakness of ECU, thumb and finger
extensor, APL
Radial nerve - Entrapment

Posterior interosseus compression

Electrodiagnostic studies

Can be confirmatory
Radial nerve - Entrapment

Posterior interosseus compression

Treatment

Conservative



Splinting
Systemic steroids (short course)
Surgical

Indicated if no recovery after 3 months of
conservative treatment
Radial nerve - Entrapment

Wartenberg’s syndrome

Presentation

Involvement of superficial sensory branch of
radial nerve


Dorsoradial aspect of the hand
Emerges between brachioradialis and ECRL

Compressed by scissor like action with pronation
Complaints of pain and paresthesias with
forearm pronated
 Differentiate


deQuervain’s tenosynovitis
Radial nerve - Entrapment

Wartenberg’s syndrome

Provocative tests

Forceful pronation of forearm against
resistance



30-60 seconds
Tightens brachioradialis across the nerve
Diagnosis
Electrodiagnostic studies
 Local anaesthetic block

Radial nerve - Entrapment

Wartenberg’s syndrome

Treatment

Conservative





Splinting
NSAIDs
Local steroid injection
Changes in work activities
Surgical


Failed conservative treatment
Release fascia of brachioradialis and ECRL
Lumbar Plexus



Formed by the anterior
rami of L1-L4.
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



Formed by the
anterior rami of L4-L5
and S1-S4.
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


Formed by the
anterior rami of S4-S5
and the coccygeal
nerves.
Supplies a small area
of skin in the
coccygeal region.
Copyright 2009, John Wiley & Sons,
Inc.
Dermatome

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.