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Pathophysiology of
Peripheral Nerve Lesions
Part 2: Upper Extremity
Entrapment Syndromes
David A. Lake, PT, PhD
Department of Physical Therapy
Armstrong Atlantic State University
Savannah, GA
Examination of Entrapment
Peripheral Neuropathies
• History
– Focus on occupational/activities
that involve repetitive motion
– Have patient trace rather than
verbalize paresthesia or pain
pattern
– Distinct symptoms suggest a distal
lesion
– Complex symptoms suggest a
proximal lesion
Examination of Entrapment
Peripheral Neuropathies
• Sensory Exam
– Sensory symptoms before motor
– Light touch, 2 pt discrimination
over distribution of nerve
– Inspect for trophic changes to
skin - often an effect on
autonomic fibers to an area
Examination of Entrapment
Peripheral Neuropathies
• Motor Exam
– Check reflexes bilaterally
– Inspect for atrophy - again
bilateral comparison
– Bilateral testing for muscle
strength in muscles along the
nerve course
Examination of Entrapment
Peripheral Neuropathies
• Reproduction of symptoms
– Positioning to narrow tunnel
through which the nerve progresses
– Muscle contraction against
resistance is compression is caused
by passing through a muscle
– Percussion tests - tapping on nerve
or tapping/applying pressure to area
of compression
Examination of Entrapment
Peripheral Neuropathies
• NCV & EMG testing
– > 50% reduction in amplitude of
compound action potential in nerve
conduction velocity tests (NCV) sign
of impairment
– EMG shows abnormal spontaneous
activity within 2 weeks of acute
compression/trauma if deficit in
motor axons - and is gold standard
if motor deficit
Examination of Entrapment
Peripheral Neuropathies
• NCV & EMG testing
– Abnormal spontaneous activity
includes:
• Positive sharp waves
• Fibrillation potentials
Examination of Entrapment
Peripheral Neuropathies
• NCV & EMG testing
– Abnormal EMG activity also includes:
• Enhanced insertional activity
Examination of Entrapment
Peripheral Neuropathies
• NCV & EMG testing
– Abnormal EMG activity also includes:
• Reduced maximal evoked activity
(interference pattern)
Normal
Interference
Pattern
Reduced
Interference
Pattern
Examination of Entrapment
Peripheral Neuropathies
• NCV & EMG testing
– Abnormal EMG activity also includes:
• Eventually the replacement of normal
biphasic MUAPs with polyphasic MUAPs
Biphasic
MUAPs
Polyphasic
MUAPs
Examination of Entrapment
Peripheral Neuropathies
• NCV & EMG testing
– Compare bilaterally and there are
normative standards for
• Conduction velocity
• Compound action potential amplitudes
• Distal latencies
Examination of Entrapment
Peripheral Neuropathies
Brachial Plexus and
Early Branches of
the Brachial Plexus
Entrapment
Neuropathies
• Thoracic Outlet Syndrome (TOS)
– Name change suggested to cervicoaxillary syndrome because of
anatomical terminology
• Anatomical thoracic outlet from thorax to
abdomen - covered by the diaphragm
• But TOS still most commonly used
– Three major forms of TOS
• Scalene entrapment syndrome
• Costoclavicular entrapment
• Costopectoral Tunnel syndrome
Entrapment
Neuropathies
• Scalene Entrapment Syndrome
– The brachial plexus passes out between
the anterior and middle scalene muscle
Anterior Scalene
Middle Scalene
Brachial Plexus
Entrapment
Neuropathies
• Scalene Entrapment Syndrome
– Most commonly caused by:
•
•
•
•
scalene muscle hypertrophy
poor posture
prolonged overhead work
less often due to abnormal presence of
a cervical rib or a scalene minimus
muscle
– Most commonly affects the lower
plexus C8 & T1 spinal nerves
Entrapment
Neuropathies
• Scalene
Entrapment
Syndrome
– Symptoms most
commonly include:
• Numbness in
fingers, hand and
anterior forearm
Entrapment
Neuropathies
• Scalene Entrapment Syndrome
– Symptoms most commonly
include:
• Clumsiness & loss of fine motor
control of the hand
• Occasionally vascular signs such as:
– UE ischemic changes
– Raynaud like symptoms
– Ischemic finger ulcerations
Entrapment
Neuropathies
• Costoclavicular Entrapment
– Subclavian artery & brachial plexus
pass between clavicle and first rib
Entrapment
Neuropathies
• Costoclavicular Entrapment
– Most commonly the result of:
• Poor posture
• Congenital fibrous bands
– Can occur secondary to a clavicular
fracture and callus that develops as part
of fracture healing
– Most commonly affects lower plexus
– Vascular problems more common than
in scalene entrapment syndrome
Entrapment
Neuropathies
• Costoclavicular Entrapment
– Symptoms include:
• Numbness of the fingers, hand and
forearm
• Arm and hand pain
• When vascular problems occur they are
similar to those seen with scalene
entrapment syndrome but may also
include hand edema secondary to venous
compromise
Entrapment
Neuropathies
• Costopectoral Tunnel
syndrome
– Costopectoral tunnel
formed by the pectoralis
minor lying over the
anterior thoracic wall
and the corocoid
process of the scapula
– Brachial plexus (blue) &
brachial artery (red) run
through it
Entrapment
Neuropathies
• Costopectoral Tunnel syndrome
– Most common cause is 1) hypertrophic pectoralic minor or 2)
prolonged overhead activities
– Less commonly caused by 1) an
abnormal muscle, the chondroepitrochlearis muscle arising from the
pectoralis minor or 2) scar tissue in
the subpectoral space
– More commonly accompanied by
vascular problems than the other two
forms of TOS
Entrapment
Neuropathies
• Costopectoral Tunnel syndrome
– Symptoms include:
• Pain and parethesias in the fingers and
hand
• Made worse by arm abduction
• Hand ischemia and edema
Entrapment
Neuropathies
• Long Thoracic
Nerve
entrapment
– Lies deep to the
brachial plexus
on top of the 2nd
rib and may be
compressed
against this
second rib.
Long Thoracic Nerve
Potential Entrapment Site
Entrapment
Neuropathies
• Long Thoracic Nerve entrapment
– C5 and C6 fibers of the long thoracic nerve
may pass through the middle scalene
muscle and may be compressed by it
Entrapment
Neuropathies
• Long Thoracic Nerve entrapment
– Compression can come from:
• Tight bandage across the lateral chest,
trauma to the shoulder
• Poorly adjusted crutches
– Symptoms generally include:
• Vague anterior shoulder pain or
paresthesias
• Distinct winging of the scapula is
generally seen
Entrapment
Neuropathies
• Long Thoracic Nerve entrapment
• Scapular winging
Entrapment
Neuropathies
• Long Thoracic Nerve Damage
– Damage can occur during a radical
lymph node resection or mastectomy
Entrapment
Neuropathies
• Quadrilateral Space Syndrome
– Space formed by teres major, teres minor,
shaft of the humerus & long head of the
triceps through which runs the axillary nerve
Axillary Nerve
Post Humeral
Circumflex Artery
Entrapment
Neuropathies
• Quadrilateral Space Syndrome
– Closure of this space results
subsequent to:
– Scapular or humeral fractures
– Shoulder dislocations
– Teres major hypertrophy
Entrapment
Neuropathies
• Quadrilateral Space Syndrome
– Symptoms
• Paresthesia - lateral shoulder and proximal
arm
• Deltoid paresis and atrophy
• Shoulder abduction paresis with
compensatory actions of the supraspinatus
and biceps
• Tenderness over the quadrilateral space
• Abnormal scapulohumeral rhythm
Entrapment
Neuropathies
• Suprascapular Nerve Syndrome
– Suprascapular nerve runs under the
transverse scapular ligament through the
scapular notch
Entrapment
Neuropathies
• Suprascapular Nerve Syndrome
– 50% of individuals have an inferior transverse
scapular ligament as an additional connective
tissue roof which can entrap nerve
& Transverse
Scapular Ligament
Inferior Transverse
Scapular Ligament
Transverse Scapular Ligament
Entrapment
Inferior Transverse
Scapular Ligament
Entrapment
Entrapment
Neuropathies
• Suprascapular Nerve Syndrome
– In addition to possible entrapment beneath
the superior and inferior transverse scapular
ligaments, other possible causes include:
• Supraglenoid ganglionic cyst can narrow
gap
• Scapular fracture
• Repetitive overhead activities
• Weight bar resting on shoulders during
squat exercises
Entrapment
Neuropathies
• Suprascapular Nerve Syndrome
– Signs and Symptoms
• Posterior shoulder or acromioclavicular
pain
• Nocturnal pain
• Positive crossed-arm adduction test
• Supraspinatus and infraspinatus atrophy
• Paresis of shoulder abduction and external
rotation
Entrapment
Neuropathies
Median Nerve
Entrapment
Neuropathies
Entrapment
Neuropathies
• Median nerve syndromes- there are
several potential points of median
nerve entrapment:
– Supracondylar tunnel - Rare
– Pronator teres
– Anterior interosseous nerve
– Carpal tunnel
Entrapment
Neuropathies
• Median nerve syndromes- Supracondylar
tunnel (RARE)
– Supracondylar process - anomalous growth
proximal to the medial epicondyle on the
humerus.
– More common would be entrapment by the
medial intermuscular septum as the
supracondylar process is a rare, anomalous
structure occurring in only 1-3% of the
population
Entrapment
Neuropathies
• Median nerve syndromes- Supracondylar
tunnel
– If the supracondylar process exists, there is
a connective tissue link between the
supracondylar process and the medial
epicondyle (Ligament of Struthers) forms a
tunnel through which the median nerve runs
– Sometimes seen secondary to humeral
fracture or prolonged immobilization of the
elbow
Entrapment
Neuropathies
• Median nerve
syndromesSupracondylar
tunnel
– Supracondylar
process - anomalous
growth proximal to
the medial epicondyle
on the humerus.
– Ligament of Struthers
forms the Supracondylar tunnel
Supracondylar
Process
Supracondylar
Tunnel
Ligament
of
Struthers
Entrapment
Neuropathies
• Median nerve syndromes- Supracondylar
tunnel
– Median nerve runs through this supracondylar tunnel
Entrapment
Neuropathies
• Median nerve syndromes- Supracondylar
tunnel
– Sometimes seen secondary to humeral
fracture or prolonged immobilization of the
elbow
– Symptoms
• Carpal tunnel like symptoms of paresthesias and
pain along the median nerve distribution & atrophy
and paresis of hand intrinsic flexors
• Except that pain radiates up into the forearm &
long wrist and finger flexors are also involved.
• NCV changes both proximal and distal to the
carpal tunnel seen
Entrapment
Neuropathies
• Median nerve
syndromesSupracondylar
tunnel
– Symptoms
• Example of pain
radiates up into the
forearm along
median nerve
distribution
Entrapment
Neuropathies
• Median nerve syndromes- Pronator teres
– Median nerve runs between the two heads of
the pronator teres to desend to run
superficially to the flexor digitorum profundus
and deep to the flexor digitorum superficialis
– However at times the nerve can penetrate
through the pronator teres or the pronator
teres can have an anomalous head that
narrowly surrounds the median nerve or has
extra fibrous connections between the heads
Entrapment
Neuropathies
• Median nerve syndromesPronator teres syndrome
– Median nerve runs between
the two heads of the
pronator teres to desend to
run superficially to the
flexor digitorum profundus
and deep to the flexor
digitorum superficialis
Entrapment
Neuropathies
• Median nerve syndromesPronator teres syndrome
– However at times:
• Median nerve can penetrate
through the pronator teres
• Pronator teres can have an
anomalous head that
narrowly surrounds the
median nerve
• Pronator teres has extra
fibrous connections between
the heads
• Pronator teres hypertrophy
Entrapment
Neuropathies
• Median nerve syndromes- Pronator teres
Syndrome symptoms include:
– Carpal tunnel like symptoms of pain and
paresthesias along the median nerve
distribution
– Atrophy and paresis of hand intrinsic flexors
– Impaired thumb, index and middle finger
flexion
– Tinel's sign over the pronator teres
– Symptoms get worse with resisted pronation
or sustained forearm supination with elbow
extension
Entrapment
Neuropathies
• Median nerve syndromes- Anterior
interosseous Nerve Syndrome
– Anterior interosseous nerve is a motor nerve
that innervates the flexor digitorum profundus
(digits 2 & 3), flexor pollicis longus and
pronator quadratus
Entrapment
Neuropathies
• Median nerve syndromes- Anterior
interosseous Nerve Syndrome
– Anterior interosseous nerve dives through the
flexor digitorum profundus
Entrapment
Neuropathies
• Median nerve syndromes- Anterior
interosseous Nerve Syndrome
– The nerve runs along the interosseous
membrane between radius and ulna
Anterior - up
Posterior down
Medial - right
Lateral - left
Arrows:
Yellow - Anterior
Interosseus Nerve
Red - Flexor Digitorum
Profundus
Blue - interosseus
membrane
Entrapment
Neuropathies
• Median nerve syndromes- Anterior
interosseous Nerve Syndrome
– Possible causes include:
•
•
•
•
Forearm bone fracture
Fibrous adhesions
Dialysis shunts to that area
Compartment syndrome of the flexor forearm
(Volkmann Contracture or ischemic neuropathy
due to pressure buildup in the tissues surrounding
the nerve)
• A combination of forearm fracture, edema & tight
casting
Entrapment
Neuropathies
• Median nerve syndromes- Anterior
interosseous Nerve Syndrome
– Symptoms
• Inability to pinch between thumb and 2nd digit due
to lack of distal phalangeal flexion of digits and
thumb
• Decreased ability to handle pen and write, hold
onto coffee cup - any strength or coordination
involving thumb and first second and perhaps
third digit (sparing of perhaps 3rd, 4th and 5th
digits)
• Diffuse ache along proximal third of forearm but no
sensory loss
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Entrapment of the median nerve as it passes
through the carpal tunnel
– Occurs most commonly in ages 30-60
– Occurs more commonly in women 3.5-5:1
ratio
– 50% bilaterally
– Genetic predisposition - small wrists
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Mostly associated with:
• Certain hand, wrist, forearm and finger
postures
• Repetitive motions that put pressures on
the wrist even with mild to moderate loads
• Exposure to high vibratory loads
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Carpal tunnel is formed posterior and laterally
by carpal bones & their ligaments, and
anteriorly by the transverse carpal ligament
Transverse Carpal Ligament
Trapezium
Trapezoid
Hamate
Capitate
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Carpal tunnel is on average 2-5 cm in length &
2-3 cm in width and 1-1.5 cm in depth
WIDTH
DEPTH
LENGTH
Entrapment
Neuropathies
• Median nerve
syndromesCarpal Tunnel
Syndrome
– Carpal tunnel
contains, median
nerve, fat, 9
tendons & tendon
sheaths of finger
flexors
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– During flexion and extension median
nerve can translate 20 mm rubbing
against flexor tendons or transverse
carpal ligament and any increased
pressure in the carpal tunnel will increase
friction
– During flexion both the median nerve and
flexor tendons are thicker filling the tunnel
and during extension they are stretched
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Normal pressures in the carpal tunnel
are 2.5 mm Hg at rest and up to 31
mmHg during flexion and extension.
– In radiographically diagnosed carpal
tunnel disease, intra-canal pressures
have been shown to be 31 mm Hg at
rest and up to 94-110 mm Hg during
flexion and extension.
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Pressures greater than 50 mm Hg will
compress and produce complete
conduction block in the median nerve
– Flexion of the metacarpophalangeal
joints can also increase intra-canal
pressures
Entrapment
Neuropathies
• Median nerve syndromes- Carpal Tunnel
Syndrome
– Contributors to increased pressure & Carpal
Tunnel Syndrome include:
• Sustained or repetitive flexion and extension of the
wrist
• Fracture of the wrist or dislocation of the carpal
bones
• Post-traumatic scarring
• Inflammatory flexor tenosynovitis
• Hypertrophic tenosynovitis
Entrapment
Neuropathies
• Median nerve syndromes- Carpal Tunnel
Syndrome
– Contributors to increased pressure & Carpal
Tunnel Syndrome include:
•
•
•
•
•
•
•
Rheumatoid arthritis
Extracellular shifts of fluid during pregnancy
Neurinoma, lipoma, hemangioma or ganglion cyst
Calcium or gouty tophus deposition
Amlyoidosis
Diabetes
Renal insufficiency myxedema
Entrapment
Neuropathies
• Median nerve syndromes- Carpal Tunnel
Syndrome
– Contributors to increased pressure & Carpal
Tunnel Syndrome include:
• Vitamin B6 difficiency
• Hypothyroidism
• Hypoproteinemia
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Major clinical signs and symptoms include:
• Sensory abnormalities in palmar surface of digits
1-3 and half of 4 (in one study of 1059 wrist with
carpal tunnel syndrome 42.5% had all fingers
affected indicating concurrent ulnar nerve
involvement)
• Sensory abnormalities range from hyperesthesias
to numbness and often occur at night with patient
waking up with the sensations or being woken up
by the sensations
Entrapment
Neuropathies
• Median nerve
syndromes- Carpal
Tunnel Syndrome
– Major clinical signs
and symptoms
include:
• Tinel’s sign
• Early on the sensory
changes may be the
only ones seen & are
enhanced by direct
compression or with
Phalen's test positions
Tinel’s Sign
Phalen’s Test
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Major clinical signs and symptoms include:
• Phalen's test has been criticized because of low
predictive value relative to electrodiagnostics
(Kaul, et al, 2000)
– The sensitivity of the Phalen’s Test was 50%
– The specificity was 59.1%
– The positive predictive value was 61.7%
– The negative predictive value was 47.3%
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Major clinical signs and symptoms include:
• Loss of 2 point discrimination and vibratory sense
• Raynaud's syndrome occurs at higher frequencies
than expected in patients with carpal tunnel
disease
• As disease progresses, loss of fine coordinated
grasp due to loss of coordinated thumb
positioning
• Atrophy of thenar muscles
Entrapment
Neuropathies
• Median nerve syndromes- Carpal
Tunnel Syndrome
– Major clinical signs and symptoms include:
• Electrical testing - reduction in SNAP & CMAP
potentials, distal motor latencies and EMG of
forearm versus instrinsic thumb flexors &
abductors for differential diagnosis
• Positive signs of narrowing of the carpal tunnel
seen on CT or MR of wrist
Entrapment
Neuropathies
Radial Nerve
Entrapment
Neuropathies
Entrapment
Neuropathies
• Radial Nerve Entrapment can occur at
several points:
– C5-T1 - proximal radial nerve
– Radial Groove
– Lateral Intermuscular Septum
– Radial Tunnel
– Supinator
– Superficial Radial Nerve
Entrapment
Neuropathies
• Radial Nerve Entrapment: C5-T1
Syndrome
– Once formed the radial nerve runs medial to
humeral head and anterior to long head of
triceps
– Injured by:
•
•
•
•
Glenohumeral subluxation
High riding crutches
Arm over chair back (Saturday night palsy)
Surgery on axillary lymph nodes tumors or radical
dissection of axillary lymph nodes following
mastectomy
Entrapment
Neuropathies
• Radial Nerve Entrapment: C5-T1 Syndrome
– Signs & Symptoms include:
• Paresis/paralysis of elbow extension (if damage
high enough such as glenohumeral subluxation)
• Drop wrist, paresis/paralysis of wrist and finger
extension
• Dorsal forearm and radial side of hand
paresthesias, numbness
• Weakness of elbow flexion in a pronated position
Entrapment
Neuropathies
• Radial Nerve
Entrapment:
Radial Groove
– Radial nerve then
runs through the
radial groove
(sulcus) on
posterior humerus
– Injured by
fractured humerus
Entrapment
Neuropathies
• Radial Nerve Entrapment:
Radial Groove
– Signs & Symptoms include:
• Drop wrist, paresis/paralysis of
wrist and finger extension
• dorsal forearm and radial side
of hand paresthesias,
numbness
• Weakness of elbow flexion in a
pronated position
Entrapment
Neuropathies
• Radial Nerve
Entrapment:
Lateral
Intermuscular
Septum
– Runs between
brachalis &
triceps brachii
– Adhesions in
this area
Entrapment
Neuropathies
• Radial Nerve Entrapment: Lateral
Intermuscular Septum
– Signs & Symptoms include:
• Drop wrist, paresis/paralysis of
wrist and finger extension
• dorsal forearm and radial side of
hand paresthesias, numbness
• Weakness of elbow flexion in a
pronated position
• Weakness of supination
Entrapment
Neuropathies
Brachialis
• Radial Nerve
Entrapment:
Radial Tunnel
Syndome
– Deep radial nerve
runs under
connective tissue
of superficial
supinator - called
the Arcade of
Frohse
Medial
Epicondyle
Radial Nerve
Wrist
Flexors
Nerve to
Supinator
Arcade
of Frohse
Pronator Teres
Supinator
Superficial Radial Nerve
Entrapment
Neuropathies
• Radial Nerve Entrapment: Radial
Tunnel Syndrome
– Causes of damage:
• Microtrauma and repetitive motion
from supination or wrist/finger
extension
• Extensor carpi radialis brevis
often damaged in throwing injuries
& subsequent inflammation can
result in radial tunnel syndrome
Entrapment
Neuropathies
• Radial Nerve Entrapment: Radial
Tunnel Syndrome
– Sparing of the innervation of the
extensor carpi radialis longus and
perhaps the brevis
– Symptoms
• Pain with pressure for lateral
epicondyle & radial tunnel area
• Weakness of wrist & finger extension
with possible drop wrist and no
superficial sensory changes
Entrapment
Neuropathies
• Radial Nerve
Entrapment: Supinator
Syndrome
– Posterior interosseous
branch of radial nerve
which enters the
supinator
Entrapment
Neuropathies
• Radial Nerve Entrapment:
Supinator Syndrome
– Results from:
• Radial head subluxations
• Distal humeral fractures,
proximal radial fractures
or Monteggia fracture
(seen at right - proximal
ulna fracture and radial
head subluxation)
Entrapment
Neuropathies
• Radial Nerve Entrapment: Supinator
Syndrome
– Results from:
• Rheumatoid arthritis particularly of
radiohumeral, ulnohumeral joint and
proximal radioulnar joints
– Sparing of the innervation of the
extensor carpi radialis longus and
perhaps the brevis
Entrapment
Neuropathies
• Radial Nerve Entrapment: Supinator
Syndrome
– Symptoms
• Pain with pressure distal to the
lateral epicondyle
• Weakness of wrist & finger extension
with possible drop wrist
• Deep posterior forearm pain
• Symptoms may be aggrevated by
"wringing linen" motion
• May mimic lateral epicondylitis
Entrapment
Neuropathies
• Radial Nerve
Entrapment: Superficial
Radial Nerve Syndrome
(Cheiralgia
paresthetica)
– Superficial radial nerve
passes:
• superficial to lateral fibers
of pronator teres and
distal attachment of
brachioradialis
• dorsal radial forearm
Entrapment
Neuropathies
• Radial Nerve
Entrapment:
Superficial Radial
Nerve Syndrome
– Superficial radial
nerve crosses wrist
through the dorsal
fascial bands of the
distal radiocarpal
joint - this last point
is where it may
become trapped
Entrapment
Neuropathies
• Radial Nerve Entrapment:
Superficial Radial Nerve Syndrome
– Can be caused or excerbated by
• Tension or fibrosis of
brachioradialis muscle
• Tight casts, cuffs, watchstraps and
handcuffs have been documented
as causes
• Concurrent with de Quervain's
tenosynovitis
• Chronic use of screwdrivers, writing
instruments and keyboards
Entrapment
Neuropathies
• Radial Nerve Entrapment: Superficial
Radial Nerve Syndrome
– Signs & symptoms:
• Tinel's sign as it exits the fascia
• Sensory symptoms along radial/dorsal
hand
• Noctural pain
• Trophic changes on dorsal-radial hand
• May mimic de Quervain's tenosynovitis
Entrapment
Neuropathies
Ulnar Nerve
Entrapment
Neuropathies
Entrapment
Neuropathies
• Ulnar Nerve Entrapment- Medial
Intermuscular Septum
– Like the median nerve, there is the
possibility of entrapment by the medial
intermuscular septum - sometimes
referred to as the Arcade of Struthers
– Symptoms are often indistinguishable
from Ulnar Groove Syndrome so that will
be discussed in more detail
• Ulnar Nerve
Entrapment- Ulnar
Groove Syndrome:
– Deep to medial
head of triceps &
posterior to medial
epicondyle & lateral
olecranon (ulnar
groove)
Entrapment
Neuropathies
Entrapment
Neuropathies
• Ulnar Nerve
EntrapmentUlnar Groove
Syndrome:
– Causes
• Pressure
to medial
elbow
• Ulnar
fracture
Entrapment
Neuropathies
• Ulnar Nerve Entrapment- Ulnar
Groove Syndrome:
– Causes
• Adhesions to flexor carpi
ulnaris or medial triceps along
with traction injury to nerve
• Hypermobile nerve can be
damaged
Entrapment
Neuropathies
• Ulnar Nerve Entrapment- Ulnar Groove
Syndrome:
– Signs and symptoms
• Parethesias & pain along ulnar distribution
in hand (medial palm and dorsal hand of
digits 4 & 5
Entrapment
Neuropathies
• Ulnar Nerve
EntrapmentUlnar Groove
Syndrome:
– Signs and
symptoms
• Decreased grip
strength, intrinsic
muscle atrophy
with hollows
between
metacarpals
Entrapment
Neuropathies
• Ulnar Nerve
EntrapmentUlnar Groove
Syndrome:
– Signs and
symptoms
• Inability to
abduct and
adduct
digits
Abduct
Adduct
Entrapment
Neuropathies
• Ulnar Nerve
EntrapmentUlnar Groove
Syndrome:
– Signs and
symptoms
• Clawhand
deformities
• + Froment’s
sign (- thumb
adduction)
Entrapment
Neuropathies
• Ulnar Nerve Entrapment- Ulnar
Groove Syndrome:
– Signs and symptoms
• + percussion test over ulnar
groove
• EMG, NCV, H-wave & F-wave
deficits
Entrapment
Neuropathies
• Ulnar Nerve
EntrapmentGuyon's Canal
(Ulnar Tunnel)
Syndrome
– Guyon's tunnel formed
by pisiform (P), hamate
& hook of hamate(H),
part of transverse carpal
ligament (TCL) referred
to as the pisohamate
ligament (PHL)& tendon
of flexor carpi ulnaris
N - ulnar nerve
A - ulnar artery
VCL - volar carpal ligament
Entrapment
Neuropathies
Three views of the course
of the ulnar nerve
Entrapment
Neuropathies
• Ulnar Nerve
Entrapment- Guyon's
Canal (Ulnar Tunnel)
Syndrome
– Dorsal branch of ulnar
nerve passes over the
transverse carpal
ligament but palmar
branch goes under the
ligament and through
Guyon's canal.
Entrapment
Neuropathies
• Ulnar Nerve Entrapment- Guyon's Canal
(Ulnar Tunnel) Syndrome
– Causes of damage
• Repetitive motion with some tools
• Use of heel of hand as hammer
• Fracture of hamate hook
• Pisiform bursitis
• Hypertrophy of flexor carpi ulnaris
• Tumor, ganglion cysts, inflammation,
metabolic diseases or vascular disorder
Entrapment
Neuropathies
• Ulnar Nerve Entrapment- Guyon's Canal
(Ulnar Tunnel) Syndrome
– Causes of damage
• Ganglion cysts
• Inflammation
• Metabolic diseases
• Peripheral vascular disorders
Entrapment
Neuropathies
• Ulnar Nerve Entrapment- Guyon's Canal
(Ulnar Tunnel) Syndrome
– Symptoms:
• Similar to higher ulnar nerve damage but
sparing of paralysis to flexor carpi ulnaris
and portions of flexor digitorum profundus
• Tinel's sign over medial ventral wrist
• MRI shows narrowing of Guyon's canal
Entrapment
Neuropathies
Musculocutaneous
Neuropathies
Entrapment
Neuropathies
• Musculocutaneous Neuropathies
– Isolated neuropathies of the
musculocutaneous nerve are very rare
and most times weakness of the biceps
brachii, coracobrachialis or brachialis is
due to lesions higher in the brachial
plexus than to the proximal
musculocutaneous nerve
– When it is damaged selectively it is most
commonly secondary to penetrating
trauma
Entrapment
Neuropathies
• Musculocutaneous Neuropathies
– Possible non-traumatic causes of
musculocutaneous neuropathies
include:
•
•
•
•
Excessive weight lifing activities
Hypertrophy of the coracobrachialis
Excessive traction on the nerve
Surgical repair of the shoulder or shoulder
arthroscopy
Entrapment
Neuropathies
• Musculocutaneous Neuropathies
– Symptoms include”
• Weakness of elbow flexion and forearm
supination with atrophy of the biceps brachii
and brachialis
• Paresthesias or pain along the lateral aspect
of the forearm