entrapment neuropathies at elbow

Dr. Mahima Agrawal
MBBS, MD, DNB, MNAMS PMR
Assistant Professor, Dept. of PMR,
JLNMC, Ajmer

Definition
Etiology
Pathophysiology
Diagnostic evaluation
Differential diagnosis
Management
Specific Entrapment neuropathies

 It is a neuropathy due to a structural abnormality, such as
compression, displacement, or traction of the nerve, or by
an intrinsic abnormality of the nerve, such as nerve cell
tumor
 With these lesions, stretching and angulation of
the nerve may be as important a source
of injury as compression

 Trauma, direct pressure and space-occupying lesions
at any level in the upper extremity
 There are other situations that are not a direct cause of
nerve compression, but may increase the risk and may
predispose the nerve to be compressed specially when
the soft tissues are swollen like synovitis, pregnancy,
hypothyroidism, diabetes or alcoholism

Epineurium
Fascicle
Endoneurium
Perineurium
Artery and Vein
within the
perineurium
Layers of nerve

Acute nerve compression
 Pressures exceeding 20 mm Hg Reduced
epineurial blood flow
 Pressures exceeding 30 mm Hg Inhibits
anterior and retrograde axonal transport
 Pressures exceeding 80 mm Hg Cessation of
intraneurial blood flow
 These changes are transitory Reversible in
short term
 Example is Tourniquet palsy

Repetitive stress, prolonged
compression
Wallerian degeneration
Localized demyelination
Demyelination of
nerve fibres

 A proximal level of nerve compression could cause more distal sites
to be susceptible to compression
 The summation of compression along the nerve would result in
alterations of axoplasmic flow and subsequent pathology and
symptomatology
 The possibility of a distal site of compression making the more
proximal nerve susceptible to secondary compression: A reverse
double crush
 Systemic diseases such as obesity, diabetes, thyroid disease,
alcoholism, rheumatoid arthritis and neuropatthies lower the
threshold for the occurrence of a nerve compression and alter
axoplasmic transport rendering that nerve more susceptible to
develop compression neuropathy and act as a ‘crush’

 DM is a significant predisposing factor for entrapment
neuropathies
TN-C(Tenascin-C) expression in the
endoneurium is closely correlated with nerve function
Metabolic and phenotypic abnormalities of endoneurial and
perineurial fibroblasts lies behind the vulnerability of DM patients
to entrapment neuropathy
 In contrast to angiopathies, retinopathy, and nephropathy, three
representative complications of DM, mast cells do not
play significant roles in the onset or progression of the
entrapment neuropathy associated with DM
 Ref: Histol Histopathol (2008) 23: 157-166
http://www.hh.um.es

Temporal sequence
Irritative or
inflammatory pain
Paraesthesia
(Tingling , Burning)
Ablative Numbness
Weakness and
atrophy
Dry, thin, hairless skin
Ridged, thickened,
cracked nails
Recurrent skin ulcerations

 Clinical evaluation
 History
 Electro diagnosis: mainstay
• Nerve Conduction studies(NCS)
• Electromyography(EMG)
 Electromyography (EMG)
 EMG tests detect abnormal electrical activity in motor
neuropathy and can help differentiate between muscle and
nerve disorders

Sensory nerve conduction
studies are the earliest to show
abnormality of slowing (focal
demyelination) in the nerve
across the site of the
entrapment
Slow transmission rates and
impulse blockage tend to indicate
damage to the myelin sheath,
while a reduction in the strength of
impulses at normal speeds is a sign
of axonal degeneration
Motor conduction abnormalities
generally present later with
slowing across the site followed
by loss of axons (both sensory
and motor) if the entrapment is
unrelieved
Needle electromyography is
used to detect axon loss
which is chronic unless there
is a super added acute
external pressure on an
existing entrapped nerve

 Nerve biopsy Although this test can provide valuable
information about the degree of nerve damage, it is an
invasive procedure that is difficult to perform and
may itself cause neuropathic side effects
 Skin biopsy (examine nerve fibre endings) This
test offers some unique advantages over NCV tests
and nerve biopsy. Unlike NCV, it can reveal damage
present in smaller fibres; in contrast to conventional
nerve biopsy, skin biopsy is less invasive, has fewer
side effects, and is easier to perform

 Magnetic resonance imaging (MRI) can show
muscle quality and size, detect fatty replacement of
muscle tissue, and can help rule out tumors, herniated
discs, or other abnormalities that may be causing the
neuropathy
 Ultrasound: The impact of sonography on clinical
management has yet to be determined, even though
upper extremity nerves are well-depicted
Sonographically

 Myelopathy
 Brachial plexopathy
 Radiculopathy
 Other central nervous system disorders, that can
mimic peripheral nerve entrapment
 Painful rheumatologic and orthopaedic disorders;
and other psychological entities, such as
somatoform and factitious disorders

Treat the
underlying cause
Infection
Toxin exposure
Medication
related toxicity
Vitamin
deficiencies
Hormonal
deficiencies
Autoimmune
disease
Management of
systemic diseases
Early management
of injuries
TREATMENT
Healthy lifestyle
Optimal weight
Balanced diet
Exercising
Limiting alcohol
consumption
Correcting vitamin
deficiencies

 Symptom Management
 1. Nonsteroidal anti-inflammatory drugs (NSAIDs) for mild
pain
 2. Antidepressants (tricyclic antidepressants such as
amitriptyline or newer serotonin-norepinephrine reuptake
inhibitors such as duloxetine hydrochloride or venlafaxine)
 3. Anticonvulsants (tricyclic antidepressants such as
amitriptyline or newer serotonin-norepinephrine reuptake
inhibitors such as duloxetine hydrochloride or venlafaxine)
 4. Antiarrythmics (Mexiletine)
 5. Narcotic agents ( Tapentadol)

 6. Topically administered medications
• Lidocaine
• Capsaicin
• Topical agents are generally most appropriate for
localized chronic pain such as herpes zoster neuralgia
(shingles) pain
 7. TENS
 8. Allied medicine (Acupuncture, massage etc.)
 9. Orthosis
 10. Surgery
 11. Trans cranial magnetic stimulation

 Steroid injections (such as cortisone or prednisolone) shrink the
swollen tissues and relieve pressure on the nerve
 Corticosteroid injections are helpful for pregnant patients, as their
symptoms often go away within 6 - 12 months after pregnancy
 Most doctors limit steroid injections to about three per year, because
they can cause complications, such as weakened or ruptured tendons,
nerve irritation, or more widespread side effects
 Low-Dose Oral Corticosteroids: A short course (1 - 2 weeks) of oral
corticosteroid medicines may provide relief for some people, but the
relief does not usually last.


 USG guided percutaneous injection, hydrodissection,
and fenestration
• An extension of blind steroid injection with advantage
of safety, accuracy of medication placement,
effectiveness, non invasiveness, ease of performance
and lower cost than open surgical release
REF: Vol.10,No.3,2010,Journal of Applied
research

CLASS AGENT(S) ACTION
Neutrophic Factors and
Chemoattractants
Ciliary Neutrophic factor
(CNTF)
Nerve growth factor
(NGF)
Insulin-like growth factors
(IGFs)
Brain-derived Neutrophic
factor
(BDNF)
NT-3
NT-4
Promote neuronal survival
and
regrowth
Attract and guide axon
Chemorepellent Factors Semaphorins
Netrins
Others
Selectively repel some
types of
axons
Inhibitors of Connective
Tissue
Formation
Inhibitors of fibroblasts
Collagenases
Others
Decrease fibrosis at the
site of
nerve injury to promote
axonal
regeneration

Nerve involved Site of entrapment
Median N.(wrist)
(Elbow)
Ulnar N. (wrist)
(Elbow)
Lower trunk or medial cord of
branchial plexus
Suprascapular N
Radial Nerve
(Elbow)
Carpal tunnel
Between heads of Pronator teres
Anterior Interosseous Nerve syndrome
Guyon’s canal (Ulnar tunnel)
Bicipital groove, Cubital tunnel
Cervical rib or band at thoracic outlet
Spinoglenoid notch
Radial tunnel—at point of
entrance into supinator muscle (arcade
of Frohse)
Posterior Interosseous Nerve syndrome

Median nerve in anterior
elbow. Passing between two
heads of Pronator teres muscle
and into the forearm beneath
the edge of the fibrous arch of
flexor digitorum sublimis

 Possible areas for median nerve compression proximal
to the carpal tunnel:
 The ligament of Struthers
 The bicipital bursa
 Anomalous arteries, and anomalous muscles (such as
Gantzer's muscle, an accessory FPL muscle)
 Pronator syndrome
 Anterior interosseous nerve syndrome
 The last two remain the two most frequently referenced
compression neuropathies of the median nerve in the
forearm

 Compression of the median nerve as it passes between the
two heads of the pronator teres muscle, Bicipital
aponeurosis
 Compression is due to hypertrophy and imbalance of
regional tissues
 Development of fibrous tissue
due to inflammatory processes
from repetitive stress,
decreasing range of motion and
increasing stresses

 Symptoms
 Insidious onset
 No history of trauma
 Aching pain in the proximal, volar forearm
 Paraesthesias radiating into the median innervated fingers
 Worsened by repetitive pronosupination movements and
wrist flexion
 Carpenters, frequent computer users
with a mouse, weight lifters,
athletes especially yoga, golf and
tennis
PRONATOR SYNDROME

 Discriminating clinically between PS and CTS:
 Loss of sensation over palmar cutaneous branch territory
 No Tinel's on the wrist
 No nocturnal disturbance
 Pain on resisted pronation from a neutral position, especially as the
elbow is extended
 If resisted contraction of the FDS to the middle finger reproduces
symptoms, median nerve compression at the level of the fibrous arch
between the heads of the FDS might be suspected
 If symptoms are elicited by resisted flexion of the forearm in full
supination, compression at the more proximal level of the lacertus
fibrosus might be considered

 Site of compression essentially same for both Pronator
syndrome(PS) and AIN
 PS:Vague volar forearm pain,Median nerve
parasthesias,minimum motor findings
 AIN:Pure motor palsy of any or all three 1.FPL,2.FDP
of index and middle fingers,3.PQ.
 Surgical indications for nerve decompression include
persistent symptoms for >6 months in patients with PS
or for a minimum of 12 months with no signs of motor
improvement in those with AIN syndrome

 Pain may be present in the forearm along the course of the
nerve
 Inability to make an “OK” sign when asked by the
examiner to flex his thumb interphalangeal joint and index
finger distal interphalangeal joint
 In patients with mild AIN compression, subtle weakness
of these muscles may be the only clinical finding
 Such weakness of the FPL and index finger FDP may be
uncovered by asking the patient to pinch a sheet of paper
between his thumb and index finger using only the
fingertips and then trying to pull the paper away

 A patient with AIN syndrome may be unable to hold
on to the sheet of paper with just his fingertips and
may compensate by using a more adaptive grip in
which the interphalangeal joint of the thumb and
distal interphalangeal joint of the index finger remain
extended
 Differential diagnosis
 Brachial neuritis
 Viral neuritis (Parsonage–Turner syndrome)
 Rupture of the FPL tendon

Anterior view of radial nerve course.
PIN entrapment occurs because of
prominent radial recurrent artery(RRA),
medial edge of ECRB, proximal edge of
S (Arcade of frohse, RN (Radial nerve),
SRN (Superficial Radial Nerve)

 Anatomy- Formed from posterior cord to emerge
between long and lateral heads of triceps, spiral
groove of humerus proceeding medially to laterally to
emerge between brachialis and brachioradialis on
lateral elbow to enter the radial tunnel
 On exit from radial tunnel, the deep branch pierces the
supinator and exits the posterior aspect to emerge as
Posterior interosseous nerve

 Anatomically, there are five potential sites of compression
of the Radial nerve in the area of the radial tunnel
• Fibrous bands of tissue anterior to the radiocapitellar joint
between the brachialis and brachioradialis
• The recurrent radial vessels that fan out across the PIN at the
level of the radial neck as the so-called leash of Henry
• The leading (medial proximal) edge of the extensor carpi radialis
brevis (ECRB)
• The proximal edge of the superficial portion of the supinator,
commonly referred to as the arcade of Fröhse
• The distal edge of the supinator muscle

 Radial nerve compression can lead to either radial
tunnel syndrome or posterior interosseous nerve
syndrome (also called Supinator syndrome)

 PIN is a branch of the radial nerve, originating in the
lateral intermuscular septum
 Purely motor function
 Innervates the supinator, extensor carpi ulnaris, extensor
digitorum communis, extensor digiti minimi, abductor
pollicis longus, extensor pollicis longus and brevis, and
extensor indicis proprius muscles
 Most common in racquet sports, bowlers, rowers, discus
throwers, golfers, swimmers
 All involve repetitive supination and pronation
 May occur in synovitis, neoplasm etc

 Symptoms and signs:
 Inability to extend fingers and thumb
 ECRL function intact—the wrist extends and radially
deviates
 Whereas patients with PIN syndrome have a loss of motor
function, patients with RTS typically, present with mobile
wad and lateral forearm pain without motor involvement

 Symptoms and signs:
 Pain distal to lateral epicondyle, tenderness over the radial tunnel
along the path of PIN
 Pain worsened by extending the elbow, pronating the forearm and
flexing the wrist
 Pain with resisted active supination or wrist extension
 Pain with active supination against resistance
 Pain with wrist extension against resistance
 Pain with resisted middle finger extension at the
metacarpophalangeal joint
 No neurological deficit
 Pain disappears after instilling local anaesthetic at the site of entry of
PIN

 There is no motor weakness
 Unlike a case of lateral epicondylitis the pain is not on the
lateral epicondyle of the humerus but slightly distal to it
 It is described as being in the area of the mobile wad and
radial tunnel
 Differential diagnosis:
 Lateral epiconylitis
 Osteoarthritis of the radial capitellar joint
 Impingement of the articular branch of the radial nerve
 Synovitis of the radiocapitellar joint
 Muscle tear of the extensor carpi radialis brevis

Course of ulnar nerve from posterior
view. It travels deep to the flexor
carpi ulnaris muscle beneath the
arcuate ligament

 Entrapment of the ulnar nerve is the second most common
compression neuropathy in the upper extremity after CTS
 The arcade of Struthers is a band of fascia that connects the
medial head of the triceps with the intermuscular septum of the
arm
 The cubital tunnel is a fibroosseous channel formed by the
olecranon process laterally, the posterior cortex of the medial
epicondyle medially, the elbow joint capsule and posterior
bundle of the medial collateral ligament anteriorly, and the
ligament of Osborne (the cubital retinaculum) posteriorly

•Truck drivers who lean the flexed
elbow against the open window of
their truck
•Constant cell-telephone users
•Baseball pitchers are also at risk
because of the valgus stress that is
induced in the late cocking and
early acceleration phases of
throwing
•Recurrent anterior
dislocation of the ulnar nerve
•Risk factors for ulnar nerve
dislocation
include cubitus varus deformity,
an absent or lax ligament of
Osborne, a hypertrophic medial
head of the triceps, or an
accessory head of the triceps
and the dislocation may be
associated with activities that
involve resisted elbow
extension, such as the early
acceleration phase of throwing
and bench press
CUBITAL TUNNEL SYNDROME

 Entrapment neuropathies are far
more common than thought
 These syndromes are
underdiagnosed
 Early diagnosis can lead to
faster and near complete
recovery
 Conservative management
followed by surgery in non
responsive cases gives good
results

Theodore T. Miller, William R. Reinus. Nerve
Entrapment Syndromes of the Elbow,
Forearm, and Wrist
Adam’s and Victor’s Principles of neurology
Entrapment Neuropathies John D. England,
MD

entrapment neuropathies at elbow

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