ENTRAPMENT NEUROPATHIES

PRESENTER:Dr. Bikash Ch.Nanda1st YEAR,PG(INTERNAL MEDICINE)

PRECEPTOR:Dr. L Ravi Kumar,MD Asst Professor

Dept of Internal MedicineVSS MCH Burla

DEFINITION

Entrapment Neuropathy is defined as: Pressure or Pressure induced injury to a segment of a peripheral nerve secondary to anatomical or pathological structures

INTRODUCTION entrapment neuropathies

The nerve is injured by 1. chronic direct compression, 2. angulations 3. stretching forces

causing mechanical damage to the nerve.

Anatomy

Anatomy

Anatomy

PATHOPHYISOLOGY Focal slowing of Nerve conduction is the principal

electrophysiological feature of entrapment neuropathy

Mild degrees of pressure(suprasystolic) applied to the nerve for short periods produce reversible dysfunction d/t ischemia(entrapped nerve more sensitive to ischemia than normal nerve)

Acute ischemia may be responsible for paresthesias and dysethesias

Prolonged ischemia may l/t neural tissue infarction

PATHOPHYSIOLOGYPeripheral nerve

PATHOPHYSIOLOGY • Relevance

*Epineurium protects against compression

*Epineurium and perineurium protect against stretch

• NEUROPRAXIA:Segmental axonal conduction block

• CONDUCTION SLOWING:(in the absence of histological change) Myelin is slightly damaged,widening of nodal areas(NOT

destruction of internodal segment)-longer time to activate

Conduction is slowed,but not completely blocked Characteristic of Entrapment Neuropathies(Old

term:Axonostenosis)

Double Crush and multiple crush syndromes

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

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’.

Double Crush Syndrome

Entrapment Neuropathy in Diabetes

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

Clinical scenario

Either or all Pain Numbness Tingling Burning Weakness Muscle wasting(severe cases) in respective anatomical areas

Diagnosis Electro diagnosis: mainstay

• Nerve Conduction studies(NCS)• Electromyography(EMG)

NCS assess integrity of sensory and motor neurons

EMG assess electrical activity of a muscle from a needle inserted into a muscle

ELECTROMYOGRAM

TYPESnerve Site of entrapment

Median N.(wrist) (elbow)Ulnar N. (wrist) (elbow)Lower trunk or medial cord of branchial plexusSuprascapular NPost.interosseous N

Common Peroneal nerveLateral femoral cutaneous(meralgia paresthetica)Posterior tibial

Interdigital plantar (Mortonmetatarsalgia)Obturator

Carpal tunnelBtwn heads of pronator teresGuyon’s canal( ulnar tunnel)Bicipital groove,cubital tunnelCervical rib or band at thoracic outlet

Spinoglenoid notchRadial tunnel—at point ofentrance into supinatorMuscle (arcade of Frohse)

Fibular tunnelInguinal ligament

Tarsal tunnel; medialmalleolus–flexorRetinaculumPlantar fascia: heads of thirdand fourth metatarsalsObturator canal

Carpal Tunnel Syndrome

Why does Median Nerve get compressed?

Median Nerve :Position and Morphology• Round or oval at distal radius level• Elliptical at the pisiform and hamate• Morphology changes with flexion and extension• Wrist flexion :elliptical shape flattens• Wrist extension :least morphological change• Frictional forces btwn the median N.adjacent tendons and the

transverse carpal lig compounded by morphologic changes irritate nerve

Mechanism: demyelination f/b axonal degeneration.

Sensory and autonomic fibers affected before motor

Epidemiology: F:M::3-10:1,Age peak 45-60yrs

Etiology

Aging,female,Increased BMI,Square shaped wrist,short stature,dominant hand ,white race,caffeine,alcohol, nicotine

Linked to body morphology,DM,thyroid disease,hereditary neuropathies,RA,Acromegaly,Amyloidosis

High amounts of repititive wrist movements and exposure to vibration/cold

Lack of aerobic exercise,preg,BF,Use of wheelchairs,walking aids,recent menopause,renal dialysis(elbow positioning during dialysis, upper extremity vascular-access, and underlying disease is one cause of ulnar entrapment.)

REF:Journal of Research in Medical Sciences Oct 2012

Clinical PAIN :aching over ventral wrist extending

distally to finger and proximally to forearm

SENSORY :hyperasthesias,parasthesias

Mus.atrophy and weakness are late findings

Autonomic changes:Incr sensitivity to temp changes

Intermittent sym and increase with driving,reading the paper,crocheting,painting

Sensory domain and muscular atrophy

Diagnosis ELECTRODIAGNOSIS

• 1st LINE INVESTIGATION• Prognosticates severity and used to follow disease process

over time

• Positive in >90 % pts. with clinical CTS

• Distal Motor latency is usually prolonged(50%)• -stimulate the Med N> at the wrist, record at APB-latency

>3.7-4.5ms is abnormal• Distal sensory latency is abnormal

-Antidromic sensory study: stimulate at wrist and record at index or middle finger,8cm distally->3.5ms

• Condn vel across carpal tunnel slowed:<41m/s

Diagnosis SPECIAL:

• Hoffman Tinel,Phalen,Reverse Phalen,carpal compression test,square wrist sign

• USG more cost effective and non invasive-may detect minute details which Electrophysiology may miss

• Lacks standardisation

• REF:J Korean Neurosurg Soc. Feb 2013; 53(2): 132–135

TREATMENT Physical therapy-

• Aerobic exercise,Modalities(iontophoresis,phonophoresis,ultrasound) Occupational therapy

• Work site ergonomic assessment (posture)• Wrist-hand orthosis(worn at night for 3-4 wks)• Stretching/strengthening

Pharmacotherapy:• NSAIDS,diuretics,steroids,Vit B6/12-no proven benefit,reduce

caffeine,nicotine,alcohol intake• Local 40mg methyl pred inj results in significant improvement in mild CTS

Surgery-release of transverse carpal lig• Indicated for failure of conservative care or severe category at

presentation• Open vs endoscopicREF:EURA MEDICOPHYS 2007;43:327-32

REF:Clin neurophysiol 2012 Apr;123(4):838- 41. doi: 10.1016/j.

Corticosteroids In CTS, steroid injections (such as cortisone or prednisolone) shrink the swollen tissues

and relieve pressure on the nerve. they offer short-term symptom relief in a majority of CTS patients. However, in about half of cases, symptoms return within 12 months. Generally a second injection does not provide any added benefit.

Another concern with the use of these injections in moderate or severe disease is that nerve damage may occur even while symptoms are improving.

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. Long-term use of these medications can cause serious side effects.

Source: Carpal tunnel syndrome University of Maryland Medical Center

Recent Advances USG guided percutaneous

injection,hydrodissection, and fenestration• An extension of blind steroid injection with

advantage of safety,accuarcy 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

OTHER MEDIAN NERVE COMPRESSION SYNDROMES

Anterior Interosseous Nerve (AIN)syndrome

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

Cubital Tunnel Syndrome

CUBITAL TUNNEL SYNDROME

MECHANISM Repititive bending or leaning on

elbow for long periods Fluid build up in the elbow Trauma

• All of these cause narrowing and constriction of the nerve

Symptoms Aching pain on the inside of elbow Numbness, tingling ring and index

finger esp when bending the elbow Weakening of grip,difficulty in finger

coordination,muscle wasting- when more severe compression

Diagnosis

Treatment In situ or simple decompression Incising the aponeurotic arch

between the olecranon and medial epicondyle if conservative treatment failsIn situ decompression is simple and does not influence the

blood supply of the ulnar nerveSecond, it is also effective because it addresses the primary focus of the lesion, the cubital tunnel. Third, it has lower rate of postoperative complications and more opportunities for quicker rehabilitations

Simple decompression, however, is not appropriate in a poor bed, severe cubitus valgus, or a subluxing nerve

Guyon’s canal entrapment Typically in cycling,wt lifters,jackhammers Seen also in hook of hamate compression

of ulnar nerve at Guyon’s canal Symptoms may be motor or sensory

• Feeling of pins and needles in the ring and little fingers, which is often noticed in the early morning

• This may progress to a burning pain in the wrist and hand followed by decreased sensation in the ring and little fingers.

• The hand may become clumsy when the muscles controlled by the ulnar nerve become weak.

Treatment Proper bicycle fitting, handlebar

adjustments, frequent change in hand position, handle bar and glove padding

Wrist splints

Surgical decompression from failed non-op mgmt., especially with structural lesions such as hook of hamate fracture

Radial Nerve Entrapment

Radial Nerve Entrapment Syndrome

Radial nerve entrapment at one of 5 sites

Anatomy- 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

Susceptible:Racquet sports, rowing and wt. lifting

Radial Nerve Entrapment Sensory and motor complaints, although

typically less weakness than with Posterior interosseous Nerve entrapment

Dull, deep lateral elbow pain

Tenderness over extensor muscle group

Pain reproduced with resisted forearm supination with elbow flexed

Radial Nerve Entrapment May mimic or coexist with lateral epicondylitis

Rx:Conservative neural mobilization techniques

Neural mobilization is a manipulative technique by which neural tissues are moved, relative to their surroundings

Surgery for persistent symptoms usually involves releasing the entrapped location

Posterior Interosseous Nerve (PIN)Syndrome

PIN is a branch of the radial nerve, originating in the lateral intermuscular septum

Purely motor function Innervates the supinator Most common in racquet sports,

bowlers, rowers, discus throwers, golfers, swimmers

All involve repetitive supination and pronation

PIN Syndrome

Specifically, pain with resisted supination;

EMG/NCS may be helpful to differentiate between lateral epicondylitis and PIN

Rx:minimize supination during rehabilitation

Suprascapular Nerve. Entrapment

Throwers, other overhead athletes and weight-lifters

Arises from superior trunk of brachial plexus

Innervates supraspinatus and infraspinatus

Compression most commonly suprascapular or spinoglenoid notch

Suprascapular Nerve Entrapment

Etiology Notch narrowing

Ganglion cyst from intraarticular defect• Often indicative of a labral (SLAP) tear

Nerve kinking or traction from excessive infraspinatus motion

Superior or inferior (spinoglenoid) transverse scapular ligament hypertrophy causing compression

Clinical Vague posterior shoulder pain, weakness

and fatigability• Weakness/atrophy without pain often suggests

compression at spinoglenoid notch (nerve purely motor beyond this)

Symptoms may mimic rotator cuff pathology or instability

Exam reveals rotator cuff weakness and possibly supra- and/or infraspinatus atrophy

Infraspinatus atrophy

Infraspinatus Atrophy

Diagnosis and Treatment MRI may exclude rotator cuff tears, demonstrate atrophy

and/or reveal a ganglion or space-occupying lesion- if present, strongly consider surgical excision

NCS/EMG may assist with the diagnosis Typically begin with non-operative mgmt.

Rx:Rest from repetitive hyperabduction

NSAIDs and corticosteroid injections considered

Nonresponders may benefit from a spinoglenoid notchplasty, transverse scapular ligament release, nerve decompression or surgical exploration

Thoracic Outlet syndrome

Investigations Plain films may reveal a cervical rib

or exuberant callus from a clavicle/upper rib fx

MRI and MRA can reveal brachial plexus anatomy, subclavian vein anatomy or vascular occlusion/compression

MRA with the arm in abduction can demonstrate subclavian vein obstruction in baseball pitchers

Treatment Nonoperative treatment focuses on rest, stretching of the nearby

soft tissue structures and posture mechanics; gradual improvement

Injection of botulinum toxin into the muscles of the thoracic outlet (scalenes, pectoralis minor, subclavius) has potential for obtaining long-term symptom relief, but further research is needed.

REF:Foley JM, Finlayson H, Travlos A. A review of thoracic outlet syndrome and the possible role of botulinum toxin in the treatment of this syndrome. Toxins (Basel). Nov 2012;4(11):1223-35. [Medline]

Surgical treatments• Rib resection• Brachial plexus neurolysis and sympathectomy• Effort thrombosis also treated with clot lysis with urokinase or heparin

Meralgia parasthetica

Meralgia parasthetica Mech:Compression (entrapment)may occur at the point

where it passes between the two prongs of attachment of the inguinal ligament.

Clinical:numbness,mild sensitivity of the skin,or occasionally persistent burning

Perception of touch and pinprick are reduced in the territory of the nerve; there is no weakness of the quadriceps or diminution of the knee jerk.

The symptoms are characteristically worsened in certain positions and after prolonged standing or walking

Diagnosis Dx: The sensory response is absent in

71% of patients with meralgia paresthetica and is prolonged in 24%

Electromyographic test results with needle are normal which may help to differentiate it from an upper lumbar radiculopathy

Treatment Weight loss

Adjustment of restrictive clothing or correction of habitual postures

Neurectomy of the nerve,

Hydrocortisone

Piriformis syndrome (false sciatica)because instead of actual nerve irritation, it is caused by referral pain. caused by tight knots of contraction in the piriformis muscle,

Sciatica refers to irritation of the sciatic nerve, that arises from nerve roots in the lumbar spine. The most common cause of “true” sciatica is compression of one or more of its component nerve roots due to disc herniation or spinal degeneration in the lower lumbar region

Obturator Nerve entrapment

Etiology During delivery as a result of compression of the

nerve between the head of the fetus and the bony structures of the pelvis,

As a consequence of compression of the nerve between a tumor and the bony pelvis. in the obturator canal during surgery or with total hip arthroplasties.

Malposition of the lower limb for prolonged periods, entrapment in the adductor magnus in athletes,

Diagnosis Clinical: difficulty with ambulation

and the development of an unstable leg.

Dx: Membrane instability (positive sharp waves and fibrillation potentials) will occur within 3 weeks of the nerve injury, and needle examination should be performed on patients with groin pain of longer than 3 months

Treatment With physical therapy, cryotherapy or a

transcutaneous electrical nerve stimulation (TENS) unit may be tried.

"TENS" is the acronym for Transcutaneous Electrical Nerve Stimulation. A "TENS unit" is a pocket size, portable, battery-operated device that sends electrical impulses to certain parts of the body to block pain signals. The electrical currents produced are mild, but they can prevent pain messages from being transmitted to the brain and may raise the level of endorphins (natural pain killers produced by the brain).

TENS

Common peroneal nerve entrapment

habitual leg crossing, compression of the nerve against a bed

railing or hard mattress in

debilitated patients, or prolonged

immobility, such as that observed in patients under

anesthesia

Tarsal Tunnel Syndrome

Diagnosis Mech:Thickening of the tendon sheaths,or connective tissue or

osteoarthritic changes

Clinical: Tingling pain and burning over the sole of the foot develop after standing or walking for a long time

Dx: EMG and NCV testing values include the following:

Prolonged distal motor latency: Terminal latencies of the abductor digiti quinti muscle (lateral plantar nerve) longer than 7.0 ms are abnormal.

Terminal latencies of the abductor hallucis muscle (medial plantar nerve) longer than 6.2 ms are abnormal.

Fibrillations in the abductor hallucis muscle may be present.

Treatment Rest, NSAIDs, corticosteroid injection

Footwear adjustments, including a medial arch support

Surgical release ~75% success rate

Morton’s Metatarsalgia

Morton’s Metatarsalgia Mech:perineural fibrosis and nerve degeneration due to

repetitive irritation

Incidence:occurs most frequently in women (F:M 8:1) aged 40-50 who wear high-heeled, pointed-toe shoes

Clinical:common digital nerve to the third/fourth metatarsal spaces is most often affected pain is only felt when the patient wears shoes. There is localized tenderness over the site of the neuroma

Dx :USG is the modality of Choice

Rx: If there is no relief from symptomatic padding then the neuroma may be excised

Research areas in nerve injury”Molecular factors”CLASS AGENT(S) ACTION

Neurotropic Factors andChemoattractants

Ciliary neurotrophic factor (CNTF)Nerve growth factor (NGF)Insulin-like growth factors (IGFs)Brain-derived neurotrophic factor(BDNF)NT-3NT-4

Promote neuronal survival andregrowthAttract and guide axon

Chemorepellent Factors

SemaphorinsNetrinsOthers

Selectively repel some types ofaxons

Inhibitors of Connective TissueFormation

Inhibitors of fibroblastsCollagenasesOthers

Decrease fibrosis at the site ofnerve injury to promote axonalregeneration

Summary

References Hassouna H, Singh D. Morton's metatarsalgia

: pathogenesis, aetiology and current management. Acta Orthop Belg. 2005;71(6):646-55

Neurosurg Focus. 2009 Feb;26(2):E13. doi: 10.3171/FOC.2009.26.2.E13

Adam’s and Victor’s Principles of neurology

Entrapment Neuropathies John D. England, MD

References Brain’s Textbook of Neurology Ann R Coll Surg Engl. Nov 2011;93(8):634-

8. Sanders RJ, Hammond SL, Rao NM.

Diagnosis of thoracic outlet syndrome. J Vasc Surg. Sep 2007;46(3):601-4

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