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The role of nerve conduction Studies and EMG in Clinical Practice WCSO Devon 17th March 2007

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Title: The role of nerve conduction Studies and EMG in Clinical Practice WCSO Devon 17th March 2007


1
The role of nerve conduction Studies and EMG in
Clinical Practice WCSO Devon 17th March 2007
  • Ibrahim Ali
  • Specialist Registrar
  • Grey Walter Department of Clinical
    Neurophysiology Frenchay Hospital

2
Role of the Clinical Neurophysiologist
  • Clinical Neurophysiology

Electroencephalography EEG
Evoked potential EP
NCS EMG
3
EEG
  • Epilepsy (diagnosis, management, epilepsy
    surgery)
  • Intensive Care Unit (monitoring the therapy,
    prognostic, diagnostic)
  • Encephalopathy
  • Dementias
  • Sleep disorders (narcolepsy)

4
Evoked Potentials
  • Somatosensory Evoked potentials
  • Radiculopathy
  • Multiple Sclerosis
  • Prognostic in ischemic-hypoxic damage
  • Intra-operative monitoring scoliosis surgery
    correction
  • Visual Evoked Potentials
  • Optic nerve diseases
  • Intracerebral lesion
  • Brain Stem Auditory Evoked Potentials
  • M.S
  • Prognostic
  • Intra-operative monitoring posterior fossa tumour

5
Nerve Conduction Studies Electromyography (EMG)
  • Is a diagnostic procedure to check the integrity
    of the peripheral nervous system. As an extension
    of the neurological examination.
  • Nerve conduction studies consist of stimulating a
    nerve and recording the evoked potential either
    from the nerve itself or from the muscle
    innervated by the nerve.
  • Needle EMG record the action potential from the
    muscle extracelluar space.

6
Role of Nerve Conduction Studies and
Electromyography (EMG) in Clinical Practise
  • Localization of the lesion
  • Underlying pathophysiology
  • Assessment of the severity correlation with
    clinical symptoms
  • Assessment of temporal course

7
Peripheral Nervous System Structure
8
Peripheral Nervous System Structure
9
Motor Neuronopathy Anterior Horn Cell Diseases
  • Causes
  • MND
  • Polio
  • Hereditary e.g SMA

10
Sensory Neuronopathy Dorsal Root Ganglia
  • Causes
  • Paraneoplastic SCLC
  • Autoimmune (Sjogren syndrome)
  • Infection H.Z
  • Toxic

11
Nerve Root
  • Radiculopathy
  • Disc herniation
  • Spondyliosis
  • Neoplasm
  • Infection (herpes Zoster/ CMV)
  • Inflammatory/ demyelination
  • Infarction
  • Trauma

12
Radiculopathy
  • One of the most common diagnosis referred for NCS
    EMG.
  • Disc herniation is common cause of radiculopathy
  • Even with widespread MRI scan use, EMG play
    important role in the evaluation of
    radiculopathy.
  • To localise the lesion as well as asses nerve
    root function.

13
Radiculopathy
  • Clinical history
  • Pain parasthesia in the nerve root distribution
  • Often sensory loss paraspinal spasm
  • Motor dysfunction may be present
  • Commonly affected C4-C8 L3-S1 by disc disease
    or bone degeneration
  • Movement of neck or back may exacerbate pain
  • Tendon reflex may be absent or depressed
  • Herpes Zoster radiculopathy- skin lesion

14
Radiculopathy
  • Differential Diagnosis
  • Plexopathy
  • Entrapment
  • Regional muscle bone problem
  • Nerve Conduction Studies and EMG
  • Sensory NCS is usually normal
  • Motor NCS may be abnormal (depends on level of
    lesion)
  • F-waves studies may be abnormal
  • Needle EMG is the most helpful

15
Plexus
  • Plexopathy
  • Radiation induced
  • Lymphoma, Ca breast, lung, pelvic, neck tumours
  • Painless
  • Insidious/ progress for years
  • Neoplasm
  • Painful
  • Sign of recurrence
  • More rapid progressing
  • Diabetes/ Diabetic Amyotrophy
  • Inflammatory/ Idiopathic Brachial Plexopathy
  • Thoracic outlet syndrome/ Cervical Rib
  • Traumatic- Motorcycle
  • post-surgery
  • NCS EMG

16
Peripheral Nerves
  • Neuropathy
  • Entrapment
  • Polyneuropathy
  • Mononeuritis Multiplex
  • Nerve Injuries

17
Nerve Entrapment Carpal Tunnel Syndrome
  • The most common entrapment neuropathy (most
    common referral to our clinic)
  • Compression occurs at carpal tunnel at wrist
  • Little correlation between clinical symptoms and
    the severity (on nerve conduction studies)
  • Female more than male
  • Usually bilateral but the dominant hand more
    severe

18
Carpal Tunnel Syndrome
  • Main symptoms signs
  • - Nocturnal parasthesias awaking patient from
    sleep (shaking or wringing the hands)
  • Pain/ parasthesias with driving, holding a phone,
    book, or newspaper
  • Sensory disturbance of digits 1,2,3, lateral 4.
  • Weakness/ Wasting of thenar eminence
  • Phalens maneuver.

19
Carpal Tunnel Syndrome
  • Other possible symptoms signs
  • - Hand, wrist, forearm, arm and/ or shoulder pain
  • - Perception of parasthesias involving all five
    digits
  • - No fixed sensory disturbance of digits
  • - Decreased hand dexterity
  • Tinels test.
  • Inconsistent or doubtful symptoms signs
  • Neck pain
  • Parasthesia and no pain
  • Weakness of hypothenar muscles, thumb flexion,
    arm pronation and/ or elbow flexion/ extension
  • Reduced biceps or Triceps reflexes

20
Carpal Tunnel Syndrome
  • aetiology
  • Idiopathic
  • Endocrine disorders (hypothyrodism, acromegaly
    diabetes)
  • CTD (RA)
  • Tumours (ganglia, lipoma, schwannoma,
    neurofibroma, hemangioma)
  • Congenital disorder (congenital small carpal
    tunnel)
  • Infection/ Inflammatory (Sarcoid, TB,
    histoplasmosis, septic arthritis, lyme)
  • Trauma
  • Other (hemodialysis, amyloidosis, pregnancy)
  • Differential diagnosis
  • Median neuropathy at elbow
  • Brachial plexopathy
  • Cervical Radiculopathy (C6 C7)
  • CNS causes (small lacunar infarct at lateral
    thalamus or internal capsules

21
Carpal Tunnel Syndrome
  • Nerve Conduction Studies
  • Demonstrate focal slowing of median nerve fibers
    across the carpal tunnel.
  • Exclude median neuropathy at elbow
  • Exclude cervical radiculopathy
  • Check for coexisting polyneuropathy

22
Carpal Tunnel Syndrome Nerve Conduction Studies
Sensory
Motor
23
Carpal Tunnel Syndrome
  • Treatment
  • Splint
  • Physiotherapy
  • Steroid injection
  • Surgery

24
Ulnar Neuropathy at Elbow
  • The second most common nerve entrapment
  • Ulnar groove/ Cubital tunnel
  • Localisation may be difficult

25
Ulnar Neuropathy at Elbow
  • Sensory disturbance in digit V medial side of
    digit IV
  • Pain at elbow
  • Wasting of small muscle of hand
  • Weakness
  • Differential Diagnosis
  • C8-T1 root lesion
  • Lower trunk/ medial cord plexopathy

26
Ulnar Neuropathy at Elbow
  • NCS Localisation/ prognostic/ exclude other
    condition
  • Treatment
  • - Avoid predisposing factors
  • - Surgical/ transposition

27
Other Type of Peripheral Nerve Lesion
  • Diffuse peripheral neuropathy
  • Acquired (GBS) / Hereditary (CMT)
  • Mononeuritis Multiplex Due to vasculitis
  • Nerve injury

28
Neuromuscular Junction Disorder
  • Presynaptic
  • . Lambert-Eaton-Myasthenic Syndrome
  • . Botulism
  • . Black Widow Spider
  • Postsynaptic
  • . Myasthenia Gravis
  • . Snake Venom
  • . Organophosophorous

29
Neuromuscular Junction Disorder
  • Myasthenia Gravis
  • Autoimmune disease caused by antibodies against
    Acetyl choline receptors.
  • Muscle fatigue and weakness
  • Ptosis, extraocular ophthalmoplegia, bulbar and
    proximal muscle weakness.
  • Mestinon test, A.Ch receptors Ab,
  • NCS RNS/ SFEMG
  • Pyridostagmine, immunosupression, plasma
    phoresis.

30
Myopathy
  • Muscular Dystrophy
  • Congenital myotubular myopathy
  • Inflammatory polymyositis, Dermatomyositis, IBM
  • Toxic Statin
  • Metabolic Acid maltase deficiency McArdles
    disease
  • Endocrine Excessive of steroid
  • Presentation Weakness, Fatigue, Muscle ache

31
Myopathy Examples

Dermatomyositis Inclusion Body Myositis
Myotonic Dystrophy
  • Investigation NCS EMG/ CK/ Muscle biopsy/
    Genetic testing.

32
Role of Nerve Conduction Studies and
Electromyography (EMG) in Clinical Practise
  • Localization of the lesion
  • Underlying pathophysiology
  • Assessment of the severity correlation with
    clinical symptoms
  • Assessment of temporal course

33
Underlying pathophysiology
  • Demyelinated/ Axonal/ Mixed
  • Type of fibres motor/ sensory
  • Acquired/ Hereditary

34
Role of Nerve Conduction Studies and
Electromyography (EMG) in Clinical Practise
  • Localization of the lesion
  • Underlying pathophysiology
  • Assessment of the severity correlation with
    clinical symptoms (mild, moderate, severe)
  • Assessment of temporal course

35
Role of Nerve Conduction Studies and
Electromyography (EMG) in Clinical Practise
  • Localization of the lesion
  • Underlying pathophysiology
  • Assessment of the severity correlation with
    clinical symptoms
  • Assessment of temporal course (Acute, Subacute,
    Chronic)

36
Approach to the patient
  • 1- History and directed examination
  • presenting complain/ drug history/ past medical
    and surgical history/ family history/
    neurological examination
  • 2- Formulate differential diagnosis
  • 3- Formulate study based on differential
    diagnosis
  • 4- Explain test to the patient
  • 5- Perform NCS
  • 6- Perform needle EMG.

37
Explain test to the patient Expectation!
  • NCS EMG tests are designed to assess the
    function of nerve muscles
  • Tiny electric pulse to stimulate the nerves which
    may produce twitching of the muscle or tingling
    on skin. It is uncomfortable. Few patients find
    it painful
  • EMG is fine needle electrode (wire) is placed
    into muscles being examined.
  • The EMG may be repeated for different muscles
  • Length of test from 30-60 minutes, but may be
    longer
  • Loose fitting clothes
  • No moisturiser cream
  • Infection, Warfarin, Cardiac pacemaker

38
Nerve Conduction Studies Technical issue
39
Perform NCS Sensory nerve conduction studies
40
(No Transcript)
41
Perform NCS Motor Nerve Conduction Studies
42
Perform NCS Late responses
43
Repetitive Nerve Stimulation Neuromuscular
Junction Disorder
44
Blink Reflex Trigeminal Facial Nerves
45
Perform needle EMG
46
Special Considerations
  • Age
  • Paediatrics
  • Immature nerves after birth (incomplete
    myelination). 3-5 years become mature.
  • The test should be quick and focusing to answer
    the questions with minimum nerve conduction
    studies.
  • Elderly
  • - Motor Sensory (fibres loss) responses drop
    with age

47
Special Considerations
  • Temperature
  • hand feet temperature affect in the conduction
    (cold temp. slow it) as well as the amplitude
    (increases by cold limbs) of the nerve conduction
    studies
  • Affects other electrodiagnostic techniques (EMG
    RNS for myasthenia Gravis)
  • Height
  • Intensive Care Unit Noises from ITU machine

48
Precaution/ Contraindications
  • Risk of bleeding warfarin, haemophilia
  • Infection MRSA/ C-diffi, skin infection
  • ITU Proximal stimulation (with central line)
  • Pacemaker/ Defibrillator
  • Pregnancy?? !! In February 2007 American
    Association of Neuromuscular Electrodiagnostic
    Medicine (AANEM) found no contraindications to
    performing needle electromyography (EMG) and
    nerve conduction studies on pregnant patients.

49
Result
  • Clinical History
  • NCS EMG findings
  • Comments/ Conclusions

50
Conclusion
  • Nerve Conduction Studies and EMG are helpful to
    find out the site and nature of lesion. And, have
    some prognostic values
  • These tests should be taken in conjunction with
    the clinical context.

51
Thank You
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