Neurology Book

Cerebrospinal Fluid Disorders

Miscellaneous

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ElectromyogramAka: Electromyography, EMG

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  1. Indications
    1. Muscle disease
    2. Neuromuscular junction disease
    3. Nerve or nerve root disease with denervation
  2. Background
    1. Electrical test to measure muscle physiology
  3. Myopathy Findings
    1. Nonspecific for Myopathy type
    2. Motor unit potential abnormalities
      1. Low amplitude
      2. Short duration
      3. Complex, polyphasic
    3. Increased Insertional activity
      1. Ectopic high frequency discharges
    4. Fibrillation potentials present in some myopathies
      1. Polymyositis
      2. Muscular Dystrophy
  4. Myotonia findings
    1. Waxing and waning hyperexcitability
    2. Repetitive discharges
      1. Electromyogram machine creates "dive bomber" sound
  5. Neuromuscular junction disorder findings
    1. General
      1. Increased variation in muscle response time (latency)
    2. Presynaptic disorders
      1. Examples
        1. Botulism
        2. Eaton -Lambert Syndrome
      2. Findings
        1. Enhanced response to repetitive nerve stimulation
        2. Normal amplitude miniature end-plate potentials
    3. Postsynaptic disorders
      1. Examples
        1. Myasthenia Gravis
      2. Findings
        1. Decreased response to repetitive nerve stimulation
        2. Subnormal amplitude miniature end-plate potentials
  6. Denervation Findings
    1. Increased polyphasic action potentials
    2. Ectopic high frequency discharges
    3. Fibrillations
      1. Onset 3 to 4 weeks after nerve injury
    4. Fasciculations
    5. Positive sharp waves
    6. F Response prolonged (proximal motor nerve reflex arc)
      1. Guillain-Barre Syndrome
    7. Hoffman Reflex (Stretch reflex arc - sensory and motor)
      1. Sensory nerve root lesion
      2. Motor nerve root lesion

Electromyography (C0013839)

Definition (MSH)Recording of the changes in electric potential of muscle by means of surface or needle electrodes.
Definition (CSP)measurement and interpretation of the electrical manifestations of muscle activity.
Definition (NCI)A test that assesses the health of the muscles and the nerves controlling the muscles.
ConceptsDiagnostic Procedure (T060)
ICD993.08
MSHD004576
EnglishELECTROMYOGR, Electromyogram, Electromyographies, Electromyography, EM-Electromyography, EMG, EMG - Electromyography
Spanishelectromiografia, electromiograma
Parent ConceptsElectrodiagnosis (C0013816), electrical measurement (C0596482), Diagnostic physical therapy procedure (C0203886), Myography (C0027081), diagnostic procedure (C0430022), Muscle function study (C0204035), Peripheral neurophysiological procedures (C0430804), Reason not stated concept (C1276325), Procedure by device (C1285536), Duplicate concept (C1274013)
SourcesAOD, CSP, ICD9CM, LCH, LNC, MSH, MTH, NCI, SCTSPA, SNOMEDCT
Derived from the NIH UMLS (Unified Medical Language System)



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