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electrodiagnosis 2 - Coggle Diagram

- - - - A computer & the associated hardware & software
      - recording electrodes
        
        surface electrodes
        -ring or disk electrodes,
        -disposable or non-disposable
        
        needle electrodes:
        -monopolar
        -bipolar
        -or concentric
        
        EMG
        
        Active (needle electrode)
        
        reference (surface electrode)
        
        ground (surface electrode)
        
        pics
        
        amplifiers
        
        magnify the signal so that it can be displayed
        
        preamplifiers attenuate the biological signal before it gets to the amplifier
        
        filters
        
        are used to reproduce the signal we want while trying ti exclude both high & low frequency electrical noise
        
        display system
        
        vedio or computer screen
    - - can be divided unto 4 components
        
        insertional activity
        
        examination of ms at rest
        
        analyzing the motor unit
        
        recruitment
      - 1.insertional activity
        
        if the needle is properly placed the ms you are testing you will hear & see brief electrical activity associated with the needle movement.
        this is called insertional activity
        
        the sound associated with this needle movement has been described as ' crisp' & it's temporally related to the high-frequency positive response & negative spikes that are easily visualized on the monitor.
        
        normal insertional activity typically only lasts a few hundred milisecs, just barely longer than the needle movement itself
        
        decreased insertional activity occurs when the needle is inserted into an atrophied ms
        
        increased insertional activity may occur
        when there is ms pathology
        & is evidenced by
        the presence of positive sharp waves
        & sometimes fibrillation potentials that are apparent only on insertion & do not persist.
        
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        2.examination of ms at rest
        
        normal ms
        
        spontaneous activity
        
        spontaneous activity generated by the muscle
        
        fibrilation potentials (fibs)
        
        positive sharp waves (PSW)
        
        myotonic discharges
        
        complex repetitive discharges
        
        Fibrillation potentials (fibs)
        
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        spontaneous activity generated by the nerve
        
        myokymic discharges
        
        cramps
        
        neuromyotonic discharges
        
        tremors
        
        multiples ( multiple motor unit potentials, ie, doublets or triplets
        
        fasciculations (can be considered muscle or nerve generated)
        
        Myokymic discharges
        
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        is typically abnormal & occurs in the presence of pathology
        
        should be electrically silent after needle insertion
      - 3.analyzing the motor unit
        
        minimally contract the muscle.
        
        Amplitude:
        
        Amplitude of the motor units may be
        
        increased
        
        Increased amplitude of motor units
        can be seen with reinnervation
        
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        decreased
        
        may be seen in myopathies.
        
        normal
        
        Rise Time:
        
        An acceptable rise time is 0.5 milliseconds or less.
        
        Duration:
        
        Normal duration is about 5–15 milliseconds.
        
        Phases:
        
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      - recruitment
        
        Recruitment refers to the orderly addition of motor units
        so as to
        increase the force of a contraction.
        
        A contraction becomes stronger in 2 ways:
        
        the firing motor units incr their rate of firing
        
        additional motor units commence firing.
        
        Normally the motor unit will fire in a regular pattern at about 5Hz.
        
        At around 10 Hz - another MUAP will be recruited to fire.
        
        Neuropathic recruitment, also called neurogenic recruitment, can be seen in:
        
        neuropathies,
        
        radiculopathies,
        
        motor neuron disease and
        
        nerve trauma.
        
        Few motor units fire at an
        
        increased rate, or firing frequency.
        
        The firing rates of these MUAPs are greater than 20 Hz (20 cycles per second)
        and may increase to over 30 Hz or more.
        
        Myopathic MUAPs
        tend to have an early recruitment of
        
        short duration low amplitude MUAPs
        
        firing at increased rates.
        
        Polyphasicity and spontaneous potentials
        can be seen in both
        neuropathies and myopathies.
        
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