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(EMG examination) - Coggle Diagram

- - - - 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.
    - - decreased insertional activity
        
        increased insertional activity
        
        any electrical activity that lasts longer than 300 ms is considered increased
        
        graph
        
        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.
        
        occurs when the needle is inserted into an atrophied ms
      - typically only lasts a few hundred milisecs, just barely longer than the needle movement itself
  - - - should be electrically silent after needle insertion
    - - spontaneous activity
        
        spontaneous activity generated by the muscle
        
        Fibrillation potentials (fibs)
        
        PSWs
        
        Myotonic discharges
        
        CRD
        
        1 more item...
        
        Myotonic discharges are the action potentials of ms fibers firing in a prolonged fashion after activation.
        
        Clinically this is seen as delayed relaxation of a ms after a forceful contraction.
        
        Pattern of biphasic or triphasic potentials.
        
        These potentials tend to fire
        at a variable rate with a waxing and waning appearance.
        
        The frequency varies between 20 to 100Hz;
        
        ‘dive bomber’ sound.
        
        2 more items...
        
        positive sharp waves (PSWs) are ms fiber action potentials that can be recorded frm a ms with impaired ms innervation
        or frm an injured potion of a ms.
        
        they tend to fire regularly at a rate of 0.5 to 15 Hz
        
        amplitudes 20-1000microvolts with
        
        durations of 20-30 ms.
        
        PSWs sound like dull thuds.
        
        conditions associated with positive sharp waves & fibrillation potential
        
        2 more items...
        
        graph
        
        are the spontaneous action potentials of single muscle fibers that are firing autonomously.
        
        This can occur in the presence of impaired innervation.
        
        Usually fire in a regular pattern at rates of 0.5–15 Hz,
        
        Usually triphasic in morphology
        
        range from 20 to 1000 microvolts in size.
        
        They sound like raindrops hitting a tin roof.
        
        are of 4 types
        
        fibrilation potentials (fibs)
        
        positive sharp waves (PSW)
        
        myotonic discharges
        
        complex repetitive discharges
        
        spontaneous activity generated by the nerve
        
        Myokymic discharges
        
        Myokymic discharges are groups of spontaneous motor unit
        potentials that have a regular firing pattern and rhythm.
        .
        
        In the continuous form they are seen as single or paired discharges of motor unit potentials that fire
        at rates of 5–10 Hz.
        .
        
        In the discontinuous form they are seen as bursts of motor
        potentials,
        which repeat at 0.1–10 Hz.
        .
        
        sounds like soldiers marching.
        
        Seen in
        
        facial muscles in Bell’s palsy,
        
        multiple sclerosis, and
        
        polyradiculopathy.
        They are also seen in
        
        limb muscles in
        chronic nerve lesions and in radiation plexopathy.
        
        A fasciculation potential
        
        is the potential associated with the
        random and spontaneous activation of a group of muscle fibers
        or all of the muscle fibers originating from a motor unit.
        .
        
        This is generally thought to be due to the abnormal discharge of
        an alpha motor neuron,
        resulting in contraction of all the muscle
        fibers innervated by the motor unit.
        .
        
        They are usually from 0.5 to 3 mv in amplitude and
        -7 to 20 ms duration.
        -The firing pattern is irregular,
        
        has a low frequency of 1 to 2 Hz, and
        .
        
        sounds like a “large raindrops on a tin roof.”
        
        It occur in
        
        benign myokymia and
        
        motor neuron disease.
        
        Endplate Region
        
        MEPPs (miniature endplate potentials)
        
        Endplate spikes
        
        Pain (the patient may feel a dull ache or increased pain relative to other positions).
        
        1 more item...
        
        myokymic discharges
        
        cramps
        
        neuromyotonic discharges
        
        tremors
        
        multiples ( multiple motor unit potentials, ie, doublets or triplets
        
        fasciculations (can be considered muscle or nerve generated)
        
        occurs in the presence of pathology
  - - - Amplitude:
        
        Amplitude of the motor units may be
        
        increased
        
        Increased amplitude
        of motor units
        can be seen with
        
        reinnervation
        
        as is seen with neuropathic
        injuries after a period of months.
        
        decreased
        
        axonal loss
        
        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:
        
        Normally, motor unit potentials have
        
        4 or fewer phases.
  - - - A contraction becomes stronger in 2 ways:
        
        the firing motor units incr their rate of firing
        
        additional motor units commence firing.
        
        normal
        
        Normally the motor unit will fire in a regular pattern at about 5Hz.
        
        At around 10 Hz - another MUAP will be recruited to fire.
        
        abnormal
        
        Neuropathic recruitment, also called neurogenic recruitment
        
        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.
        
        can be seen in:
        
        neuropathies,
        
        radiculopathies,
        
        motor neuron disease and
        
        nerve trauma.
        
        Myopathic MUAPs
        
        tend to have an
        
        early recruitment of
        
        short duration low amplitude MUAPs
        
        firing at increased rates.
        
        graph
        
        Polyphasicity and
        
        spontaneous potentials
        can be seen in both neuropathies and myopathies.