Neuromuscular Stimulation

Neuromuscular Stimulation

1. Russian

   • What is it?
     • a high energy pulsed alternating current designed to stimulate motor nerves and muscle fibers
       • muscle frequency alternating current (MFAC)
         • carrier frequency is preset or can be set
       • duty cycle varies
     • burst frequency - packages of AC current
     • ON:Off ratio - Work:rest ratio
     • ramp time
   • Medium frequency alternating current (MFAC)
     • uses medium carrier frequency
       • 2500-10000 Hz
       • higher frequency meets less skin resistance - will likely go deeper into tissue
         • Deep muscle > or equal to 5000 Hz
     • duty cycle
       • calculated w/ continuous alternating current
         • so the stimulation is not uncomfortable - it is an internal time (ON/ON + OFF) = %
           • increases comfort allowing maximum contraction and comfort
     • Phase duration aka duty cycle
       • higher duty cycle is not always better but will deliver more energy
       • 100% - a continuous alternating current not available for muscle
       • 40-50%: most machines preset here but may allow 10-50%
   • Evidence Based Medicine
     • burst frequency is set for the type of stimulus you want: Twitch, tetany, or fatgiue
     • ON:OFF times for work to rest ratio
       • on time is when the current is provided
       • off times set for rest
       • mimics repetitions and rest
         • re-education - 1:1 of 1:2
         • atrophy reduction - 1:4 or 1:5
         • total duration along with ON:OFF ratio set determines the # of repetitions you will do in the tx

2. HiVolt for muscle contraction

   • interphase interval
   • Theratouch 7.7; RichMar and Winner; Intellect and Vectra
     • cant change
       • phase duration = 50 microseconds
       • interpulse interval = 100 microseconds
   • high voltage monophasic pulsed currents
     • variable interphase interval from 10-20 microseconds

3. Patterned electrical nerve stimulation (PENS)

   • Omnistim machines
     • form of muscle stimulation that replicates the correct firing patterns of muscle
     • precise reproduction of EMG firing patterns of agonist and antagonist muscle pairs
       • agonist/antagonist/agonist - "triphasic"
     • precisely timed input to the nerves and muscle stretch receptors
       • Goal to re-establish proper firing sequence in the spinal and supraspinal central pattern generators
         • reboot of spinal reflex system an may have an effect on corticospinal activity
   • Can ehnace correction of foot drop, walking speed, and balance in individuals with hemiparesis
   • combining w/ voluntary muscle contractions in untrained and/or injured pts
     • PENS trained muscle will "learn" the firing pattern associated with "trained" muscle
   • What is changing with the neuromuscular system
     • Ca2+ channels - accumulation
     • interneuron efficiency
     • central control improving
     • decreasing chronic inflammation stimuli
   • Recent research
     • active changes - a single bout of isometric training combined with PENS increased voluntary extension torque
       • neuromuscular efficiency: motor unit recruitment, median firing frequency and motor unit synchronization
       • decrease of inhibitory signals - interneuron efficiency