Neurodyn II

The equipment

NEURODYN II transcutaneous neuromuscular stimulator is a four-channels stimulator with independent controls for current therapies using: RUSSIAN CURRENT (Medium Frequency Current modulated in Burst), FES CURRENT (Functional Electrical Stimulation), TENS CURRENT (Transcutaneous Electrical Nerve Stimulation

The equipment is for use only under the prescription and supervision of a licensed professional.

Technical features

Electric Descripition

  • Input: 100 – 240 V ~ 50/60 Hz

  • Input power: 85 VA

  • Electric class: CLASS II

Dimension of equipment
Widht 10.4 in (26.4cm)
Depth 10.3 in (26.1cm)
Height 4.6 in (11.6cm)
Net weight 1.5 kg

Russian Current

  • The frequency for Russian is fixed; therefore, the rate of polarity inversion is also fixed. The frequency is 2500 Hz which represent a period of 0.4ms, so this inversion occurs at every 0.2ms.

  • Minimum

    Russian Fixed at 2500 Hz/ period =0.4ms /polarity inversion = 0.2ms

  • Maximum

    Russian Fixed at 2500 Hz/ period =0.4ms /polarity inversion = 0.2ms

  • For TENS and FES currents, the frequency can be adjusted by the user; therefore, the polarity varies according to the frequency. The frequency may be adjusted between 0.5 to 250 Hz which represents a period from 2s to 4ms, so the polarity inversion may vary between 1s to 2ms.

  • Minimum

    TENS and FES Frequency minimum = 0.5 Hz /period = 2s / polarity inversion =1s

  • Maximum

    TENS and FES Frequency maximum = 250 Hz /period = 4ms / polarity inversion =2ms

  • Between the minimum and maximum frequency, the polarity changes by 1 seconds to 2 milliseconds for TENS/FES and 0.2milliseconds for Russian.

    For example: (Frequency =250Hz):

    Period = 1/Frequency

    Period = 1/250 Period =4milliseconds

    Polarity Inversion = Period/2

    Polarity Inversion = 4/2, Polarity Inversion =2milliseconds

  • The polarity changes through the type of current and frequency chosen (i.e. Russian, TENS or FES) . There is no direct option to control the polarity. The rate charge depends on the frequency set by the User. There are no specific modes to have the polarity changed by the user.

TENS Symmetrical Biphasic

  • Output Mode: Electrodes

  • Output Intensity (CC*): 0-120 mA peak to peak

  • Frequency: 0,5-250 Hz

  • Phase Duration Adjustable: 50-500 μs

  • Burst Frequency: 2 Hz

  • Modulation of Burst Frequency: 250 Hz

  • Frequency/Phase Duration Variation: VIF

  • VIF Frequency: 2-247 Hz

  • VIF Phase Duration: 50-500 μs

  • Current Mode

    Conventional (Normal): Tens (R 0.5-250 Hz; T 50-500 μs)

    Burst Modulation: Tens Burst (R 250 Hz; T 50-500 μs)

  • Treatment Duration: 1-60 min

  • Set Intensity: Individual channel intensity setting 1, 2, 3 or 4.

Functional Electrical Simulation

  • Output Mode: Electrodes

  • Output Intensity (CC*): 0-120 mA peak to peak

  • Frequency: 0.5-250 Hz

Current Mode

  • Synchronous: FES Sync (1, 2, 3 &4 channel)

  • Reciprocal: FES Rec (1&3, 2 & 4 channel)

  • Frequency/Phase Duration Variation: VIF (R 2-247 Hz; T 50-500 μs)

  • Phase Duration: 50-500 μs

  • VIF Frequency: 2-247 Hz

  • VIF Phase duration: 50-500 μs


  • Rise (Time of Increase Gradient): 1-9 s

  • On (Time of Muscular Contraction): 1-60 s

  • Decay (Time of Decrease Gradient): 1-9 s

  • Off (Time of Muscular Relaxation): 1-60 s

  • Treatment Duration: 1-60 min

  • Set Intensity: Individual Channel Intensity Setting

  • Available on Channels: 1 or 2

Russian Current

  • Output Mode: Electrodes

  • Output Intensity (CC*): 0-120 mA peak to peak

Current Mode

  • Continuous: Russa Cont (1, 2, 3 & 4 channel)

  • Synchronous: Russa Sync (1, 2, 3 & 4 channel)

  • Reciprocal: Russa Rec (1 & 3, 2 & 4 channel)

  • Duty Cycle: 10%, 20%, 30%, 40% or 50%

  • Burst Frequency: 10-100 Hz (steps of 10 Hz)


  • Rise (Time of Increase Gradient): 1-9 s

  • On (Time of Muscular Contraction): 1-60 s

  • Decay (Time of Decrease Gradient): 1-9 s

  • Off (Time of Muscular Relaxation): 1-60 s

  • Treatment Duration: 1-60 min

  • Set Intensity: Individual Channel Intensity Setting

  • Available on Channels: 1 or 2

Mechanisms of action and Physiological effects

Currently, electrotherapy or therapy using electrical currents has been widely used in the context of rehabilitation, with satisfactory clinical results. These currents are classified according to their frequencies: low frequency (up to 1000 Hz), medium frequency (1000 Hz to 100 KHz) and high frequency (greater than 300 KHz).


Depending on the therapeutic objective, the current is chosen as well as the selection of its parameters. In lower stimulus there is a sensory stimulation without muscle contraction and in higher stimulus, the motor threshold is reached, leading to physiological mechanisms that generate muscular contraction. Among the therapeutic objectives, we have: analgesic, excitomotor, anti-inflammatory effects; muscular strength gain, range of motion and improvement of function.

Russian Current

The Russian current is defined as an alternate current of medium frequency (2.5 kHz), which provides a greater depth range, due to its lower resistance, thus contributing to a greater recruitment of motor units without significant discomfort to the patient. Their bursts have rectangular or sinusoidal shapes. It is an excitomotor current that uses surface electrodes for its application. The mechanism of action is the depolarization of the lower motor neuron, generating muscular contraction in the muscles that present their full motor innervation. It is used in therapies whose objectives are: prevention or delay of atrophy due to disuse, motor re-education, increase of muscular torque, maintenance or increase in range of motion, relaxation of muscle spasms, increasing local blood flow.

FES Current

The Functional Electrical Stimulation (FES / EMS) is a low frequency electrical current (approximately 1 to 100Hz), which has the following characteristics: alternate, depolarized, with symmetrical pulses.

This electrical stimulation generates an evoked potential of action that will act at the motor level, in a bidirectional way, leading to a depolarization of the motor neuron. This potential of action passes through the neuromuscular junction, reaching the motor neuron; as a result, the plastic membrane generates an action that will spread through the T tubules, thereby causing the release of calcium from the endoplasmic reticulum. This will then stimulate muscular contraction, by means of synchronous stimulation of the motor units. This synchronism leads to an efficient muscular contraction.

FES / EMS is used in rehabilitation for the purpose of preventing or delaying atrophy due to disuse, motor re-education, increasing muscular torque, maintenance or increase of joint movement amplitude, relaxing muscle spasms and increasing local blood flow.

TENS Current

The Transcutaneous Electrical Stimulation (TENS) is a low-frequency current, very common in rehabilitation for the purpose of analgesia.

A physiology of the action of TENS is explained by “floodgate theory”, where the transcutaneous electrical stimulus, activates the larger caliber mechanoreceptor fibers that send signals in the posterior horn of the spinal cord before smaller caliber fibers. Occurs then a depolarization of the gelatinous substance and a modulation of the stimulus in the spinal cord, which causes inhibition of the nocioreceptive stimulus. With the faster arrival of the proprioceptive stimulus in the posterior horn of the spinal cord, will occur activation of interneurons besides the release of opiate substances, such as: endorphins, dynorphins, enkephalins, noradrenaline and serotonin; these substances, acting as inhibitory neurotransmitters.

This way, TENS therapy is used in the symptomatic treatment of intractable chronic pain, relief of postoperative acute pain and increasing local blood flow



  • Temporary relaxation of muscle spasms

  • Prevention or retardation of disuse atrophy in post-injury type conditions.

  • Increase local blood circulation.

  • Muscle re-education.

  • Maintaining or increasing range of motion.


  • Stimulation of leg and ankle muscles of partially paralyzed patients to provide flexion of the foot, thus improving the patient’s gait.


  • Symptomatic relief of chronic intractable pain.
  • Post-traumatic acute pain.
  • Post-surgical acute pain.

Powered muscular stimulators should be used only under medical supervision as an adjunctive therapy for the treatment of medical diseases and conditions.



Do not use this device on patients who have a cardiac pacemaker, implanted defibrillator, or other implanted metallic or electronic device because this may cause electric shock, burns, electrical interference, or death. Do not user this device on patients whose pain syndromes are undiagnosed.


Do not apply stimulation over the patient’s neck because this could cause severe muscle spasms resulting in closure of the airway, difficulty in breathing, or adverse effects on heart rhythm or blood pressure;

Do not apply stimulation across the patient’s chest, because the introduction of electrical current into the chest may cause rhythm disturbances to the patient’s heart, which could be lethal;

Do not apply stimulation over open wounds or rashes, or over swollen, red, infected, or inflamed areas or skin eruptions (e.g., phlebitis, thrombophlebitis, varicose veins);

Do not apply stimulation over, or in proximity to, cancerous lesions;

Do not apply stimulation in the presence of electronic monitoring equipment (e.g., cardiac monitors, ECG alarms), which may not operate properly when the electrical stimulation device is in use;

Do not apply stimulation when the patient is in the bath or shower;

Do not apply stimulation while the patient is sleeping;

Do not apply stimulation while the patient is driving, operating machinery, or during any activity in which electrical stimulation can put the patient at risk of injury.

Consult with the patient’s physician before using this device, because the device may cause lethal rhythm disturbances to the heart insusceptible individuals;

Apply stimulation only to normal, intact, clean, healthy skin.

Adverse reaction

Patients may experience skin irritation and burns beneath the stimulation electrodes applied to the skin;

Patients may experience headache and other painful sensations during or following the application of electrical stimulation near the eyes and to the head and face;

Patients should stop using the device and should consult with their physicians if they experience adverse reactions.

Application techniques

The electrodes placement can be performed using the bipolar or monopolar technique. The adequate positioning and contact of the electrodes will assure comfort and efficacy of treatment.

Examine the skin for any wounds and clean the treatment area by rubbing the skin with medical grade alcohol.

Remove the self-adhesive electrodes from the protective backing and apply to the treatment area as prescribed.

Ensure the entire electrode surface is in contact with patient skin by pressing into place.

Check the electrode contact regularly during treatment.

Examine the skin again after the treatment.