Definition:
Are those current in which direction of electrons flow changes periodically with frequency varies from 1-2000 Hz.

Types:
v Faradic current
v Diadynamic current
v Galvanic current
v Sinusoidal current
v High voltage pulsed galvanic current


Faradic Current

§ Is a short duration interrupted direct currents with a pulse duration ranging from 0.1-1ms & a frequency of 50-100 Hz.

§ Faradic currents are always surged for ttt purposes to produce a near normal titanic- like contraction & relaxation of ms.

§ Surging current means the gradual increase & decrease of peak intensity.


Physiological effects:

1. Stimulation of sensory nerves is not very marked because of the short duration it causes reflex vasodilatation of the superficial blood vessels leading to slight erythema. The vasodilatation occurs only in the superficial tissues.

2. Stimulation of the motor nerves, if the current of sufficient intensity, causes contraction of the muscle which they supplied by the nerve distal to the point of stimulus. The contraction is titanic because the stimulus repeated 50 times or more/s if this type is maintained for more than short time, muscle fatigue is occurred. So the current is commonly surged to allow for muscle relaxation i.e. when the current is surged the contraction gradually increase and degrease in strength. In a manner similar to voluntary contraction.

3. Stimulation of the nerve is due to producing a change in the semi-permeability of the cell membrane by altering the resting membrane potential when it reaches a critical excitatory level; the muscle supplied by the nerve is activated to contract

4. Faradic currents will not stimulate denervated muscle. the nerve supply must be intact to the muscle being treated because the intensity of current needed to depolarize the muscle membrane is too great be comfortably tolerated by the patient (in the absence)

5. Reduce swelling and pain due to alteration of the permeability of the cell membrane leading to acceleration of fluid movement in the swollen tissue & arterial dilatation increase metabolism and get red of wastes

Types of mode:
1. Continues mode:
A.C. at 50 Hz producing a constant contraction of normally innervated musculature (to obtain relaxation in muscle spasm)

2. Surged mode:
In A.C. to stimulate muscle for exercise purpose peak is reached microseconds with relative slowness to stimulate slow fibers

3. Interrupted or pulsed mode:
A.C. current reaches peak intensity immediately causing brisk response in muscle, this mode is used to stimulate fast fibers e.g athletics.

Indications:
§ Facilitation of muscle contraction when inhibited by pain or recent injury
§ Re-education of a muscle action e.g. flat foot
§ Training a new muscle action e.g. tendon transfer
§ Strengthening and increased muscle bulk
§ Edema reduction

Contraindications:
§ Skin lesions and dermatological disorders
§ Infection
§ Inflammation
§ Thrombosis
§ Marked loss of skin sensation
§ Active T B or cancer
§ Cardiac pace makers (faradic current is not used in area of shoulder or thorax)
§ Thrombophlebitis
§ Unreliable patients
§ Metal implant


Clinical application
Patient preparation:
§ Explain the treatment fully to the patient
§ Position the patient in a comfortable position
§ The skin should be un covered and examined for any contraindications to treatment
§ Reduce the skin-electrode resistance
o Minimize air-electrode interface
o Keep electrode clean of oils, etc.
o Clean the skill on oils, etc.

Equipment preparation:
§ Test the equipment
§ Select the appropriate treatment parameters
§ Always turn the intensity the to zero before beginning of treatment
§ Place the electrodes as for the treatment
o Electrodes placed close together will give a superficial stimulation and be of high density
o Electrodes spaced far apart will penetrate more deeply with less current density
o Generally the larger the electrode the less density. If a large “dispersive” pad is creating muscle contractions there may be areas of high current concentration and other areas relatively inactive, thus functionally reducing the total size of the electrode
o A multitude of placement techniques may be used to create the clinical and physiological effects you desire
§ Never lift the active electrode from the skin without turning intensity to zero
§ Increase intensity gradually until the desired response is produced



Types of electrodes:
1. Carbon- rubber electrode
2. Pen electrode (used in facial)


Duration of ttt:
15-20 min. can be repeated daily or alternative days according to the case.

Instructions giving to the patient:
§ there is a mild pricking sensation will be felt
§ there should be no sustained intense pricking or burning sensation
§ not to touch any equipment if power from main source is used
§ not to move during ttt
NB:
§ Wet spongy pads are used to place electrodes in


§ The active electrode is placed on motor points
§ Motor points are certain points on our body where faradic stim. of enervated ms can be elicited with least intensity.
§ Motor points are located over the belly of the ms at junction between upper & middle third.


Galvanic current

- It is a direct Current used to activate muscle directly, without activation of the peripheral nerve.
- Direct muscle stimulation requires pulse or phase durations of at least 1 milliseconds, and more often uses even longer durations.
Evidence for:
  • appropriate electrical stimulation can cause a denervated muscle to contract
  • contraction of a denervated muscle may help limit edema and venous stasis within the muscle, and therefore delay muscle fiber degeneration and fibrosis
  • recovery time following denervation appears to be shortened with appropriate electrical stimulation
Evidence against:
  • contraction of the denervated muscle may disrupt regenerating neuromuscular junctions and subsequently delay re-innervation
  • denervated muscle is more sensitive to trauma than innervated muscle, and electrical stimulation may further traumatize the denervated muscle
  • prolonged electrical stimulation until reinnervation occurs is not worth the financial and time costs involved
  • High Voltage Pulsed Galvanic Stimulation

- High voltage pulsed galvanic stimulators provide a high voltage current with a high peak intensity and very short duration, the peak intensity can reach 300 to 400mA. The pulse duration lies between 50 and 100μs

Physiological Effects

§ Physiological response can be excitatory and non-excitatory
§ Excitatory
o Peripheral nerve stimulation for pain modulation (sensory, motor and pain fibers)
o Promote circulation: inhibits sympathetic nervous system activity, muscle pumping and endogenous vasodilatation
§ Non-Excitatory (cellular level)
o Protein synthesis
o Mobilization of blood proteins
o Bacteriocyte affects (by increased CT micro-circulation there is a reabsorption of the interstitial fluids)

Indications:
¨ muscle reeducation (requires 150V)
¨ nerve stimulation (requires 150V)
¨ edema reduction
¨ pain control
¨ Healing of ulcers



Contraindications:
¨ Cardiac disability
¨ Pacemakers
¨ Pregnancy
¨ Menstruation
¨ Cancerous lesion
¨ Infection
¨ Metal implants
¨ Nerve sensitivity

Treatment Duration
l General - 15-30 minutes repeated as often as needed
l Pain reduction - sensory 30 minutes with 30 minute rest between tx


Application Techniques
v Monopolar: 2 unequal sized electrodes. Smaller is generally over the treatment site and the large serves as a dispersive pad, usually located proximal to the treatment area
v Bipolar: two electrodes of equal size, both are over or near the treatment site
v Water immersion - used for irregularly shaped areas
v Probes: one hand-held active lead
l advantages: can locate and treat small triggers
l disadvantages: one on one treatment requires full attention of the trainer



Diadynamic Current

Definition
Is a type of low frequency current involves a single or double phase rectification of an alternating current introducing them in a continuous or combined form to produce sensory or motor effect.
Physical Properties
§ Fixed Diphase (DF): This a full wave rectified alternating current with a frequency of 50 Hz.

§ Fixed Monophase (MF): This a half wave rectified alternating current with a frequency of 50 Hz.

§ Short Period (Courtes Periods CP): Equal phases of DF and MF are alternated without interval pause.

§ Long period (Longue Periods LP): This consists of 10 seconds of MF, followed by a5 second phase of DF in which the peak intensity is varied , with a tendency to rise and fall

§ Rhythmic Syncope (RS): This consists of 1 second MF followed by a1 second rest phase.
Physiological effects
§ Masking: DF current is effective in masking pain. Sensory stimulation may not always cause excitation, but its excitability is altered so that the stimulation threshold is raised
§ Vasomotor effects: There are vasodilatation and hyperemia
§ Muscle stimulation: Particularly with CP and LP
§ Stimulation of vibration sense

Indications
§ Relief of pain and edema
§ Soft tissue injuries as sprains , strains and contusions
§ Joint disorders, post immobilization and arthritis
§ Circulatory disorders- Raynaud disease, migraine
§ Peripheral vascular disorders as neuralgia, neuritis, herpes zoster and radiculopathy

Contraindications
§ Skin lesions and dermatological disorders
§ Infection
§ Inflammation
§ Thrombosis
§ Marked loss of skin sensation
§ Active T B or cancer
§ Cardiac pace makers (faradic current is not used in area of shoulder or thorax)
§ Thrombophlebitis
§ Unreliable patients
§ Metal implant

Methods of application
§ Pain spot application: The two electrodes may be placed as bipolar technique with the anode applied over the painful spot and the cathode adjacent to it

§ Nerve trunk application: The two electrodes are placed along the course of appropriate peripheral nerve where the nerve lies superficially

§ Para vertebral application: The two electrodes are placed on both sides of the spine at the level of nerve root

§ Vasotropic application: The electrodes are placed along the vascular path in case of vascular disorders

§ Myo-energitic application : Two electrodes are placed on each side of muscle belly or one electrode on motor point and the other proximal to it ( Monopolar technique)

§ Trans regional technique :Electrodes are placed on either side of the joint

Current type

§ DF is primarily used for the initial treatment and before the application of other currents. It is also used in the treatment of circulatory disorders .The patient should feel a prickling sensation

§ MF is used for the treatment of pain without muscle spasm

§ CP is used for the traumatic pain

§ LP is used mainly for the myalegia

§ RS is used for faradic stimulation

Duration
Treatment should not exceed 10 to 12miutes .Most single applications are given for 3 minutes
Frequency
Generally 6or 7 treatments are given daily or every second day


Sinusoidal Current

§ Sinusoidal current is an alternating low frequency current.
§ It has a frequency of 50 Hz and pulse duration of 10ms providing 100stimuli per second
§ Sinusoidal current may be used as surged or un surged

Physiological effects
§ Effects on Sensory and motor nerves
§ Muscle contraction
§ Prickling sensation
§ Vasodilatation

§ Effects on the tissue of the body
§ If there is any swelling or inflammatory exudates, an unsurged sinusoidal current will help absorption of the exudates

Indications
§ Relief of pain (10 m application can relieve pain for 30 m)
§ Decrease swelling

Contraindications
§ Skin lesions
§ Infection
§ Impaired sensation