Didynamic Currents

Didynamic Currents

It is basically a variation of sinusoidal currents. Sinusoidal currents are alternating low frequency currents, having frequency of 50 Hz and pulse duration of 10 msec, providing 100 stimuli / sec.

Physical properties:

There are five different currents available for didynamic therapy.

1. DF (Fixed di-phase):

Full-wave rectified alternating current, with a frequency of 50 Hz.

2. MF (Fixed mono-phase):

Half-wave rectified alternating current, with a frequency of 50 Hz.

3. CP (Short periods):

I-sec DF I-sec MF I-sec DF

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Equal phases of DF and MF, alternating without interval pauses.

4. LP (Long periods):

10-sec MF 5-sec DF 10-sec MF

It includes 10-sec phase of MF, followed by 5-sec phase of DF, in which peak intensity is varied with a frequency to rise and then fall.

5. RS (Syncopal Rhythm):

It comprises 1-sec phase of MF, followed by a 1-sec rest phase.

Physiological Effects:

The main effect is pain relief through:

* Pain masking (increase of the stimulation threshold): By DF current, stimulation of the sensory nerves may not always cause excitation but it can be altered.

* Vasodilatation and hyperemia: Due to release of histamine in the tissues. The same can occur in deeper structures by reflex activity.

* Muscle fibers stimulation: Didynamic current stimulates the muscle fibers, causing muscle contraction. CP and LP currents stimulate increase blood flow to the muscle and reduce edema.

* Stimulation of vibration sense: This leads to central masking of pain sensation.

Indications:

Didynamic stimulation causes relief of pain and edema in the following conditions:

- Soft tissue injury (sprains, strain, contusion and epicondylitis).

- Joint disorders (post-immobilization and arthritis).

- Circulatory disorders (Raynaud's disease and migraine).

- Peripheral nerve disorders (neuralgia and sciatic neuritis).

Contraindications:

* Open skin: The current tends to concentrate at this point; small broken areas can be insulated by Vaseline.

* Bony areas: It may produce burn.

* Loss of sensation: It can produce burn.

* Skin lesions: Eczema fungi can be irritated and made worse.

* Infections: It may cause spreading of infection.

* Thrombosis.

* Cardiac pace makers.

* Superficial metal.

Dosage:

* Intensity: It should be increased gradually until definite vibration or prickling sensation occurs.

* Duration: Not more than 12 minutes; each type for 3 minutes.

* Frequency: Daily or every other day for 12 sessions.

- DF: It is used for the initial treatment and before application of other currents. The patient feels a prickling sensation, which subsides after a short time.

- MF: The patient feels a strong vibration for longer time than the sensation of DF. It is used for treatment of pain without muscle spasm.

- CP: In DF phase, there are fine tremors in MF phase (strong and constant vibration). There are rhythmic contractions, being used for treatment of traumatic pain.

- LP: It has a long-lasting analgesic effect. It is used with combination of CP in treatment of neuralgia.

- RS: It can be used for faradic stimulation of the muscle and as a test for motor nerve excitability.

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