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
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.
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* 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.
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* 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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