why SWD and IFT in sciatica?

[sdkashif]

Whether to use the heat treatment or cold treatment as dealing with the inflammation, it depends upon the nature of inflammation. As in acute trauma or inflammation or during the first 72 hours the principle is R I C E - Rest, Ice, Compression and elevation. And afterwards or in sub acute or chronic inflammation you have to shift the treatment to heating modalities. And Why do therapist prefer SWD, is the reason because the lesion is situated deep and superficial heating agents or superficial modalities do not produce effects in deep tissues at the site of pathology. Both SWD and Interferential therapy produce effects in the deep tissues. That is why they are preferred to the other agents regarding the application. Let us have a look over the effects produced by the SWD and Interferential therapy.

The Use of Heat and Cold in Pain Modulation

Thermal modalities are passive modalities, whether they are applied by the patient or the nurse, physical therapist,
athletic trainer, or parent. It is essential that each patient is evaluated for the cause of pain in order to make an
appropriate clinical decision about the use of passive modalities. The passive role may be appropriate for patients
in acute pain, for those with recurrent pain from reinjury or exacerbation of disease, or for palliative care. Some
modalities may be appropriate for chronic pain, but only if their application is associated with a functional goal, and
are best applied by the patient himself. Self-application of heat or ice can be used to provide symptomatic relief
from pain which permits a more active treatment approach, and can be used as a reward for accomplishing a
functional goal. These modalities are easy to apply, and can be used effectively in an overall plan of care for a
variety of pain patients. They are most often effective in conjunction with techniques of soft tissue mobilization,
exercise, stretching, and stabilization.

Heat

There are three theories of pain relief using heat. The vascular theory is based on the finding that heat application
induces vasodilatation, which can increase tissue blood flow up to 30 ml per 100 g of tissue. The increase in blood flow reduces pain by effectively supplying oxygenated blood and nutrients while washing out metabolites (including those that contribute to nociception, such as K+) accumulated during
muscular activity. Through this mechanism it is expected that there will be an increased potential for edema formation due to the increase in capillary permeability induced by heat.

The counterirritation theory is based on the gate control mechanism originally proposed by Melzack and Wall
(1965). Pain may be modulated by thermoreceptor afferent input which can act as a gating mechanism in the dorsal
horn of the spinal cord at the spinal level of the pain and thermal sensory input. The dual affective stimulation is
said to block pain transmission to higher centers. Also, heating of a painful part can induce whole body relaxation,
perhaps through a descending pain inhibitory pathway which influences the same gate in the dorsal horn, and helps
to inhibit painful muscle spasm or muscle tension.

The third theory involves the direct influence of heat on neuromuscular tissue, including muscle spindles and on
sensory nerve conduction. When animal muscle spindles and exposed nerve endings are directly heated, a
significant decrease in neuronal activity of the secondary endings and an increase in activity of primary endings and
Golgi tendon organs have been measured. This produces a net inhibitory influence of the motor neuron pool that
breaks the vicious circle of pain-spasm-pain. It presumably takes a very intense amount of heat to achieve direct heating of nerves in situ.

Many people associate better penetration with wet heat, rather than dry. Examples of wet heat include hot packs
and whirlpool and dry heat include an infra-red heating lamp, and ultrasound. Dry heat actually elevates skin
temperatures more than deeper structures, while wet heat elevates both skin and deeper tissues slightly more.
A variety of hot packs are commercially available for self-application of heat. Each type has advantages and
disadvantages in terms of price, ease of reuse, temperature control, length of heating, and portability. Patients are
instructed in the use of superficial heat to warm muscles before stretching and exercise, for relaxation, and for
transient pain reduction when there is no edema present. Once patients are instructed in the safe use of superficial
heat, including the appropriate use of a protective barrier such as toweling to prevent burns, patients may be invited
to use heat independently before or after exercise or functional activities.

For acute injuries, heat is contraindicated.Many physical therapists apply ultrasound as a heating modality. It has deeper heating effects, as well as nonthermal benefits, and penetrates to structures such as joints, muscle, and bone. It has been shown in experimental studies to stimulate tissue regeneration and bone growth and increase pain threshold and collagen extensibility.

In a meta-analysis of 22 studies on the effect of ultrasound application in the treatment of musculoskeletal disorders, however, no significant effect of ultrasound on pain reduction was found.

Cold

Cold therapy can be delivered in three basic forms: cold packs, ice massage, or vapocoolant spray. Cold packs are
commercially available or can be made at home with crushed ice, ice cubes, or bags of frozen vegetables (not to be
eaten after use!). Cold packs are useful for postexercise soreness, acute inflammation, or inflammation associated
with edema, and transient reduction of pain (symptomatic relief).

In ice massage, ice is rubbed directly over the skin until numbness is felt. Ice massage delivers cold to a more focal
area with greater efficiency than a cold pack and may also provide more effective counterirritant therapy for pain
relief. Patients are instructed in the safe use of ice massage, the warning signs of frostbite, and the four stages of
sensation during ice massage (cold, burning, aching, and numbness). Ice massage is useful for relaxation, transient
pain reduction, and treatment of local inflammation.
Cold application for pain relief can achieve peripheral or central responses. Brief, intense cold such as that delivered with a vapocoolant spray most likely produces peripheral receptor adaptation. The counterirritation discussed in the section on heat therapy also applies to cold therapy. Brief, intense cold can slow conduction velocity in C fibers carrying nociceptive input to the spinal cord. This action and receptor
adaptation may be the mechanism of the trigger point therapy advocated by Travell and Simons (1983).

For every 1°C decrease in intramuscular temperature, a decrease of 1.2 m per second in motor nerve conduction
velocity and a 2 m-per-second drop in sensory nerve conduction velocity has been rcorded. The “hunting response,” characterized by cold-induced vasodilatation
after an initial vasoconstriction, occurs in the ears, nose, fingers, and toes. This phenomenon is seen when tissue
temperature is reduced by more than 10°C. Under conditions of continued intense cold, this reversal continues as a
cycling of vasoconstriction-vasodilatation, permitting tissue temperature to be kept somewhat constant, although
lower than precooled temperatures.

Prlonged cold can also produce vasodilatation in deeper
muscle tissues and stimulate profound hyperemia (increased blood flow to the effected area) after withdrawal of the
cold .

Which is best, heat or cold?

The choice between using heat or cold for pain should take into account several factors. Heat decreases pain and
induces relaxation. Therefore, it may have a ounterproductive sedative effect if used before exercise. It increases issue extensibility (softer and easier to stretch—think of what happens when mozzarella cheese is warmed), which is advantageous when addressing stiff joints through self-mobilization and stretching. Heat decreases overall
stiffness of musculoskeletal tissues. It may result in edema and should be used carefully if swelling is already a
component of the patient’s problem.

Cold decreases pain and swelling and is especially indicated in an acute injury; however, it increases overall stiffness and decreases tissue extensibility. Some patients have a profound aversion to cold and experience anxiety with its use. Many patients with neuropathic pain do not tolerate cold well.

The clinician should choose a modality based on the patient’s preferences and, in the case of chronic pain, convenience for self-treatment. In pain that has persisted well beyond an expected healing time, the emphasis is not on pain relief, but on using the modality as a method of coping with pain. It should be possible for a patient to learn to safely apply a modality as a specific part of the total pain rehabilitation program.

Interferential Therapy

The basic principle of Interferential Therapy (I/F) is to utilise the strong physiological effects of low frequency (@ <250pps) electrical stimulation of muscle and nerve tissues without the associated painful and somewhat unpleasant side effects of such stimulation.

To produce low frequency effects at sufficient intensity at depth, most patients experience considerable discomfort in the superficial tissues (i.e. the skin). This is due to the resistance (impedance) of the skin being inversely proportional to the frequency of the stimulation. In other words, the lower the stimulation frequency, the greater the resistance to the passage of the current & so, more discomfort is experienced. The skin impedance at 50Hz is approximately 3200W whilst at 4000Hz it is reduced to approximately 40W . The result of applying this latter frequency is that it will pass more easily through the skin, requiring less electrical energy input to reach the deeper tissues & giving rise to less discomfort.

Interferential therapy utilises two of these medium frequency currents, passed through the tissues simultaneously, where they are set up so that their paths cross & in simple terms they interfere with each other. This interference gives rise to an interference or beat frequency which has the characteristics of a low frequency stimulation.

The exact frequency of the resultant beat frequency can be controlled by the input frequencies. If for example, one current was at 4000Hz and its companion current at 3900Hz, the resultant beat frequency would be at 100Hz, carried on a medium frequency 3950Hz amplitude modulated current.

By careful manipulation of the input currents it is possible to achieve any beat frequency that you might wish to use clinically. Modern machines usually offer frequencies of 1-150Hz, though some offer a choice of up to 250Hz or more. To a greater extent, the therapist does not have to concern themselves with the input frequencies, but simply with the appropriate beat frequency which is selected directly from the machine.

Excitable tissues can be stimulated by low frequency alternating currents. Although to some extent, all tissues in this category will be affected by a broad range of stimulations, it is thought that different tissues will have an optimal stimulation band, which can be estimated by the conduction velocity of the tissue, its latency and refractory period. These are detailed below:

Sympathetic Nerve 1-5Hz

Parasympathetic Nerve 10-150Hz

Motor Nerve 10-50Hz

Sensory Nerve 90-100Hz

Nociceptive fibres 90-150Hz (?130Hz specific)

Smooth Muscle 0-10Hz

The clinical application of I/F therapy can be based logically on this data together with a knowledge of physiological behaviour of stimulated tissue. Selection of a wide treatment band can be considered less efficient than a smaller selective band in that by treating with a frequency range of say 1-100Hz, the appropriate treatment frequencies can be covered, but only for a relatively small percentage of the total treatment time. Additionally, some parts of the range might be counterproductive for the primary aims of the treatment.

The are 4 main clinical applications for which I/F appears to be used:

Pain relief

Muscle stimulation

Increased blood flow

Reduction of oedema

In addition, claims are made for its role in stimulating healing and repair.

As I/F acts primarily on the excitable tissues, the strongest effects are likely to be those which are a direct result of such stimulation (i.e. pain relief and muscle stimulation). The other effects are more likely to be secondary consequences of these.

Pain Relief:

Electrical stimulation for pain relief has widespread clinical use, thought the direct research evidence for the use of I/F in this role is limited. Logically one could use the higher frequencies (90-150Hz) to stimulate the pain gate mechanisms & thereby mask the pain symptoms. Alternatively, stimulation with lower frequencies (1-5Hz) can be used to activate the opoid mechanisms, again providing a degree of relief. These two different modes of action can be explained physiologically & will have different latent periods & varying duration of effect. It remains possible that relief of pain may be achieved by stimulation of the reticular formation at frequencies of 10-25Hz or by blocking C fibre transmission at >50Hz.

Muscle Stimulation:

Stimulation of the motor nerves can be achieved with a wide range of frequencies. Clearly, stimulation at low frequency (e.g. 1Hz) will result in a series of twitches, whist stimulation at 50Hz will result in a tetanic contraction. The choice of treatment parameters will depend on the desired effect, but to

combine muscle stimulation with an increase in blood flow and a possible reduction in oedema, there is some logic in selecting a range which does not involve strong sustained tetanic contraction & a sweep of 10-25Hz is often used.

There is no primary nervous control of oedema reabsorption & the direct electrical stimulation of blood flow is limited in its effectiveness. It is suggested therefore that in order to achieve these effects, suitable combinations of muscle stimulation can be made.

Short Wave Diathermy

Short wave diathermy is the therapeutic application of high-frequency currents; it uses radiofrequency electromagnetic fields for therapeutic heating of tissues. For application, it uses capacitor plates or inductive coil applicators.

Continuous shortwave diathermy is the technique of choice when uniform marked elevation of temperature is required in the deep tissues. This heating can be targeted accurately by using an appropriate applicator positioned correctly. SWD also allows superficial structures to be heated selectively, although for this the various methods of surface heating are usually preferable. Sub-acute or chronic conditions respond best to continuous shortwave diathermy which, when used properly, can be as effective as ultrasound. Acute lesions are better treated with pulsed shortwave diathermy. Continuous shortwave diathermy can help to relieve pain and muscle spasm, resolve inflammatory states and reduce swelling, promote vasodilation, increase the compliance of connective tissue, increase joint range and decrease joint stiffness.


Common Indications

Localized musculoskeletal pain

Inflammation (joint or tissue)

Pain/spasm

Sprains/strains

Tendinitis

Tenosynovitis

Bursitis

Rheumatoid arthritis

Periostitis

Capsulitis

Precautions or Contraindications

Malignancy

Sensory loss

Tuberculosis

Metallic implants or foreign bodies

Pregnancy

Application over moist dressings

Ischemic areas or arteriosclerosis

Thromboangiitis obliterans

Phlebitis

Use extreme care with pediatric and geriatric patients

Cardiac pacemakers

Contact lenses

Metal-containing intrauterine contraceptive devices

Metal in contact with skin (eg, watches, belt buckles, jewelry)

Use over epiphyseal areas of developing bones

Active menses


Types of Applications

The condenser field method (commonly used)
Cable method


Where useful?

Inflammation of shoulder joint
Inflammation of Elbow Joint (Tennis Elbow)
Degeneration of joints of neck (Cervical Spondylosis)
Degeneration of joints like knee and hip (Osteoarthritis)
Ligament Sprains in knee joint
Low Back Ache
Plantar fascitis (Heel Pain)
Sinusitis

Where it should not be used?

General

High Fever
Fluctuating Blood Pressure
Very sensitive Skin
Persons with Untreated Fits
Persons using Cardiac Pace Maker
Severe kidney and heart problems
Pregnant Women
Mentally Retarded Individuals
Tuberculosis of Bone
Malignant cancer


These can be basically divided into two types - those of the electric field & those of the magnetic field. There appears to be almost no literature/research concerning the effects of pulsing the electric field, & almost all the research revieved is concerned with the therapeutic effects of the magnetic field. This is not to say that pulsing the electric field has no effect, but that the research evidence for such an effect is lacking. The information which follows relates therefore to the effect of pulsing the magnetic field.

The primary effects of the pulsed magnetic field appears to be at the cell membrane level & is concerned with the transport of ions across the membrane.

Normal cell membranes exhibit a potential difference due to the relative concentration differences of various ions on either side of the membrane (reviewed in Charman 1990). Of these ions, sodium (Na+), potassium (K+), calcium (Ca++), chloride (Cl-), & bicarbonate (HCO3-) are probably the most important. Cell membrane potentials vary according to the cell type, but a typical membrane potential is -70mV, internally negative. It is actively maintained by a series of pumps & gated channels, & cellular energy (ATP) must therefore be utilised to maintain the potential.

A cell involved in the inflammatory process demonstrates a reduced cell membrane potential & consequently, the cell function is disturbed. The altered potential affects ion transport across the membrane, & the resulting ionic imbalance alters cellular osmotic pressures. It is suggested that the main clinical effects of this are pain & oedema (probably indirectly).

The application of pulsed SWD to cells affected in this way is claimed to restore the cell membrane potential to their normal values & also restores normal membrane transport & ionic balance. The mechanism by which this effect is brought about is not yet established, but the two theories suggest that this is either a direct ionic transport mechanism or an activation of various pumps (sodium/potassium) by the pulsed energy

It is claimed that the energy has little or no effect on normal cells as `sick' cells respond to lower energy levels than normal cells. A time period of 4 days has been attributed to this process (see Hayne 1984 for a useful review).

The following are the primary effects of pulsed SWD:

1) Increased number of white cells, histocytes & fibroblasts in a wound.

2) Improved rate of oedema dispersion.

3) Encourages absorption of heamatoma.

4) Reduction of the inflammatory process.

5) Prompts a more rapid rate of fibrin fibre orientation & deposition of collagen.

6) Encourages collagen layering at an early stage.

7) Stimulation of osteogenesis.

8) Improved healing of the peripheral & central nervous systems.

With respect to the effects of pulsed SWD, there is an element of tissue heating which occurs during the `on' pulse, but this is dissipated during the prolonged ‘off' phase & therefore, it is possible to give treatment with no NET increase in tissue temperature. The `non thermal' effects of the modality are generally thought to be of greater significance. They appear to accumulate during the treatment time & have a significant effect after a latent period. It is suggested that the energy levels required to produce such an effect in humans is low.

An active research programme has been conducted for several years now relating to the thermal nature of PSWD. It was unclear just what power levels were required to bring about a real tissue heating, and in fact, there has been some opinion that PSWD was a non thermal modality per se. Recent work from this research unit has demonstrated that PSWD does have a thermal component, and real tissue heating can occur under different treatment settings. This is important in that if the modality is to be applied in circumstances where the heating would be inappropriate or contraindicated, it is essential to know then power / energy levels where the thermal effects begins. The pages on PSWD Research include the experimental details and summary results of the work we have done over the last 5 years. In essence, it has been shown that a measurable heating effect can be demonstrated at power levels over 5 watts, though on average, it will become apparent at some 11 watts mean power.

If a ‘non thermal’ treatment is the intended outcome of the treatment, it is essential that the mean power applied remains below this level. If a thermal effect is an intentional outcome of the intervention, then it may be perfectly appropriate to deliver power levels in excess of 5 watts, but if doing so, the therapist must ensure that the precautions are taken as for any other thermal intervention.

Cholnoky's Indication's for SWD: See Cholnoky

The table below, as the rest of similar tables below are given for comparison and scientific research only.

Infectious Diseases: The Common Cold
Pneumonia
Pulmonary Tuberculosis
Erysipelas (pre gangrenous condition)
Erysipeloid (infective dermatitis)
Actinomycosis (infects soft tissues & bone of lower jaw)
Allergic Diseases
Bronchial Asthma

Metabolic Diseases:

Gout
Obesity
Diabetes Mellitus
Disorders of the Endocrine Function

Disease of the Respiratory Tract:

Laryngitis
Bronchitis
Bronchiectasis
Emphysema
Pleurisy
Empyema
Abscess of the Lung
Pulmonary Gangrene
The Oral Cavity:

Dental structures:

dental granulomas, parodontitis
Tonsillitis
Spasm of the Esophagus

The Stomach:

Gastritis
Peptic ulcer
Gastric neuroses

The Intestines:

Tuberculous colitis
Chronic appendicitis
Abdominal adhesions
Spastic colitis
Perityphlitis
Peritonitis

The Biliary Passages:

Cholecystitis
Cirrhosis of the liver
Hepatitis
The Urinary Tract:
Cystitis (Tuberculous)
Puelitis
Nephritis
Perirenal Abscess

Diseases of the Skin:

Furuncle
Carbuncle
Axillary Sweat-gland Infection and Abscess
Phlegmon
Streptococcus
Eczema (chronic ulcers, lupus)
Acne vulgaris
Pruritus


Diseases of the Head:

Sinusitis (acute and chronic)
Empyema of the antra, adjacent, and ethmoid sinuses

The Female Genital Tract: Pelvic Inflammation and Infections:
Old Adnexal Tuberculosis
Acute salpingitis
Adnexal tumors
Peritonitis
Gonococcal adnexitis
Adnexal swelling due to infection following miscarriage or pregnancy
Chronic adnexitis
Metro endometritis
Bartholin's Gland Abscess
Dysmenorrhea

The Male Genito-Urinary Tract:

Gonorrheal Urethritis
Epididymitis
Diseases of the Prostate
Tuberculous disease of the testicles, bladder, and kidney

Diseases of the Locomotor System:

The Muscular System:
Myalgia
Lumbago
Spastic contractures
Rheumatism, etc.
Tendovaginitis
Bursitis

The Bones:

Periostitis
Osteomyelitis

The joints:

Arthritis
Gonorrheal arthritis
Traumatic arthritis
Atrophic arthritis
Hypertrophic arthritis
Tuberculosis

Traumatic injuries:

Hematoma, Sprain, Lesions, Lacerations

Diseases of the Nervous System:

Neurosyphilis
Neuritides
Neuralgia of the Lumbosacral Plexus
Trigeminal, Brachial, Exipital, and Intercostal Neuralgias
Polyneuritis
Migraine
Parkinson's Disease
Epilepsy
Hiccup
Urinary Incontinence of Nervous Origin (due to multiple sclerosis, syphilis, traumatic hematomyelia, enuresis nocturna)
Neuroma (e.g., amputation neuroma)

Diseases of the Eye:

Atrophy of the optic nerve
Corneal ulcer
Orbital phlegmons
Iridocyclitis, tuberculous lesions, inflammatory disorders, and palsies of the ocular muscles

Diseases of the Ear:

Otitis media
Mastoiditis
Mastitis
Malignant Diseases


See further

Short-wave diathermy: current clinical and safety practices.