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Therapeutic Electrical Modalities

Therapeutic Electrical Modalities. Learning Objectives. Be familiar with the characteristics of electric modalities that are applied for therapeutic purposes Identify physiological and therapeutic effects of electric modalities

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Therapeutic Electrical Modalities

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  1. Therapeutic Electrical Modalities

  2. Learning Objectives • Be familiar with the characteristics of electric modalities that are applied for therapeutic purposes • Identify physiological and therapeutic effects of electric modalities • Be familiar with contraindications and precautions in using electric modalities • Identify adverse effects for each modality

  3. Learning Objectives Cont’d . . . • Be familiar with the multiple uses of electrical stimulation (ES) • When given a clinical scenario, be able to: • Define goals of treatment with ES • Choose the appropriate device • Select the appropriate parameters • Apply the treatment safely and competently • Modify treatment if needed

  4. Therapeutic Electrical Currents • The application of electrical current to the body for therapeutic purposes, such as: • Pain relief • Neuromuscular Electrical stimulation • Tissue/wound healing • Direct stimulation of denervatedmuscle

  5. Charge Current Resistance Conductance Impedance Current: AC DC Pulsatile/pulsed Amplitudeor intensity Terminology

  6. Pulsed currents • Monophasic or biphasic • Pulse duration • Pulse frequency - interval between pulses • can be manipulated independently • Modulations • Frequency • Amplitude • Burst

  7. Therapeutic Electrical Stimulation Applications • Pain Relief • Neuromuscular Electrical Stimulation (NMES) • Tissue/wound healing • Iontophoresis • Deinervated muscle

  8. Transcutaneous Nerve Stimulation (TENS)

  9. TENS • Stimulates nerve fibers for the symptomatic relief of pain • Device applies an electrical signal through lead wires and electrodes attached to the patient's skin • Electrode placement varies: • Typically placed in a peripheral nerve distribution • Locations can be distal or proximal to pain site

  10. How It Works • Gate Control Theory: • Pain signals can be blocked at the level of the spinal cord before they are transmitted to the thalamus • TENS stimulates large Iamyelinated afferent nerve fibers that stimulate the substantiagelatinosa in the spinal cord, closing the gate on pain transmission to the thalamus

  11. Gate Control Theory

  12. Physiological Effects of TENS • Selective stimulation of large diameter, myelinatedfibres • Gate Control Theory • Stimulates release of endorphins • Endorphin/opiate theory • Stimulates release of other transmitters • NA, 5-HT • ?mild heating  enhanced healing? • Placebo

  13. Therapeutic uses of TENS • PAIN RELIEF: • Acute, Subacute, Chronic & Referred • Musculoskeletal • Neurologic • Obstetric • Oncologic* • Cardiac- angina

  14. Modes of TENS • Conventional • Acupuncture • Burst mode • Brief-intense/noxious level

  15. Conventional TENS • High-frequency, low-intensity stimulation • most effective type of stimulation • Amplitude is adjusted to produce minimal sensory discomfort • Pain relief begins after 10–15 minutes and stops shortly after removing stimulation • Useful for neuropathic pain • Duration of treatment is 30 minutes to hours

  16. Acupuncture • Low frequency, high intensity stimulation • Amplitude high enough to produce muscle contraction • Onset of pain relief can be delayed several hours • Pain relief persists hours after removing stimulation • Useful for acute musculoskeletal conditions • Treatment sessions last 30–60 minutes

  17. Burst Mode • High frequency stimulation bursts at low frequency intervals • Delayed onset of pain relief • Treatment can range 30–60 minutes

  18. Brief-intense/Noxious Level • Hyper-stimulation • High frequency, high intensity stimulation • It is considered that this mode stimulates C-fibers causing counter-irritation • Rarely tolerated more than 15–30 minutes

  19. TENS Unit intensity timer frequency Pulse width mode

  20. TENS Dosage

  21. Modulation Modes • SD: strength-duration • Amplitude and width modulate alternately – subtle change in sensation • Allows higher total amount of charge to be used • MW: modulated width • Stronger Weaker • MR: modulated rate • Faster  Slower • CM: combination modulation • Rate and width • ‘Diffuse’ sensation

  22. Electrode placement • Single channel: • 2 electrodes • Dual channel: • 4 electrodes

  23. Single channel • Surround the pain • Over the pain • Within dermatome/myotome • On trigger points or acupuncture points within dermatome • Spinal segment: one near spine, other over pain or trigger point within the dermatome/myotome

  24. Dual channel • Bracket • Cross – fire • Bilateral placement- both limbs • Contralateral: • Phantom pain, skin irritation or wound • General placement: flood the limb • Overlap channels

  25. Precautions • Decreased sensation • Pregnancy • Malignancy • Decreased mentation Be careful with repeated applications and prolonged use, adhesives/tape and gel can all cause dermatitis Make sure the entire electrode has good coverage for gel and don’t use too high a current - can cause electrical burns on the skin!

  26. Contraindications • UNDIAGNOSED PAIN • ANY electronic implant • Some Pacemakers (fixed rate ok but rate responsive are affected) • Cardioverter-defribrillators • Some Bladder stimulators • Metal implants???

  27. Interferential Current(IFC)

  28. Interferential Current • Another form of TENS: • Differs from TENS as it allows deeper penetration with more comfort (compliance) and increased circulation • AMC (amplitude modified current) • Frequencies interfere with the transmission of pain messages at the spinal cord level

  29. How does it work? • 2 “medium frequency” currents • Low frequency (e.g. TENS) = <1000Hz • Medium frequency 1000-10,000 Hz • 2 currents with different frequencies • Currents ‘interfere’ with one another • “Beat frequency” is the difference between the 2 currents

  30. Example • C1 = 5000 Hz • C2= 5100 Hz • fixed Beat frequency = 100 bps

  31. Indications for IFC • Urinary incontinence • Pain relief • Blood flow/edema management • May be effective due to the combination of pain relief (allowing more movement), muscle stimulation and enhanced blood flow

  32. TENS vs. IFC • Physiological effects: • Depolarize sensory and motor nerves • Why not TENS? • “Medium frequency”  less skin impedance • Less impedance  more patient comfort • More patient comfort  tolerate higher amplitude current  deeper penetration

  33. Contraindications • Same as TENS • Plus: • With suction cup electrodes: • Bruising • Cross-infection from sponges

  34. IFC Application • Stimulator type • Electrode placement • As precisely as possible so that patient feels the stimulation over the targeted area • Electrode fixation • Self-adhesive pads • Non-adhesive taped in place • Coupling medium • Gel for electrode pads

  35. Sweep • Beat frequency is modulated • Thought to prevent adaptation • E.g. • C1 fixed at 5000 • C2 varies • Gives a VARIABLE BEAT FREQUENCY

  36. Uses of sweep • Sweep ranges: • Pain relief 80-150 bps • Muscle rehab 10-100 bps • Edema 1-10 bps (intermittent muscle contractions) • Selection of a wide frequency i.e 1-100Hz is less efficent + ? Counter-productive

  37. Set-Up of IFC • Bi-polar • Quadripolar • Quadripolar with scan

  38. Bi-polar method • “Pre-mod” • 2 electrodes • Single channel • Current is ‘modulated’ within the machine • Similar to TENS

  39. Quadripolar method • 4 electrodes • 2 channels • Interference occurs where the fields cross one another WITHIN the tissues • Cloverleaf pattern

  40. Quadripolar field

  41. Quadripolar With Scan • “Automatic vector scan” • AMPLITUDE is varied by the machine • E.g. • C1 fixed amplitude/intensity • C2 variable amplitude • Pattern of interference is different

  42. Quad With Scan

  43. IFC Scan • Uses of scan: • Large area of treatment • Diffuse pain • Location of pain difficult to pinpoint

  44. Neuromuscular Electric Stimulation(NMES)

  45. NMES • Consists of transcutaneous electrical stimulation for muscles with or without intact PNS, or central control • More powerful than TENS unit • Multiple muscles can be activated in a coordinated fashion to attain certain functional goals (ambulation, transfers)

  46. Types of Muscle Contraction • Voluntary: • Recruits Type I first, then Type 2 • Spatial summation • Recruitment of additional motor units • Temporal summation • Increased firing rate • Gradual increase in force generated

  47. Types of Muscle Contraction • Electrically stimulated contraction: • Reverse pattern of recruitment • Type II Type I • All motor units fire at once • Easy to produce fatigue • Use “Ramp up” for comfort

  48. Features of NMES Currents • Pulse duration • Pulse rate/frequency: 30-50 pps

  49. Therapeutic Uses of NMES • Strengthens muscles • Motor Re-education • Increases ROM • Enhances endurance • Reduces muscle spasm/spacity

  50. Strength Training • Recruits maximum numbers of motor units • Used if volitional control affected by • pain • reflex inhibition • motivation • Works by overload fatigue

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