Introduction to Electrode Selection

1. Introduction to Electrode Selection

  • Importance: Careful consideration of electrode types, placements, and configurations is crucial for the success of electrical stimulation therapy.

  • Lab Exploration: Specific electrode placements for various electrotherapy methods (NMES, FES, IFC, TENS) will be covered in lab sessions.

2. Electrode Types and Materials

  • Variety: Electrodes come in various shapes, sizes, materials, and methods of adherence.

  • Common Types:

    • Carbon and sponge reusable electrodes.

    • Self-stick adhesive reusable or disposable electrodes.

    • Probes (neuroprobe, microcurrent probe).

  • Sanitary Reasons: Patients should have their own set of electrodes to prevent sharing.

3. Electrode Inspection

  • Before and After Use: Always inspect electrodes for proper condition of the connector and conductive surfaces.

  • Purpose: Prevents adverse events and improves effectiveness.

  • Replacement Indicators:

    • Patient reports altered stimulus quality.

    • Clinician observes decreased physiological response (e.g., less muscle contraction).

4. Electrode Placement Considerations

  • Target Tissue: Placement depends on the target tissue and therapeutic goals.

  • Locating Maximal Stimulation Points:

    • Charts: Utilize charts outlining motor points, trigger points, myotomes, dermatomes.

    • Probes: Use a neuroprobe or microcurrent probe.

    • Human Electrode Technique: Therapist places one electrode on their hand to feel for maximal stimulation points on the patient.

  • Knowledge Application: Use knowledge of dermatomes, myotomes, peripheral nerve distribution patterns, motor points, trigger points, and acupuncture points for optimal outcomes.

  • Standard Charts: Useful for treating pain related to specific dermatomes, myotomes, or peripheral nerve patterns.

5. Electrode Configurations

Configurations vary, but here are some examples:

  • Bilateral Neck Pain Example (Slide 7 illustration):

    • Channel 1 electrodes for bilateral neck pain at a cervical level.

    • Additional electrodes for pain radiating down an extremity (e.g., C6-C7 distribution).

  • Crossed Configuration (Slide 8 illustration):

    • Channels 1 and 2 crossed (e.g., at the left shoulder).

    • Common in various treated areas.

    • Only option for Interferential Current (IFC) delivery.

  • Bracketed Method (Slide 9 illustration):

    • Beneficial for target tissues with varying levels of stimulation.

    • Channel 1 electrodes placed over areas of similar stimulation (e.g., motor points).

    • Channel 2 electrodes placed over areas of different stimulation (e.g., non-motor points).

    • Avoids uneven sensation where some electrodes are felt more than others on the same channel.

  • Unilateral/Linear Electrode Placement (Slide 10 illustration):

    • Channels 1 electrodes on one side (e.g., right low back).

    • Channels 2 electrodes along a continuous path (e.g., posterior thigh and knee).

    • Useful for localized pain and radicular symptoms (e.g., right-sided low back pain with radicular symptoms down the posterior right lower extremity ceasing at the knee).

  • Unilateral/Linear and Overlapping with Distal Point (Slide 11 illustration):

    • Channels 1 and 2 electrodes overlap along an extremity (e.g., left lower extremity).

    • Creates a "glove-like" sensation for generalized pain or symptoms along an extremity.

6. Electrode Size and Current Density

  • Current Density: Greater under a smaller electrode for the same amount of current.

  • Proportionality: The unit area of the electrode should be proportional to the target area to be treated.

  • Rule: Larger treatment area requires larger electrode size for appropriate current density.

7. Electrode Distance

  • Effect on Current Travel: Electrode distance dictates the depth of current penetration.

  • Closer Electrodes: Current travels more superficially, impacting superficial tissues.

  • Further Electrodes: Current travels deeper, reaching deeper tissues.

  • Example: Placing electrodes for wrist extensors too far apart might stimulate wrist flexors instead, causing wrist flexion.

8. Electrode Polarity and Configurations (Monopolar, Bipolar, Quadripolar)

  • Poles: Always two poles (anode and cathode) are required for a complete circuit.

    • Cathode: Electrode with a greater concentration of negative ions or electrons.

  • Monopolar Configuration (One circuit, two electrodes; left image on Slide 14):

    • Active electrode: On or over the target tissue.

    • Inactive electrode: On or over a nearby non-treatment area.

    • Commonly used for: Pain modulation, iontophoresis, tissue healing.

  • Bipolar Electrode Configuration (One circuit, two or more electrodes; middle image on Slide 14):

    • Both or all electrodes of a single circuit are on or over target tissue/tissues.

    • Commonly used for: Pain modulation, muscle contractions.

  • Quadripolar Electrode Configuration (Two circuits, four electrodes; right image on Slide 14):

    • Four electrodes from two circuits are on or over target tissue/tissues.

    • Commonly used for: Pain modulation (e.g., TENS, Interferential Current, pre-modulation applications).