PHT 5216 - Unit 5: Biofeedback

Introduction to Biofeedback

  • Definition: Biofeedback is a technique that allows individuals to learn about their performance and modify it to improve deficiencies in activities such as muscular contractions, joint motions, and functional tasks.

  • Reference Material: Further details can be found in the textbook at the end of Chapter 13 - Electrotherapy for Musculoskeletal Disorders.

Objectives of the Lecture

  1. Explain the principles, indications, and expected outcomes for using biofeedback.

  2. Recognize clinical examples of facilitatory and inhibitory uses of biofeedback.

  3. Explain the proper usage of biofeedback devices, including electrode positioning and manipulation of the unit.

  4. Provide examples of biofeedback use from a diagnosis-specific perspective, including orthopedics vs. neurology.

Electromyographic (EMG) Biofeedback

  • Definition: EMG biofeedback is a method that provides information regarding muscle activity, which can be utilized by both the patient and clinician to enhance or reduce future muscle activity.

  • Functionality: Unlike other forms of electrotherapy, EMG biofeedback does not deliver electrical current. Instead, it detects the electrical activity generated by contracting muscles used for therapeutic purposes.

  • Example: The electrode placed on the skin over the vastus medialis muscle records the muscle's electromyographic activity.

Process of EMG Biofeedback

  1. Information Transmission: Biofeedback provides information about a patient’s performance, usually through visual and auditory signals.

    • Example: A study showed how electromyographic biofeedback impacts knee extension following anterior cruciate ligament (ACL) reconstruction.

    • Electrode Placement: Electrodes are placed over the vastus medialis muscle to record EMG activity. A reference electrode is also positioned.

    • Signal Display: The equipment transduces signals to visualize on a laptop, allowing the patient to match their muscle contraction to the display established by the clinician.

Types of Biofeedback Responses

  • Facilitatory Feedback: Used for conditions where muscles are weak or inhibited due to trauma or surgery.

  • Inhibitory Feedback: Applied in cases of spasticity in neurological patients or muscle spasms resulting from chronic pain.

Equipment and Electrode Considerations

  • Electrode Types: Many biofeedback machines can also provide electrical stimulation, employing similar adhesive electrodes used in electrotherapy.

  • Electrode Placement:

    • For biofeedback, the electrode placement width is crucial:

      • Wider Placement: Detects larger muscle volumes, suitable for activating muscles.

      • Narrow Placement: Indicates inhibition of muscles and is recommended for related therapies.

  • Concerns: Muscles must be partially innervated, and there are no contraindications for using EMG biofeedback since it does not apply electrical stimulation.

Measurement and Sensitivity in EMG Biofeedback

  • Recording Parameters: Biofeedback records muscle activity in microvolts, amplified to millivolts for transduction into visual/auditory signals.

  • Sensitivity vs Gain:

    • Sensitivity: Refers to the device’s ability to detect electrical activity associated with muscle contraction—higher sensitivity corresponds to lower gain.

    • Gain Example:

    • Low gain of 1 microvolt indicates high sensitivity, detecting minimal changes in muscle activity.

    • High gain of 1000 microvolts implies less sensitivity, only detecting larger changes.

Clinical Application of EMG Biofeedback

  • Patient Case Study: Example of a patient post-ACL reconstruction requiring facilitatory treatment.

    • Initial Post-Surgery: Clinician sets machine for high sensitivity (gain of 1 microvolt) to detect subtle muscle contractions due to weakness.

    • Progression: As the patient's muscle contraction improves to 60%, the clinician adjusts the machine to low sensitivity (gain of 500 microvolts) requiring stronger muscle contractions for detection.

Criteria for Using Biofeedback

  1. Patient Suitability: Must consider whether the patient is appropriate for EMG biofeedback versus other electrotherapy types like NMES or FES.

  2. Target Muscles: Identification of the specific muscles needing monitoring is critical for effective treatment.

  3. Determining Treatment Type: Assess whether the goal is facilitation or inhibition based on a thorough physical therapy evaluation.

  4. Assessment Sensitivity: The degree of sensitivity in measuring muscle activity needs careful consideration based on patient assessment and disease phase.

    • Initial Phase: Typically involves high sensitivity for facilitatory treatment.

    • Later Phase: Involves low sensitivity for more robust contractions.

  5. Electrode Configuration: Close placements for facilitatory treatments vs. wider placements for inhibitory treatments.

  6. Adjustment with Improvement: As patients progress, adjustments will lead to lower sensitivity settings and more functional tasks.

Additional Resource

  • Visual Example: The lecture includes a video demonstrating EMG biofeedback setup for quadriceps muscles.