Electrodiagnosis: Low Frequency Currents PDF - Bowen University 2024/2025

PST 410 LOW FREQUENCY CURRENTS Electrodiagnosis Joana O. Adeleke Physiotherapy Programme College of Health Sciences Bowen University, Iwo 2024/2025 Sessio...

PST 410 LOW FREQUENCY CURRENTS Electrodiagnosis Joana O. Adeleke Physiotherapy Programme College of Health Sciences Bowen University, Iwo 2024/2025 Session Electrodiagnosis is a powerful tool used to evaluate the electrical activity of nerves and muscles It provides valuable insights into neuromuscular health Aids in the diagnosis and management of various conditions. What is Action Potential? Advantages and L imitations B enefits L imitations Objective assessment of nerve and Potential discomfort during testing muscle function, Variations in test results Accurate diagnosis, Need for skilled interpretation Guidance for treatment planning. Electromyography (EMG) Types: Needle EMG: Involves inserting a fine needle electrode into the muscle to record electrical activity. Provides detailed information on muscle fiber activity, useful for diagnosing myopathies and neuropathies. Surface EMG: Non-invasive; uses electrodes placed on the skin to measure muscle activation. Commonly used in rehabilitation settings. Procedure: It Involves patient relaxation and contraction of specific muscles while recording electrical signals. 1. Electromyography (EMG) Needle EMG: the needle electrode is inserted into various locations within a muscle to evaluate both insertional activity (the response of muscle fibers to needle movement) and spontaneous activity (resting electrical activity). Surface EMG records signals from the skin surface above the muscle being tested. Interpretation of Waveforms: Analysis of insertional activity, spontaneous activity, motor unit potentials, and recruitment patterns. Clinical Applications: Diagnosis of conditions like ALS, peripheral neuropathies, radiculopathies, and myopathies. 2. Nerve Conduction Studies Motor and sensory nerve conduction studies assess the speed and strength of electrical signals in peripheral nerves. These studies are crucial for diagnosing various neuropathies and other nerve-related conditions. Key Parameters Latency: This measures the time taken for an electrical impulse to travel from the stimulus site to the recording site. Prolonged latencies can indicate nerve damage or dysfunction. Amplitude: This reflects the number of nerve fibres activated during the test. A decreased amplitude suggests a reduction in the number of functioning nerve fibers, which is common in conditions like axonal degeneration. Conduction Velocity: This indicates the speed of the nerve impulse. It is particularly important for identifying demyelinating conditions, where the myelin sheath around nerves is damaged, causing slower conduction speeds. Common Findings in Neuropathies In neuropathies, typical findings include: Reduced Conduction Velocity Slower speeds can indicate demyelination or other forms of nerve damage. Prolonged Latency: Increased latency times suggest impaired nerve function. Decreased Amplitude: Lower amplitudes indicate fewer active nerve fibers, which can be a sign of axonal loss or damage. These parameters are essential for diagnosing various conditions, including diabetic neuropathy, Guillain-Barré syndrome, and other peripheral nerve disorders The Strength-Duration Curve Graphical representation that illustrates the relationship between the strength (intensity) of an electrical stimulus and the duration required to elicit a muscle response. This curve helps in understanding how different intensities and durations of electrical stimulation affect muscle activation. Curve depicts a partially Curve depicts a Normal Curve depicts a denervated muscle innervated muscle completely denervated muscle The Strength-Duration Curve Clinical Relevance Differentiates between innervated and denervated muscles The shape and position of the SDC can indicate whether a muscle is fully innervated, partially denervated, or completely denervated. Monitoring nerve recovery after injury: Changes in rheobase and chronaxie over time can help assess nerve regeneration and recovery following injury.  Three Important Applications Assessment of muscle denervation Evaluation of peripheral nerve injuries Diagnosis of neuromuscular disorders The Strength-Duration Curve Key Parameters Rheobase: the minimum current Rheobase needed to elicit a minimal muscle contraction with a long-duration stimulus. Represents the threshold current required for stimulation at infinite duration. Chronaxie: refers to the minimum time required to stimulate a muscle Chronaxie using a current that is twice the rheobase intensity. Provides insight into the excitability of the nerve or muscle tissue.  Role of Physiotherapists Collaboration Physiotherapists collaborate with neurologists and other healthcare professionals to utilize electrodiagnostic findings in designing targeted rehabilitation protocols. Evidence-Based Practice Electrodiagnosis plays a vital role in evidence-based practice, providing objective data to guide treatment decisions and monitor patient progress