Finals: Electrodiagnosis and Electromyography Flashcards
Study of electrical activity in motor units when stimulated by electrical pulse, providing diagnosis and prognosis in the neuromuscular complex.
Electrodiagnosis
Assessment Tools in Electrodiagnosis
Includes EMG (Electromyography), ECG (Electrocardiography), and EEG (Electroencephalography).
Includes anterior horn cell body and axon, neuromuscular junction, muscle cells, sensory neurons, and Schwann cells.
Motor Unit Components
Physiological Basis of Electrodiagnosis - Nerve Fiber Stimulation
Requires stimulation higher than the threshold of excitation (-70 mV).
History of Electrodiagnosis - Erb’s Observations
Negative response to faradic shocks.
Positive response to galvanic currents with long duration in muscles deprived of their supply
Accommodation in Denervated Muscles
Denervated muscles lack the power of accommodation to slowly increasing stimulation intensities, respond only to interrupted DC with brisk contraction.
Physiological Basis of Electrodiagnosis - Muscle Fiber Stimulation
Requires stimulation higher than the threshold of excitation (-90 mV) to induce muscle contraction.
A short-lasting event where the electrical membrane potential of a cell rapidly rises and falls, crucial for cell-to-cell communication.
Action Potential
Levels of RD and their implication
Partial Reaction of Degeneration (PRD) - Decreased response to tetanizing current.
Complete Reaction of Degeneration (CRD) - No contraction, brisk muscle twitch only.
Absolute Reaction of Degeneration (ARD) - No contraction with any stimulus.
Indicates the status of muscle innervation:
Reaction of Degeneration (RD)
Indicates long-standing denervation with atrophy and fibrosis, showing no response to both interrupted current and rapid sinusoidal current.
Absolute Reaction of Degeneration (ARD)
Indicates neurotmesis with no response to tetanizing current but positive response to interrupted direct current (IDC), resulting in brisk contraction or muscle twitch.
Complete Reaction of Degeneration (CRD)
Indicates partial lesion of the motor unit (neuropraxia) with decreased response to tetanizing current.
Partial Reaction of Degeneration (PRD)
Involves observing muscle contractions and assessing nerve continuity or lack thereof through evoked potentials.
Nerve and Muscle Potentials Assessment
Currents for Testing Reaction of Degeneration
Interrupted current or rapid sinusoidal current using a bipolar technique.
In direct current (DC), striated muscle does not contract; muscle contraction occurs only during the opening and closing of the circuit.
Law of Du Bois - Raymond
Uses the least current to produce a positive muscle contraction, making it the best method for muscle stimulation.
Cathode Closed Contraction (CCC)
For muscles with degeneration and atrophy, the anode is positioned as the active electrode.
Anode Positioning
Includes conditions such as poliomyelitis, progressive muscle atrophy, amyotrophic lateral sclerosis, syringomyelia, myasthenia gravis, Lambert-Eaton syndrome, nerve root injuries, neuritis, Guillain-Barre syndrome, muscular dystrophies, infections, and endocrine dysfunction.
Lower Motor Neuron Lesions (LMNL)
Involves observation, analysis, and interpretation of bioelectric muscle and nerve potentials using surface or needle electrodes.
Electrophysiological Evaluation
Reaction of degeneration test, faradic-galvanic excitability test, strength-duration curve, rheobase, chronaxie, and galvanic twitch-tetanus ratio test.
Traditional Tests
Plots the threshold values of stimulation (y-axis) against the duration of the stimulus (x-axis) to assess nerve integrity.
Strength-Duration Curve
___is the minimum current intensity required to produce a muscle response.
___is the duration of time that an electrical current twice the rheobase must be applied to elicit a muscle contraction.
Rheobase and Chronaxiez
Measures the electrical activity of muscles at rest and during contraction to diagnose motor neuron diseases and other neuromuscular disorders.
EMG
