ENMG

electroneuromyography consists of the observation, analysis, and interpretation of the bioelectrical activity of muscle and nerve in response to volitional activation or electrical stimulation

• sensory nerve action potential
• b/c sensory nerves contain some of the large axons and are most vulnerable to neuropathies, abnormalities in the SNAP are often the first indication of pathology
• sensory latency is usually the only finding reported

• compound motor action potential
• is defined as the sum of electrical activity of all of the muscle fibers in the region of the recording electrode that are innervated by the nerve being stimulated
• biphasic in nature

• is considered negative
• is considered positive

• stimulating, recording, reference, and ground
• needle (generally recording only)
• surface can be all 4

• time from the application of the stimulus until a response is recorded (initial negative deflection)
• is measured in msec and is the time the action potential takes to travel down the nerve, cross the neuromuscular junction, and initiate the muscle action potential

electrode placement

• normal- normal or partial axon loss or partial conduction block
• prolonged- focal demylenation
• absent- complete axon loss or complete conduction block

occur with acute or chronic compressive lesions also certain diseases that disrupt the myelin

• how big a response is from the baseline to the (-) peak
• total number of muscle fibers innervated by the nerve that is being stimulated
• is measured in uV
• no change in amplitude with changes in distance of electrodes

occur in wallerian degeneration lesions such as lacerations, traction injuries, infarctions, significant compression, or carcinoma infiltrations and axonal degeneration lesions associated with some metabolic diseases also occur moderate and severe myelinopathies

• normal- normal or focal demyelination
• reduced- partial axon loss or partial conduction block
• absent- complete conduction block or complete axon loss

• measured in msec
• function of the different speeds of the axons stimulated
• time period that begins with the initial negative deflection and ends when that deflection returns to baseline

diseases that disrupt the axon or myelin

• focal demyelination
• partial conduction block
• complete conduction block

• partial axon loss
• complete axon loss

stimulate distal record proximal

stimulate proximal record distal

• helps define where the lesion could be
• inc intensity and amplitude
• amplitude inc can only inc so high