EMG Lewis Flashcards
Purpose of EDX
Determine if there is a problem in PNS and where
Complete exam - must be interpreted w/whole clinical picture
Represents real time physiologic info about nerve/muscle
Who performs EDX
Physiatrists
Neurologists
PT/Techs
Reasons for EDX
SX: numbness/tingling, weakness, extremity/radicular pain
PX: reflex loss/asymmetry, weakness, sensory loss, limp, atrophy
Timing of EDX
No earlier than 21 days after injury/onset of SX
Wallerian Degeneration
Degenerative changes occurring in distal axonal segments and myelin sheath secondary to proximal axonal injury or death of cell body
Neurapraxia
Failure of nerve conduction across affected nerve segment combined with normal conduction above/below segment
No Wallerian Degeneration
Axonotmesis
Disruption of axon continuity with Wallerian Degeneration but perineum and/or endoneurium in tact
Neurotmesis
Severance of nerve - poor prognosis and surgical repair needed for functional recovery
Contraindications for EDX
Severe bleeding
AICD
Active skin/soft tissue infection (cellulitis)
Complications of EDX
Infection
Bleeding
Accidental penetration other than muscle
Criteria for Ordering
Establish correct DX
Localize Lesion
Determine TX
Provide info about prognosis
Purpose of NCS
Determine if there is pathology of nerve and what level it originates
Latency
Interval between stimulus and onset
Amplitude
Proportional to number/size of nerve fibers depolarized
Estimate of amount of nerve tissue electrically active
Conduction velocity
Speed at which nerve fibers are carrying stimulus
Comparison of conduction between two segments of same nerve can localize lesion
