To Assess the Time from Injury
Depending on how long symptoms have been present, electrodiagnostic testing can tell us different things:
- Axonal lesions <1 week are typically normal except reduced recruitment on needle EMG
- Axonal lesions between 1-2 weeks may show nerve conduction abnormalities (secondary to Wallerian degeneration)
- Axonal lesions between 2-6 weeks may show muscle membrane irritability on needle EMG
- Axonal lesions >6 weeks may demonstrate remodelling of motor unit potentials, reinnervation, or superimposed acute on chronic lesions
