Axon numbers distal to a nerve repair may double in the months after repair, returning to normal in the rat only after 18 months. Compound motor action potential (CMAP) of reinnervated nerve may return to normal after nerve repair, nerve conduction velocity (NCV) is reduced by 25-50%, and the compound nerve action potential (CNAP) often remains below 50% of normal. Walking electromyogram (EMG) patterns after rodent sciatic nerve repair become disordered and asynchronous. Retrograde tracing unmasks a substantial failure of topographic specificity during regeneration. The sciatic functional index (SFI) returns to normal after lesions that spare the Schwann cell basal lamina, but not after transection injuries. Gait analysis reveals abnormalities that are not reflected in the SFI. A new experimental outcomes scale is based on the correlations among outcome measures: Category 4, regeneration has occurred; Category 3, end organs are reinnervated; Category 2, regeneration is specific; Category 1, voluntary function is restored. Measures at Grade II usually predict function, whereas those at Grades III and IV can predict function only under special circumstances.
Chapter. 22251 words. Illustrated.
Subjects: Sensory and Motor Systems ; Rehabilitation Medicine
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