Single-fiber EMG demonstrates reinnervation dynamics after nerve injury.

Serial single-fiber EMG (SF-EMG) studies in the frontalis muscle showed increased jitter with normal fiber density 15 days after facial nerve trauma. Both measurements were increased thereafter. The maximum increases occurred at 37 days, coincident with the initial return of function, and persisted until 67 days, when function had returned to normal. Thereafter, both features returned toward normal values, but were still elevated 34 months after injury.