Changes in axonal excitability and burst pattern behaviour in synkinesis

Synkinesis after severe facial nerve paralysis has been related to the processes of aberrant reinnervation and increased excitability of the facial nucleus. We present the electrophysiological features of synkinesis in a 32-year-old woman who developed grouped 'myokymic-like' discharges with eye blinking in the absence of spontaneous muscle activity. With eye blinks, the interspike intervals of discharges in the orbicularis oris varied between 25-150 Hz, overlapping with rates of myokymia and neuromyotonia. Analysis of the discharge patterns in the present case suggests that synkinesis reflects aberrant regeneration with effects mediated by properties of axonal excitability that determine the burst pattern characteristics.