Blink reflex excitability recovery curves in patients with dysfunctions after facial nerve palsy
加島, 健司 徳島大学
excitability recovery curve
Postparalytic facial dysfunctions (PPFD) such as associate movements, crocodile tears and facial contracture are well-known sequelae of peripheral facial nerve palsy. The physiological basis for those disturbing conditions are unknown. Peripheral hypothesis such as misdirection theory or ephaptic transmission theory have been widely accepted.
On the other hand, some investigators made the hypothesis that hyperexcitability of the facial motoneurons had some contribution to the onset of the PPFD. A few physiological studies indicated the evidence of hyperexcitability of the facial motoneurons, however, there is not enough evidence of physiological changes in the nuclear or supranuclear system in patients with PPFD. Therefore, the blink reflex excitability recovery curves were studied in 10 patients with PPFD and 10 healthy control subjects to detect if physiological changes had occurred in the patients with PPFD. The inhibitory effects of the conditioning stimuli on the ipsilateral R 2 (iR 2) and contralateral R 2 (cR 2) responses observed in normal controls were significantly less in patients with PPFD. The results of this study indicate that patients with PPFD have increased excitability of central interneurons which mediate the R 2 pathway. We suggest that not only changes in the peripheral facial nerve but also changes in the central nervous system may contribute to the onset of PPFD.
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