Abstract
Compression of the extratemporal facial nerve of guinea pigs induces facial nerve paralysis reversible in two or three weeks. This animal model is very useful in the assessment of drugs conventionally used in the treatment of facial palsy.
In the first group of guinea pigs, 20mg/kg of methylprednisolone acetate was injected intramuscularly immediately after the compression and then once a week. In the second group, 1000μg/kg of methylcobalamin was injected intramuscularly immediately after the compression and every 48 hours. In the third group, both 20mg/kg of methylprednisolone acetate and 1000μg/kg of methylcobalamin were injected in the same schedule. In the control group, the same volume of physiological saline was injected as in the second group.
The facial paralysis and its recovery were assessed by evoked electromyograms of the orbicularis oculi muscle, and by blink reflexes elicited by air puffs. In selected animals, nerve specimens obtained from the compressed site were stained by toluidine blue and examined by light microscope.
1) Injection of either steroid hormone or methylcobalamin accelerated the repair of the facial nerve.
2) Steroid hormone was very effective in selected cases, while methylcobalamin was moderately effective in all cases.
3) The earliest recovery of the palsy, confirmed by the blink reflex, evoked electromyogram and histological findings, were found in the animals injected with both steroid hormone and methylcobalamin.
