ELECTROPHYSIOLOGICAL STUDY OF FACIAL NERVE INJURY SECONDARY TO OPERATION OF BENIGN PAROTID GLAND TUMORS

Objective:To study the implications of electroneurography in evaluating the facial nerve injury caused by parotidectomy.Methods:Eletroneurography (ENoG)was applied to 50 patients with unilateral benign parotid gland trmors at the time of 24 hours before operation and 3 ,10 ,20 ,40 ,60 ,80 ,100 day postoperative intervals.The detected indexes included amplitute(Am),latency time(LT),and duration time(DT)of action potential,and degeneration rate (DR) as calculated.Results:After 3 day intrerval,DR,Am,LT,and DT showed marked changes and reached summit reflect at 10 day.An evident recovery of the facial nerve was manifested from 20 to 40 days,while.the recovery after 80 days slowed down.Conclusion:The facial nerve injury caused by parotidectomy mostly belongs to one type of reversible facial neurapraxia.LT and DT are sensitive indicators for structural nerve damages,while DR and Am mainly reflect nerve degeneration and the transforming process from degeneration to regeneration.