OBJECTIVETo determine the incidence of post-operative delirium after oral and maxillofacial surgery under general anesthesia in elderly patients, and to examine its association with plasma concentrations of beta amyloid protein 1-40 (Abeta1-40).

METHODSFifty patients underwent elective oral and maxillofacial surgery were divided into two groups: Group C (n=20) aged from 20 to 60 years old, and Group T (n=30) aged from 62 to 78 years old. The two group received the same general anesthesia. Delirium rating scale-revised-98 (DRS-R-98) was used as an instrument to diagnose and access the postoperative delirium of the two groups. The scores of DRS-R-98 were recorded before operation (T0) and at 24 h (T1), 48 h (T2), 72 h(T3) and 96 h(T4) after the operation. Serial measurements of serum concentrations of Abeta1-40 were also performed at the same time.

RESULTSThe incidence of post-operative delirium after oral and maxillofacial surgery in Group T was 20.0%. The concentrations of plasma Abeta1-40 in group T were much higher than group C at TO, T1, T2 and T3 significantly (P < 0.01). The concentrations of plasma Abeta1-40 at T1 and T2 were higher than those at TO in the same group (P < 0.05). The scores of DRS-R-98 in Group T at T3 and T4 were much higher than those at T1 and Group C significantly (P < 0.01).

CONCLUSIONThe constant increase of plasma Abeta1-40 may be one of the important factors related to post-operative delirium in elderly patients underwent oral and maxillofacial surgery.