Characteristics of brainstem auditory evoked potential and preservation of facial and auditory nerves in patients with acoustic neuromas / 中华神经医学杂志

ABSTRACT

Objective To study the variational features of the brainstem auditory evoked potential (BAEP) and the preservation of the facial and auditory nerves during the microsurgery in patients with acoustic neuromas (AN). Methods We retrospectively analyzed the data of 76 patients with AN, admitted to our hospital fi'om May 2006 to May 2009: preoperative BAEP were examined; the peak latency (PL) of Ⅰ, Ⅲ and Ⅴ waves and their interpeak latency (IPL) were noted and compared. The tumors were microsurgically removed under intraoperative electrophysiologic monitoring to preserve the facial and auditory nerves. The relationships between the preservation of facial and auditory nerves and both the tumor size and the utilization of intraoperative monitoring were discussed. Results Before the operation, the 100% abnormal rate of BAEP was showed on the diseased side with the disappearance of Ⅲ and Ⅴ waves as its main features, while 82.9% (63/76) of that was noted on the contralateral side with the IPL ratio of Ⅲ-Ⅴ / Ⅰ-Ⅲ greater than or equal to 1 as its main features; the BAEP features between the 2 sides had statistical significance (P<0.05). Seventy patients (92.1%) were found abnormal of BAEP on the contralateral side during the operation; the BAEP features of the contralateral side had statistical significance between preoperation and intraoperation (P<0.05). The tumors were totally removed in 69 (90.8%), subtotally removed in 6 (7.9%) and partially removed in 2 (1.3%). The preservation of facial and auditory nerves increased obviously through monitoring the response of BAEP during the surgery and a positive correlation was observed between the preservation of facial and auditory nerves and the response of BAEP in the contralateral side(r=0.912, P=0.000; r=0.613, P=0.000). However, an inverse correlation was observed between the preservation of facial and auditory nerves and the size of AN (r=-0.869, P=0.000; r=-0.738, P=0.000). Conclusion Preoperative BAEP can help to make an exact diagnosis on patients with AN and the preservation of facial and auditory nerves can increase obviously through monitoring the normal response of BAEP during the surgery. The anatomy preservation of facial and auditory nerves depends on the size of AN.