청신경종양에서 나타나는 청성뇌간반응 잠복기의 진단적 가치

Background and Objectives: It is important to rule out acoustic neuroma when treating patients who have tinnitus or monaural hearing loss. The most accurate diagnostic tool is MRI but due to high costs, auditoiy brainstem response (ABR) latency is often used. The aim of this study is to confirm the diagnostic value of ABR latency in acoustic neuroma. Patients and Methods: The medical records of 20 patients who were diagnosed acoustic neuroma in MRI and evaluated with pure tone audiometry, speech audiometry and ABR were retrospectively reviewed from January, 2003 to January, 2010. Tumor size and hearing classification system of 2003 Consensus Meeting was used. Using I-V interpeak latency (IPL) and I-V interlatency difference (ILD) , we identified the diagnostic value of ABR latency in diagnosing acoustic neuroma. Results: Among 20 patients, there were 2 cases of intra-meatal tumor, 2 cases of grade 1, 6 cases of grade 2, 6 cases of grade 3, 2 cases of grade 4 and 2 cases of grade 5 according to the acoustic neuroma classification system of 2003 Consensus Meeting. There were 9 cases with no wave in ABR. 4 cases showed over 4.4 msec in I-V IPL and 6 cases showed over 0.2 msec in I-V ILD. There were 3 cases that showed over 4.4 msec in I-V IPL and over 0.2 msec in I-V ILD. Therefore, there were 16 cases that showed abnormal reactions to ABR among acoustic neuroma patients, false negative rate was founded to 20%. Conclusion: The smaller tumor size, the better prognosis in treating tumor and preserving hearing and facial nerve function, so that early diagnosis of acoustic neuroma is important. Because false negative rate of ABR was 20% in this study, using ABR as screening test of acoustic neuroma needs attention. (J Clinical Otolaryngol 2010; 21:46–49)