Carrier D A, Arriaga M A
Department of Neuroradiology, Wilford Hall Medical Center, USA.
Otolaryngol Head Neck Surg. 1997 Jun;116(6 Pt 1):567-74. doi: 10.1016/S0194-59989770229-8.
The poor sensitivity of audiometric brain stem response for small vestibular schwannomas (acoustic neuromas) creates a dilemma for the physician evaluating a patient with signs and symptoms of retrocochlear disease. Magnetic resonance imaging is recognized as the gold standard for the evaluation of these problems, but if a complete examination of the internal auditory canals and head is done on every patient, the cost is high. Although less expensive, screening with audiometric brain stem response risks missing up to 33% of small tumors. Therefore we developed a focused magnetic resonance imaging sequence for evaluation of patients with asymmetric sensorineural hearing loss and/or nonpulsatile tinnitus. The protocol includes a T1-weighted sagittal localizer, pregadolinium and postgadolinium T1-weighted 3-mm contiguous axial slices through the internal auditory canal and the region of the cerebellopontine angle, and T2-weighted axial images through the entire brain. Total scanning time is about 12 minutes, and the estimated cost is $300 to $500. We retrospectively reviewed the imaging records of 485 screening examinations done during an 18-month period. Twenty-four patients had diagnoses definitely or probably producing the hearing loss for an overall positive rate of 5%. By eliminating the need for follow-up audiometric or electrophysiologic studies, we believe a focused magnetic resonance imaging-based diagnostic scheme is actually more cost-effective on a cost-perpatient basis.
听性脑干反应对小型前庭神经鞘瘤（听神经瘤）的敏感性较差，这给评估有蜗后疾病体征和症状的患者的医生带来了难题。磁共振成像被公认为评估这些问题的金标准，但如果对每位患者都进行内耳道和头部的全面检查，成本会很高。虽然听性脑干反应筛查成本较低，但有高达33%的小肿瘤可能会漏诊。因此，我们开发了一种针对性的磁共振成像序列，用于评估不对称性感音神经性听力损失和/或非搏动性耳鸣患者。该方案包括一个T1加权矢状位定位像、钆剂注射前和注射后的T1加权3毫米连续轴位像，穿过内耳道和脑桥小脑角区域，以及穿过整个脑部的T2加权轴位像。总扫描时间约为12分钟，估计成本为300至500美元。我们回顾性地审查了18个月期间485次筛查检查的影像记录。24例患者的诊断明确或可能导致听力损失，总体阳性率为5%。通过无需后续的听力或电生理研究，我们认为基于针对性磁共振成像的诊断方案在按每位患者计算成本的基础上实际上更具成本效益。
