- 期刊
右側耳鳴與第八對腦神經壓迫症候之探討─病例報告
Right Tinnitus with Suspected Cochleovestibular Nerve Compression Syndrome-Case Report
摘要
神經血管壓迫症候群（neurovascular compression syndrome）通常為血管直接接觸腦池中的顱神經（cisternal portion of a cranial nerve）而造成症狀。本篇報告為一30歲男性有心悸病史，患有右側耳鳴、耳悶伴隨偶發性頭暈約3個月，至本院耳鼻喉科求診。檢查發現外耳道正常及耳膜完整且無中耳腔積液之表現、鼻咽部無腫塊且其他理學檢查皆無異常。常規抽血報告顯示正常範圍內。神經學檢查無眼震且Romberg test、Tandem gait及Mann's test檢查皆為正常。純音聽力檢查四項平均純音聽力閾值（0.5 k、1 k、2 k及4 kHz）右耳為12.5 dB，左耳平均為25 dB且有4 kHz凹陷（4 kHz notch），聽性腦幹反應檢查（auditory brainstem response, ABR）雙耳第II波皆無明顯波型；雙耳波間潛時比較中發現，第I-III波及第III‒V波的波間潛時差（interpeak latency difference）皆≥0.16 ms，符合Møller's ABR criteria。電生理檢查結果無法與症狀相符合，故安排腦部核磁共振檢查發現右側內聽道前下小腦動脈（anterior inferior cerebellar artery）環繞第八對腦神經，懷疑神經血管壓迫症候群又稱血管迴圈症候群（vascular loop syndrome）。由於過往的經驗，病人主述及症狀與電生理檢查無法相符合時，須排除耳蝸後病變等其他原因。此病人常規檢查及右側聽力檢查皆為正常範圍內，無法解釋其右耳持續性耳鳴，現階段唯有影像上發現血管迴圈症候，但臨床上若懷疑為其導致耳蝸前庭神經壓迫症侯群（cochleovestibular nerve compression syndrome）所造成耳部症狀，仍須先排除其他原因，或在高度懷疑此疾病的病人接受腦部血管減壓手術後症狀消失方能確診。此案例之耳鳴成因還尚需釐清，現階段無法確診為耳蝸前庭神經壓迫症侯群，但仍希望藉由此案例探討影像學檢查發現耳蝸前庭神經壓迫症侯與耳鳴症狀之間的關係。
並列摘要
Neurovascular compression syndrome (NCS) usually results from the direct contact of blood vessels with the cisternal portion of a cranial nerve (CN). This is a 30-year-old man with a history of palpitations. He suffered from right-sided tinnitus, aural fullness and occasional dizziness for about three months. The physical examinations were all normal. The routine blood test was within the normal range, and the neurological examination also showed no abnormal findings. Pure-tone audiometry of the right ear average was 12.5 dB, and the left ear average was 25 dB with a 4 kHz notch. The auditory brainstem response (ABR) revealed absent wave II on both sides and interaural latency difference of wave V was 0.5 ms. The wave I-III and wave III-V interpeak latency difference were both ≥0.16 ms and met Møller's ABR criteria for diagnosing NCS of the CN VIII. The results of above examinations were not compatible with the symptoms, so brain MRI was arranged and revealed that the anterior inferior cerebellar artery surrounded the CN VIII within the right internal auditory canal. Cochleovestibular nerve compression syndrome (CNCS) , also known as vascular loop syndrome, was suspected. After discussion with the patient, medication was given first with regular follow up. Retrocochlear lesions should be excluded when symptoms do not match the electrophysiological examination. Only CNCS was suspected in this case by brain MRI. In this article, we discuss the relationship between CNCS and tinnitus.