耳鳴病患表現於聽性穩態磁場與電場之中樞聽覺可塑性－腦磁圖研究

Central Auditory Plasticity in Patients with Tinnitus as Revealed by Auditory Steady-state Fields: MEG Study

張智惠(Angela Chih-Hui Chang) ； 邱天成(Tian-Cheng Chiu) ； 李柏磊(Po-Lei Lee) ； 蕭安穗(An-Suey Shiao)

《台灣耳鼻喉頭頸外科雜誌》 54卷4期 (2019/12) Pp. 185-192

https://doi.org/10.6286/jtohns.201912_54(4).185

摘要

背景：聽性穩態磁場（Steady-State Auditory Evoked Field, SSAEF）是利用連續穩態的聲音刺激大腦聽覺皮質層所誘發出來的反應磁場，此誘發磁場可做為探討大腦聽覺功能區的指標。然而，聽性穩態磁場的反應強度偏低且帶有許多雜訊，為了提高其訊雜比，我們使用經驗模態分解法（Empirical Mode Decomposition, EMD）來處理此訊號，這項技術能可適性的將聽性誘發磁場萃取出來，以得到大腦聽覺皮質層的活化資訊。方法：本研究選擇7名聽力正常之健康受試者為對照組，7名右側耳鳴患者以及5名左側耳鳴患者為對象，分別給予六段聲音刺激。腦磁圖（Magnetoencephalography, MEG）是一種非侵入性的腦部檢查儀器，以全頭式腦磁波探測儀蒐集腦部磁場信號具有高時序解析度。本研究開發以經驗模態分解法（EMD）為基礎的大腦聽覺皮質誘發磁場分析技術，並應用此技術於耳鳴醫學的應用探討。EMD的基底是經由解析信號而得，可經由觸發大腦聽覺皮質層所誘發的反應磁場，加以分析研判之。結果：本研究利用經驗模態分解法，針對耳鳴患者（實驗組）與健康受試者（對照組），給予單耳穩態聲音刺激，紀錄其偶極強度以進行統計，發現兩組間有諸多異同。包括符合「對側優勢」現象的結果（在單耳或雙耳刺激下，對側所反應的偶極強度比同側所反應的偶極強度來的強）。以及單耳刺激的偶極強度比雙耳刺激的偶極強度有較強的反應。結論：此研究開發了利用連續穩態的聲音刺激大腦聽覺皮質層所誘發出來的反應磁場，做為探討大腦聽覺功能區的指標，此項技術將有助於耳鳴等臨床研究的診斷，治療及預後，扮演有療效的評估工具。此研究發現針對耳鳴病患，尤其針對一些耳蝸無病灶的聽力正常之耳鳴患者，對於評估中樞神經系統抑制失調的程度已經具有實用價值。相信該技術可推廣至臨床使用，提供更大量的有效數據。

關鍵字

SSAEF（Steady-State Auditory Evoked Field） ； MEG（Magnetoencephalography） ； EMD （Empirical Mode Decomposition） ； tinnitus ； source modeling（聽性穩態磁場 ； 腦磁圖 ； 經驗模態分解法 ； 耳鳴 ； 波源定位）

並列摘要

BACKGROUND: Steady-state auditory evoked field (SSAEF) is a technique which utilizes magnetoencephalography (MEG) to measure the magneto-physiological responses evoked by repetitive auditory stimuli. SSAEFs have been widely used in clinical application and suggested as a clinical index for diagnosing the function of auditory cortex in human brain. Nevertheless, the SSAEF is susceptible to be affected by task-irrelevant noise and may sometimes deteriorate the correctness in clinical diagnoses. Accordingly, this study aims to develop an empirical mode decomposition (EMD)- based technique to extract SSAEFs so that the signal-to-noise ratio (SNR) of SSAEF can be greatly improved. The efficacy of the proposed method has been applied to study clinical tinnitus patients. METHOD: Experiments were done among clinical tinnitus patients and healthy controls without tinnitus. Six different tones of stimulations were given to every subjects. We utilized EMD-based technique to extract SSAEFs in evaluating and interpretate the results of all subjects. RESULTS: The genesis of tinnitus is still unclear and lacks of a reliably objective procedure for diagnosis in clinics. Recent studies have shown the auditory evoked potential / field (AEP/AEF) in patients with tinnitus are deviant from normal subjects. These evidences imply the pathogenesis of tinnitus might be associated with the central auditory plasticity, i.e., the functional reorganization of the auditory cortex, rather than the dysfunction of peripheral auditory sensory networks. In this study, we apply the concurrent measurements of auditory steady-state fields (SSAEFs) to investigate the profound signal processing of the interhemispheric inhibition and binaural interaction. CONCLUSIONS: With the localization of auditory-related neural sources by applying electric current dipole (ECD), the proposed EMD-based method may be a powerful tool to shed light on studying the development of tinnitus.

並列關鍵字

steady-state auditory evoked fields(SSAEFs) ； empirical mode decomposition (EMD) ； tinnitus ； source modeling