眼肌型肌無力症之診斷工具比較

Comparison of Diagnostic Tests for Ocular Myasthenia Gravis

葉建宏(Jiann-Horng Yeh) ； 陸宸玄(Chen-Hsuan Lu) ； 陳威宏(Wei-Hung Chen) ； 邱浩彰(Hou-Chang Chiu)

《輔仁醫學期刊》 5卷4期 (2007/12) Pp. 173-179

摘要

背景與目的：傳統測試對於眼肌型肌無力症(ocular myasthenia gravis, OMG)之診斷率大約都只有5到7成。眼科的冰敷測試診斷率雖可達80%，唯其肌力評估過於粗糙，且未詳細追蹤臨床病程。方法：本研究收集14 例有眼皮下垂或眼肌無力病人，符合症狀波動及早晚差異特性，完成edrophonium、重覆電刺激、單纖維肌電圖、乙醯膽鹼受體抗體及冰敷共5項測試。結果：單纖維肌電圖在11例中8例(73%)不正常。抗體在11例中6例(55%)為陽性。13例中7例(54%) edrophonium測試為陽性，14例中5例(36%)冰敷測試為陽性，重覆電刺激在11例中僅2例(18%)不正常。此5項診斷工具中，僅有1項異常有5例，2項異常6例，3項異常1例，4項異常2例。上下眼皮間距(interpalpebral distance, IPD)在edrophonium測試後平均增加1.9 mm，冰敷測試後平均增加1.3 mm。抗體陰性組中，edrophonium測試IPD值變化愈大，單纖維肌電圖值較低(p值0.020)。抗體陽性組的單纖維肌電圖值顯著高於抗體陰性組（p值0.020）。結論：單纖維肌電圖應是OMG的最敏感診斷工具，依次為抗體，edrophonium測試，冰敷測試，重覆電刺激。

關鍵字

眼皮下垂 ； 冰敷測試 ； 連續電刺激測試 ； 單纖維肌電圖

並列摘要

Background and Purpose: The sensitivities of traditional diagnostic tests for ocular myasthenia gravis (OMG) are around 50%~70%. The ice pack test developed by ophthalmologists was reported to have over 80% diagnostic accuracy for OMG. However, the less-objective evaluation with ptosis and limited description of the clinical course jeopardize the universal acceptance of this test for OMG. Methods: We applied 4 sets of diagnostic tests to 14 OMG patients including the edrophonium test, repetitive nerve stimulation (RNS), single-fiber electromyography (SFEMG), acetylcholine receptor antibody (AchRAb), and ice pack test. Results: Eight of 11 patients (73%) had an abnormal SFEMG test. AchRAbs were positive in 6 of 11 patients (55%). The positive rates were 54%(7 of 13 patients) for the edrophonium test, 36% (5 of 14 patients) for the ice pack test, and 18% (2 of 11 patients) for the RNS test. Only 1 test was abnormal in 5 patients, 2 were abnormal in 6 patients, 3 were abnormal in 1 patient, and 4 were abnormal in 2 patients. The mean increases in the interpalpebral distance (IPD) were 1.9 mm for the edrophonium test and 1.3 mm for the ice pack test. The increases of the IPD in seronegative patients were inversely correlated with the jitters (p=0.020). The jitters were significantly higher in seropositive patients compared to their seronegative counterparts (p=0.020). Conclusions: The diagnostic sensitivity for OMG patients was best with the SFEMG, followed by AchRAb, edrophonium test, ice pack test, and RNS.

並列關鍵字

ptosis ； ice pack test ； repetitive nerve stimulation test ； single-fiber electromyography