From the Dipartimento di Scienze Biomediche e Neuromotorie (M.P.G., P.A., R.L.), Università di Bologna; IRCCS Istituto delle Scienze Neurologiche di Bologna (M.P.G., C.Z., V.D.S., V.D., P.A., R.L.); UO Neurosonologia e Cefalee (M.P.), Università Campus Bio-Medico, Rome; and UO Neurologia (M.P.), Ospedale M. Bufalini, Cesena, AUSL Romagna, Italy.
Neurology. 2020 Sep 29;95(13):e1800-e1806. doi: 10.1212/WNL.0000000000010619. Epub 2020 Aug 11.
To compare the diagnostic accuracy of ice pack test (IPT) and single-fiber EMG (SF-EMG) in patients with suspected ocular myasthenia (OM) presenting with ptosis.
We studied consecutive patients referred for the clinical suspicion of OM. Patients underwent IPT and stimulated SF-EMG on the orbicularis oculi muscle. Receiver operating characteristic curve analysis was performed to determine the accuracy of IPT, SF-EMG, and their combination.
We included 155 patients, 102 with OM and 53 with other diagnosis (OD). The IPT had a sensitivity of 86% (95% confidence interval [CI] 79-93) and a specificity of 79% (95% CI 68-90). SF-EMG showed a sensitivity of 94% (95% CI 89-98) and a specificity of 79% (95% CI 68-90). Overall, IPT and SF-EMG showed discordant results in 30 cases, 16 OM and 14 OD. The combination of IPT and SF-EMG, using the positivity of at least one test for OM diagnosis, increased the sensitivity to 98% (95% CI 95-100), reducing the specificity to 66% (95% CI 53-78), whereas using the positivity of both tests, we obtained a sensitivity of 82% (95% CI 75-90) and a specificity of 92% (95% CI 85-99). The negativity of both tests had a 94% (95% CI 87-100) negative predictive value. Comparison of the areas under the curve showed no differences in the diagnostic accuracy of IPT, SF-EMG, and their combinations.
IPT and SF-EMG have similar diagnostic accuracy in patients with OM presenting with ptosis. The negativity of both tests strongly suggests another diagnosis.
This study provides Class I evidence that both the IPT and SF-EMG accurately identify patients with OM.
比较冰敷试验（IPT）和单纤维肌电图（SF-EMG）在以眼睑下垂为首发症状的疑似眼肌型重症肌无力（OM）患者中的诊断准确性。
我们连续研究了因临床疑似 OM 而就诊的患者。患者接受了眶匝肌的 IPT 和 SF-EMG 刺激。通过受试者工作特征曲线分析确定了 IPT、SF-EMG 及其组合的准确性。
我们纳入了 155 例患者，其中 102 例为 OM，53 例为其他诊断（OD）。IPT 的敏感性为 86%（95%置信区间[CI] 79-93），特异性为 79%（95% CI 68-90）。SF-EMG 的敏感性为 94%（95% CI 89-98），特异性为 79%（95% CI 68-90）。总体而言，IPT 和 SF-EMG 在 30 例患者中结果不一致，其中 16 例为 OM，14 例为 OD。IPT 和 SF-EMG 联合使用，至少一项检测结果阳性用于 OM 诊断，可将敏感性提高到 98%（95% CI 95-100），特异性降低到 66%（95% CI 53-78），而两项检测均阳性时，敏感性为 82%（95% CI 75-90），特异性为 92%（95% CI 85-99）。两项检测均阴性的阴性预测值为 94%（95% CI 87-100）。曲线下面积的比较显示，IPT、SF-EMG 及其组合的诊断准确性没有差异。
在以眼睑下垂为首发症状的 OM 患者中，IPT 和 SF-EMG 的诊断准确性相似。两项检测均为阴性强烈提示另一种诊断。
这项研究提供了 I 级证据，表明 IPT 和 SF-EMG 均可准确识别 OM 患者。
